Engine Rebuilt 306 Cam Degreeing: 6.5 Degrees Off?

ZephyrEFI said:

I did get myself a pushrod measuring kit. I just figured with the heads milled a bit for compression and all the changes to the valvetrain, I was better off measuring before I bought some.

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08GT500 said:

Hi Zephyr,
Good you had a break, if you needed one, thought this was done, already.
Most get to the point where They need drop the Wrenchbf orva bitb& reset.
Went back through the thread started in early June, to refresh my memory, looks as though the last portion was aimed at Heads going on, as you did the nd were also thinking of the Lower Intake porting. Also, the importance of keeping it as stock looking as possible. Had most of your parts, wasn’t certain about the Cobra’s intake piping, the factory airbox is great in most Mustangs, it’s the ducting from the box, to MAF, and MAF to T.Body that’s the restriction.
As you’re looking between the 280-310HP (RWHP) range, that restriction shouldn’t hurt you much, but I’ve seen 375RWHP made with a Cobra’s airbox & Intake Tuning, i wouldn’t be that concerned about that, you can always use a retrofit of a larger size with the factory look out of another vehicle of the same Genre’ without catching the eye of most, like a piece of later model Ford’s Diesel engine piping to the OE box. (Just an example). All of this isn’t anything to worry about just yet, have to get it running, Driving, seat those rings in, after 200 miles- Full Synthetic Oil after the initial Oil with Lucas oil stabilizer- contains lots of:
1) ZINC, important where everything rides on a film of oil, as it should.and PTFE (Equivalent to wet ice on wet I’ve, but with detergent oil, it helps assembly debris from adhering, getting it into the Filter. changed after its initial run and a few miles on it, going to the same (cut the filter open each time and see what your catching, if it looks good, another round with 10-30 Detergent, Lucas oil Stabilizer
Net benefit of this is a strong performing, fun to drive Cars & well worth a few busted knuckles, money to make it solid, both inherent side effect(s). .
KR-1 GT40 Cam should be a Great Cam for your GT40 Setup, with the larger exhaust valve.
You were having trouble Degreeing the Cam in, then got past that with the 9 position Crank Gear & Billet Cam Gear with the Thrust bushing & then the Cam bushing fitting Has anything changed(?) Thought it was already set in terms of valvetrain Geometry & P/V clearance.. Inwent backwards and reviewed the thread from the beginning to get re-acquainted with the build.
Whatever information You need to finish it, will help you in that capacity, no
Problem. where are you at, if you’re stuck on something? All you need to do is ask- no question about this is irrelevant, needs to be correct
If you want to get this up and running, id focus on acquiring the Pushrods you need, I’m thinking they SHOULD be around you
Pedestal Mount Rockers are a bit more difficult to size a pushrod, no adjustment, you may need to Shim some, others not.
it’ll handle your 125lb/closed-340lb open Spring loads just fine. Pedestals will work fine, not the ideal choice, but they’ll work for you just fine. You’d bought a pushrod checker just for some closure, Block Casting anomalies are rare in this area, only slight- 0.010-0.060 pedestal height differences, unless you had an earlier flat Tappet Block, now changed to
a Roller Block. You’re running the “Doggie bones” for lifter roller/Cam alignment, not the Hi-Po Rockers?
Other explanations may be:
1) Running a Cam with a smaller Base circle. GT40”KR” Hyd. Roller Cam-right?
2) Work done to the Heads, possibly new seats installed, may have lessened the installed height. Typically, creates a taller Valve height, not always
4) Head gaskets thicker to offset flycut cthickness, they’re based on how much the piston is “in the hole” at TDC.
5) Valve Stem ends surface ground, affecting overall height.
6) Valve lash Caps installed on Valve stem’s.

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He Zephyr, I apologize- for the Syntax errors, my Device was typing characters that were sometimes ok, others using a different App Store keyboard, and other times totally out of sequence. Damn..Apologies. Hope this dissertation helps, or opens your eves to something you missed.
Again, not getting a laugh out of anything, just trying to help how i can. I DO suggest you get a SHOP Manual for your Mustang. Lots of accurate info and diagrams, Mechanical, Electrical/Electronic, Vacuum, emissions, more..
BTW “Keepers” and “Locks” are the same thing,
Shop setup your Beehive springs? For 90$ in parts, you can run adequate Springs from TrickFlow, including Springs, Retainers, locks, Seals.
“You’re running the same physical sized Lifters, even when checking with 1 or 2 solid lifter(s).(!ALWAYS Check your at BDC if rolling over one lifter, all the rest- no Pushrods!)
Reset, my Cell seems to be OK. it seems OK.
- Onto your issue. Play-Doh is what most people use for P/V checking. Cheap & it’ll harden. Examining from beginning to end, there’s a component that is not the same as the rest if you’re that far off with Rocker height. I’ve not seen a single pedestal exceed 0.080, and that was once (1) time, of many rebuilt, prepped for stock or other, assembled & installed.
(Pic’s below).
As every motor is different, Heads have been cut(?), Gasket thickness(?), all components in that Cylinder the same(?) New Valve seats, Guides, retainers & keepers, pushrod ballpark centerline is 6.250- should be relatively close. What size did you run that are far too short now?
Ref: Piston to Valve: Minimum 0.080 with Intake & 0.125 Exhaust.
As “Close” is not good enough, of course. Should check with checker Springs & a Pushrod checker. Valve Stem Sweep starts from the actual motor side, outwards to max lift, and back toward the Bl. Near center sweep, smaller the better, but centered & within 0.070 is ok for maximum.
You’ve done P/V, all is ok? I imagine it should be, just checking..
I do the same setting Ford’s Geometry as in the video, initially. Don’t use it every time. Then I mark the top of the Valve Stem with a narrow, permanent marker line between the two using a straightedge across the outside of the Rocker, facing front of Block, #1 (Intake) Cylinder solid roller Rockers, light checker Springs,, line on Rocker should be parallel with the valvecover mating surface @
50% of Full Valve lift.
Pics below of yet another coil bound GT-40 Head, this one ate the Motors Cam Bearings, too.
Repaired, good for pictures below.
1) Find and mark the approx center of the Rockers ‘Trunnion’, Rocker laying on its side (pivot point where the 5/16-18 Bolt goes through the Rocker, and the approx. center of its Roller tip Trunnion to centerline of Roller tip pineach, and aim for the valve cover mating surface at 50% of total Cam lift, the line drawn should be level with that surface. the same angle with line drawn to cover mating surface
The Valves sit at the identical height on GT40, GT40P Heads. It’s the installed height on the Springs that differ.
I’ll explain the Spring/Retainer/Keeper(Locks)/Valve Stem workings.If you’re already familiar with this, well- it’s typing practice for me, lol! You’d also once said too much information is good, lol!
Retainers have an angle on the inside. In the Installed orientation, it’s tapered..smaller down bottom, larger up top. .
The locks are 2 Pc’s. Viewing the outside of the locks- held up & viewing with two fingers against a Valve Stem- you’ll note they also have an external angle present. Inside the keepers is a precisely cut, raised groove that fits into the 360 degree receiver groove ground into the Valve Stem, holding it in the correct spot.
This raised groove in the keeper fits perfectly into the grooves ground into the Valve Stems, the Retainers inner angle & the keepers outer angle forces the (2) keeper’s raised groove(s) solidly into the Valve Stem’s groove by the terrific force the Valve Springs exert on the retainer, combined with the angles on the Keeper(s), and the Retainer.
The original GT40/P Heads had a rotator Ass’y on the Exhaust Valve(s), but Installed Stem heights are identical. The Stem’s groove was simply ground higher up, running lighter Springs on the Exhaust side to accomodate the extra room the Rotator required.
When you drop in different retainers to gain Coilbind clearance, there’s one retainer that sits lower, the Exhaust Valves, higher for Intakes. This is to ensure equal Valve Spring pressures on the Cam. Adding Springs, Retainers, and keepers can gain you around 1/16”+ clearance to run a more aggressive Cam without pulling a Head. concern.
You had larger Exhaust Valves installed. “Equal height”
Believe that Equates to the grooves ground into the Valves as now being identical, so Retainers and Locks between Intake & Exhaust are now the same, I.e. Intakes or Exhaust retainers & keepers can be bought as “standard”, may be run on either Valve.
Every Cam has specific Springs that should be run with it, each new spring should be tested for PSI at installed height, and at full lift, tested for. Sent back if highly inconsistent, shims added underneath Springs if off slightly, an important step.
Quickly, take a straightedge & verify that the height of all the Pedestals on the bare head surfaces is consistent. Then check the tops of the Valve Stems with a straightedge, if you had it setup to be equal Valve length, the straightedge should reflect that, no gaps or Valves, nor spring retainers higher than the other.

-No, if there’s something that’s 0.300
too long, Rocker won’t come down far enough to be bolted solid to the Head, i’m Not aware of a Casting that was ever that far off. Typical issues:
1) potentially a Valve installed that’s longer than the others. A mixup.Did.the Shop griund Valve Stem tips? Possible you accidentally had a valve hit a piston and bend?
2) A Valve seat that was installed incorrectly.
3) Rocker is different in some dimension, Bolt not the same length as other’s?
4) Doubtful, an abnormally ground cam lobe, or -for overall pushrod shortness, Cam is ground on a smaller base circle. Which Cylinder/Valve is this?Still GT40 KR-1 Cam?
5) A component that was grabbed in error, Pushrod, Lifter, lash cap not used on one cylinder.
6) A Rocker Trunnion is upside down, or the Trunnions radial Block that affixes the Rocker to the u-channel height dimension incorrect. I know you’ve tried other Rockers, just being extra cautious.;
You may be able something by doing the tests below. Sure there’s a logical
Explanation. This is a different block, is it possibly a flat Tappet block converted to a Roller Block? That would explain Pushrods being short.
Pic verifying Pedestal mounts are reasonably level with each other using a straightedge, you’ll spot something unusual right off the bat. Pre-Geometry Checks.


Lining up Rocker centers and marking once you have light springs, solid lifter, this works well & gets Geometry very close in a SBF.

Line connecting the two center lines, 50% of full lift, checker Springs, solid lifters, pushrod checker will allow you to check Geometry and get it right without concern of P/V clearance. Verify 100% the Piston of the Valve you check first ( #1 Intake) is at BDC, only connect ONE pushrod- the Checker pushrod (!Check AGAIN to again, ensure this Cylinder’s Piston is at BDC!). Rotate the Cam Gear, checker should easily be able to check with the very light springs; w/Solid lifter.
Put your Mag base indicator on the Retainer, and verify max Valve lift as correct on Card, stock ratio (you’re running 1.6-correct?) I/2 of that lift-the line should be parallel with your Rocker line as marked (adjust your checker until it is). Then, clean the stem, apply non permanent/dry erase marker, see how centered you are, and how the sweep is- should be centered, and sweep total
no wider than 0.080, preferably.



.
Run a straightedge across all your Valve Stems, Rockers removed. Should be very close. Ask if any questions arise.
I channel with hardened Rocker risers w/radiuses, Shims in proper spots, if needed. Too much Shim may hang a valve open, too little will sound like a Solid, Flat Tappet Cam.lol.
Need help setting this up, just ask..
Hop this Book helps, lol
Good luck!
-John

ZephyrEFI said:

The pushrods I mocked up that were way too short were the original HO motor ones. I ran them with the P heads installed on my old engine with no problems. I used original rockers then.
I have not done piston to valve yet. It was when I went to do it that I found that the original pushrods were CRAZY short. Yes, the heads have been milled. Twice, even. There was a valve job done before I got the heads in my hands.
The way I talked about the valves was confusing, I see above. Stock P heads have different lengths between the groove on the valves and the tops between intake and exhaust. The valves on mine are not like that. When the intake valves were swapped to enlarged ones, the exhaust valves were also swapped, and the gap distance is now the same for both. The rotators are gone.
It's the same cam, and we're dealing with cylinder 1. I asked Mr. Curtis if his cams have a smaller base circle, and he says they do, but not very much. Not like if it was a retrofit cam.
Rockers are 1.6 ratio.

Yesterday I got a little time, so I thought i would turn the engine over with what the Half Lift method told me. Look at this pic. I can't even get the rocker level with the retainer with the bolt at its farthest extent. It's barely biting in this pic.


After trying to run the bolt down the 5 turns, it's not really .300". It's more like .130". Not as crazy, but still a LOT. Here's what things looked like.

I tried my best to get the pushrod length at a point where it was at zero lash with the bolt turned 5 turns and the solid lifter, but I'm not all that confident it's right.

Here's the pattern it turned.


I know I've got more to do, but that's all I had time for yesterday.

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Hi, Theres issues, not severe There’s always a logical explanation.
1) One one hand, your Pushrods previously used on these Heads before they were sent to the shop are now too short, milling the Heads would cause them to be on the longer side.Were they 6.5”?
2) The other, the Rockers are now unable to bolt to the Pedestals because the clearance between Rockers & Pedestals are too great.
The best way to approach this is by measuring the height of the Pedestals, the thickness of the fulcrum which the rockers sit atop, installed height of the Valves.overall length of the Rocker retaining Allen Head Bolts, how much Thread & how much unthreaded shoulder the Bolts have
-One thing is pretty much set in stone for Pedestal mount valvetrains..
1) The installed Valve Height needs to fall within certain tight parameters, Valves selected too long or in seats installed too deep sit too high, preventing you from locking down Pedestal mount Rockers at the factory height.
Pushrods have nothing to do with this portion. Adding Shims are intended only to make up for small inconsistencies, 0.010-0.030, .060 being the high end. 0.125 is too much, the u channels will barely be holding the radiused fulcrum under the Rocker, keeping it aligned.
0.130 is excessive, but makes more sense-than 0.300, nonetheless. Rotating a 16 pitch thread yields around 1/16” movement (up/down) per a 360 degree turn. Let’s forget about Pushrods, their lengths for a minute. Also forget about the Heads being flycut..twice..
The only way to change the rocker geometry on pedestal mount rockers is with shims. And, by definition, you can only raise the rocker - not drop it, unless you machine the pedestal.
On that note, is it just illusion, or are there fresh Milling marks on the top of the Pedestal as viewed In this picture?

May just be cleaned with a wire wheel, or is possible when the shop had them, they machined the Pedestals down in prep for screw in Studs?
Let’s.check that theory:

1” Tall Pedestal Height, measured from where shown, GT40P’s. They’re also similar to the Valvecover surface height. With the alignment u groove plate & Rocker fulcrum (About 1-5/8” measured to the lowest portion of, or base of the Radus in the Rocker cradle). Measured in the same fashion, is it similar to yours?
Did you run a straightedge across all the fulcrums to check for variance?
If the Shop installed Valves with a ridiculously tall stem height, unlikely-yet possible, it may provide some explanation.
Was this an Automotive machine shop- aware you were running Pedestal mounts & not Screw in Studs the same that setup the Valves, or did they not ask?
I’ll look for your response.
-John

Hi,
So these Heads, after modification, have run successfully on since they were modified?

Or, this is the first time the Heads, since modified have been on a Block? Makes no sense to me that the distance from the Pedestals with the alignment tracks installed, the radiused risers/supports under the Rockers & the Rockers, themselves are at such a bizarre angle sitting on the Valve Stems. Not to mention you would have to Shim the Rockers up a further 1/8”+ to work.
Pushrods requiring to be longer will necessitate the Pedestal height to be higher yet, the Rocker will need to sit higher up. Ultimate Rocker Geometry is when the Rocker swings equal distance back & forth across the Stud from the Cams Base circle,((zero Valve lift) to full Valve lift.
- see what your measurements reveal.

Hi, Well- if no other Machining was done, there shouldn’t be any reason it shouldn’t still work. Springs are stiffer. Installed height is 2.80. Set it up with Shims and see how much it takes to get it where it was, using the original parts (all of them, u channels, alignment/riser fulcrum, Rockers.bolts). Snap a pic of it using a checker pushrod at the longer size requiredçIf it’s different, ask the Shop if they did anything else to explain how the pedestal(s) are so far off.
Flycutting the Heads would require shorter Pushrods, but you’re also running a reduced Base circle cam, which- depending on how reduced it is, would necessitate linger Pushrods. I’d assemble 1 that way + see where the dust settles.
Lifter types are the same as before-correct?
Is every one off, or only #1 Cyl Intake, or is it just the worst of all of them?
-John

ZephyrEFI said:

Alright, pics time.

Pedestals are about 1"


Pedestals are nice and consistent.


Intake valves are consistent. Exhaust valves are all a touch shorter.


Car as she sits for fun.


Just for the heck of it, I put a .040" shim in there (w/no other washers or anything else) and rolled a pattern. It was dead center on the valve. Still too long (rolled too far), but a definite improvement.

Also, just so I can get something straight:
The LENGTH (distance the roller tip rolls) of your sweep is caused by the pushrod length. You're testing whether your pushrod is the right length.

The POSITION on the valve tip of the sweep, whether centered or not, is caused by the position of the rocker itself on its pedestal. You're testing whether it's shimmed correctly or not.
Is that right?

So that means the .040" shim is about right, and I pretty much just need to tweak the pushrod?

I tried a piston to valve test also. What i got was .230" inch for the intake. Does that sound reasonable? These pistons do have some seriously deep valve reliefs....

I'll keep fiddling....

Also, started a new thread, FYI.

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Hi, GREAT!.. measurements! Looks like you’ll be OK, keep all your parts clean & covered, sediment gets inside Motors very fast.
Poor Pony needs a good gallop!!
.You need to separate Pushrods and Rockers as entirely separate entities when setting a valvetrain up.
Pedestal mount setups cannot run shorter nor taller Valve Stems, pretty much set in stone with Pedestal mounts, installed Valve height & consistency of Pedestal height needs to be checked. Your’s seem good!
Pushrods being short positions the Rocker tip too far to the inside; or on the intake manifold side of the valve stem. Contrawise, a pushrod that is too long, positions the Rocker tip too far in the opposite direction (towards the outside of the Valve Stem).
Rocker ratio’s, only value in distance altered is in the pushrod to Rocker Bolt area. Trunnions to Rocker tip is identical. (Rounded Off, here...) Formula: Lobe lift X R.Ratio= Actual Valve lift. Only have Valve lift? Valve lift/ Ratio= Lobe lift.
Example: Ford E303 Cam,.0498 Lift. Single pattern..498/1.6=.311Lobe Lift. Add 1.7 Rat.Rockers, .311x1.7= .529 Lift.
PISTON TO VALVE CLEARANCE:
Your 0.230. Intake P/V is very good.
1) Spec’s are >0.080 P/V on the Intake side, >0.125 P/V on the Exhaust side.
2) I prefer 0.100+Intake, 0.150+Exhaust.
3) Not running Aluminum Rods-Correct?
4) Did you do this with an old gasket, same type & thickness you’re going to run?
5) Head Bolts torqued around the Cylinder you checked?

I’d texted about striking a centerline on the Rocker, line should be near parallel with the valvecover surface @ 50% lift. Also need to verify retaining bolt to Rocker slot has adequate clearance, valve closed & @ Full Lift. Lateral Rocker to Valve contact needs to be centered. That’s where the Shim thickness and pedestal height questions were going. Take a quick look@ lateral.
You want an equal amount of rocker to stud (Pedestal Mount, you insert an Allen wrench into the bolt) angle at 0 lift, and full lift; inverted. I.E..(-)15 Degree angle when Rockers sitting backwards at 0 lift, (+)15 degree angle when Rockers tilted forward at full lift.(“15 Degrees” just used for example).
Strong Springs need be verified as adequate running 5/16” Rocker Bolts.
Thread engagement%, Tensile & Shear strength need be considered, 8740 Moly Bolts would be good for your App., But I don’t see a big issue, providing Bolt rotates a minimum of (6-1/2) 360 Deg.turns, Will give you a 0.364 bite, handle your Springs OK with no issues..565/.555 Lift-Correct?You’ll get more bolt rotations than that. Next build, I’ve a feeling you’ll consider Screw in Studs, lol.
Many run helicoils in Castings, Aluminum, provides superior strength over existing threads,
Stud girdles are another popular type of insurance as they clamp the tall type adjuster Studs to distribute heavy Valve spring loads across many studs VS. one Stud, alone.3.5”-4” tall valve covers are required for clearance when running girdles.
ROCKERS/PUSHRODS
Each Rocker tip starts from the intake manifold side of the stem at zero lift & travels towards the outward edge of the Valve until full lift is reached, then rolls back inwards as Valve lift decreases & back to the original spot at zero lift again.
I saw a time lapse video of a Chevy 396 running- Cover modified, a valvetrain specific years back, Roller motor- had. 9” Pushrods, no guideplates. 1,000-5,000RPM. Rocker had a reflective dot on it, watching it afterwards dimmed down it appeared to travel in a diametric fashion, pushrod deflection, Spring resignation- very interesting. I’ll look for it and post it on SN. Point being, there’s a lot going on in a valvetrain, good example to how vital setup is.Spring oscillation, deflection, etc. Great for any on SN to view if it helps anyone new with the learning process. Setting valvetrain s up correctly is an Art, so many factors involved.
TIP- Picture the Valve Stem in 3 equal sections..Set the Rocker tip so it lands on the first 1/3 (towards the rear of the Valve Stem (with the checker to locate it & verify) inner 1/3 (Towards the Intake) area of the Valve Stem. Spin the Crank two full turns, you’ll be surprised how close to if not dead on you will be when viewing the witness mark (or.”sweep”)..
Reduction of this path width decreases friction, reducing heat, freeing up H.P..For a Pedestal Mount, that won’t be sitting at 8 Grand, a path of 0.080 (MAX) or less is fine
Ok,Ok, I’ll explain it anyway..lol.
Using a pushrod checker, using very small moves-rolling the Motor over 720 Degrees at the Crank, slowly adjusting the checker, over and over- there will be a spot where the Rockers tip to Valve Stem travel will be the smallest, may not be a dead center sweep, very close, it’s O.K..And that IS best spot.
Sometimes you can nail it, harder with your setup, and large differences in pushrod sizes available. It’s normally done with multi-point Adjustable Rockers, with fine pushrod adjusters, specific rail types.
Many high end, high performance Rockers have an adjuster/locknut on the back of the Rocker to provide very fine pushrod adjustments, to ascertain “perfect” pushrod length. They make these for Pedestal mount applications to make it easier to get adjustments, almost like having a pushrod checker’s ability to change length- without installing a different pushrod, but very costly.
Cheaper to run 3/8” Stud w/stud mount Rockers & adjusters, Including Machining.
Ok, anything I’d missed, or you’re uncertain of- please ask. Happy to do what I can.
-John

Hi ephyr,
Yes, to your first question, they affect each other, but initial setup requires looking at one at a time, 1st.
Don’t sell yourself short, you’re doing everything to ensure a proper outcome, and well! Didnt desire to confuse, apologies. I’ll be happy to fill in any blanks if desired re:valve-trains as needed. or afterwards,.Just explaining valve-train Intricacies,, lots occurring simultaneously.
Your question is, indeed an important one.
With your P/V test, that number is great And you’re doing a dynamite job! This can be very confusing, exacting, tedious work.There are two areas to cover with P/V testing. Your Pistons are generously relieved.
I don’t envision any P/V issues, here. Cam is not that radical, but an excellent choice for the combination. P/V Test Considerations:
1) Cam/Valve lift clearance @ TDC, full lift
2) Cam/Valve Duration clearance when both are in motion..
Many pay dearly skipping step #2, for whatever reason. As important as #1.You should perform it, Here’s (2) methods of doing this.
A) With checker springs installed @ zero lash, solid lifters, Pushrods, Rocker is on Intake #1 Cyl., gasket installed (Use new one you now need to replace*, LMR leave that out? Tighten bolts around of the target cylinder-same as you did.
B) Correct the math if planning on using a different Gasket thickness than used during test, or add to clearance if using no Gasket at all. I run an old, clean gasket to protect siurfaces.
C) Install everything with both valves @ TDC on compression stroke. Dial indicator on Exhaust valve retainer @ zero. No Pushrods installed, degree wheel mounted & set at TDC, roll back ten degrees BTDC on the exhaust stroke.
D) Move the Valve by hand, no clay, until the Valve lightly contacts the piston. Mark readings down from the indicator of how far the Valve moved, repeating every couple of degrees.
E) Repeat the test on the Intake side, comparing with your Cam Card, this will give you accurate information as to whether Duration may cause an P/V issue, moving the valve(s) by Hand causes no damage, providing you’re gentle with your efforts.
Second method:
A) You may also set motor at TDC, Compression stroke, with Pushrods installed and solid rockers set at zero lash. Piece of 1/8’ clay on Piston Head. Dial indicator on Valve Stem you’re working with- set at TDC. Degree wheel is preferable, but may without, very slowly, carefully.
B) As you slowly rotate motor a couple of degrees, you can verify your clearance is OK by pushing the valves down, verifying P./V clearance remains clear of physical interference as result of piston motion and valve Duration, using multiple points of where Piston approaches Valve as it nears TDC., Valve moves to get to its seat
C) Use extra care IF clay can be felt, when pushing Valve down, clearance less than 1/8”. At this point. Move to slower, more frequent steps of rotation.**
Now you’ve cleared everything, Piston to Valve@ TDC,.Both int & Exh.Duration P/V clearances. This will give you very accurate measurements for both lift and duration.
-Now perform a clay test. across 2 full Crank revolutions with fresh clay on Piston.
Both Valves setup fully, keep checker Springs on, Pushrods, Rockers, invaluable information, know you’re P/V is safe & correctly tested.
Will give insight if you choose future upgrades., i.e. Rocker Ratio to 1.7, etc.
*NOTE: If you tightened the new Head gasket at all in the last Claytest, the Head Gasket shouldn’t be re-used. Cylinder Crush/ring around is made to be done once, not worth the chance.
Have you considered running Cylinder Head Studs? Superior to Bolts, ARP’s around 100$ for Studs, Washers, Nuts, Lube.
**INOTE If you feel that you’re too close, you likely are. Stop & understand you can make the scenario work by Advancing /Retarding Cam timing, you have 2 Degree increments.
>0.125 Exhaust clearance, > 0.080 Intake are minimum specifications P/V.
This will be the last step before the simplest portion, final checks & Assembly. Pick up some Blue (Non-Permanent) Loctite, High temp RTV, Anti-seize, others you’ll need. 1 Week of focused, part time work & you’ll be firing this motor off.
Fire away at further questions, I’m curious, about the Rocker Bolts once adjusted after zero lash? You can see Hyd.lifter plunger, needs to travel.°020-0.060 after pushrod/Rocker lifter plunger contact, (1/2-3/4) turn further, bolt should then tighten. Shim if beyond 3/4 turn before tightening fully (?)
Talk soon!
-John

Hi Zephyr,
I’ll try to make this relatively simple, hate having to give info.regarding your build requiring more work than thought. On the other hand, you need to know so you don’t overlook a serious issue.. No two Motors are the same. Look at your Cam Card. All those numbers are very important, using it & a degree wheel to its intended extent helps pinpoint potential issues like this.
Intake, Compression, Combustion, Exhaust. The cycles we all know occur in a 4 cycle engine. Simplified, when significantly Increasing performance with a Cam, three main parameters are modified by Cam manufacturers. Valve lift, at what point a valve opens & how long it remains open.
The earlier the Intake Valve opens (Events) & the longer it stays open (Duration), the more fuel/air will be pulled into the cylinder equalling more Horsepower. And the possibility of a Piston/Valve collision.
Exhaust valves also help with gains, they open further, earlier & for longer periods to allow combustion gases to evacuate more effectively, it’s valve also has to be clear before the Piston can strike it.
The Piston has no idea as it’s heading on the upstroke to TDC that an Intake or Exhaust Valve may be already open or still open & in it’s path & may collide with it, destroying the valve and Piston, maybe more.
You need to ensure that. It’s not about lift, it’s also about duration.
Cam Mfg’s push Cam parameters for more HT/Torque & sometimes a cam grind is simply beyond a certain motor’s setup, adjusting cam timing retard or advance may allow such a Cam to work, that otherwise won’t installed Heads up (Dot to Dot).
Retarding Cam timing for more top end, advance for low end both Valve(s) or other reasons may also cause issues. So, to ensure there is adequate clearance throughout, checking as I’d previously mentioned, and running one full cycle of both I & E valves is very important.
You’re fortunate with a motor with generous Piston reliefs, as i’d said, I don’t believe you’ll have interference issues with that cam’s spec’s, it’s stout, but setup with good parts. Nonetheless- it should always be checked, not worth risking such an investment.
The video’s posted on YouTube are generally insufficient in this capacity, even by Cam MFG’s. They don’t get into these highly important details, you really need to get the info from a good, reliable source. Folks on Stangnet all want people to do what’s necessary, the first time & Enjoy your Pony.
Good luck!
Any questions- don’t hesitate.
-John

ZephyrEFI said:

Oh, I've always intended to check the exhaust valve too. I just haven't gotten to it yet and I only have the one solid lifter and adjustable pushrod.

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Hi, Should have your Pushrods soon, use one of your old lifters & fill it with washers so the top gretaining clip just snaps back into place. Running the final clay test, be sure to use solid lifters on both the Intake & Exhaust Valves. Not a race, take your time, save the racing for after you break-in the Piston rings !ol ‘m

ZephyrEFI said:

So, what you're getting at is that I need to clay test with both valves operating at once. Roger that.

Also, just curious about something. Have you personally achieved proper rocker arm geometry using pedestal mount roller rockers on Ford heads? I seem to be getting a fair amount of feedback telling me it can't be done. I haven't had time to fiddle with it lately so I haven't had the chance to try again yet.

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Hi,
Yes, I have done quite a few, actually- over the years, all successfully. TrickFlow stage 2 Cam on a 93’ 302 being the most aggressive cam. I Strongly suggest to all going past stock, max.an E-303 Cam’s parameters & needs to run Studs, you’re Heads have enlarged Valves- lots of work done to them, milled twice, etc.
I was extremely surprised the shop that worked with you didn’t suggest making the leap to 3/8” ARP Studs. As initially said, the one thing id have done differently with that build was run Studs.
Combining the near nonexistent adjustment Pedestal mounts have, & running a reduced base circle cam to boot, 5/16” Pedestal mounts not such a great idea.
It’ll be more difficult to set this up, but providing your at stock GT40 Valve Stem Height is accurate, it’s far from not possible. If your Valve stems are any longer- it’s not worth the effort with Pedestals.
Have you established a decent sweep pattern & preload at this point?Have you been able to get your Bolts in a Cylinder’s Rockers without Geometry being far off?
What’s occurring?
-John