Engine Cylinder balance results

rockyracoon

10 Year Member
Nov 23, 2005
874
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margate NJ
So the test keeps coming up 50, cyl 5 issue. I can hear the injector pulsing, the spark plug has been swapped out, compression is good in that cylinder. I guess the only thing left is the ignition wire. Does this sound like a reasonable assumption ? Or could there be another scenario ? Mis adjusted rocker arm not letting intake or exhaust open far enough or worn cam lobe ? Motor does have a miss of sorts as evidenced by engine shaking at idle which becomes less pronounced as RPMs increase.
 
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The ignition wire is the most likely culprit. If it was a misadjusted rocker than the compression test would come up much slower on that cylinder than the others if at all.

Kurt
 
^X2!
Hi Rocky,
Agree with that as well, keeping it simple. Quick check, Swap out plug wires between #5 & #6 and see if the issue migrates to #6 or remains. Then you’ll know.
If you were running a loose Rocker due to it’s fastener, bent pushrod, worn lifter or lobe you’d quite likely be hearing it slapping away before it affected your idle.
Good luck!
-John
 
I think I found the issue. A while back I replace one of the injector plugs with one from a newer sn 95 4.6 setup . They are a little different but do still work on our injectors. Anyway when I repinned the connector I must have forgotten to put the keeper back in and one of the contacts slid upwards. The newer connectors are nice since you only have to press the sides to remove, no screwdriver needed.
 
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I think I found the issue. A while back I replace one of the injector plugs with one from a newer sn 95 4.6 setup . They are a little different but do still work on our injectors. Anyway when I repinned the connector I must have forgotten to put the keeper back in and one of the contacts slid upwards. The newer connectors are nice since you only have to press the sides to remove, no screwdriver needed.

Glad you found the problem. You can get the correct pigtail at the parts store.

Kurt
 
So my car now passes the balance test but it is still running rough/ shaking idle. Checked timing, firing order, fuel pressure.
Have a slight valve tap but not major.timing is set at 14 with spout out, fuel psi was 37 with vac line on and 41 unhooked Car has pro comp heads, a gt-40 upper and lower, a tfs stage one cam. 5 speed and 4.10 gears Vacuum at idle is 12-13 took car out for a short ride and it was stalling when idling had less power than when it was stock and did backfire in intake once when under load. No koeo codes or koer codes except for cylinder head thermactor passage delete. Cats are still receiving air from smog pump. Dont know what else to check. Have cleaned maf element and am receiving new o2 sensors by saturday. I still think I have a vacuum leak in lower intake but have not been able to verify it. After researching posts with other tfs stage 1 cammed cars it appears around 13 inches of vacuum is normal. I wish I had a wideband a/f gauge to see if im near 14.7-1 I do have a narrowband sitting in my garage but I dont think will tell me much. Maybe I will install it just for giggles.
 
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New build kurt. However before the rebuild but after the HCI swap it was actually doing the same thing or close to it. Keep in mind my compression is right around 150 psi in all cylinders cold. The rings seated immediately pretty much just from idling. Still running the stock pistons and original crank. Block was honed by machine shop. Crank was polished. Crank miced out fine.Piston to cylinder clearance was right on the edge but acceptable. Even got away without file to fit rings. So what I did today to check for vacuum leak at lower intake was remove pcv hose from upper and plug the end, then I inserted another hose with pcv in the grommet and plugged it, so in essence stopped any vacuum going to the crankcase and sealed off the crankcase. I then checked for any vacuum at the hose coming off the oil fill neck and there was slight pressure while engine was running.
So I think that ruled out a lower intake vacuum leak. But why the backfire in the intake if im not lean ? Maybe I was mistaken and it was a backfire from the exhaust but I doubt it. Although is my fuel psi at 37 with the line hooked up a little high ? I dont think my issue is sensor related because the motor shakes right from the start so in both open loop and closed loop. Couple that with good compression and what does it leave ? TFI possibly ?
The car revs up fine but is pig slow, wouldnt even chirp second with 410s.
Cam timing possibly ?
 
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Ok, so it is possible that it might have been a problem before the engine install, but the ECU in SNs is notoriously bad for being agreeable with modifications, and you have done some substantial mods to the car. The PIP sensor in the distributor is a known problem. So a new distributor could go a long way, or it could be money flushed, who knows. However, generally after doing an engine mod like that, this ECU needs a tune done anyway. So that's something you are either going to do now, or later either way. I would recommend taking the car to a reputable tuner to get a good measurement on what's going wrong, and then optimize the performance. It's killing two birds with one stone.

Kurt
 
Hi,
Rocky, new build? Didn’t know it was new.
Geez, to me vacuum seems low for that Cam. Stage 1 TF, correct?I’d expect 15 on the low side..see more like 17 or 18 in that healthy a motor.
Just FYI..Rings should be seated under varying loads while driving, realize things look good with compression- but they really need some good varying load lugging to seat for the long run.
How many miles (or hours) on this new build?
Did you run this Cam straight up, was it degrees in?
Did you retorque your lower intake? Just make a torque wrench pass over them & check- engine cold.
Has any tuning been performed?
Valve lash settings, I’d start there. You mentioned hearing valve-train noise. May have one Intake valve a tad tight or less likely sticky.
Best!
John
 
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John

Maybe like an hour or two run time.
degreed straight up
no tuning.
the dizzy is a reman unit from advance
Have retorqued the lower intake bolts twice at 18 ft lbs
The duration on the cam is much more than the stocker so would you not expect to see lower vacuum readings, plus their is some substantial overlap.
I do wish I had a wideband to verify A/F
If it was a valve lash issue wouldnt that cause lower compression numbers, at least if one was set too tight ?
After doing a google search for tfs stage one cam vacuum readings, most guys are stating between 12-14" at idle.
I understand the need for a tune but should the car actually be slower than before everything that was upgraded ?
If my issue was ignition related like the pip or TFI wouldnt that affect the condition of the spark plug electrodes in regards to carbon build up or fouled with gasoline ?
 
Hey Rocky,
You could take 2 near identical 95’ GT’s and modify the same as you have, one may run well with no Tune, other may not. As Kurt mentioned, it’ll need a Tune to perform best, but any possible issues first need be identified and repaired prior to Tuning.
Over time I‘ve found associating engine Vacuum numbers with a solid RPM gives more consistent results, I use 1,000RPM’s.
-For modified motors untuned, or with issues it’s more realistic an RPM a finicky motor will tend to agree to run stable at for certain testing, has helped.
Since I do top ends on all Mfg’s frequently, I’ve logged the numbers of most TF parts.
As you’re not new to all this, I’m just trying to establish exactly what the build is, there’s things you’ll already know, I’m just suggesting where I’d start, what direction I’d go...
-Which ProComp head’s are you running?
-And, what’s your Vacuum at 1,000RPM’s?
I’d suggested that possibility of preload being tight on a Cyl, as you mentioned hearing a Tap, and an intake backfire under load. That would be where I’d start, pull the covers and run through the cylinders & move on once you confirm as correct.
Check #1 Piston and Balancer’s lineup @ TDC to rule out any timing issue. Sounds as if it’s OK, but easy to confirm.
Keep lash more on the conservative side, as your chasing this, at 025-.040.(1/2-2/3 turn past zero lash & lock). Norm.is pushrod .020-.060 into the lifer after zero lash.
You won’t always see a slightly tight lash setting affect numbers in a cold compression test, but you’ll feel it engine hot.
No Wideband yet? Have faith in reading your spark plug electrodes for now, they won’t lie.
Motor was running OK before the rebuild, no
Systemic issues, just tired?
I’m uncertain if you’re relying on the stock Oil Pressure Gauge, or aftermarket..It’s absolutely in your best interest & a very well spent 25-30$ if you buy a Mech Gauge to run on a fresh motor..
Still running conventional motor oil for the Ring & bearing break in? Running a High Volume or High Pressure oil Pump of type, both HV/HP...or OE? ARP Pump Drive?
Oil pressure, Cold?..Operating Temp?

Where does the car idle, does it hunt at all?
Is the IACV, TPS set, you adjustEd idle up manually?
I’d be looking at your spark output via spark tester on each cylinder, see how far a gap you can get a spark to jump & see if the others can repeat the same, try it SPOUT in & out, sometimes it has an impact if the PIP’s loose, or on its way out. Usually Injectors are affected first, not always..
Is your Dizzy stabbed correct for proper Injector timing?
When your fresh Engine Mechanical basics are all correct, your new parts functional & become exhausted, keep in mind to view it as you would if troubleshooting any other 86’-95’ Mustang GT, vacuum lines, grounds, Alternator output, aftermarket ignition component avoidance, and all the other basics.
Also consider how the R&R of the engine may wreak havoc on the wiring, connections disturbed and sometimes less than optimal when reterminated, etc.
Build questions, etc.. to get on the same page?
1) Drain your Tank & full up with fresh fuel? If not, how long has the fuel your running been in your tank?
**2) Are you running the Cam’s springs, retainers...did the Shop tear down the heads & check guides, seats, etc, pressure test?
3) Exactly what’s been added to the build, car wasn’t bone stock previously-correct? 3B)Already running a rechipped EEC before the build (you mentioned a deleted Smog item).(?) What injectors, MAF, TB, other Mod’s are you running? Headers? Shorty’s, LT’s?
4) You did verify fuel pressure, also perform a Volume test? You‘ll then know it can keep up during heavy engine demand.
5) Most Smog still intact, are you running an aftermarket exhaust, Cat’s? Mentioned new 02 sensors enroute, improvement?
6) Check all the new Injector connectors you added, add AD grease to improve connections, tested all for correct Voltage at all injectors & presence of pulse.
7) Have you tried Clocking the MAF a bit to see if you can get an improvement in running conditions? Unplug it & the motor should really fall on its face..
8) Been checking the EEC for trouble codes right along?
9) I’d expect the Car to run decent with the parts you’ve mentioned, uncertain what your ProComp head’s have for Chambers, and your resultant C.Ratio. .040 thick Gaskets?
Hopefully, this will get you moving and the questions answered will help to narrow things down.
Best of luck Rocky!
Enjoy the weekend!!
Best! -John
** ProComp head’s, in my own experience, are head’s that should be carefully checked out before using. I’m not saying other’s are exempt from this, the days are over where you can bolt up 95% of new head’s & have certainty they’ll work as desired.
 
John here is the specs on my cylinder heads. evidently they are not pro comp but the vendors own castings.

These heads feature closed style 64cc combustion chambers and 190cc intake runners. In addition to the nearly 40lb weight savings these heads offer over factory cast iron heads, they will yield about a 55hp gain over stock E7TE castings. In unported form these heads will support 500+ horsepower on pump gas. If you are looking for a race grade head that is comparable to Edelbrock, Dart, Trick Flow and AFR at a fraction of the price look no farther then these.These heads are machined and assembled by us, they work great on Carburetor and fuel injection applications!! The features of these are as follows:

Heads are pressure cast from premium quality 2024 aluminum alloy. Unlike many inexpensive aftermarket heads that are sand cast these are cast in steel permanent type molds. This offers a stronger more durable cylinder head with consistent thickness throughout. These castings incorporate .400 thick deck surfaces for maximum head gasket longevity. If you are running nitrous or a supercharger and have had problems with blown head gaskets and stock heads the thicker surfaces will virtually eliminate this problem.
After machining the heads have magneese bronze valve guides installed along with stellite valve seats. This is the best available combination for street use with unleaded gas. If you are racing the stellite valve seats offer much longer seat life then most competitors ductile iron valve seats
Both the intake and the exhaust incorporate three angle valve seats to maximize both low and medium lift flow.
The heads come fully assembled with 2.02 1 piece stainless steel intake valves and 1.60 exhaust valves. These valves Qual cast severe duty 1 piece stainless steel polished valves and undercut stems. These heads require NO extra knotching or relieving for piston clearencing with stock or af


So im going to go back and check the rocker arm geometry just to make sure I measured for the hardened push rods correctly.the ones I installed are 6.650" considerably longer than the stocker pushrods however the tfs stage 1 cam does have a a reduced base circle.

I have ran both koeo and koer with no codes that would be relevant to my issue.
Yes still relying on the stock oil pressure gauge, using conventional oil for breakin, electrodes are all good in visual inspection, car does hunt at idle, I will try some of the other things you suggested after I recheck the push rod geometry. the car was in fact bone stock before, heads were brand new so did not have the machinist look at them, injectors are stock 19 pounders, all sensors are stock, stock headers and exhaust. no chip in ecu.

one other thing of note is the fact that the exhaust exiting the tailpipes is super hot to the point that it would burn your hand if you kept it there for more than 5 or 10 seconds, thats another reason why I think it is running lean. the engine miss is present at all rpms and is present in open loop as well as closed loop although the engine does tend to run even worse (if thats possible) once it gets up to operating temperature.

I just checked one of the the pushrods coloring in the stem with a dry erase marker and it appears the mark on the valve stem is about 3/4 of the way towards the intake manifold (not perfectly in the middle of the stem) but the width of the sweep looks good right around fifty thousandth. That was not the method I originally used to measure for the proper length as my initial check for correct length was measured strictly by geometry however it appears this is how most guys are doing it. It is my understanding that being exactly in the middle of the stem is not as important as the width of the sweep.

Edit, evidently I will have to re check the pushrod length as I forgot to swap out the springs for the lighter ones I used for the initial mock up.
much easier at this point than installing a solid lifter.
 
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John here is the specs on my cylinder heads. evidently they are not pro comp but the vendors own castings.

These heads feature closed style 64cc combustion chambers and 190cc intake runners. In addition to the nearly 40lb weight savings these heads offer over factory cast iron heads, they will yield about a 55hp gain over stock E7TE castings. In unported form these heads will support 500+ horsepower on pump gas. If you are looking for a race grade head that is comparable to Edelbrock, Dart, Trick Flow and AFR at a fraction of the price look no farther then these.These heads are machined and assembled by us, they work great on Carburetor and fuel injection applications!! The features of these are as follows:

Heads are pressure cast from premium quality 2024 aluminum alloy. Unlike many inexpensive aftermarket heads that are sand cast these are cast in steel permanent type molds. This offers a stronger more durable cylinder head with consistent thickness throughout. These castings incorporate .400 thick deck surfaces for maximum head gasket longevity. If you are running nitrous or a supercharger and have had problems with blown head gaskets and stock heads the thicker surfaces will virtually eliminate this problem.
After machining the heads have magneese bronze valve guides installed along with stellite valve seats. This is the best available combination for street use with unleaded gas. If you are racing the stellite valve seats offer much longer seat life then most competitors ductile iron valve seats
Both the intake and the exhaust incorporate three angle valve seats to maximize both low and medium lift flow.
The heads come fully assembled with 2.02 1 piece stainless steel intake valves and 1.60 exhaust valves. These valves Qual cast severe duty 1 piece stainless steel polished valves and undercut stems. These heads require NO extra knotching or relieving for piston clearencing with stock or af


So im going to go back and check the rocker arm geometry just to make sure I measured for the hardened push rods correctly.the ones I installed are 6.650" considerably longer than the stocker pushrods however the tfs stage 1 cam does have a a reduced base circle.

I have ran both koeo and koer with no codes that would be relevant to my issue.
Yes still relying on the stock oil pressure gauge, using conventional oil for breakin, electrodes are all good in visual inspection, car does hunt at idle, I will try some of the other things you suggested after I recheck the push rod geometry. the car was in fact bone stock before, heads were brand new so havel the machinist look at them, injectors are stock 19 pounders, all sensors are stock, stock headers and exhaust. no ch

one other thing of note is the fact that the exhaust exiting the tailpipes is super hot to the point that it would burn your hand if you kept it there for more than 5 or 10 seconds, thats another reason why I think it is running lean. the engine miss is present at all rpms and is present in open loop as well as closed loop although the engine does tend to run even worse (if thats possible) once it gets up to operating temperature.

I just checked one of the the pushrods coloring in the stem with a dry erase marker and it appears the mark on the valve stem is about 3/4 of the way towards the intake manifold (not perfectly in the middle of the stem) but the width of the sweep looks good right around fifty thousandth. That was not the method I originally used to measure for the proper length as my initial check for correct length was measured strictly by geometry however it appears this is how most guys are doing it. It is my understanding that being exactly in the middle of the stem is not as important as the width of the sweep.
Hi Rocky,
These heads I’m not familiar width, but is a good idea to have them torn down before install, even moreso new. Pushrods too short valve sweep runs inboard, too long, valve sweep runs outboard. Yours sound short. Optimally,
Every new Cam should be degreed in and P/V & pushrod length should all be done together, collectively.
An adjustable pushrod, 2 solid roller lifters, light checker springs, Degree wheel kit and you’re good to go.
Since you’re all together, you can check your pushrod length in a different fashion. Be happy to run through it with you. First..
Rockers Pedestal Mount? Unless misread, I didn’t see screw-in studs listed, and pushrods seem short for stud Rockers- which vaguely are in the 7.5” range for these motors, Pedestal’s about 6.7”..
The rockers sweep path should be equally distributed across either side of the valve stem centerline to reduce any side loading wear of the guide(s), maintaining as narrow a roller tip path as possible, maximum of 0.080 or less. I shoot for 0.060 max.
If one needs to be traded for the benefit of the other, run a wider path, but keep it centered equally. Roller tip also centered laterally (left-right) ?
Excess heat means running lean, advanced timing, clogged Cat(s), obstructed exhaust, etc.
The flow increase efforts to gain performance by the H/C/I swap are being bottlenecked by some of the stock components, like the exhaust, air intake, etc.
Once the valve train’s buttoned up, it’ll be easier to move forward.
Any questions, please post!
Best!
John
P.S.: You lost a few Compression tenths with these head’s, no biggie.
Note- Saw the edit you’d made, just now. Going to run an adjustable pushrod with a checker spring installed from the top?
 
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Thanks for the replies fellas.
John to answer your question im actually running stud mount with guide plates. And I did end up removing the lower so swapping in some modified lifters will be no issue.
I severely hate swapping out springs for lighter checking springs with the heads on the car for fear a keeper will launch or fall down an oil return. Could I get by with using just the modified lifters for a pushrod length check, I would assume as long as the lifters cant collapse the measurement would be ok.
 
Thanks for the replies fellas.
John to answer your question im actually running stud mount with guide plates. And I did end up removing the lower so swapping in some modified lifters will be no issue.
I severely hate swapping out springs for lighter checking springs with the heads on the car for fear a keeper will launch or fall down an oil return. Could I get by with using just the modified lifters for a pushrod length check, I would assume as long as the lifters cant collapse the measurement would be ok.
Hi Rocky,
Glad to hear you’re running stud mount rockers with guide plates. Pulling the springs from above how I was taught is easy, I’ll explain in detail, you will not lose a keeper. First, I’ll explain why.
MOST pushrods checker tools sold are designed for use with light checker springs.
They may collapse under full spring loads.
With the Cam’s springs installed you’ll need a pushrod checker tool capable of full open-ValveSpring loads (330lbs for that Cam).
I made the ones I use, but they did and believe they do still sell them.
Which type of pushrod checker do you own?
If you have the first type listed, and don’t plan on buying another, there’s two things you’ll want to pickup.
First is one of those narrow telescopic magnets about the diameter of an antenna they sell at Car parts store counters for around 5$.
The other is a small tube of white lithium grease.
Have these already?
Long reach needle nose pliers
Compression tester kit
Small air compressor.
Valve spring compressor tool type...
Do you have an overhead latch spring compressor? (Pic #1).
Or own a rocker stud mount spring compressor? (Pic #2

Pic #1 Overhead latch.
D0AC679A-0EAE-4F0B-8785-D43E1A77501E.jpeg
Pic #2 Stud Mount.
14B221A7-1300-4E30-8CDB-16F2054503A3.jpeg
I’ll look for your response.
Best!
-John