351c 2bbl cam/hydraulic lifters problem/ choice

Sep 26, 2018
5
0
1
43
Buffalo NY
#1
Good afternoon! I have a 70 mach 1 H code with a 2bbl 351C. I have been having a real hard time Trying to get the car tuned, so I replaced the Autolite 2150 with a Holley avenger 500CFM. I am not looking to change the Manifold or go to a 4bbl ( this is a car my 17 y/o and I acquired and we are finishing together and will be his summer daily driver..BTW this car was sitting in a barn since 85') I recently did a compression test and found 1-4 at 110 or so, and then 5-8 around 110-125. to increase the compression I ran a bottle of Restore through the engine and the compression numbers jumped to 125-140. (same test and not wide open throttle on either test). Now I am getting a "firecracker" noise in the carb/manifold. it is not popping out of the carb like a back fire, but more in the manifold. I remove plug wire for the last cylinder at the firewall on the passenger side and the "firecracker" noise goes away, and when re connect the wire, it comes back immediately. I am left with the belief that there is an issue with the lifter rod or lifter for that cylinder. Also a quick note, there is NO play at at all in any lifter on the passenger side, and haven't checked driver side as the noise goes away only when I remove that plug wire. I have New plugs, wires, Cap, rotor, and running a electronic ignition and new coil. until I ran the restore the car never made that noise, but I was told that the lifter has an issue due to the increased compression (110-125) specifically on that cylinder, and the restores components. I am going to replace all Lifters, rocker arms, push rods, pivots, studs, timing chain and water pump (because I have it off and might as well) , so my question is , does this make sense? The engine idles beautifully (except that noise) and if this does make sense, does anyone have any recommendations for a hydraulic lifter/cam set for 2 bbl with a holley avenger 500cfm? I am not trying to go all power, this is a daily local driver car for my son. Im aware the carb is a big carb, but I bought it before fully understanding the CFMs and I do not want to buy another Carb if I don't have too.
Sorry if there isn't enough info or too much!..lol
Thank you!
Brian
 
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rbohm

SN Certified Technician
Apr 12, 2002
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#2
i think before condemning the cam and lifters, lets find out where you compression is going first. your number should be higher than they are, on the order of 150-175. i am betting that you have leaky valves causing the compression loss here.

and a leaky intake valve will backfire through the intake.
 
Sep 26, 2018
5
0
1
43
Buffalo NY
#3
With No history on the engine, I'm not sure where go other than addressing the problem in front of me. I am not very educated on the internals of the engine ( although I have a pretty good knowledge on how to replace and sort of trouble shoot. the numbers on the comp test where
(starting at fire wall on pass side to 1
110 -120 120-120
110 -130 105-120
110 -118 120-140
125 -140 115-120
First set BEFORE the Restore, second set after the restore.

Like I said, there is NO play in the lifters and I know there should be some "movement" on the open ones, which lead me to believe the plungers are staying open.

How do I test for leaky valves? when I had the 2150 carb on, there was no smoke from exhaust. Only time it was "killing mosquitos" was when I was tuning the carb and went too rich.
Thanks
 
Jul 12, 2018
122
12
18
Massachusetts
#4
Hello Brian,
How many miles on your 351C Motor, did you drive it pre-85 with no issues? Do you have a Mechanical Oil pressure Gauge, what’s it reading @ Idle, & at 3,000RPM’s? Over the years there have been around a few that have benefited from using those types of Oil additives & other products, others- not so much. Motor is running Hydraulic, Flat Tappet Lifters-Correct? It’s a 335 Series, Non H.O. Motor with non-adjustable Rockers (Not Stud Mounted?).
The noise you’re hearing sounds like an Intake Valve hanging up, slightly..the Combustion process leaking slightly back into your Intake. Removing the Plug Wire just allows a little Compression to backup in your Intake- versus actual Combustion, hence; the “Pop”.
Cause being either the result of a longtime partial blockage inside the Lifter Cleared, or excess internal clearances of the Lifter, either (or BOTH) being helped by the additive (sounds as there may have been a sticky Lifter issue present prior to storage.
It’s important to do a good leakdown test, and add Oil to the Cylinders to establish whether the Piston Rings are compromised or it’s Valve-train. The Compression Numbers given are low, with a Stock Cam. 150-180PSI is a typical range, Stock. Cylinders should be within 10% of each other. Then, you know if the Valves, or Rings are the issue.
Note:
If all is well below and you desire to freshen up the Valvetrain, it’s always best to get your Heads off to a reputable Shop and so they can Boil them, install new Springs/Retainers/Keepers (Matched to the Cam, Springs Checked for variances/shimmed if needed). Grind your Valves, Seats, Check Guides to Valve clearances, and resurface (if deemed necessary). On the Non-Adjustable Pedestal mount Rocker Motors, adding Screw-in Studs will save you from a lot of headaches, too.
 
Sep 26, 2018
5
0
1
43
Buffalo NY
#6
I purchased the car last year and the car was in a barn since 1985.(But was a driver before putting it away, her and father started working on the body getting rid of the rust. The engine had never been started since it went to bed. life happened and she was not going to restore it. I don't know about the mileage, the odometer said 49k and change. However, she did not buy it until 79, and does not know previous history. I can say the engine is a Cleveland, but cannot say its original ( she believes it is an engine that came out of a 70 Torino). So d say bone stock
It does have a high pressure oil pump, at warm idle the gauge is in the middle, at cold start its pushing the needle to the right (obvious difference in needle position depending on rpm. Currently it has the fixed non adjustable lifters ( was thinking of going to a hydraulic lifter).
I also should clarify, when I completed the compression test, I did NOT have it wide open. I will run the compression test dry and then do a little oil in the cylinder and do another comp test tomm.
I am also going to try and loosen the bolt on the #8 a quarter to half turn and see if that does anything.
Once I have those numbers I will do the Leak down test and will post all the numbers Tomm. Thank you for the pathway!
 
Jul 12, 2018
122
12
18
Massachusetts
#7
Hello, Your Motor has the Fixed Rocker Arms (Pedestal mount) & you want to go with Adjustable Type (Stud mount)- correct? The H.O. Motors had the Stud mounts. When you get to doing the Heads, the Machine Shop will Drill out & Tap the existing Rocker mount Holes, Helicoil them to 3/8-16 (for a near Stock Build, that’s fine) and Mill them down a little Bit.
They’ll also Cut the Castings externally to allow you to run good, positive lock Valve Seals. For now, you should try to establish that ALL your Rocker arms have proper lash settings, are right and not holding Valves open, takes very little to drop Compression largely. Then, you should be able to do a true Compression Check, and leakdown Test. Once you’re sure you’re solid, in the Bottom end of the Motor-Then move forward with your desired Top end Mod’s.
I’d forgotten to mention, the Holley 500 CFM Carb is just fine for that, may have to Jet it- but getting this done is more important first.
If you are going to try & loosen that #8 Cyl.’s Intake Valve Rocker arm, make a thin Shim (.062) with a Hole punched through the center to go underneath the Rocker correctly (Check the link below) & lock the Bolt down tight, (you don’t want that loose Bolt to bend and shear off). If the Rocker’s too tight & hanging the Valve open by not giving enough clearance, that should be adequate.
When you spin the Motor over, Coil disconnected, you want it to sound dead even, you can hear the Starter RPM change when Compression’s leaking..
That’s how you achieve correct Valve lash with the 80’s-90’s 302’s, and the 70’s 351C/400/460’s with that Rocker arm type (Pedestal mount). They Sell different thickness Shims, look at Summit or AM, or just Google ‘Ford 351C Pedestal Mount Rocker arm Shims’. They continued that design through the 90’s on Single Cam V-8’s. Not one of their best ideas, lol.
You should order a set of Shims, they’re inexpensive, you need to go to each Cylinder when it’s at TDC (ready to Fire) Both Valves closed, and Shim all 16 Rockers. One may need none, another-0.080.
You can find the correct information regarding this, here:
https://performanceparts.ford.com/download/instructionsheets/FordInstShtM-6564-All.pdf
Post any info/questions you may have. All happy to try & help, here! Good luck!!
 
Jul 12, 2018
122
12
18
Massachusetts
#8
The bottom page will be most beneficial to you, now on the link. The beginning explains swapping to Stud mounted Rocker Arms, that will help you more, later.
 

WORTH

15 Year Member
Nov 18, 2002
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#9
Just throwing this out there, description of sound is tough over the internet, the firecracker sound as you call it, if it's a crisp bang, it could be the exhaust manifold gasket on that cylinder and it would go away if you pulled that plug wire. Just trying to go back to basics here, I hate it when I miss the little :poo:..
 
Sep 26, 2018
5
0
1
43
Buffalo NY
#10
Thank you for ALL that info! I have ordered the shims and waiting for those to come in.. also ordered new flat top hydraulic tappetts..
I have done a leak down test and a wet compression test (oil in the cylinder and compression test) here are the results
Dry Wet Dry Wet
1 120 125 5 115 120
2 130 130 6 140 145
3 118 135 7 120 180
4 140 140 8 120 120

Leak down

1 40% 5 50%
2 35% 6 40%
3 35% 7 50%
4 35% 8 35%
I do believe I had at TDC as I had a dowel in and then turned until it topped off..
I also kept the compressor at 50-75lbs sonas not to push the cylinder down.. ( not sure if I was successful! Lol)
I have to run a bore scope through to decide what’s next.. it inevitably has to come out and get redone, I am hoping to make the popping sound in the manifold to go away and get 1 more summer out of it so my son can enjoy it before he heads off to college. Then I will pull it and have it all done. The question I have now, can I just re ring number 7, replace lifters and gaskets, and hopefullybthe noise goes away.. can I drive it for a couple thousand miles without doing too much damage? And any thoughts on what I can “budget friendly” do before I tear down in a year or so?
I really appreciate all the info..this is tremendously helpful!
 
Sep 26, 2018
5
0
1
43
Buffalo NY
#11
Thank you for ALL that info! I have ordered the shims and waiting for those to come in.. also ordered new flat top hydraulic tappetts..
I have done a leak down test and a wet compression test (oil in the cylinder and compression test) here are the results
Dry Wet Dry Wet
1 120 125 5 115 120
2 130 130 6 140 145
3 118 135 7 120 180
4 140 140 8 120 120

Leak down

1 40% 5 50%
2 35% 6 40%
3 35% 7 50%
4 35% 8 35%
I do believe I had at TDC as I had a dowel in and then turned until it topped off..
I also kept the compressor at 50-75lbs sonas not to push the cylinder down.. ( not sure if I was successful! Lol)
I have to run a bore scope through to decide what’s next.. it inevitably has to come out and get redone, I am hoping to make the popping sound in the manifold to go away and get 1 more summer out of it so my son can enjoy it before he heads off to college. Then I will pull it and have it all done. The question I have now, can I just re ring number 7, replace lifters and gaskets, and hopefullybthe noise goes away.. can I drive it for a couple thousand miles without doing too much damage? And any thoughts on what I can “budget friendly” do before I tear down in a year or so?
I really appreciate all the info..this is tremendously helpful!

UPDATE———

So I pulled off the valve covers, manifold, and valley pan to find the exhaust port push rod was laying in the middle of the valley! Also found 3 lifters that where seized up.. finally, the number 4 exhaust valve wasn’t seating.
I am in the process of putting it all back together and I believe that will definitely fix the problem for now. I did notice a very littl play in a couple of the cylinders, but I’m not going to pull it and send it off until next fall..
overall the engine is very clean, but goes to show you that you can’t let these things sit in a barn for 30+ years without ever running!
( I bought it from someone who left it in there and was hoping to restore and never could).
Thank you again for all of the info! It’s been quite a job seeing as how I’ve never seen the inside of an engine before! Lol
 

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