At wits' end

R

Reds34

Well-known member
Guys,

I've been dealing with this engine for almost 10 years now. I'm including a link to my previous post with the issues.

https://www.fordbarn.com/forum/showthread.php?t=142110

For a "quick" synopsis, here is what's happening:

'34 BB truck with a 35 or 36 V8 Babbitt bearing engine in stock configuration.

I was driving the truck going up a slight incline and shortly after I downshifted, the truck started running on 4 cylinders. Come to find out, 2 of the valve guides broke ( I'm assuming) causing the issue with how the truck was running.

I brought the engine to a guy that does mostly race engines (has worked on flatheads before) to have it rebuilt. It took a while (about 3 years) to get it back. He polished the crank, installed new rings, new valves and guides and new gaskets. I got a distributor and carburetor rebuilt (the fuel pump was rebuilt a few years prior). The heads are for dome top pistons, but those are the heads that were on the truck for as long as I can remember. The truck idles poorly with low vacuum. The best way to explain it is that the truck sounds like it has a big race cam in it.

I have done the following things chasing down the issue with this truck:
Tried 2 different distributors with no change with either one.
Tried at least 2 different intake manifolds with no change.
Tried at least 2 different carburetors with no change.
Adjusted the timing on the distributor with no change.

I drove the truck down to the rebuilders so he could hear the truck running. He agreed that it sounded like the truck has a big cam (but it doesn't), or the timing is retarded. He was thinking that the cam may have been off a tooth.

The engine is back at the rebuilders so he can check the timing out. He gave me a call today to let me know that he checked the engine out and everything looks good. He double checked the valve timing and said that it's good. He's at a loss as to what the issue is. He was almost positive that he was going to find that the valve timing was a tooth off.

What do you guys think? I'm at my wits' end here.

Thank you.

Red
 
Shoovel,

I haven't checked it recently (in the last year or 2), but I believe that it ranged from 52(ish)psi- 65(ish) psi. I understand this is low, but it has incorrect heads on it currently, and has for as long as I can remember.

Thank you

Red
 
How did he 'double check' the valve timing? Did he use the split overlap method or just visually check the timing marks [which could be off].
What does a vacuum gauge tell you?
 
A long shot, but I have experienced it; a leak inside the inlet manifold to the exhaust cross over. Easy check; plug the two heat riser holes and try.
 
Brian,

I'm under the impression that he took the head off and used a dial indicator and degree wheel. He said it was about 9.5 degrees BTDC that the intake opened.

Do you think there would be a problem with 2 separate intake manifolds?

Thank you

Red
 
OK, valve timing is right, the inlet manifold is aluminum, is it not? Could be cracked internally. What does a vacuum gauge tell you?
 
Richard Crow,

Valve springs are new, although I guess some could be bad.

Brian,

I may do that if we can't find anything else that doesn't add up.

Red
 
Vacuum is low, but so is compression. Whilst vacuum is low, is it steady, or is it fluctuating? steady low vacuum could be symptomatic of a vacuum leak....I always install inlet manifold gasket with a healthy layer of grease as an aid in sealing.
 
Brian,

I wouldn't say it fluctuates, but would call it more of a "flutter". I'm pretty sure that I did a coat of copper spray on the intake gasket when I installed it.

Red
 
I read your earlier posting in it's entirety. I see you WERE using a cracked manifold. You changed it, but the replacement still could be internally cracked. We now begin the process of elimination... Remove the existing intake, check gasket. If damaged at all, replace with new. Irrespective, coat both sealing surfaces of the gasket with grease. Slip a piece of shim [stainless if possible]over the heat riser holes each side. Leave an 'ear' sticking out each side so you can remove later if required. Torque down the manifold. See how that runs.
Read this; https://www.onallcylinders.com/2015...d-a-vacuum-gauge-to-pinpoint-engine-problems/
 
Brian,

That's good info there, thank you. I pulled out another intake from the stash, is there a good way to check them for cracks? It's just a pain because I'm going to have to put the engine back in the truck to try it. I guess I could just run it on the stand it's on now. Hmm.

Red
 
Thing is...if the intake has an internal crack, by plugging the heat risers you'll be eliminating the contamination of the intake charge from the exhaust, with the result it'll run.
A few years back I spent literally months trying to figure out why my 35 wouldn't run right. The longer it ran, the rougher it got. I was convinced it was electrical. Finally, in desperation, I removed the manifold and plugged the heat risers. Viola!! what a beautiful thing!!
Now, I don't know if this is your particular problem, but reading through your previous posts, it appears you've done most things. What I am suggesting is easy to do, especially as your engine is on a stand
 
As the saying goes, spark compression and fuel all at the right time and it runs. I had an issue recently with a Model A. I had put this engine together a number of years ago and suddenly needed it. Got it installed and it ran nice. About 75 miles later it started missing like a bad condenser. We finished the tour we were on but the power was low. Change out condenser and no change. Change spark plugs and it runs like a charm. They did not look fouled but actually looked pretty good so perplexed as to what happened. It's been 600 miles since with no problems.
 
The Stromberg carb is made for the early motors if you use a holly or Ford carb on the early manifold it can leak vacuum through the heat riser into the power valve base . Ted
 
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You need an engine builder who understands the Ford flathead.V-8. From what I read including your previous posting there's a lot some one who understands how to rebuild a flathead would have done differently than the guy who did this work for you.
Ronnieroadster
 
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