Which thread?

DRG-ler

DRG-ler

Senior Member
Hello guys, a quick question.
The screws that attach the intake manifold to the exhaust manifold are worn out on me. I do not want to order these screws separately in the USA now (coming from Berlin) but buy them here in a screw shop. Can someone quickly tell me what thread and what degree of hardness these screws have?

I think 5/16 "-18. Am I right? I would need a tap to cut the thread.

Thanks Andy
 
From the " Ford Model A Standard hardware 1928-1931" By Mick isbell:
Part# 20718. Intake manifold to exhaust manifold bolt. 5/16"-18 x 3/4". Plain finish.
No mention of hardness. I would personally go with a plain unmarked bolt head.
 
Yes, it has already happened. Fortunately, the exhaust manifold is broken, welded and warped anyway, so I don't have to worry about the broken screw anymore.

But so that they don't tear off again so quickly, I will buy more stable screws this time.


Thanks
 
DRG-ler said:
Yes, it has already happened. Fortunately, the exhaust manifold is broken, welded and warped anyway, so I don't have to worry about the broken screw anymore.

But so that they don't tear off again so quickly, I will buy more stable screws this time.


Thanks
Click to expand...

I would not use a hardened bolt,if it ever snaps it would be more difficult to drill out and tap.
 
To avoid cracking the tabs off of the intake manifold, I urge you to connect both manifolds together using the 5/16 bolts before mounting the manifolds on the car. If the gasket surfaces of each manifold are not true (flat) to each other:
> Have the manifolds machined flat while connected as a set;
> Or install the manifolds with the two 5/16 bolts left out. Measure the gap between the intake & exhaust manifolds and shim it closed. Then install the bolts;
> Or do nothing to close any gap and install the bolts loose so as not to clamp-up the gap. If you tighten the 5/16 bolts with a gap, the tabs on the intake manifold will crack.

The function of the 5/16 bolts is hold the intake manifold against the exhaust manifold so there is a hot spot for efficient engine warmup in cold weather. I have been running with a gap between the manifolds for several years without issues.
 
"use never seize."
Click to expand...
"Never Seez"
Click to expand...
All right, now it clicked. The translator played a trick on me. Yes ... I will definitely use copper paste. This is a means that is common here. I think it will be something like "Never Seez".

To avoid cracking the tabs off of the intake manifold, I urge you to connect both manifolds together using the 5/16 bolts before mounting the manifolds on the car.
Click to expand...


I will do so, thanks for the tip.
I once looked at the old exhaust manifold. The area of ​​the internal outlets for cylinders 2 and 3 was rotated by approximately 1 degree. There was a gap of 1mm. Such a manifold cannot be installed properly! The flap of cylinder 4 had already been broken off and welded again. I will avoid such a problem. Tomorrow I will get my intake manifold back from the metal coater, then I will screw the intake and exhaust manifold together and take them to the engine manufacturer. This should then mill the entire sealing surface flat. I think so prepared should keep things going forever.

Thanks Andy
 
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