Cylinder Head questions

[richard]

Before you finally assemble the manifolds make sure they fit ok.
You have a aftermarket exhaust manifold and I have seen some that were sitting against the intake manifold so that it looked it fits ok but then after a while start to leak.
Also when I look at your gasket the indent were the exhaust sits is much better then were the intake manifold sits.
That also can be cause by a different hight between intake and exhaust were the nut and washer (also a wrong one as said) so that there is not enough clamping force and start to leak after a while.

[Pierre]

Before you finally assemble the manifolds make sure they fit ok.
You have a aftermarket exhaust manifold and I have seen some that were sitting against the intake manifold so that it looked it fits ok but then after a while start to leak.
Also when I look at your gasket the indent were the exhaust sits is much better then were the intake manifold sits.
That also can be cause by a different hight between intake and exhaust were the nut and washer (also a wrong one as said) so that there is not enough clamping force and start to leak after a while.

Hi Richard,
Thank you very much for your advice!
It seems to fit right, but how can I be sure that it fits perfectly?

[C.Costine]

I must have missed something here despite reading through three times, but how is the coolant getting into the intake? and where is it coming out of it's proper containment in order to get to the intake? those large washers look way to thin to me, at least they are only 1/4 the thickness of the ones on my 1600. Like Richard said if that after market header flange is not really close in thickness to the flange of the intake one or the other may not have adequate clamping force. The short stud could actually be the correct length and got wound in too far and penetrated the water jacket. It happens with certain studs and bolts on certain motors.

[Linda]

Ah, Richard to the rescue! Hi Richard!

Linda

[david premo]

Pierre,
The correct stud for the intake manifold to exhaust manifold with the thick washer is 36MM long measured installed from head to tip. There are 3 different studs used on the U-20 manifold to head mounting. Also I think your washers look a little thin where they bridge the manifolds, but I could be wrong.
Dave

[jhayden]

For those who may not be familiar with the U20 and are trying to make sense of how coolant can find its way into the intake:

Note the holes (coolant passages) below intakes nr. 1 and nr. 4 on both SU (top) and Solex (bottom) manifolds. A less than perfect seal against the head can easily result in the symptoms Pierre describes, where the high vacuum draws water into the intake.

Hope this helps.

Jon Hayden

[C.Costine]

pierre, in oder to get it clean enough to seal you need 2 inch surface conditioning discs. they will enable you to get around and in close to the studs.

[Gregs672000]

Assuming that the manifolds match up, I don't see any problems with the washers... they appear about at least 1/8" thick, are not distorted, are the right size, and there's plenty of bite for the nut and washer. Yes, there's no lock washer, but loctite or adding a locker would take care of that. What's the problem? I've seen far worse, so somebody please tell me specifically why these would not work and work well... I have not seen the originals seal up any better, and I sure haven't used those super thick ones on my engine in 34 years (there's no room with my header and heat shielding). And seriously Dave, I love ya man, but having the guy worry about changing out a stud that's a couple mm shorter than it may have come with when there's absolutely no thread issues??? Let's not freak the poor guy out!

[Linda]

I would not change the studs unless they were too short to seal. Why risk one breaking, then you have to drill, maybe tap.... no thanks.I had to tap a rocker tower stud once that pulled out and that was way too stressful for an amateur....
But I would want to check the intake and header for flatness because if the head won’t seal if it is not essentially flat, why would the exhaust or intake seal if not flat? Maybe pressures are different, but basically flat seals and warped does not.Right?
So a machine shop can do a quick check and if warped , shave it a bit and then, all fixed. Or get new parts if warped.
Thoughts?
Linda

[david premo]

Alright Richard nailed it as you can see in the picture of the manifold gasket. The exhaust portion is being compressed much more than the intake portion of the gasket. If the intake and exhaust Components have different heights where the washer clamps both components at the same place and more Clamping force is Applied to one component than the other a leak is sure to occur. Also you can remove the stud and replace it with the correct length. Yes on rare occasions this does not work out but I think I would try to make this right as now would be the time to do it.
Dave

[Linda]

You have a aftermarket exhaust manifold and I have seen some that were sitting against the intake manifold so that it looked it fits ok but then after a while start to leak.

I had to slightly file my intake where it just barely touched the header, to ensure no interference with being flat to the block.

Richard also might have the correct exhaust washers, which are thicker. Datsunparts has them at 2.08ea.

Linda

[Pierre]

Ok that's a lot of info . Much more I can handle
I checked an the exhaust an intake seem to fit .
There is no gap.
So I decided to put everything together again. Might be a mistake or not we will see...
You guys have a lot more experience than I do.
I might have to learn it the hard way
Taking everything apart an putting it back together was not as hard as I thought, but you learn a lot about the build of the car.
I guess I will drive for a couple of 100 km or miles and we will see what's going on.
The only thing what happened is that I loosened the exhaust manifold at the flex pipe and there seem to be a leak .
Mine is welded to the exhaust manifold and all in all the exhaust from manifold to the end is not in a very good shape and I will replace it anyway . Sooner or later.
I saw that Richard sells a very nice one on his website , just not sure if it is sold with or without a manifold.
But thx everyone for the support and very helpful tips !!!
Great community !!

[Linda]

Well, report back so we know what happened after you put it together!
Linda

[Gregs672000]

Looking forward to hearing how it's running, and congrats on your work and learning! There's lot of opinions here but all are only concerned with helping you be successful, no egos involved!

[Pierre]

Well, report back so we know what happened after you put it together!
Linda

Thx Linda, I will definitely do it !!