TR2/3/3A Anyone running an aftermarket header on their TR3?

[karls59tr]

I'm having an issue with a vacuum leak at the intake manifold and I came across this statement: "Aftermarket headers have flanges that are thinner than the factory cast iron intake manifold leaving the thicker intake manifold loose causing a vacuum leak. The fix is to shim the clamping bridges so that both the intake manifold and the aftermarket header present a perfectly level surface for the clamping bridges" Has anyone here done this and have any further advice on doing this? Karl

 

[Hamish Racing]

Karl
Some of the after market exhaust manifold plates are thin.
But the typical effect is that the exhaust is loose to the head as the football ( your type of football) shaped clamps tighten to the thicker inlet manifold first.
The typical fixes are to put a blob of weld on the exhaust manifold to raise the needed clamp area.
And or
Grind off the inlet side of the clamp enough to clamp both inlet and exhaust.
Some tack weld a small nut to the exhaust side on the clamp.
The first picture is an early set up I had with Su carbs and a 1970’s after market exhaust with thin plate to the head. With built up welds.
The other picture is my Weber set up with Phoenix big bore exhaust manifold and you can see they are close enough to equal thickness.

 

[karls59tr]

Karl
Some of the after market exhaust manifold plates are thin.
But the typical effect is that the exhaust is loose to the head as the football ( your type of football) shaped clamps tighten to the thicker inlet manifold first.
The typical fixes are to put a blob of weld on the exhaust manifold to raise the needed clamp area.
And or
Grind off the inlet side of the clamp enough to clamp both inlet and exhaust.
Some tack weld a small nut to the exhaust side on the clamp.
The first picture is an early set up I had with Su carbs and a 1970’s after market exhaust with thin plate to the head. With built up welds.
The other picture is my Weber set up with Phoenix big bore exhaust manifold and you can see they are close enough to equal thickness.
View attachment 109880View attachment 109881

Thanks Hamish. I read this post after I sent my other reply on the other post.Now I see what needs to be done. I'm not even sure I used lock washers between the nut and the football clamps. I will look into that.

 

[Brian_Jones]

I'm having an issue with a vacuum leak at the intake manifold and I came across this statement: "Aftermarket headers have flanges that are thinner than the factory cast iron intake manifold leaving the thicker intake manifold loose causing a vacuum leak. The fix is to shim the clamping bridges so that both the intake manifold and the aftermarket header present a perfectly level surface for the clamping bridges" Has anyone here done this and have any further advice on doing this? Karl

Karl - I have just dealt with this just this week. After failing with stock gaskets twice, I noticed the 1/16" (2mm) discrepancy in the clamping plates. My thickness difference is a little over 2mm, and I took my vernier calipers to go metal shopping. I found angle iron of the neccessary thickness, which I cut down to small L-shaped tabs that hook on top of the exhaust manifold and hang down where the clamp would land.

I used uprated gaskets from Racestorations (I'm in the UK), but I imagine there will be something similar in your market. Mine were 10x the cost of regular gaskets with more crush to accommodate any variation in the plane of the exhaust manifold.

I also decided to use a copper RTV designed for inlet and outlet manifolds. I found I had some ooze into the inlet bores and I used a scope and made a couple of 'tools' from coat hanger wire, hammered to a chisel point, to hook the cured globs out of the manifold.

The manifolds are now sealed. It has made sorting the SUs so much more straight forward.