I have a 66 Valiant with a 225 slant-6 engine. I decided to convert it to a 2bbl setup. I found a 2bbl intake and exhaust manifold setup in a junkyard that was in a later model pickup.
I installed the setup with a 2 bbl Holley carb. Everything went ok and I had no problem modifying the linkages and carb mounting area. However I have a vacuum leak at every intake port and I cannot find a way to correct it. I started out with Felpro gaskets and silicone copper sealant…. No luck. Then I tried a Remflex gasket torque it down to the recommended 5 foot pounds…still no luck.
I have checked the manifolds and engine mounting surface for warpage with a straightedge and they seem almost perfect.
I car has only 32,000 original miles on it. Any ideas ??
Thanks

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rick smith

Don't know if this helps but:

How did you verify that it is leaking at every intake port?

There are people on here with a lot more experience with these engines than me(I've only put 3 together) but when I put the manifolds on, I bolted the intake/exhaust together snugly but still movable.

Then I bolted the intake /exhaust assembly to the head. Torqued it about half way then finished tightening the intake/exhaust together. Then finished torquing the assembly to the head.

If you tighten the intake/exhaust together before you install the assembly, there is a chance that the two are not aligned and the exhaust could be holding the intake off the head just enough to not seal.

I've used Felpro on all of mine and had no problems but I torque them to 10 lbs. Haven't used Remflex so I don't know what their recommendations are but 5 lbs. seems a little light but by all means, follow their recommendations.

Never used the silicone copper sealer for this type of duty but have read pros and cons on it. You're n your own there. Dennis

Is this an iron intake or Aluminum?

CJ

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Part of Tyrde-Browne Racing

I used a Remflex gasket. I followed the same procedure as Valiant 1966. Torqued to 10 ft pounds.

Before I did all of this, I used brake cleaner and a sharp gasket scraper to make sure the head surface was perfectly clean. I replaced all the studs with new ones (nasty threads will prevent an accurate torque), and used new brass nuts (both from Dorman - part#'s elsewhere on this site). I put blue Locktite on the studs before screwing them into the head. I used anti-seize on the threads where I screwed the nuts on.

I used a flat block with 400 grit sandpaper to hand sand the intake and exhaust manifold surfaces as flat as possible (they were pitted). I didn't use any gasket sealer or any kind of goop on the Remflex.

No leaks. Everything is perfectly sealed...

Thanks for the info.

I believe my problem is the studs. The threads are shot.
Do you know where I can get replacements and how hard is it to replace them?

One other question.. Where do I hook up a vacuum gauge to check pressures? At the carb distributor hose or pvc hose or somewhere at the manifold itself?

Thanks again.

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rick smith

You can order the studs from O'Reilly Auto Parts (or other parts stores).

Dorman Part Numbers
Studs: 675-093
Brass Nuts: 680-001 or 849-001