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JOHNSHENOUDA 10-11-2012 06:34 AM

rtv on manifold
 
I installed an aluminum intake manifold on a sbc 350 last night. I did not have any of the black RTV so I used the regular high temp on the ends as well as on the bolts. I also used some Teflon tape on the bolts. Am I ok with the regular high temp. I know the black stuff is supposedly formulated for the intake manifolds. I really dont see what the difference could possibly be.

cdminter59 10-11-2012 08:24 AM

rtv on manifold
 
The info on the package says Permatex Ultra Black Maximum Oil Resistance RTV Silicone Gasket Maker. The High Temp info does not have oil resistance on the package anywhere. Permatex High-Temp RTV Silicone Gasket maker will probably eventually leak if used around oil.

Mr. P-Body 10-11-2012 03:09 PM

Please explain why you put sealer on the intake BOLTS? I've heard of this, but never have I seen it in actual practice. We often get engines in "loaded up" with bubba-cone (vernacular for RTV). Never quite understood it.

Agreed, if you must use RTV, "Ultra-Black" is the best stuff for engines. Drops in the corners where gaskets and parts "meet" is all we use. Occasionally, we'll use it on the "ends" of the intakes for small blocks. Usually, we use the
peel and stick" gasket that comes with the Felpro Performance stuff, and a drop of RTV in the corners. No leaks.

For sealing bolt threads, RTV is too thick. It will alter your torque readings. We use Permatex "Aviation". Super 300 and "Indian Head" are similar. You brush on a TINY bit in the threads. You still get accurate torque readings AND no leaks.

When it comes to sealants, if a little is enough, a lot is NOT better. Where two machined surfaces come together, a paper gasket "dry" is far and away the most effective method of sealing.

We've rebuilt several over the years where the bearings or oil pump were "taken out" by excessive RTV in the system.

FWIW

Jim


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