Intake gaskets questions.

[Sport/Truck]

Originally Posted by Billla

I kinda hate "arguing" this stuff, and I get a bit cranky - so bear with me.

Millions of people have been building GEN I's for a five decades, and it's become very clear what works - and what doesn't. Completely agree regarding starting with the manufacturer's suggestions - and deviating only when experience proves the need - and also that engineering changes over time. At the same time, consider that most of these intake manifold sets come with the front and rear rubber valley seals...and we KNOW (for sure) that these don't work. Look in any SBC overhaul book and see what's recommended here...it's going to look very familiar.

An intake MUST move around a bit as it's torqued down, this is why I'm opposed to anything that tries to hold the gasket in place. RTV is a flexible seal exactly for that reason.

The FelPro "PermaSeal" beads in the gasket around the water passages need a little help in my experience. This is due to the slight misalignment of angles between the intake and heads - the shop will typically take at least a "clean up" cut of .003 or so from the block and heads, but usually won't ask to cut the manifold unless there's a total of .025 combined from the block and heads. This leaves a little misalignment that the VERY THIN RTV bead ensures doesn't result in a coolant leak into the cam valley.

Finally, street installation is very different than race installation (broken record for me). A small vacuum leak in a racing engine running at high RPM isn't a big deal, whereas in a street engine it results in a poor idle and reduced fuel economy. On a street engine you're going to install the intake *once*, not make "6-10 intake manifold changes". I'll lay a $20 on the bench and bet that if you don't put a goober of RTV in the corners you'll have an intake leak within 10K miles.

I'm usually not a "one way - my way" kind of guy, but if you do a search you'll find two things. 1) the most common street SBC tuning problem is an intake vacuum or coolant leak and 2) the approach I use is the most commonly recommended approach to intake installation.

Thanks for "arguing" your point....
I'm glad you took the time to explain this. I've got everything to get this put on this weekend. I was wondering why Edelbrock wanted so much sealant, just seemed excessive.
Thanks,
s/t