installing intake manifold on 3.4

[Kreb]

I've heard that these are somewhat leak-prone. My engine is a fresh rebuild and I'm putting on an Offenhauser manifold. The Fel-Pro gaskets are a design that I've never seen before - they are not a consistent plane, rather they have roughly 3/32 offsets built in to them in several places.

I know that I'll need to use RTV where there are no gaskets, but should I use them on the gaskets or go dry?

Are there any special tricks, cautions or what not that I should know?

Thanks in advance.

-Berk

[geoffinbc]

So this is an iron head? just clean all surfaces with brake cleaner or acetone and use the gaskets dry. With the beads on the end extend is 1/4" up the heads to ensure an overlap between the silicone and gasket

[Guest]

Hwo about some pics of that intake?

[hamondale]

Hwo about some pics of that intake?

Shaun, one just sold on eBay, good pictures of it. See

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=36474&item=7930893350&rd=1

or search on item number 7930893350 if the url does not work.

[hamondale]

And now I see that Kreb is the guy who bought it. Well, duh.

[Kreb]

I have an Edelbrock as well, and closely compared the two. Here's my obervations:

The Offy is a little nicer casting, not exceptionally so. It's 1 1/2" or so shorter. It's also a dual-plane manifold, so the primary's and secondarys follow different passages untill the air gets close to the port. In theory this should enhance lower end characteristics.

The upper maifold piece on the Edelbrock basically is a plenum, where the air is dumped into a big chamber, with six holes in the lower manifold to route air to the ports. This looks to my untrained eye like a recipe for mega turbulence and restriction.

There is one bit of weirdness with the Edelbrock, and that is that the ports on one bank are significantly smaller than the other. The port matching is attrocious. The Offy matches up pretty sweet. I have to think that the Edelbrock detail is a conscious design decision, but it's not clear why.

In summation, to my poorly trained eye the Offy looks like a better piece - especially at lower RPMs. I expect to run my engine to 7000 RPM, so we'll see how it breathes higher up.

[geoffinbc]

The Edelbrock intake has smaller ports for a reason. It was intentional. The idea was to make 1 bank perform better a low RPM and one better at high rpm. This makes the power band more flat I guess. The headers they sell are the same way. Small one side big on the other.

[TurboZ24]

You should also place RTV on the gasket around the coolant passages leaving the head.

[Anonymous]

You should also place RTV on the gasket around the coolant passages leaving the head.

I wouldn't use any gasket sealer if I were you. I know I have a TDC and you have a pushrod, but the same applies. I put gasket sealer on mine, and it LITERALLY took my engine hoist to get it off. IMO the gaskets, with even tighting, will do just fine. But TurboZ34 has a turbo, so it is pressurized, in which case I would use sealer.

I had to take the hoist, and wrap a chain around the underside of my UIM, then hoist it up. And the lift was exerting a lot of upword force before it broke loose.

[SappySE107]

Once again, ignore aaron. I use RTV as well around the coolant passages as a "just in case" factor. Its not that hard to remove later on and unless you tear your engine down often to do work/upgrades/testing, the intake manifolds won't need to come back off again any time soon anyway.

I think aaron used epoxy...not rtv.

[geoffinbc]

LOL yea no shit. All it takes is a big blade screw driver to pull the intake up. I donnt care how much silicone you use. I never use silicone around the coolant passages. Never had a problem but hey whatever floats your boat.

[RacerX11]

His name is TurboZ24, not Z34. And what would having a turbo engine have to do with cooling system pressure?

I always use the RTV around the cooling passages with no adverse affects.

Marty

[hamondale]

Kreb, I'll be interested to hear how you like that manifold when you get it set up. I looked at the Edelbrock too, but it was higher than I wanted to run, would have looked garish making the carb stick out of the hood too far. I have the Offy on a 3.4 crate and it looks to me like the mixture distribution is a little lean on 1 and 2, about right on 3 and 4, and a little rich on 5 and 6. Just by plug color, I have no exhaust data. I do like the way it runs - idles fine at 1100, is smooth in the low - mid range and really pulls 3500 through ~6000. I have not run it past that.