Zane

I have a 78 corvette with a stock 350 in it and I just got my rebuilt heads on. I like to know what the best ways to install my stock intake manifold that I just got powder coated :D . All the Chevy 350's I owned always had leaks on the rear seal. Also I just had a friend tell me after it was too late that I might need sealant on my Head Gaskets? :confused: If this is true I need to pull my heads back off and redo them. This C3 forum rocks! Any ideas would be great. :seeya

Chris@VetteFinders

No sealant on head gaskets.

Some guys who have been doing this a long time (not that I qualify) use black weatherstrip sealant around the coolant passages on the intake manifold and RTV on the fuel ports. Then throw away the rubber seals at the front and the back, and load it up with RTV there instead.

Pedro'74

Here's what I used on the intake:

-Edelbrock's Gasgasinch (sp?) around the intake ports, to glue the gasket in the right place.

-Thin beads of Ultra-Black RTV around the water ports.

-Instead of the front and rear seals, thick (1/4") beads of Ultra-Black RTV on the "China Walls", "climbing" the head surfaces and connecting to the beads around the water ports.

-Pedro



[Modified by Pedro'74, 8:37 PM 1/11/2002]

Paul 75 L82

Welcome to the forum. you'll be installing a cam soon if you hang around this forum very long. Anyway, welcome aboard.

Chris@VetteFinders

Very good point. If you are pulling the manifold, you may as well put in a new cam :D

Vetterodder

Yup, I've seen a bunch of leaky sb intakes and, like you mentioned, most of the problems have been at the rear. In addition to the good advice already posted, make sure that the sealing surfaces are TOTALLY clean! RTV doesn't want to stick to an oily surface. A common problem area is where the head meets the block at the rear rail so be sure to use a clean rag and "floss" that area. I also recommend letting the RTV set up over night before starting the engine because until it sets up engine oil can disolve it. I've had good luck speeding up the process by using a hair drier to heat the manifold and block at the rails.

Zane

Hay all this advice is great! What should I use to remove the oil with? I have paint thinner. Will that work? Also still need to know if I should of used sealant on the head gasket?:flag

Geoff H

Dont worry about pulling heads again, i have used a copper coat spray b4 on head gaskets 99.9% nothing but clean mating surfaces will do the job.
Throw away stupid cardboard type front and rear vally gaskets and i use hi temp rtv, good blobs in the four corners of the valley/head mating area, and generous strips across front and rear of block top of valley. i try to do these two surfaces in one hit rather than building up layers of rtv. u can always wipe excess of front of motor later for appearances sake.
Thin smear around water jackets on side manifold gaskets, as i think has already been mentioned above.

Good luck

ddecart

What kind of head gaskets did you use? That will help answer the question about sealing them. If you used any fel-pro or other gasket that isn't just a stamped steel shim, you should be fine.

As for the intakemanifold. Take those rubber gaskets they give you for the front and rear and throw them away. Use black RTV in a nice thick bead front and rear & make sure it meets the gaskets on the sides at the corners.

How to sealdepends again on what kind of gasket you're using. if it's a Mr gasket orfel pro "Print-o-seal" type, then you're pretty much all set. The directions should tell you. Probably has you adding a THIN bead of RTV around the water ports & maybe theintakeports on one side of the gasket. Done this and never had problems.

If you're using just a paper gasket, the best luck I've had is by applying a thin coat of #2 gasket maker sealant (gooey sticky black stuff) to both sides of the gasket before installing them. It seals the paper stuff up REAL nice. :yesnod: Makes it a major PITA to take it off later, butit seals good.

Whatever you do, don't use a pressed metal type intake manifold gasket. :nono:

Good luck!

74-Roadster

I know several people have told you to toss the rubber valley seals, but if you have the holes in the valley for the rubber plugs to insert into like I did, then you can use them. I put a small bead of ultra black on the top side of the rubber gasket, a glob in each of the corners and smeared a little around the water ports on both sides of the head to intake gasket and mine doesn't leak.

Ensuring clean surfaces is by far the most important. The guys on the forum suggested lacquer thinner. I used Q-Tips and lacquer thinner to clean out each of the holes in the front and rear valley as well as the head bolt holes. I must have used 100 Q-Tips. I kept cleaning until a Q-Tips came out of the holes clean. Then I used a tap with lacquer thinner on it to chase the holes one more time and back to the Q-Tips . . . the holes were dirty again. Then, as recommended by one of the forum members, I used teflon tape on new ARP intake bolts. No leaks anywhere . . . too bad it's not a new 383! :D

The two problems I had were:

1. I used a new torque wrench and I didn't understand that it'd just click and then re-engage, so I over-torqued one of my bolt holes and even yielded some threads in the hole but I let it go for now (just temporary 'til the car gets pulled apart) and it's holding fine and no leaks, the bolt measures about 20 ft lbs of torque.

2. When I chased the bolt holes on the heads, one of the holes lined up with a push rod and I nicked the push rod. :mad She's not a screamer, so that hasn't presented a problem either.

Good Luck and welcome aboard!!!