350 Freshin Up

[wayne4252004]

I've got a 350 in my truck and I've got a few oil leaks. I was going to pull apart the top end and replace all the gaskets and thought about going over the heads as well to freshen them up. I'd like to port and polish them. Anyone have some good information on doing this job. Such as steps, tools, what to look for etc.
Greatly Appreciated.
Wayne

[Marv D]

How many miles are on the engine. Was it just assembeled with poor gaskets or is it tires is whay it's leaking? Point is, just a gasket job and freshen the heads will typically show any weak link in the rest of the motor. It's a lot of work to tear it apart. Not freshening the bottom end also is a lot of wasted effort unless it's a 15000-20000 mile motor.

Doing a backyard port job is a good way to screw up a decent set of heads. If you don't know what your doing and don't have a flow bench it can be a lot of wasted effort, or worse the demise of a OK set of heads. Without a compression change and cam change it may show SERIOUSLY small returns in power.

But... if you must...

http://www.small-block-chevy.com/images/port1.jpg
http://www.small-block-chevy.com/images/port2.jpg
http://www.small-block-chevy.com/images/port3.jpg
http://www.small-block-chevy.com/images/port4.jpg

Just remember these drawings are for some of the more popular performance heads and you need to verify casting thickness before you blindly sit down with a bunch of tootsie rolls and an air grinder and and start hogging out material.

And wear eye protection and a DUST MASK. The nostrils and the lungs really don't like the fine metalic shards a carbide burr and/or a tootsierolls send into the air.

[gofastnut]

The way I've done it, twice only, was to lay an intake gasket (that matches the intake manifold) up against the head and use a black marker to trace out the shape of where you will want to remove material to blend in, and be all in by maybe an inch.
I know this is called gasket matching, but if you can get a junk cylinder head and practice this part, you'll get an idea of what needs to be done to the rest of the head.
Always take too little, it's way better than taking too much, which you can't put back!

[hotrod 80]

A topend job with a reseal will find a bad ring seal in a cylinder of a older long block . Also need a bit more info on the combo .

[wayne4252004]

So what I have is a late 70's 350 four bolt main with 2.02/1.94 cast iron heads. I've replaced the valve cover gaskets with the steel lined gaskets. This has really helped. But I've still got some leaks in other places. Hence I thought about pulling off the top half of the motor to replace the gaskets. Figured I would do some work on it while I had it apart.

[GASoline71]

You don't need to pull the heads to fix any oil leaks. The heads have no oil passages in them. The intake valley is prolly leaking. Also check the oil pressure sending unit to see if it is leaking.

Doing any headwork (even a valve job with new seals) is a waste of time and money on any high mileage engine. You'll be huffin' oil smoke out the tail pipe as it sucks oil past the worn out rings into the combustion chamber.

Gary

[wayne4252004]

Thanks for all your input. The back four bolts on my intake manifold were not tight I was able to remove them with my fingers. So I went ahead and removed the intake manifold and installed new gaskets and resealed it. Runs great and no more leaking.