Inliners International Forums General Discussion Hi Performance Rebuild the head first or port first?

Im gonna get my head rebuilt on a 235 and some port work done. The place that rebuilds doesnt port. Im thinking that getting it ported first would be better so i can send the head as a bare casting to the rebuilder. The only worry I have is not getting the exact head back after the rebuild.The rebuild company is a huge company out of Oakland, Ca.

It looks like the intakes cant be ported to big cause then I cant use the locator rings. How I get around that?

Thanks,
Dan Nelson

check for cracks aka magnaflux

do the port work

have the head "rebuilt"


Good luck

Dear Dan;

You can inlarge them to the size of the 'A' rings and use the 50-52 Powerglide intake valves as well.

Check with Sissel's in Covina on costs.

Good luck.

Have you done any porting before, or have you done any reading on the subject? just "hogging it out" isn't the way to approach this issue...

Understanding how air "flows" through the passages, much like water in a creek, is the key to knowing where and how much to modify. Air does not travel through it evenly from top to bottom or left to right, if it was, then "just make it bigger" is all you would need to do, and nobody would need a flow bench...

Start with the most constricted area.
Bowl porting is where you will make most of the difference. Enlarging the port openings isn't really necessary with this engine, especially for street use. Using the larger valves will only have a small effect at higher rpms.

There are two books out there by David Vizard that are about the SBC V8, but the info is useful for any engine.
"How to build max performance Chevy small blocks on a budget"
"How to build & modify Chevrolet small-block V-8 cylinder heads"

I dont intend to do the porting myself, but have done some research on the matter. The only reason I am geting the rebuild done at the place in oakland is cause it is $375 parts and labor out the door. Cant beat that! I dont know if it will even be worth the money to port this head out for a mild cam and mostly daily driver. I look around here and see how much it is.

when you pay cheap you get cheap. those places are the reasion i got into doing my own heads. could not get a good valve job any where and then could not get good guide work.
frist you have to bronze wall the guides not replaace them with new cast iron guides if you want to run on unleaded gas. and dont even think about knerling it lasts about as long as it takes to talk about it.
then you have to do a good valve job that means holding seat runout to .001 or less not the .003 or more the factory says. and the valves should run no more then.0005 out. and yes you have to grind new valves.
if you get one of those cheap heads set it up and pour kerosene in the ports and see if it comes past the valves if it does you did not get a good valve job.
i did that and took the head back and the shop told me they will saet in when you run it a while. that was 20 years ago and i have been doing heads ever since.

Why use kerosene to check for leaks? This place is cheap cause they do tons of heads. Its called American Cylinder Head, has any one ever had experience with them? The way I see it I can either pay the cheap price and it will still be better than the job I would do myself. The only thing I can do myself is lap the valves, and put new spring/keepers on it.

As for porting, Pocket porting is the most effective. Match the gaskets on the intake and exhaust. The area within 1" of the valves is where most performance is realized. Streamline the area around the guide into a teardrop shape facing toward the ports or round them leaving at least 18th inch material around the guides. The short-side radius turn on floor to port has a sharp edge that needs to be removed. Blend 1/2inch below the seats into the ports and smooth the turns.

Object not to enlarge improve flow remove sharp edges.

Most of the flow occurs at the top of the ports.
Think of a piston pushing or pulling.

In the ports themselves match to gaskets at the openings remove casting bumps sharp edges and polish the existing shapes.

Good for20-40hp on stock to modified engines.

A pocket ported gasket matched head with stock cam will run stronger than a factory head with a race cam.

1.94 1.6 Valves aren't needed look at the valve size on Ford 289 302 and the chevy 283 engines. About the same as this six.

Correction 1/8th of an inch around the guides.

Dear Dan;

These guys are telling the truth.

What did Sissel's say??

I dont have any info on how to get in touch with Sissel's. Although I think I might send it to him or some one who has done this head before, then get it rebuilt at american cylinder head.

Thanks to everyone who has helped out. This board is great.

for the question you do the port work first that way if you nick a seat. you dont have to do a valve job over again.

Dear Dan;

Bob's right.

Sissel's Automotive is in Covina or West Covina, California.

If you can't find it I'll look it up in an old TPN.

Good luck.