Machining/porting
 

Hello everyone,,
Before I get into my question, I’d like to introduce myself since this is my first post. My name is Mike and I live in Victoria BC Canada. I own a 1957 Pontiac chieftain with a 1959 389 in it. I am looking at building a 461 stroker for it and am looking for a machine shop either on Vancouver Island or on the mainland that can port cast heads.
I came across an article in hot rod magazine, that mentioned SD performance, but unfortunately they are no longer around after the deviating fire.
I would like to stick with cast heads just for the look and old school feel but might go to aluminum heads if I can’t find a somewhat local place to have porting done.
Any help pointing me in the right direction would be much appreciated.
Take care
Mike

Can’t help you with a shop recommendation, but welcome to the forum. Sounds like a cool project. Any pix of your car?

A big necessary part of the criterior for the shop you choose to do the porting on your heads should be that they number 1, have a flow bench and #2, are familiar with porting Pontiac heads, especially if your looking for them to get more then 240 cfm out of the heads.

It would great if they can provide you with flow sheets of Pontiac heads they have ported as a reference.

I save flow sheets on every head I have ever ported (be they Pontiac or not ) unless they repeat previous results.

Also note that in terms of your 1959 389 heads they can not even BE ported to even 230 cfm @28”without making them prone to leaking coolant.

A later 389 iron head like a 1965 casting fitted with a 1.96” intake valve will go 258 cfm@28”.

In terms of iron heads for your stroker you need to run at least a 68 and up head.

Any big valve 68 and up head even stock ( but fully rebuilt ) should make you 370 to about 415 hp depending on how much Cam you run.

If you want more then 415 and not have to run a Cam that will kill your driving fun on the street the it’s time to port the heads.

You’ve shared some really valuable insights here — especially the reminder that consistent flow bench results are the only reliable way to judge whether a shop truly knows how to handle Pontiac heads. A lot of people underestimate how much variation there can be between castings, especially with older iron heads like the early 389s. Your point about not chasing high CFM numbers at the cost of structural integrity is spot-on, too.

It’s also interesting how much power range you can achieve even with a basic rebuilt 68–up head when everything is matched correctly. For many street builds, that 370–415 hp window is a sweet spot without sacrificing drivability or needing an overly aggressive cam.

By the way, while researching different tuning strategies, I came across Indwin, which offers some surprisingly detailed analytical tools and comparisons. Not engine-related, but still useful for people who like digging into performance metrics and optimization.

Dig around for similar topics for suggestions....

https://www.facebook.com/groups/Coff...1815421741908/

https://www.facebook.com/groups/West...4055427416465/

Your quest for someone for competent*cylinder headwork with a flow bench will be a challenge*!


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What is your favorite head?

Welcome Ponchomike57!

Thanks for the gambling spam link... the Ai's are talking pretty good now.

Half-Inch x 6" belt sander at Home Depot and the Valve Guide cutter tool for DIY.

I thought post 4 was strange!
Hello Admin, cut this one loose.

Have you reached out to Dave Bisschop..at SD Performance..he could recommend someone. He does have a dyno setup up and running I'm sure he could help.

Thanks for the welcome! I hope the picture got attached. The car has been in my family for 20 plus years. It was my dads

I have a set of 6X8 heads that I wanted to get ported. The problem around here is all the old guys who use to port heads and had flow benches have retired. The cost of shipping them anywhere isn’t really worth it, might as well go aluminum. I do have the Jim hand book that explains how to port the 6X heads, but still won’t really know my flow numbers. The cost of a stroker kit and hyd. Roller cam, I’d like to see 450hp and 550 torque. Don’t think that’ll happen unless I port the heads.

Nice! And welcome!

I tried sending an email to him at the website, but after the fire I’m not sure if he is even checking the emails anymore.

I am looking at possibly going with Kre heads. 260cfm out of the box

If you follow Jim Hands porting instructions you will have your 450 hp.

Awesome, thank you!

I can't remember if I read it here or on SD's website. Well before the fire, Dave stopped porting the stock heads. Too labour intensive and time consuming because of the cast iron.

Yes, Dave stopped doing CNC porting on iron heads due to the time it takes no less the toll on tooling I am sure was a big consideration also.

India 😂