Jump to content
Forums Gone... but not forgotten!
Pontiac of the Month

Steve Morris' 1967 GTO

2021 April
of the Month

  • Welcome!

    Welcome to Forever Pontiac, where we keep the memory of Pontiac alive with great discussion, maintenance tips, restoration/modification progression "blogs" and help from professional & DIY mechanics. Also, wonderful competitions that occur regularly. Please register for an absolutely free account to join in!

Recommended Posts

So i have a 350 Pontiac engine that is bored 030 over that was given to me and i´m trying to piece this thing together for my -64 Le Mans, its going to be a almost stock street engine with perhaps a small cam also have a Edelbrock performer intake that i intend to use with a 600cfm 4bbl carburetor.

I CCed one of the combustion chambers and it is 92CC so the compression ratio is going to be very low, probably around 7.5.

I would like to se something around 9.0-9.5 if possible and what i probably need is a cyl head with a chamber in the low70s cc so any idea what head to look for?

Found a pair of 1969 #47 heads from a 350 that i think is supposed to be 72cc.

67 #140 heads from a 326 is closed or open chamber and what size? all i find is a listing of 9,25 comp no cc numbers.

So what heads to look for and what to stay away from?  whats better closed or open chambers, does it matter?

 

  • Like 1
Link to post
Share on other sites

Tired of these Ads? Register Today!

Thank you Frosty, Wow that was a lot of good information,What is the difference between A/T and M/T heads? chamber size? and can you tell on the head?

You are listing a few 1967 heads was that a split year for open/ closed chambers? What is thoughts on open vs closed chambers?

Looking on Franks Pontiac website here in SoCal and all the Big valve heads go for around $800 or more but found two sets 1.94/1.66 heads with smaller chambers for $200-$400 is it worth the extra $ for the big valve head for a almost stock engine?  Also read somewhere about valve shrouding with big valve heads and a small bore 350, any truth to this?

The Edelbrock heads would be the way to go but comes with a pretty steep price tag unfortunately.

Any god ideas about other places to look for used heads?

 

  • Like 1
Link to post
Share on other sites
  • 1 month later...

Hi Andy - sorry it took so long to get back to you. I didn't see a response to this until today.

For a near stock engine, closed vs open chamber heads will make marginal difference in performance.

As for non-2.11 heads, I would suggest the following:

image.thumb.png.f084ca5ea80920027d58c59a860f6a37.png

That said, I would first look to find a set of 5C or 6X/6H heads, particular the 6X heads that were plentiful in the late 70s. You see 6X heads all the time at swap meets and online. If you can find a set of #18 (350 HO) heads, grab them. Again, heads from any 455 should be somewhat plentiful, but they may not be as cheap as other heads, as you have already discovered.

Also, just because Franks wants $800 for a set of heads, doesn't mean you should pay that unless you want them bad enough. Arm yourself with the list of heads you want. Check swap meets and Craigslist (both in and outside your local area) regularly. You'd be surprised what you will find out there. You might find a set for $200-500.

Since you are in Orange County California - 3 words - Pomona Swap Meet!!!! Learn to haggle. Cash is king. Brink a dolly or wagon to carry them in.

  • Haha 1
Link to post
Share on other sites

Frosty- think i got i figured out, Pomona is something i did not think about and that's i good idea, have not been there in years and we also have Long Beach swap meet but not sure i want to do that right now with everything going on, to many people.

Found three cyl heads on Franks Pontiac's web site #15, #46 and #47 so i drove out there and brought my stuff to CC the heads right there (two hour drive) and they where very cool to let me do that right there, Checked the #47 heads first and What i found on line is that they are supposed to be 72cc or 73cc but not, they where right around 80cc so no.

Next up was a set of #46 heads from a 69 428 and what i found is that they are supposed to be 10:1 or 72cc and they turned out to be around 74cc so those are the ones i got, paid $450

That should put my compression right below 9:1 witch should be OK.

The heads turned out to be really nice and did not have to have a valve job at the machine shop, seats where nice and not to wide and the guides OK, the valves needed to be ground but the valves in my old head( same size) was good so i just used those instead and hand lapped them. (I used to do valve jobs at a dealer i worked for a long time ago)

Got the block back from the machine shop, one cyl sleeved and had to go from ,030 to .040.

Now i just need to pick a camshaft.looking at a comp cam xtreme energy 51-221-4 potentially.

Currently working on tapping the front oil galley holes.

I'll post some picture of the progress with the car when i get a chance ( and figure out how to upload pictures)

Thanks for replying

 

 

  • Like 1
Link to post
Share on other sites

Frosty- Have you had or seen any heads that has been severely damaged due to this?

I have seen this discussion in several palaces through the years but really not seen any heads that had severe problems with the seats/ guides.

I am not sure what it would cost to replace all the seats and guides and also with the price of purchasing the heads it must be getting close to just buying new aluminum heads?

I remember when they started with unleaded gas that this was a big topic, all old engines was going to die but don't think that it exactly worked out that way.

Yes these heads have the original seats but I'm not going to worry about it for now, it is not to bad to pull them off in the car if i have to and it will not be a daily driver so it will probably be OK

 

Link to post
Share on other sites
11 hours ago, Andy H said:

Frosty- Have you had or seen any heads that has been severely damaged due to this?

I have seen this discussion in several palaces through the years but really not seen any heads that had severe problems with the seats/ guides.

I am not sure what it would cost to replace all the seats and guides and also with the price of purchasing the heads it must be getting close to just buying new aluminum heads?

I remember when they started with unleaded gas that this was a big topic, all old engines was going to die but don't think that it exactly worked out that way.

Yes these heads have the original seats but I'm not going to worry about it for now, it is not to bad to pull them off in the car if i have to and it will not be a daily driver so it will probably be OK

 

Best advice I can give is to call around to your local machine shops and ask for quotes. Everything that Last Indian and I have suggested is in order for you to get the maximum power out of your heads and engine. Matching the springs, valves, guides, etc. to your engine and cam is crucial. I, for one, lack all the specialty tools to do all the necessary machine work.  So if doing all this adds another $300 to the bill, I know I took it to a professional to be done right.

Now is it possible for a machine shop to screw up a set of heads., yup, it sure is. That's why it is important you do your homework and you select reputable shops. Ask for references, especially for Pontiac work.

I make it habit to have the valve guides replaced on any used heads I get. I assume they are all from back in the day and don't run the risk of burning a valve and I replace the seats and guides. It's cheap insurance.

  • Like 1
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Tired of these Ads? Purchase Enhanced Membership today to remove them!
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.