Pontiac cyl head work.

[G-Body_Vet]

I had an interesting experience today. Came across a set of Pontiac 6X-4 heads on craigslist for $50 so I decided to check them out. I get to the guys house and find out he runs a cylinder head shop out of a garage. He's been doing cylinder head work for the past 30 years.

The heads were already tanked and mag checked. So I'm already getting a deal on the heads. After bullshitting with him for awhile he offered to cc, port/polish, gasket match and assemble the heads for $450. He's going to pressure test them for free then we'll go from there if everything checks out. There's going to be the added cost of new valves too. I could re-use the old ones but they're as old as I am!

Does this sound like a decent price? I looked at some of the other heads he had sitting in there and it looks like he does decent work. Work area was clean and he seemed like a good guy.

 

[Bonnewagon]

Was the $50 for bare heads or what? For complete heads that would have been a score. Pontiacs have fully machined combustion chambers so cc'ing is not a biggie.The port and polish is good to have and new valves go for some serious coin. The last time I had 301 heads done by a shop with new valves and bronze guides they went for $200 each parts included and that was 10 years ago. I needed bronze guides because they didn't make oversize 301 valves at all. I guess $450 is a good price but let someone that has had heads done recently chime in. Do you want the compression increase? Otherwise why not have all that done to the 455 heads?

 

[khan0165]

warning: dumb question ahead...

when you say "cc'ing is no biggie", do you mean that since chambers are machined, the cc's are automatically correct between other chambers? And checking cc's again is pointless?

... just trying to understand what kind of machining is done to factory pontiac heads.

 

[G-Body_Vet]

I had another set lined up but he wanted $150 complete and it was an hour & a half drive. I wanted the compression increase and I was specifically looking for these heads. I still have my 455 heads too, but since I'm using all new springs, valves, rockers, etc it didn't matter that the 6X's were bare. I haven't been able to find any 6X's around here and I got them less than what the shipping would cost on the ebay one's I've found.

The only reason we're cc'ing the heads is because I don't know their history or if they've been milled or not. Since I'm going to spend the money on forged rods, pistons, have everything balanced and tighten up the quench area; I might as well take the extra step with the heads and do it right.

I've gone cheap and slapped bullshit together in the past but I didn't want to do that this time around.

 

[Bonnewagon]

No, not pointless. But by machining the chambers, the factory had very good control over chamber size, within a cc or two. Conversely, a cast chamber is by definition, not that accurate, and cc'ing is standard procedure. So for a street motor it's not really necessary, but for a full tilt race motor you would probably go for the cc'ing. I only mentioned it because if the guy is selling the job based on that, it's not that important on a Pontiac. Good point though, that G-Body_Vet made, unknown heads could have been shaved many times in the past, though doing only 1 chamber would show that.

 

[khan0165]

sorry, I didn't mean to thread jack... I've been following this build cuz I want to learn more about pontiac motors.
... would I be right to assume that Buick and Olds also took special care with their motors? Did they also have machined chambers? or cast?

 

[G-Body_Vet]

sorry, I didn't mean to thread jack... I've been following this build cuz I want to learn more about pontiac motors.
... would I be right to assume that Buick and Olds also took special care with their motors? Did they also have machined chambers? or cast?

No problem at all! I'm still learning about Pontiacs myself. The post '73 Pontiacs had terribly low CR's. In order for me to raise the CR and remain ping free, I have to be careful with the cam selection here. I can't justify spending $2K on E-heads so I'm trying to make the most out of the 6X's. Everything I read says you make all your power with cast iron 6X's in the porting.

As Bonnewagon said, we actually will just be cc'ing one chamber per head to see what we're working with. I know some guys don't like bumping the compression up on these engines because of having to run premium and the risk of detonation. This is going to be a pure recreational vehicle so I'm not worried about it.

 

[67rstbkt]

No problem at all! I'm still learning about Pontiacs myself. The post '73 Pontiacs had terribly low CR's. In order for me to raise the CR and remain ping free, I have to be careful with the cam selection here. I can't justify spending $2K on E-heads so I'm trying to make the most out of the 6X's. Everything I read says you make all your power with cast iron 6X's in the porting.
As Bonnewagon said, we actually will just be cc'ing one chamber per head to see what we're working with. I know some guys don't like bumping the compression up on these engines because of having to run premium and the risk of detonation. This is going to be a pure recreational vehicle so I'm not worried about it.

That's what I've been hearing too, but consider the cash you will be putting into the iron heads. I talked it over with my machine shop awhile ago and it adds up quick. I ended up buying a set of slightly used Edelbrocks on ebay for $1600. I'll probably do some light polishing on my own and have the shop check spring rates and deck flatness.

On the compression, the nice thing with using aluminum is that you can generally raise it some. I'll be running about 10:1, but I'm also at a higher altitude (about 4,000 feet). I should actually be safe running premium up to about 11:1 with aluminum heads and my altitude.

 

[shotgun]

Check to see how many Pontiac heads they have done. They are there own animal. I would not take sbc heads to my Pontiac guy either.

You can have 30 thou cut off the heads to raise compression a bit. Anything over 30 will require cutting the manifold face also.

Don't raise compression with any kind of a domed piston , zero deck is the way to go if possible.

There is power/flow in a good multi-angle valve job.

What is your true power/goals for the motor/car?

A good valve job and a mild clean up they will support 500hp.

Are they 6x-4 , what year?

 

[G-Body_Vet]

Check to see how many Pontiac heads they have done. They are there own animal. I would not take sbc heads to my Pontiac guy either.

You can have 30 thou cut off the heads to raise compression a bit. Anything over 30 will require cutting the manifold face also.

Don't raise compression with any kind of a domed piston , zero deck is the way to go if possible.

There is power/flow in a good multi-angle valve job.

What is your true power/goals for the motor/car?

A good valve job and a mild clean up they will support 500hp.

Are they 6x-4 or 6x-8?

The heads are -4's. This is an older guy that has built Pontiacs in the past. I've been looking at the Icon forged flat top's with 5.5cc reliefs. We're going to go as close to zero deck as possible. The ultimate goal is to make at least 400hp or enough to give LS owners trouble. One of the guys over on the PY forum is suggesting going with a Crower 60243 cam?
The heads are 78's.