Procomp heads

[jonorys]

I got a -67 Dart with a 383bb. It was professionally rebuilt as a shortblock several years ago. The customer put on new complete Procompheads with following (unconfirmed) specs: 265ccm Intake, 75 exhaustrunner, 2,18/1,81 valves.
There has been som machinework to make them fit better.

The car was put away and the engine has barely been running. Long story short;

I haven't read much positive about these heads, especially the ones bought complete. Due to som issues I have to take off the heads and I have given myself two options.
1. Buy new quality heads
2. Strip down the PC heads and get a complete valvetrain and install new seats.

If I go with option 2. which is cheaper, will i get as good heads as any other or will there still be higher risk for enginebreakdown?

 

[toolmanmike]

Procomp is Speedmaster. They are low dollar to buy but a good quality for the price. There have been a lot of threads here about the ir small block heads. Not much written about the big block heads though. Try "Procomp" or "Speedmaster" in the search engine.

 

[dano]

Since you have the heads, pull them and send them to a shop that builds performance heads if that option is available to you. They are going to need to know the cam specs to get the proper springs set up.

Across the board be it Ford, Mopar, Chevy the castings are good, the hardware and head work is suspect directly from SpeedMaster/Pro Comp.

Even if you bought a different brand of head, you should still have it gone through.

 

[j par]

The engine was complete and running, and now because you read something bad about pro comp, you're going to tear it down....
Okey...

 

[jonorys]

The engine was complete and running, and now because you read something bad about pro comp, you're going to tear it down....
Okey...

No, it started with a abnormal sound and I though at first it was to big valveclearance, theres mechanical lifters and arms. Then I was thinking maybe a stuck valve or two due to long storage. Still no improvement, inspected through the plugholes with a camera and found that the pistons on one side is 180 degrees wrong so the valves doesent align with the valvegrooves and has touched the pistons… Luckily i avoided total breakdown!
A little difficult to see but here is a picture of the areas on the valve and piston where it knocked together.

 

[Garrett Ellison]

The car was put away and the engine has barely been running.

Due to some issues I have to take off the heads

Do you care to elaborate as to why it's barely running and why you're tearing it down? Just curious if you've wiped a cam or something else is broken. The ProComp casting quality is as good as anything else you'll buy. With the "value priced" aftermarket heads, it's best to buy bare castings and then have quality parts sourced by your builder for installation. They're good heads for porting. Trick flow is probably the "premiere" big block head, but minimal recommended bore size is 4.32 with the 2.19/1.81 valve sizes. So unless your block is bored out .070 over (440 bore) or larger, they may not be an option. Even then, it's still best to have them gone through and checked, too.

 

[Garrett Ellison]

Okay, sorry, I missed your response! Yeah, that's going to need new valves and guides in the heads. You want go through everything with a fine tooth comb when you find that. I imagine there's more "surprises" waiting in there...

 

[jonorys]

Do you care to elaborate as to why it's barely running and why you're tearing it down? Just curious if you've wiped a cam or something else is broken. The ProComp casting quality is as good as anything else you'll buy. With the "value priced" aftermarket heads, it's best to buy bare castings and then have quality parts sourced by your builder for installation. They're good heads for porting. Trick flow is probably the "premiere" big block head, but minimal recommended bore size is 4.32 with the 2.19/1.81 valve sizes. So unless your block is bored out .070 over (440 bore) or larger, they may not be an option. Even then, it's still best to have them gone through and checked, too.

By barely running a meant running at all

Do you care to elaborate as to why it's barely running and why you're tearing it down? Just curious if you've wiped a cam or something else is broken. The ProComp casting quality is as good as anything else you'll buy. With the "value priced" aftermarket heads, it's best to buy bare castings and then have quality parts sourced by your builder for installation. They're good heads for porting. Trick flow is probably the "premiere" big block head, but minimal recommended bore size is 4.32 with the 2.19/1.81 valve sizes. So unless your block is bored out .070 over (440 bore) or larger, they may not be an option. Even then, it's still best to have them gone through and checked, too.

By barely running I meant running at all after rebuild. When I started it the engine ran quite well except for the bad metalsound. The block isn’t bored more than.030. But I guess I’m gonna try them since I already have them.

 

[jonorys]

Okay, sorry, I missed your response! Yeah, that's going to need new valves and guides in the heads. You want go through everything with a fine tooth comb when you find that. I imagine there's more "surprises" waiting in there...

Im afraid your right….

 

[PRH]

If the car will be used primarily as a streeter, then the heads you have are not a great match for that…….on a 383.

But repairing what you have will be the cheapest option by far.
Different heads will need different rockers and pushrods.

Just depends on what you’re looking for, and what your budget is.

 

[PRH]

..".found that the pistons on one side is 180 degrees wrong so the valves doesent align with the valvegrooves and has touched the pistons

I’ve seen that type of scenario before, where “some” of the pistons are in wrong.
It boggles my mind.

 

[dusterbing the peace]

Do you have a shop near you that is capable of rebuilding the heads? Should be cheaper that way considering whatever heads you buy as replacements should still be looked at (and potentially set up) by a machine shop.

Also - are you going to disassemble the "professionally" rebuilt engine and rotate the pistons to where they should be?

My condolences for the issues you're experiencing

 

[j par]

If it was a clearance problem then I don't see where the heads were at fault...
I can only go by my personal experience.With the small block speedmaster, heads that were in pro comp boxes.. I listened to the gurus here and had them checked it over even though some shops, I called laughed and said we wish we could sell heads that had to be checked over and they were just fine, completely assembled and have been in my stroker motor for years now...
If the piston is in backwards, it doesn't sound like it's the head's fault. It sounds like the person assembling wasn't checking clarence's...

 

[jonorys]

If it was a clearance problem then I don't see where the heads were at fault...
I can only go by my personal experience.With the small block speedmaster, heads that were in pro comp boxes.. I listened to the gurus here and had them checked it over even though some shops, I called laughed and said we wish we could sell heads that had to be checked over and they were just fine, completely assembled and have been in my stroker motor for years now...
If the piston is in backwards, it doesn't sound like it's the head's fault. It sounds like the person assembling wasn't checking clarence's...

Youre right about everything but it doesn’t change the fact that the pistons hit the valves….

 

[jonorys]

Do you have a shop near you that is capable of rebuilding the heads? Should be cheaper that way considering whatever heads you buy as replacements should still be looked at (and potentially set up) by a machine shop.

Also - are you going to disassemble the "professionally" rebuilt engine and rotate the pistons to where they should be?

My condolences for the issues you're experiencing

Thanks!
Yes I have to disassemble the engine and check for more damage and hopefully I just have to turn the pistons. I also got a shop to do the heads.
Anyway, this is part of the game‍.…
I was actually relieved findind it out before total disaster

 

[jonorys]

If the car will be used primarily as a streeter, then the heads you have are not a great match for that…….on a 383.

But repairing what you have will be the cheapest option by far.
Different heads will need different rockers and pushrods.

Just depends on what you’re looking for, and what your budget is.

I don’t have any experience with uscars but I find it interesting to learn new things.
In what way does these heads not match good with my engine?
I understand that it has to do with airflow and displacement etc, but how does the engine «behave» with these vs proper heads?

 

[PRH]

If it were a “race car” it would be less of an issue.
You’d run enough stall/gear/cam to allow the engine to rev high enough to get decent port velocity.

But if you’re putting them on a “small-ish” engine, coupled with a modest converter and cam, the rpm range the engine will be operated at for most of its life, the heads are fundamentally “too big”(for the application).

In the not enough gear/stall/cam scenario, I’d expect the in car performance to be not as good as if the heads were more appropriately sized(like an RPM head, which has smaller intake valves and 55cc less runner volume).
A less impressive “seat of the pants” feel is what I’d expect.

Those heads are a copy of an Edelbrock Victor head, which is more of a race head.

Just get it fixed, and see how it goes.
You might love it the way it is.

 

[496 polara]

Have the pistons installed correctly so you don't have to do this again.

 

[PRH]

Have the pistons installed correctly so you don't have to do this again.

Of course, the question is…….. are the pistons on the rods backwards, or are the rods in backwards(resulting in the pistons being backwards)?

 

[jonorys]

If it were a “race car” it would be less of an issue.
You’d run enough stall/gear/cam to allow the engine to rev high enough to get decent port velocity.

But if you’re putting them on a “small-ish” engine, coupled with a modest converter and cam, the rpm range the engine will be operated at for most of its life, the heads are fundamentally “too big”(for the application).

In the not enough gear/stall/cam scenario, I’d expect the in car performance to be not as good as if the heads were more appropriately sized(like an RPM head, which has smaller intake valves and 55cc less runner volume).
A less impressive “seat of the pants” feel is what I’d expect.

Those heads are a copy of an Edelbrock Victor head, which is more of a race head.

Just get it fixed, and see how it goes.
You might love it the way it is.

Thanks for useful and interesting info!

 

[33IMP]

The heads you have are about the same size compared to displacement, as the old big port 396 chevy heads were.
But the big port 396 had plenty compression and a good-sized solid lifter cam.
Imo (not NEARLY as valuable as PRH!) it's pretty hard to get too big a head on a big block mopar.
That said, I agree that RPM's would be a better choice for a 383. But I'd still repair the procomp/speedmaster and run em.

 

[jonorys]

Of course, the question is…….. are the pistons on the rods backwards, or are the rods in backwards(resulting in the pistons being backwards)?

Hope i can find out when disassembled..

 

[jonorys]

The heads you have are about the same size compared to displacement, as the old big port 396 chevy heads were.
But the big port 396 had plenty compression and a good-sized solid lifter cam.
Imo (not NEARLY as valuable as PRH!) it's pretty hard to get too big a head on a big block mopar.
That said, I agree that RPM's would be a better choice for a 383. But I'd still repair the procomp/speedmaster and run em.

Interesting! I’m told that theres an «aggressive» Lunati rollercam with .570 lift.
I’ll give it a try.

 

[PRH]

Most of the fitment “problems” involved with those heads revolves around the valvetrain/rockers.
Hopefully, that stuff is all sorted out already.
Before ripping it all apart, I’d turn the engine over and watch each pushrod run thru it’s full travel, to make sure they’re not touching the heads anywhere.

 

[PROSTOCKTOM]

It's been my experience with most of those lower cost Chinese heads that they aren't heat treated, or at least correctly.

Guys build engines and then the heads move around after several heat cycles.

I started baking the castings (bare) in a kitchen oven at 400 degrees for 5-6 hours prior to doing anything with them.

After that all the ones I've dealt with have stabilized and you can go on building them.

Tom