[inquiring_mind2]

I was looking at putting some aluminum heads on a 427 bbc. Right know I have stock heads that had had some work done to them. Does anyone know anything about procomp heads? Any help would be appreciated.

[OneMoreTime]

here are some threads on those..
http://www.hotrodders.com/forum/sear...earchid=631453

Sam

[inquiring_mind2]

I tried your link and it said there was no matches

[machine shop tom]

Here is a discussion on who makes different heads:

http://www.speedtalk.com/forum/viewtopic.php?t=2079

tom

[nitro_baller4692]

look at the dart heads you will be happy

[leejoy]

I wouldnt use anything from Procomp. Shy away from that brand. I made that mistake once to save a few bucks. will never do it again.

[inquiring_mind2]

ok great thanks for all the info. If I decide to upgrade I will definatly look at something else besides pro comp

[dgravagn]

I have a '70 El Camino with a 6-71 blower and formerly ran aluminum GM Performance rectangle ports. I used these heads for about 7 years without a hitch. I recently went to the machine shop to freshen up the heads and they told me that several of the guides were worn and the bill would be in the $700 range. I looked for some alternatives and found Pro Comp. I did check out several forums to see if there were any reported issues but the only negative things I saw were minor appearance issues or Australian/Chinese bashing which is not issue specific. Well, I have an issue specific complaint that you had better read. After installing the same type valve/spring combo that worked flawlessly on the GM Performance heads I took the car out for it's test drive. About 10 min. in town and then mild acceleration (no more than 3300 rpm) to get to freeway speed and then cruise at 3000 rpm for about 5 miles to get back to my off ramp. By the time I reached my off ramp I started hearing what sounded like mild knocking. Engine rpm at this point is about 1800 rpm. Checked oil pressure and that was at 64 psi. I then went to shut off the engine but before I could there was some really bad rattling and then the engine stopped. We all know it's NEVER good when that happens. Removed the heads and discovered that every single piston had come in contact with the valves and the number two intake valve was actually snapped off and ended up in the number 6 intake port. I have tried two progressively stouter valve and spring combinations with EXACTLY the same result. I won't even tell you about my Pro Comp distributor nightmare but that piece of crap ended up in the trash. I hope my experience helps others not to buy Pro Comp because my experience with both heads and distributors has been a very, very bad one

[ericnova72]

Originally Posted by dgravagn

I have a '70 El Camino with a 6-71 blower and formerly ran aluminum GM Performance rectangle ports. I used these heads for about 7 years without a hitch. I recently went to the machine shop to freshen up the heads and they told me that several of the guides were worn and the bill would be in the $700 range. I looked for some alternatives and found Pro Comp. I did check out several forums to see if there were any reported issues but the only negative things I saw were minor appearance issues or Australian/Chinese bashing which is not issue specific. Well, I have an issue specific complaint that you had better read. After installing the same type valve/spring combo that worked flawlessly on the GM Performance heads I took the car out for it's test drive. About 10 min. in town and then mild acceleration (no more than 3300 rpm) to get to freeway speed and then cruise at 3000 rpm for about 5 miles to get back to my off ramp. By the time I reached my off ramp I started hearing what sounded like mild knocking. Engine rpm at this point is about 1800 rpm. Checked oil pressure and that was at 64 psi. I then went to shut off the engine but before I could there was some really bad rattling and then the engine stopped. We all know it's NEVER good when that happens. Removed the heads and discovered that every single piston had come in contact with the valves and the number two intake valve was actually snapped off and ended up in the number 6 intake port. I have tried two progressively stouter valve and spring combinations with EXACTLY the same result. I won't even tell you about my Pro Comp distributor nightmare but that piece of crap ended up in the trash. I hope my experience helps others not to buy Pro Comp because my experience with both heads and distributors has been a very, very bad one

Sounds like you never checked valve to piston clearance when you changed to the ProComp heads and just expected that the clearance would be the same as with the previous GM heads. All the valvespring changing in the world won't change a thing there.

The ProComp heads have worked fine for me. two sets now, but they are not for "parts installers", you need to know what to look for and check as the manufactureres QC does not have a good rep.

I never buy them complete, as the Procomp valves and springs/retainers are pretty poor pieces. I buy them bare and pick the parts used to complete them myself.

I agree to stay away from Procomp distributore and electronics.

[eloc431962]

Pro Comp: Junk? This link will work read away.


Cole

[1932bantam]

just took mine to the machine shop had them disasembled checked spring heigth, spring pressure, valve guide clearance and seats the installed heigth was not as advertised. shimmed .090 spring pressure was what they said at the heigth they adv. seats good ,1 peice swirl polished valves ,10# locks, valve to guide clearance good. I bought these complete. i see were there advertised with different valves and springs for the same money. An 8 dollar valve is a 8 dollar valve no matter what. they arn't putting anything any better than what is in them . probably made in the same place with a different name.there not going to put in 20.00 valves and better springs and retainers for the same. i thought it was pretty much standard procedure to check valve to piston clearance? and also how the rocker arm rides on the valve. stupid mistakes that can be easily avoided. I have talked to them and they will tell you what you have to check for. and have talked to plenty of people that are running the crap out of them.They have been in business for awhile. If they were that bad don't think they could still be selling the crap out of them

[dgravagn]

This is for EricNova72. I will always admit if I haven't checked something and Eric, you're right. I did not check the piston to valve clearance because I'm only running a .600 lift cam with the standard 1.7 rockers. I will check that clearance and get back to you. Thanks for the input.

[ericnova72]

Originally Posted by dgravagn

This is for EricNova72. I will always admit if I haven't checked something and Eric, you're right. I did not check the piston to valve clearance because I'm only running a .600 lift cam with the standard 1.7 rockers. I will check that clearance and get back to you. Thanks for the input.

I would be looking not so much at depth of valve relief in piston as it relates to V-P clearance and more at radial clearance between the edge of the valve and the valve relief in the piston. Bigger valves or slightly modified valve angles(many aftermarket heads are this way) will create problems here with a lot of pistons.

Peak lift really has little to do with V-P clearance, the piston is far from the valve at max lift. The danger area is cam duration combined with the amount of lift occuring 10-15° either side of TDC(the overlap event when both valves are open). At this point the intake valve and the piston are moving toward each other, this is when things get tight.

[CURLIE 5549]

Sounds like U don't under stand the basics to engine building !!