Originally Posted by MILD THUNDER

Full force Tim was accidently sent solid roller springs on his heads, that had something like 750 lbs of spring pressure. How many do it yourselfer's , get heads shipped to their door, and are actually checking the spring pressure, to even verify the proper springs were installed? Let alone valve guide clearance.

Originally Posted by MILD THUNDER

Full force Tim was accidently sent solid roller springs on his heads, that had something like 750 lbs of spring pressure. How many do it yourselfer's , get heads shipped to their door, and are actually checking the spring pressure, to even verify the proper springs were installed? Let alone valve guide clearance.

Recieving heads with incorrect valve springs installed, right there, is reason enough for me not to bolt on an out of the box head. Period.

Originally Posted by Full Force

My experience with Pro Comps, came on my old engines.....I had to have them fixed in order to be confident in them... What Gellner had to do...

Valve job due to horrible sealing
New guides and fixed geometry issues to center the valves
new guides and honed guides to .0020/.0022 (does all marine that way)
fix half the Intake and exhaust bolt threads with inserts (crap aluminum)
Replace the very cheap Chinese no name valves with Manley stainless intake and inconel exhaust valves.
Replace the retainer and keepers with comp cams parts
Replace the rocker studs with arp studs.

I know I was not supposed to contribute to this thread as everyone knows my story, but maybe not and maybe once in a while I just might have useful information and experiences that might make people realize I am NOT just some hack garage grease monkey and have actually had many success story's... Mike you know that just from the conversations we had last winter.

Anyway I would based on that info steer clear away from any kind of off brand head just for the quality of aluminum alone... I will say those old engines made some real nice power with pro comps though, I believe they are based off the dart.

Originally Posted by MILD THUNDER

There's more to valve guide clearance, than whether or not it sticks a valve, or it doesnt. So, if it hasn't stuck a valve at 80 hours, its good right?

What if it was a car? My GPS Chartplotter on my boat, logs miles, avg speed, etc. My average speed, is somewhere in the 30's. This obviously includes idle time, etc. So, lets just say, 80 hours, times say 35 miles per hour. Thats 2,800 miles in the car world. Would you guys call your heads a "Success", if you bolted them on your car, and at 2,800 miles, the valves didn't seize? What if the guides were worn to chit, at 3500 miles? Would you consider that good or bad?

I can probably link up 20-30 threads in about a 5 minute search, of guys complaining about prematurely worn guides, in car forums, with aftermarket heads. I'd be willing to bet, 75% or more of them, bolted them on out of the jegs catalog, or had poor valvetrain geometry. .

Valve guides transfer heat from the valve, control oil seepage to the combustion chamber, control valve to seat contact pattern, control air leaks from manifold vacuum, and must simply be setup, to go the distance. Different guide materials, different stem/guide sizes, coolant temperatures, combustion temperatures, and other things can dictate, what the ideal clearance may be. A head that's meant to go on a 500HP car engine with a 195* thermostat, may require a different stem clearance, than a engine that runs 90* coolant temps, and making in excess of 1000HP. If NONE of that mattered, I would think AFR, would simply erase

Our typical valve guide clearances are .0013”-.0016”. In some severe applications (nitrous, marine endurance racing, or blower usage) looser guides might be required. Check with your engine builder.

Or from Dart

Valve to valve guide clearance is finished at .0012” - .002” with our valves(OD .3415”). If you have a particular clearance for your valves or application the guides should be measured and sized to your specifications.

Originally Posted by mike tkach

tim,when i said no need for you to respond it was because your deal is well known.in no way was it meant in a degrading way.your info on the pro comps is the type of thing i want to know about.

Originally Posted by mike tkach

joe,i get what you are saying.you and i are usually on the same page but what i see happening is everyone getting nervous that the guides in their heads are incorrectly sized or have other issues that may cause a failure.that was the reason i started this thread,to see how many people have had issues with an aftermarket head.i can,t imagine how many out of the box heads from the major head makers are being run in marine engines today.the thread has taken it,s own life but i am not seeing people reporting issues.we all know that things can go wrong but i just don,t see that every head is wrong,maybe i am just stupid and i sure don,t know everything but it,s hard to argue with success.but what do i know,i,m just a backyard hack.

Originally Posted by MILD THUNDER

What if it was a car? My GPS Chartplotter on my boat, logs miles, avg speed, etc. My average speed, is somewhere in the 30's. This obviously includes idle time, etc. So, lets just say, 80 hours, times say 35 miles per hour. Thats 2,800 miles in the car world. Would you guys call your heads a "Success", if you bolted them on your car, and at 2,800 miles, the valves didn't seize? What if the guides were worn to chit, at 3500 miles? Would you consider that good or bad?
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