I bought a 350/290 gmpp crate motor to replace the tired 327 in my version of a hot rod, a porsche 914. Everything was fine and I was swapping over parts from old to new when someone reminded me of the Dart pro 1 heads I have had stashed for a while now. (It doesn't take me all that long to forget things nowadays) Anyway, I have these pro 1s with 64cc chambers, 200 cc ports and 2.05 valves still in the box they came in. So I looked at those shiney heads and then at the all black chevy truck heads and thought, hmmmm. My question: Think I can get away with running those heads on the new motor without any changes or are the ports and valves just to big? The car only weighs ~2350, and I use it make loud noises when the need overtakes, sunday drives through the canyons and a few autocrosses or track days a year. I figure the cr would be about 10 to 1, I have an performer intake and carter/edebrock 600 and a few various sets of headers. <TABLE cellSpacing=0 cellPadding=0 width=660 bgColor=#ffffff border=0><TBODY><TR cl***=wbg-blacktext vAlign=top align=left><TD cl***=wbg-blacktext-12pxB vAlign=top align=left>Camshaft is 450 460 and duration @ .050 is 222 222</TD><TD cl***=wbg-blacktext vAlign=top align=left></TD><TD cl***=wbg-blacktext-12pxB vAlign=top align=left></TD><TD cl***=wbg-blacktext vAlign=top align=left></TD></TR></TBODY></TABLE> What I am after is something that will idle and still pull somewhere near 6k (which I figure is 5 or 600 more than the stock heads will do) whadaya think? Should I just put the new motor in with the cast iron heads or is there much chance it would be driveable without a cam change? patrick
terraview, i think you need to ask that question on another board. the use of the "p" word doesnt fit in around here.traditional is traditional. mike
Yeah, but a sbc is a sbc... I bet he could get some pretty good answers around here. Racefab? You out there?
Do you know the chamber volume of the iron heads? And what about the valve reliefs in the pistons?? How "stiff" are the springs on the new heads? I'd be concerned with these items first....... I'd be tempted to just run the iron heads.
One vote too big,unless you spend a lot of time around 8000 rpm. Mitch 36: Horsepower IS traditional. Bigger valves,better ports,more rpm. People ran flatheads 50 years ago,because it was what they had available,not because it was "cool'.
I can give you my .2 with some more info on the motor. What heads are on the motor now? The 64 cc chambers are on the smaller end of the scale and may bump the compression depending on what's on there now. 200cc runners are streetable but won't do much for you without a big cam and high rpm. Again, depends on what's on there now. Same with the valves. I wouldn't go too much over 2.02 on a street motor, but it all depends on the carb, intake and exhaust. For performance in an engine, a dreaded small block chevy is much like anything else: It takes a good combination of parts to work together to make power, not one outlandish piece on an otherwise stock motor. Most likely it will run, but my guess is that you aren't going to see any huge performance gains without matching the flow and chambers with pistons, intake, carb and exhaust. A couple basics to check first: straight plug or angled plug? raised port? Stahl, Reher-Morrison or other pattern header holes?
It sounds like a cylinder head that belongs on a 383/400 setup, with a single plane and 750 carb. If you bought this crate motor new, would tearing it down to swap parts affect your over the counter warranty?
Needs more cam,750-850 mechanical secondary carb. with something like a Victor Jr. intake. The current combo will run out of cam and intake just about the time the heads come on. Don't forget good headers and a stout bottom end, and let it scream!
That motor is too HEAVY for a porsche 914, you're trying to change porsche engineering and the car will never handle the same. Also, I would never mess with a GM crate motor, the engineers at GM know what they are doing when they build these and have more resources and test facilities than you do. Even Jay Leno has lectured on the quality and durability GM crate motors over some speed shop/garage built engine. Something to think about.
Ports measure 220 cc's .....airflow between the intake and exhaust averages in the mid 70% level, which is borderline decision on the single or dual pattern cam......best suited to a high winding, large displacement sb
It is good fun. I've had muscle cars, hot rods and sports cars and love them all. But I wanted a hot rod that had muscle and went around corners like a sports car. One of the reasons I want to use these heads is to save 50lbs sitting behind me. My first car was an old austin healey, my second a 49 chevy with a 265 , and so it went..
Car is light enough, with the right cam, carb, and intake to go with the heads, and if you're running a deep enough low gear to "get up on the cam" that thing ought to tear your head off.
beware of black helocopters circling your house , the krauts are onto you now..it ought to scream in a straight line but is it now gonna loose handling??
I think some people missed the fact that he already has a 327 in the car. So it's not going to change the handling etc because the 350 weighs the same as the 327 thats in the car now. Also, if I am not mistaken, the warranty on these engines only applies if you put them in the type of vehicle they came in originally. I need to find out for sure because I am thinking of putting this same engine in a '55 Nomad I am building. Sounds like a cool car. I put a SBF/C4 in a '67 XKE Jag back in the late 70s, but it probably weighed less than the old 6 I took out, wish I had the car now.
while those motors do benefit from a swap to 64 cc heads, {compression gain} you would lose your gains to the large intake runners and large valves.....those things like a 180 runner and a 2.02 valve is plenty, I have actually seen them do better with a 1.94/1. 5 with the .450 cam that is shipped with them they have 76 cc heads and are rated at 8.5-1 when shipped , tho most i have measured are closer to 8-1. I wouldnt use those heads unless as said before, you plan to change cam/intake/carb etc as well, and then you are still dealing with a PM rod and cast piston.
Run the dart heads. just make sure the valve springs match the cam. less weight, more airflow, whats not to like?? Dave
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