I have a 350 4-bolt, that is going into a '31 Chevy pickup, I have the oppertunity to use a nice set of 66-67 camel hump heads with some porting work, casting #3890462 with 64cc chambers, the cam I have is a Comp Cam flat tappet with a gross lift of 0.490, my question is this, will this be too much compression? Also I have flat top pistons..
comon chevy gurus....I can get these heads at a great price, but at the same time, I don't want to buy them for nothing...
Is your block "zero decked", what are the cam specs. If the heads are ported, its a good chance that thier not 64cc chambers anymore. What were these heads ported for, circle,drag???
Just buy them .My 69 motor Flat top pistons and powerpack heads 10/1.4 to 1 compression. 93 or 94 octane only
I bought them, 50$....I guess when my neighbour seen I was weary, he took 100$ off and said take em, or there going to the scrap yard!!!, yikes!!! so ya they are mine...thanks guys. did a quick calculation, about 10:1
OK...no offense, dude, but your second post was only seven minutes after the first one...give people some time to think. Even to come up with an answer by using assumptions takes more than seven minutes. Hi covered a lot of this, but to give you an accurate answer, we need to know: 1) Are the chambers cc'ed at 64 actual cc, or is that the size quoted by somebody? 2) Was the block decked to zero? 3) How many valve reliefs are in the piston? Better yet, do you know the part number of them, or the cc of the valve reliefs? 4) Which head gasket are you using? What's the bore of it? How thick is it? 5) What's the cylinder bore? Is it .030 over, .040 over,etc. 6) Stock crank/stroke? Stock rods? Once we know all that, then you can get an idea what the static compression will be. Whether that's too high depends on a number of things, including the cam you plan to use...the gas you want to run...the intended use of the truck...gearing & weight...etc. Anything less means a guess, which is more or less worthless....
<!-- / message --><!-- sig --> __________________ OK smart ass, I was in a rush because the guy was in my kitchen, he was asking 150$, he was in a rush, this is why I was trying to rush, but then he caved and I got them for 50$, now, nevermind all the drag motor questions, all I wanted to know was an approxiamat comp ratio....give or take... so SORRY for bothering you...
Those aren't just "drag motor" questions. I'm guessing, since you asked about whether the compression would be too high, that this is a street engine. A few cc's can make a substantial difference in the static compression ratio. Whether that resulting static compression ratio will be too high depends a lot on the particular cam you chose- the intake valve closing point, and what it does as far as "bleeding off" compression at lower rpm. But, sorry for trying to help you....I'll not make that mistake in the future.
Wow!...way-to-go on your 83rd post here. High-Five!!!!!!! You don't have a lot of friends....do you? If a decision of spending a whopping $150 on a pair of fuelie heads will be so drastic....... maybe you're in the wrong hobby dude. I have double humpers stacked up like cordwood because I buy every unhurt set that comes my way for cheap money like that. Do I need the 35 or 40 pairs I have?... Surely not, but someone will when the time is right. Hell..... I even buy singles when they come to me that cheap. Here is a free tip..... When someone comes all the way to YOU and when they are trying to unload something for CASH YOU are in the driver's seat of the deal, they NEED cash. Now you have a person needing cash ...say $150 for an item they clearly either do not know the value of, or are in desperate need for crack money. Either way, within only 7 minutes, they lower their OWN price to 1/3 the original at $50. You then hold out a crispy $20 and say that is all you have. They mumble a little and snatch the money. Then you tell them to come by every Friday with something else and you will always have $20 ready for them.
Ease the timing back(rtard),and buy good gas 90-92, you'll be fine. Someday the valve seats will pound in from the kerosene/deisel shit ass gas they've been sellin us for the last 15 years. Happy Motoring...and Nice save from the scapppp.
[QUOTE __________________ OK smart ass, I was in a rush because the guy was in my kitchen, he was asking 150$, he was in a rush, this is why I was trying to rush, but then he caved and I got them for 50$, now, nevermind all the drag motor questions, all I wanted to know was an approxiamat comp ratio....give or take... so SORRY for bothering you...[/QUOTE] Wow, is your vagina itching right now? They have an over the counter ointment that will help. You ask for help, somebody offers help, and you get menstrual over the help.
I would never buy something that the seller had to have an answer "right now" How do you know they are not cracked, warped or the porting job broke through the casting somewhere?
HEY dont mess this thread up with logic or experiance. The OP has spoken that he has what he needed, a theoretical compression ratio out of unicorn land.
Well...in an effort to maybe help someone out there who is wondering what all this means, and why this stuff makes a difference, I put together two scenarios. These are working with the information given in the original post- 350 (originally a 4.00" bore), flattop pistons, and "64cc" chambers (these heads have nominal 64cc chambers, but in original form they tend to be larger- I've seen most at 68cc or above; or, they could be milled to reduce the size, or equalized, or even angle-milled....we just don't know). #1: Assuming 4 valve relief flattop pistons (the more common type) with 8.7cc reliefs (Wiseco); 68cc chambers; a positive deck height of .060 ("in the hole"); a 4.00" bore (we don't know if it's been bored or not, or to what); stock 3.48 stroke; and a gasket of 4.2 bore/.093 thickness (unlikely to use this, but again we don't know; and I've seen people do some weird shit ) and we get a whopping 7.51:1 compression. Even assuming a common FelPro gasket with 4.125/.039 dimensions, we get 8.35:1. Everything else is the same, and all quite possible with a quick-and-dirty "rebuild" where chamber size isn't checked or the block decked to zero. #2: Assuming 2 valve relief flattop pistons (the less common, but preferred type) with 1.8cc reliefs (JE); 62cc chambers; a positive deck height of .020 ("in the hole"); a 4.060" bore; stock 3.48 stroke; and a gasket of 4.1 bore/.015 thickness... and we get 11.36:1 compression. (I am assuming a deck height of +.020 to get a bare minimum of .035 piston-to-head clearance with steel rods.) As can be seen, there is a crucial difference between 7.51 & 11.36. While backing the timing out & using 93 octane may let a 11:1+ iron-headed engine run without detonation, at least under light or no load, to me it's not much of an option...but then I'm just a smart-ass, I guess...
O.K. so I fucked up, to all people that helped me out by answering my question, and that I later pissed on....I'm sorry....I am not going to go on and cry about what is happening right now in my life, but I'm just gonna say its not good, and yesterday night I guess Homespun91's post agrevated me, and reading it now, I don't know why, so for that I am sorry.
I'm glad they never put a "Kill the Dikhead" button on my keyboard,,I'da used it many times in the forums and chats.
Hwy hauler thanx for being a man, admitting you f--ked up. You have restored my faith in that most car guys are good people. Old car people rule
The Jalopy Journal
