Topic: 17 350 head cc change from stock.
in Forum: C3 Engines
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I have a 1971 350 270hp (bore 4.00, stroke 3.48) with non matching (not original #3927185) heads on it. The heads are truck heads from what I gather @ 70cc, 1.72 intake ports and 1.50 exhaust ports. Stock had 75cc, 2.02/1.94 intake, 1.60/1.50 exhaust. No info on cam, stock exhaust manifolds (#3872735 LH), intake is high rise Edlebrok streetmaster, q-jet (# 17054923). Can anyone tell me what the result of these changes is from stock? I'm trying to figure out where I stand with this car/project and possibly what someone else has done.
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With the smaller cc's your compression ratio will go up maybe a .5 point. I don't understand the 2 diameters for each int/exe valves. The 270 hp 350 are probably 1.92/1.50
To check the cam for specs it gets a little harder. Without this and other info it is just a lot of guessing. If everything else is stock maybe 280-290 hp
To check the cam for specs it gets a little harder. Without this and other info it is just a lot of guessing. If everything else is stock maybe 280-290 hp
I believe that the 2 diff. numbers for the intake and exhaust are two different valves, one for the 270hp and one for the 370hp LT-1. Is there a way to check the cam lobe height without pulling the motor and pulling the cam? Also, do you think that this setup would be fine and run basically the same as it would with the stock heads?
Anyone???????????
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The smaller chambers will give a slight increase in compression, but the smaller valves will negate any gains from the increased compression, so that part is probably a wash...
You can check lobe lift, but it takes a specific dial indicator set-up positioned on the edge of the lifter, and, to get the most accurate results, you would need a degree wheel bolted to the crank. Is it worth it? That's a judgment call on your part.
I'd have to guess that what you have now is not all that much different from stock.
You can check lobe lift, but it takes a specific dial indicator set-up positioned on the edge of the lifter, and, to get the most accurate results, you would need a degree wheel bolted to the crank. Is it worth it? That's a judgment call on your part.
I'd have to guess that what you have now is not all that much different from stock.
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[QUOTE=Adams' Apple]The smaller chambers will give a slight increase in compression, but the smaller valves will negate any gains from the increased compression, so that part is probably a wash...
You can check lobe lift, but it takes a specific dial indicator set-up positioned on the edge of the lifter, and, to get the most accurate results, you would need a degree wheel bolted to the crank. Is it worth it? That's a judgment call on your part.
I'd have to guess that what you have now is not all that much different from stock.[/QUOTE]
One bonus out of this so far, the motor, trans. and chas. all match
You can check lobe lift, but it takes a specific dial indicator set-up positioned on the edge of the lifter, and, to get the most accurate results, you would need a degree wheel bolted to the crank. Is it worth it? That's a judgment call on your part.
I'd have to guess that what you have now is not all that much different from stock.[/QUOTE]
Thanks,
Great info
I'm not really overly concerned about it at this time, as long as these should run near as good as the stock ones. However, eventually I will need to address this rediculous head issue, as I want the car as stock as possible.
Should these heads run on this block without issue pretty much?
I think that for now as long as these things (heads) will be fine, I'll leave them. It just brings up questions in my head about things like streetmaster intake-#?, Q-jet carb-17054923 (75+), distributor-1112050 (Stock) and how they are interacting in this (mule cylinder head) cituation. Any thoughts?
One bonus out of this so far, the motor, trans. and chas. all matchin Forum: C3 Engines
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