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Discussion Starter #1
Hey, thanx for the input. I thought that the XE 268 might be too much. I dont really use this thing for off-roading much, just kind of a sleeper on the street and stoplights to make people turn their heads. Another question i had was compression that i am going to be running. The motor is a 350 and i am running flattop pistons with what i think has a 0 deck height. Would a thicker gasket help? This is pretty much a daily driver. Also, does anyone have any advice between running the Vortec Air-gap RPM or just the regular Vortec RPM? It gets pretty cold here in the winter and i realize i might have problems with cold starts and the carberator freezing over? Also, how much hp and torque is this thing worth?

350 that is .60 over
Flattops
Vortec Heads
RPM Air-Gap Intake
Comp XE 262 .462 intake .469 exhaust @ .50
Decent set of headers
Well tuned Q-jet

Thanx for any input.
 

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King of my Man-cave.
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2,896 Posts
You will be running around 10.3:1 compression, way too much for the torque-building XE cam. In fact, Comp had found out that their XE series of cams is more aggresive in regards to cylinder pressure than they originally thought. Use a cam than has 218-220 degrees at .050" lift.

Your Vortec heads have no provision for a heated intake manifold, so you will have a cold-blooded SOB in the winter.

tom
 

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Discussion Starter #3
Does anyone have any suggestions about how i can get by running the vortec heads with flattop pistons without having this high of compression. Just looking for some alternatives that would save me from putting in new dished pistons. If it were to have a 10.3:1 compression ratio with the flattops, what octane of fuel would i have to run with it, how reliable would it be, and what would be some of the troubles i would run in to?:confused: Also, if anyone can see any other problems with this combination, please let me know. Could anyone give a stab at a rough hp and torque figure for this combo, thanx?!
 

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10.3:1 is great. You will have high vacuum, good throttle response, and plenty of bottom end.

At this ratio you can run pump gas easily. Just run a cam with around a 220o duration at .050".
 

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I am running a combination similar to yours. I have flat tops w/ .025 deck, vortec heads, ZZ4 cam w/208 intake duration.

I believe this is about 9.8 and I was scared to death I wouldn't be able to run pump gas but it turns out I can run 87 octane.
 

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Discussion Starter #6
Thank you for the input. So you don't think that I would have a problem with running the Comp XE 262? Specs are 218 on intake and 224 exhaust @ .50 and .462 intake and .462 exhaust lift. I have been told that this cam would kill torque as it wont work well with this high of compression due to increased cylinder pressure. Hope I'm not beating this question to death, just want to know for sure. Thanx.
 

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http://teamrfc.gospelcom.net
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I ran a 355 with flat top pistons and vortec heads with the comp xe268h cam and it worked great. I always ran 91 octane in it, but I never had any detonation problems. The motor was in a 1972 ventura, (just like a nova). The car was used as a daily driver. As far as your compression goes with flat top pistons, you should be fine if you get your quench right. It is ok that your block is decked, just get around a 45 thousands head gasket, and it should work great. If you put a bigger gasket in the motor than that, you could actually have a better chance to detonate because of a poor quench even though you will have a slightly lower compression. I am basing this on my motor, which had flat tops with dual valve releifs. I dont know how much of a difference it would make if your pistons only had a single releif.

Good luck
Adam
 
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