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post #1 of 16 (permalink) Old 02-11-2017, 08:24 PM Thread Starter
 
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Cam for 8.3:1 389

I have a 389 that I pulled from 65 gto to rear main and oil pan and clean up. I was thinking to put cam in it while I have it apart. 6x-8 heads cut to 92cc. Comp cams recommended High Energy Camshafts 51-232-3. I have read others using extreme energy cams for lower compression. Any thoughts on this cam or others you would suggest? basically stock setup. Motor had 112cc 4x heads and cam marked 540 233 which I have seen others ask about. I dont think its worth spending money on to get it measured out. Not looking for crazy HP just something to compliment the new 92cc heads. 3.42 rear axle and 4 speed muncie. Thanks in advance
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post #2 of 16 (permalink) Old 02-11-2017, 08:46 PM
 
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Voodoo 256 or 262--assuming your ring seal is good.

Voodoo Hydraulic Flat Tappet Cam - Pontiac V8 256/262 - Lunati Power

Voodoo Hydraulic Flat Tappet Cam - Pontiac V8 262/268 - Lunati Power

And if you still have valve reliefs in the stock 389 location, be sure to check valve to piston clearance. The 6x head valves are at a different angle than the 389 head valves were. Therefore the reliefs are in a slightly different location.
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post #3 of 16 (permalink) Old 02-11-2017, 09:50 PM Thread Starter
 
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Valve reliefs are in stock locations. 4x heads were on it I am not sure if these are the same angle as the 6x. Thanks for the info. I will have to figure that out
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post #4 of 16 (permalink) Old 02-12-2017, 11:31 AM
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Helped a friend with his '65 389....stock heads but dished pistons. About 8.5 :1 max, probably a little less. 4 speed, 3.36 gear. Ran a Com Cams XE262 and a XE268, which is in it now, and it ran like a scalded cat with the 262 and still does with the 268, with a little more lope. He has a few years and a few thousand miles on it now, and it was a budget build that worked out very well.
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post #5 of 16 (permalink) Old 02-12-2017, 01:19 PM
 
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Originally Posted by mjc707 View Post
Valve reliefs are in stock locations. 4x heads were on it I am not sure if these are the same angle as the 6x. Thanks for the info. I will have to figure that out
Yes, 4x & 6x heads have the same angle. But, again, the 389 reliefs are in a slightly different place than in '68-up 400 pistons. And, the valves in the big chamber heads may be slightly further from the pistons--don't know. If so, the same cam will put the valves closer to the pistons, when using the smaller chamber heads. Valve distance from the head surface may be the same, with just a bigger chamber. I suppose the difference(if any) could be measured, with accurate measuring equipment.

Better to measure & check things BEFORE ordering parts.


"...Ran a Com Cams XE262 and a XE268..."

Most Pontiac engine builders do not recommend the XE cams. In fact, the CVMS guy is the only one I know of. For low compression builds most recommend the Voodoo cams, instead. They supposedly shut the valves more gently, making less "valve slap" noise, than the XE cams.

No, I've never run any of these cams. Just passing on info. You can search the PY site, or ask them about the XE cams & get lots of opinions.

Last edited by bigD; 02-12-2017 at 01:41 PM.
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post #6 of 16 (permalink) Old 02-12-2017, 05:44 PM
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The XE cams build a lot of cylinder pressure early, which works well with low compression applications. My friend's engine makes a ton of power from 1200 all the way past redline. That said, they are a poor choice for stock compression ratios because of the elevated cylinder pressures. Have also heard of the fast valve closure, but from what I've experienced, not an issue. your mileage may vary......
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post #7 of 16 (permalink) Old 02-12-2017, 07:50 PM
 
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If you wanna hear some feedback about XE cams, post the question on the PY forum. There are some very dissatisfied users.

And it's not just Pontiacs, the XE cams make noise in any engine, because of their aggressive lobe profiles.

http://www.clubhotrod.com/ford-fe-bi...cam-noise.html

http://www.chevelles.com/forums/18-e...s-xe-cams.html

http://www.camaros.net/forums/13-per...-question.html

http://nastyz28.com/forum/threads/va...-xe-268.76859/

The Voodoo cams have lobes which increase cyl pressure, without the noise. Not just my opinion. It's what LOTS of guys say, including many engine builders.

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post #8 of 16 (permalink) Old 02-12-2017, 07:50 PM Thread Starter
 
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Comp cams guy said he didnt recommend the XE but if I was to go with one to go with XE262 at the most. He also said I would get more vacuum since I have power brakes with the High energy. I sent in a cam recommendation form into Lunati a couple weeks ago and no response yet. I am not looking to build the whole motor at this time. I just couldnt see puting it back together the way it was
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post #9 of 16 (permalink) Old 02-12-2017, 08:22 PM
 
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The Voodoo 262 is similar to the XE 262 the CC guys mentioned, but without the noise, and has a 112 LSA, according to info I've read.

Voodoo Hydraulic Flat Tappet Cam - Pontiac V8 262/268 - Lunati Power
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post #10 of 16 (permalink) Old 02-12-2017, 09:21 PM Thread Starter
 
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bigD I see what your saying about noise on XE cams. VooDoo cam looks like good option. I guess I need to figure out springs too. However the High energy from Comp supposedly does not have this noise. decisions decisions. I appreciate all the info. I am not sure what the difference in the 2 voodoo cams would be for my application
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