Cam Analysis Paralysis
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Joined: May 2008
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From: Annandale Virginia
Piston
I have no idea what kind of piston's they are. This is a 76 L82, all the numbers are correct on the block, however the engine was rebuilt and apparently "blue printed" prior to my purchase by Tucker's Automotive in Nevada. I have the receipts and the shop did some interesting things like Z 28 springs, valve guides, comp magnum roller rockers and apparently these weird pistons. It's almost like they have a little dome on the one side. I haven't measured, but they don't look very far in the hole either. I'm wondering if these are supposed to bump the compression on the 76cc heads? I've never seen a piston with dimples.
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Joined: May 2008
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From: Annandale Virginia
Last edited by 68FireBird; Oct 3, 2011 at 10:22 PM.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
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From: Seattle WA
St. Jude Donor '14
Here's my pass on the XE274 vs the 60103. This is with my new Dynosim 5 software...and it seems to me that it's a fair bit optimistic on torque - maybe 5% or better optimistic.
The numbers went up a bit overall, and honestly I'm still working through my models to import/convert and review...but I think it's valid for comparison.
The Lunati makes a bit more torque down low, the CompCams a bit more HP at the top - very interesting! I'm going to try to use a Lunati in my next build if I can convince the owner - those curves are too interesting not to try to validate on the dyno.
I would probaby keep the XE274 as I don't see the numbers as being that significant.
Playing with the model a bit, there was indeed around 30 HP/15 TQ waiting with a better intake, a dual-plane high-rise like the Performer RPM.
The numbers went up a bit overall, and honestly I'm still working through my models to import/convert and review...but I think it's valid for comparison.
The Lunati makes a bit more torque down low, the CompCams a bit more HP at the top - very interesting! I'm going to try to use a Lunati in my next build if I can convince the owner - those curves are too interesting not to try to validate on the dyno.
I would probaby keep the XE274 as I don't see the numbers as being that significant.
Playing with the model a bit, there was indeed around 30 HP/15 TQ waiting with a better intake, a dual-plane high-rise like the Performer RPM.
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Joined: May 2008
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From: Annandale Virginia
Engine is broken in and running
Things seem to have worked out real well. Thanks for all the advice. The engine broke in with no issues. Rebuilt the carb per instructions in Cliff Ruggles book. Had to change the spring in the power piston to a lighter one to clean up the idle some but other than that the Q-Jet is right on. I used Doug's sidepipes and they fit with no issues but are loud as crap witht the max flo inserts
. The car runs strong and I'm real happy with the performance. BTW total advance looks like 30 degrees, is that enough? I'm running at 12 initial and that seems fine. I have a small oil leak at the back of the intake and want to play around with the tune, other than that this project is finished.
. The car runs strong and I'm real happy with the performance. BTW total advance looks like 30 degrees, is that enough? I'm running at 12 initial and that seems fine. I have a small oil leak at the back of the intake and want to play around with the tune, other than that this project is finished.
