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Old 08-28-2008, 11:30 AM
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Comments on this cam for my combo please

After much debating, I have decided that the cam I have in my motor now is way to wrong to try to fix. I have decided I am not building a race motor, I am looking for dependability and decent mileage. I will looking to install an overdrive tranny before too long to better enjoy the car.

I am leaning now towards keeping my heads (461s), and leaving the compression ratio alone (9.5:1), and putting in a cam to match the motor (355) as it is now, and get rid of the cam in there now. I am looking at the Comp XE274H cam. It looks like it will make respectable power, get off the line much better, and work with the combo I have now. 375 hp with 420 ftlbs. Enough for a Nova that I want to enjoy, and not be wrenching on all the time. Does this look like a good cam? 230/236 @ .050 with a .490" lift. That is including 9.5:1 compression and stock 2.02/1.60 heads according to Comp's CamFinder.

I think this would be a much better fit for my car. I am not interested in having a huge dollar motor, nor am I in need of that. I go to the track 1-2 times a year, and the car is most of the time at some local cruise ins. I have pulled my head out of the clouds, and would like the motor to have a nice idle, pull well from a standing start, and will run out of steam about 55-5800 RPMs. And that cam should work well with the 2500 stall I have now.

I know I have been a pita with this , but I am confused and now want to sort this out. I think the right cam will bring this motor alive again, and return the car to being something fun to drive. If you could, please let me know your thoughts. They are most appreciated.

Tiny

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Old 08-28-2008, 05:36 PM
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OK, you asked for comments. I'd pull back on the cam even more, to something like this....
http://www.cranecams.com/?show=brows...tType=camshaft

My reasoning is this: You have a 4.11 gear in the car now and are going to an od trans later. The od trans will have a final drive ratio of something on the order of 0.7, so if you multiply that times the 4.11, you get a 2.88 final drive. In order to cruise anywhere in 4th gear, you need to have engine rpm's down to keep speed down to around the legal limit. In order to make any power at lower engine rpm's, you need to shorten up the cam. 2,400 r's would be about 68 mph with a 28" tire and figuring 3 percent converter slip. Minimum cruise rpm's of the cam I showed above is 2,400 r's. It makes power from 1,600 to 5,400. I rest my case.
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Old 08-31-2008, 01:15 PM
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Thanks Tech, theat is almost exactly the cam I am going to install. I have settled on the Lunati 60102 cam kit with lifters and springs. Almost the same specs, maybe off very little. I have head great things about the Lunati cams, that is why I am heading that direction. Motor will be coming out by the end of Septermber and getting tore down. Fresh paint on block, new cam, and some general maintenance.

Is chinging valve springs something I can do myself, or do I need to take the heads to someone? And I will be putting new valve sealas in at the same time. If this is a do-it-yourself projectr, any advice would be most appreciated.

WildWillie
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Old 08-31-2008, 01:54 PM
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I'm sure that most on this board (myself included) would advise you to take the heads to a shop to have the valves and seats ground, however, backyard mechanics have for years successfully lapped valves if money was tight. I've done it myself on a budget rebuild. What you look for in this operation is a dull grey "witness ring" ground into the seat and the valve face, maybe 0.060" wide on the intake valves and 0.075" wide on the exhaust valves that goes all the way around in a complete circle, uninterrupted. If you can't get this witness ring on all valves, then a trip to the machine shop will be mandatory.

Assemble the heads with a set of old, worn-out, STOCK valve springs for cam break-in. After break-in, change the springs to the ones that are recommended by Lunati for that particular cam. Don't fudge on the springs. Use exactly the ones recommended.

Changing springs can be accomplished with the motor assembled by using shop air via a spark plug adapter tool to hold the valves in place during the operation. In lieu of shop air, feed a length of clotheshanger rope into the cylinder with the piston down in the bore. Bring the piston up to smash the rope up against the valves, holding them in position and keeping them from dropping down in the bore to change the valve springs. I have successfully used this tool to both assemble the springs onto the head on the bench and also to change them on the motor.....
http://www.jegs.com/p/Manley/748285/10002/-1/10797

Last edited by techinspector1; 08-31-2008 at 02:27 PM.
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Old 08-31-2008, 02:10 PM
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YOU SAID
"I think the right cam will bring this motor alive again, and return the car to being something fun to drive. If you could, please let me know your thoughts. They are most appreciated."


I would lean towards a 108 LSA and a 220 to 224* single pattern. That will give you a nice mild lope sound, snappy throttle response, and pull strongly from 1300 in the lower and mid range and feel good to 5500. I think your compression can stand it with the tighter LSA.

Lot's of guys like the Comp xe268h (224-230*), but I think the exhaust duration is too much.

JMO

Last edited by ScoTFrenzel; 08-31-2008 at 02:18 PM.
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Old 08-31-2008, 02:47 PM
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Thanks for the heads up, but I was told with the 461 heads to run a split pattern cam, that would help the exhaust flow with more duration. And I do not want to go too crazy with the lift, as I am looking for reliability. I agree I would like to have the 108LSA but I am having trouble finding that in the Lunati cam line.

WildWillie

Last edited by WildWillie; 08-31-2008 at 02:50 PM. Reason: spelling
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Old 08-31-2008, 03:02 PM
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Quote:
Originally Posted by WildWillie
Thanks for the heads up, but I was told with the 461 heads to run a split pattern cam, that would help the exhaust flow with more duration. And I do not want to go too crazy with the lift, as I am looking for reliability. I agree I would like to have the 108LSA but I am having trouble finding that in the Lunati cam line.

WildWillie
Most cam companies widen the LSA because most of the buyers are ordering too much duration for their intended purposes, and the wider LSA smooths the idle a little so the customer won't complain.

There is a trend the last 10 years or so to add exhaust duration for better high rpm scavenging with "stock" exhaust ports. That works for high rpms, but down at reasonable street user levels it hurts the scavenging. The longer exhaust duration reduces low rpm torque and adds high rpm hp..... overall flattening the torque curve. Personally I feel that giving up 10-20 down low is not offset by gaining 10-20 up high at 5500...... where I rarely am turning the engine.
If you are trying to get a snappy torque engine for street fun, killing anything down low is counter productive.
JMHO
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Old 08-31-2008, 03:11 PM
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You might check out the 268h or even the 260h commentary
http://www.compcams.com/technical/Ca...67_226-227.pdf
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