cam timing

[0ld school]

i have a comp solid roller in my 500" motor. 272/276 @.050 .661/.661. i have this same cam in 2 other cars. in this car, it just does not perform the way the other ones do. the engine combos are the same, so apples to apples comparison. it does not have the snap or the top end power, like it should.

anyway, i checked the cam timing, and it was off. the card calls for a centerline of 108*. i'm at 105*. would being that advanced kill it that much? should i re-set the timing to 108, or look somewhere else for the problem. the car runs great, just down on power

 

[805moparkid]

does it say that the LSA is 108 or that the intake centerline is on 108?

105 i would think would be a little advanced for that motor maybe some big block guy will chime in

 

[moper]

You say they are identical builds... What are the combinations? Normally the intake center line will move power up or down, but not change the peak numbers. Doi you have incrementals on a "fast" one and this one? Have you done a leakdown on it?

 

[0ld school]

does it say that the LSA is 108 or that the intake centerline is on 108?

105 i would think would be a little advanced for that motor maybe some big block guy will chime in

the intake centerline is 108*. i do not know the lsa.

 

[0ld school]

You say they are identical builds... What are the combinations? Normally the intake center line will move power up or down, but not change the peak numbers. Doi you have incrementals on a "fast" one and this one? Have you done a leakdown on it?

i did do a leakdown test. they were all about 7-10%. the motor specs on the other 500" and this one are:
500"
295 cnc sr heads
same cam solid roller 272/[email protected] .661/.661
1.6 t&d,s one has 1.7 t&d,s
indy 440-2d dualplane
13.1 cr

this one has never performed like it should. or even close to the others. i have not had this one on the dyno. the others did well on the dyno. 716hp 656 tq for the one with 1.7,s. the other one was chassis dynoed. it did 573 rwhp. i would say this one is down about 50-100 hp.

 

[moper]

What ddo the incrementals say about the runs? You say it's down.. Is it slower? Down on mph? 60'?

 

[0ld school]

something else was wrong... i did an other leakdown test today. all of the rings are stuck to the pistons

.i was loosing about 1/2 the starting pressure. it was all leaking into the crankcase. not enough use...

same thing happend on one of my other motors. pulling it out tonight, and will hone and re-ring it. the motor is only about 5 years old, about 1000 miles..... this sucks, my back is already starting to hurt

 

[Challenger340]

I have run that Cam many times, and I have had good success in at 105* atdc, which depending upon Spring Pressures and Valvetrain Deflection, seems about right for me ?

I can't comment on your Dyno Power, no 2 Dyno's are ever exactly the same it seems, but 716/656 seems more within "baseline" BR series Comp Rollers, ie the 273/.624" capabilities, even with 1.5 ratio, and far easier on parts ?
That must be a very critical Dyno or correction factor ?

 

[0ld school]

I have run that Cam many times, and I have had good success in at 105* atdc, which depending upon Spring Pressures and Valvetrain Deflection, seems about right for me ?

I can't comment on your Dyno Power, no 2 Dyno's are ever exactly the same it seems, but 716/656 seems more within "baseline" BR series Comp Rollers, ie the 273/.624" capabilities, even with 1.5 ratio, and far easier on parts ?
That must be a very critical Dyno or correction factor ?

thanks bob. my problem was stuck rings, no ring seal. it's going in the machine shop on monday, for a hone with torque plates.

 

[perfacar]

hi, guess my question, is, why are the rings stuck ? lands collasped down? just curious

 

[0ld school]

hi, guess my question, is, why are the rings stuck ? lands collasped down? just curious

i'ts from sitting. sometimes i start it just to move it, but not drive it. i think that is what is doing it. same thing happend on another motor.

 

[moper]

Yeah, better off fogging it and not running it, or starting it monthly and getting it up to operating temp. At least it was something stupid.