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Author Topic:   Cam and power
Whitelightning
Member
posted April 13, 2004 12:06 AM
MY class is currently on a cam rule of 410-410 max lift. I have howards cam 11081 which is 410/410 , 288 duration, @ 50 230 duration its rpm is something like 2400-5800 but I turn about 6400. The cam runs strong but I am getting pulled down the straits buy what seems like just pure lack of power compared to the other front runners. I know for a fact that they are running like 480 lift cams and getting by with it. I have a good strong 350 bored 30 over, speed pro hypers with coated skirts= flat tops, stock rads and crank per rules, 76 cc heads 336 shaved to 70 cc and some port and polishing, cast iron intake, and running a q jet, 342 gear trans 1.68 on a 1/2 mile dirt track. Will I cam swap to a bigger cam help because unless they are way out the rules we should have basically same engines according to tech and rules anyway


modracer09
Member
posted April 13, 2004 08:27 AM
im not an expert by any means but what dose your rules state for intake and carb can you run a 4bbl intake with a 2bbl carb or dose it have to be 4bbl 4bbl alot of guys up here went back to 2bbl 2bbl because they had problems with the q jet s but i got an cast intake pt# 14098242 its a high rise cast 4bbl it came off a boat the ports are huge this is what guys a eldora are running in there street stocks with a holley 4412

good luck this year

BrianW
Member
posted April 13, 2004 10:01 AM
You mention that you're getting pulled on the top end, and the cam's power range is spec'd up to 5800 RPM - I'm going to bet if you look at a dyno graph of your engine power is dropping off rapidly from 5800-6400 and that's where you're getting pulled... They're probably geared to pull just past the peak HP of their cams (which may be the same 6400 RPM you're running if they're really running 'illegal' cams but they're making power while yours is dropping off.) Do you pull on them just off the corner??

I'd suggest getting a dyno baseline done, find the peak HP RPM and then gear so that at the end of the stright you're 1-200 RPM beyond that - if it's 5800 peak then shoot for 59-6000 RPM.

If you *know* they're illegal and that the track doesn't tech for cams then I'd swap to whatever cam best matches the rest of the engine combo (i.e. carb, intake flow, head flow, exhaust flow, compression, etc.)

modracer09
Member
posted April 13, 2004 11:14 AM
if you give me your valve sizes carb cfm exahust type (stock manifolds, small tuberhedders so on) i can put it in my desk top dyno and get you some info


dirtbuster
Member
posted April 13, 2004 11:33 AM
how do your cars compare throught the corners? Do you gain or lose there? What I have seen a lot of times on these limited engines like this is that many times whoever can get there car to handle best and get through the corner and carry the most momentum is often faster down the straight because they are carrying more speed out of the corner. They may not be outpowering you as much as out cornering.... jsut a thought.


Whitelightning
Member
posted April 13, 2004 06:10 PM
valve size I am not sure what ever stock 336 heads had in them, Carb is 750 cfm q jet, stock manifolds. I seem to be able to get in the corner has good and if not better than most and get off the corner great as faf as handling goes it really seems awsome. BUt even coming off the corners they pull me so I dont know what else to do. I am not the type that wont to be illgal but what opition do you have. Basically I run at the tail end of the lead pack can keep up but not anything more and I always tought that if i got it handling great that would be the advantage but I really can run my car anywhere on the track and it handles great so now im confused


racer17j
Member
posted April 13, 2004 07:18 PM
it's worth a try if they don't tech it then go for it. i felt the same way but hey if you can't beat um join um. i ran a crane 107200 it's a 480 cam works real good and still has a pretty smooth sounding idle


Ego Racing
Member
posted April 13, 2004 07:19 PM
What is the least RPM you come off of the corner at? If you are comming off a 1000 above them they may be able to plant the power better then the out run the car because of your top RPM. I have seen limited cams that at 500 RPM above the max they lost over 50 HP and went downhill from there. We had a " Limited cam" in a motor that went down 150 HP at 1300 rpm over the upper posted limit. It just dropped off of the scale and the guy thought something broke on the dyno but on 5 seperate runs it did exactly the same thing. We changed the cam timing and could only gain about 500 Rpm before it would start to drop.
Try to find a gear to run the rpm the cam is supposed to run.
I have run a latemodel with a stock 307 shortblock and a solid lift cam and geared the car to run in the rpm of the cam and finished 5th of 30 cars on a 50 lap race. It was not as hard on the tires so I could drive better at the end. It was down about 300Hp from the Alky motors but it did good, I just had to stay in the correct RPM.


Whitelightning
Member
posted April 13, 2004 09:11 PM
Hey I have another cam that is A Isky camshaft that I ran in a completely stock dish piston 350 and auto trans and was not happy with it a all, but the more I look at specs it may be a better cam for this aplication. What do yall think. Isky 201-LR4
Lift 420/420, duration 296/296, @ 50 it is 248/248, lobe center is 105, rpm range 3000-7500,


[This message has been edited by Whitelightning (edited April 13, 2004).]

[This message has been edited by Whitelightning (edited April 13, 2004).]

Raz_900
Member
posted April 13, 2004 10:39 PM
It's gonna be a bit big for a low comp motor, but could work out better. You might need to spin it 300-400 rpm more to keep it from feeling flat off the turns.

Maybe try retarding the cam that's in it 4 or 6 degrees. That could gain you 300-400 rpm on the top end and it won't drop nearly as fast past the peak.

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