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Author Topic:   Camshafts!!
FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted June 01, 2005 06:51 PM  
I'm running a 1/4 mile low banked track with a 388 chevy. I'm currently running a Comp Cam but need more off the corner pick-up. Who do you guys use for camshafts?? I know a some of you run Midwest motorsports cams. Which ones do you use? Also has anyone used the camshafts from JR Motorsports?? I've always used Comp Cams, but I'm thinking about exploring into other brands. Mainly brands that are more focused on my type of racing and my type of car.
Thanks for any replys!

George Gilliland
Dirt Forum Racer

Total posts: 92
posted June 01, 2005 07:41 PM  
This seems a little odd to me in that on a flat 1/4 mile track, usually the problem is the tires spinning too easily coming off the corner. Are you geared right? Is the engine in the power band when it is coming out of the corner?

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted June 01, 2005 07:46 PM  
I'm geared 5.67. Car bites good. I've got it running in the top 5 every weekend until I tear something up LOL!! Monday we ran a Memorial Day race and in hot laps I dropped a valve and took out a piston, head and the cylinder wall!!!

Oh yeah, It's in its power band so to speak, but half way down the straights it takes off!! The problem is, when I called Comp Cams and got this cam I have now, they must have had an off day because I looked up the number a few mins. ago and its a 3/8 to 1/2 mile cam!! Thats the problem.

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted June 01, 2005 07:48 PM  
one more thing, the 1/4 mile track I run the lay-out is different from most. The turns are more of a sweeping turn, not a hairpin. Get the setup right and learn what to do with the big pedal on the right and you can hook em' up pretty good there!

andykmod
Dirt Freak

Total posts: 351
posted June 01, 2005 08:49 PM  
1/4 miler and only a 5.67, When i run a 1/4 i run a 6.00 and turn about 7200 @ the most. Maybe advance the cam and go up in gear, that's what i would do.

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted June 01, 2005 09:01 PM  
My rev limiter is set at 8000 and last year I ran a 5.83 gear. I was bumping the rev limiter as I went into the turn, about 50 feet before I needed to lift. My tel-tel quit working so I don't know what its doing now, but I have hit the limiter this year with the 5.67's. The track was tacky and I only done it once but it did happen. 5.67 is the gear most all the guys around here run.

About 3 years ago I ran a full sized clutch in my other mod and I geared it 6.00. It worked good for the big clutch but I'm afraid it would be a little too much with the small clutch!

I've heard alot of people say 5.67 isn't enough gear. I don't know what the difference is but around here its just right. Last year a guy I run with was geared 5.83(like me, but his engine was much BIGGER) and after the race his tel-tel said 9200!! I know that seems WAY high but its true. I'm not sure if he was spinning or not but he said thats what it always turns. He ended up scattering it! LOL!!

pbrcowboy2
Dirt Freak

Total posts: 380
posted June 01, 2005 10:34 PM  
i used the 14103 from speedway and loved it then i called rex at midwest he recommended the number 7 so i found 1 with match set of lifters from one of my fav late model drivers...i paid 75$

motor sounds awesome now im just waiting to race this friday i'll let ya know.....

buy the way i drive b-mods 5/16ths mile track, 4412 stock holley, 350 .060, 4 valve relief flattops, tilton triple disc, and 6.00 gear car wieghed 2650lbs after hot laps!!

I have always ran my 6.00 and tilton i have turned way close to 8000 rpms but that was way way way dry slick last year right now i have turned about 7200-7500rpms

Kromulous
Dirt Forum Champ
Total posts: 796
posted June 02, 2005 08:05 AM  
Selecting the right cam is crucial, as you know by now i guess.

Anyway there is alot to be considered when selecting one, and the people at Comp cams from my expierence are clueless.

Were running a Camcraft roller this year, good company but they arnt much into UMP style Mods. Lazer Cams would be the one i would call and get a recommendation from, they got a website as well.

Things to consider / variables when selcting a cam, rod length, rocker ratio, intake volume size, fuel type, compression ratio, carb size & a few other things. So there is alot of thought that goes into it.

First impressions thou, say you need less duration @.050 lift. Seems like your not in your power band coming out of the corner, comes on hard 1/2 way down the straights etc, RPMs to low on corner exit.

Whats the durations @ .050 lift at right now on your Comp cam?

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted June 02, 2005 03:40 PM  
what I have now is the comp cams 12-512-5. Its a tight lash cam. @.050 the duration is 250 intake and 259 exhaust. Advertised duration is 280in. 288ex. and lift is .530in. .550ex. The duration isn't as high as some of the cams I seen at MWMS for openwheels. 280/288 seems close to what I would think would be needed, but obviously not. I think MWMS had one that was 278/280 that might be better, that'll bring the RPM range down.

Kromulous
Dirt Forum Champ
Total posts: 796
posted June 02, 2005 04:08 PM  
One of the better solid lift cams i've seen is an Isky 547A i believe is the number. About the same lift, and the durations are better suited for some good torque 254 & 259 @ .050 i beleive.

Most solid lift cams i've seen the durations on the INT & EX are to far apart, to much split or not enough. 4 to 6* max i beleive, especially with 23* stuff.

Anyway, thats what i've noticed and all the things i've read so far, your mileage may vary.

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted June 02, 2005 04:36 PM  
Thanx for the help Krom, I'll check into Isky!

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