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Author Topic:   cam question for engine builders?
maniac motors
Dirt Maniac

Total posts: 128
posted December 02, 2004 04:41 AM  
on a 2 bbl 4412 cat iron gm intake gm iron head motor with flat tops and crossover headers. i was thinking of trying a solid lifter cam wit a little less lift and using 1.6 roller rockers or higher ratio.am i better to use more rocker ratio on both intake and exhaust or just intake because the restriction of the intake and 2 bbl carb.
also looking in to firing order swap cams and have heard of a 4-7 swap and another that swaps 4 cylinders in firing order.are these cams worth the extra expense in a 2 bbl dirt track motor? any help would be appreciated. Scottfowler 10xracing

KPLugnut
Dirt Forum Champ
Total posts: 1019
posted December 02, 2004 06:57 AM  
We've had good results with sticking to increased rocker ratios on the intake side only with those motors. 1.6's at least on intake and 1.5 on exhaust.
Talk with Charles at Camcraft Cams, and he'll get you in front of all the competition.
I'm not sold at all on firing order swapping in motors at this level. Not worth the expense at all...

Tell Charles we sent ya, too. :-)

KP

sdhnc29
Dirt Forum Champ
Total posts: 934
posted December 02, 2004 04:32 PM  
We too have seen gains from the higher rocker ratio's. This has been true for most everything. We are currently using 1.8 or 1.7 intake rocker's, and 1.7 or 1.6 exhaust rocker's on the 2bbl engines. But these are all custom grind's. If your looking at higher rocker ratio cam's, Crower offer's some very good shelf stock cam's that would come close to what you need.

I also agree with KP on the 4 and 7 swap. However, Crower has told us of a few thing's that he has found with this that are proving to be significent. I have personally not tested one of his new design's, so I can offer no info on this. However we may try it in a mule motor this winter.

Steve

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780

KPLugnut
Dirt Forum Champ
Total posts: 1019
posted December 02, 2004 07:39 PM  
I'd be interested in hearing the results on that, Steve. Thanks for that heads up, too. I knew there have been a lot of builders still searching for that elusive gain that is claimed by the "swapper" cams. Guess it's like a lot of things, only a matter of time, right?

KP

sdhnc29
Dirt Forum Champ
Total posts: 934
posted December 02, 2004 10:21 PM  
You got it KP. Your right, it just a matter of time.
Steve

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780

engineman
Dirt Full Roller

Total posts: 55
posted December 03, 2004 05:29 AM  
I agree with Steve and KP on rocker ratio.

So far I've only built one 4 & 7 swap engine, and it didnt impress me much....no big gains here.JMHO

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Mark's Racing Engines
(903)883-0196
www.northtexasracing.com
engineman@northtexasracing.com

[This message has been edited by engineman (edited December 03, 2004).]

maniac motors
Dirt Maniac

Total posts: 128
posted December 10, 2004 06:01 PM  
okay use this combo for an example and tell me how you think it would work?

.030 4 bolt 350
flat top 2 valve relif pistons
5.7 rods
462 heads angle milled
crower 351 cam degreed to 101 or 102 centerline
1.6 rockers on intake,1.5 exh
canadian 2 barrel
4412 holley

any ideas or better suggestions?

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