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I currently run a 602 crate in my imca mod. I'm currently turning 6500 getting into the corners. I'm upgrading to a 4-link over the winter and will need to get a little more out of the engine. Now keep in mind this engine DOES NOT need to remain stock sealed. What upgrades can I do to get a little more rpms and power out of it? Cam, lifters and valve springs? or just valve springs, retainers/keepers? Would a slightly bigger cam help all that much? I've been looking at the Howards cams #'s 11276112 and 11287108. Comp Cams suggested #12-330-4 and the Howards numbers seem to be close to that. Any suggestions are greatly appreciated. Any specific numbers, parts and such would help too.
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IMO... the comp cams one you listed is a lot better choice than either of the howards ones. The lift and duration sound like a decent upgrade from what the 602 came with, which wasn't much cam wise. -
dirtman, thanks for the info and please bare with me if my questions seem rather stupid. I'm just not up to snuff on my engine details just yet. . the comp cam is rated up to 6300 rpms. I'm expecting to be turning about 6800 max. So if i go with that cam and understanding correctly, it will make power up to 6300 rpms but will still be able to turn 6800 rpms? As long as I have the right valve springs in (i'm going heavier than the stock 602 springs) I should not float valves and be able to hit about 6800 rpms correct?Comment
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Call comp cams and talk to them they will have the answers and know what will work best with what you are trying to do.
MikeComment
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The problem is that the crate motor doesn't have a lot of compression going for it, so that makes you have to be careful on the cam that you don't have one with too much duration. The comp cams one you listed is probably on the high end for what your compression ratio will support. Something with a mid 230's for duration may be better but then the cam will not make it into the rpm range you want. Which leads me to the question... Why do you have to turn it that high (6800)?
You kinda have to compromise. Most cams will pull past the rpm range they show but you may be out of straight away before that. Most of these pull the best to around 6000-6400 rpm, after that the rpm may climb at a snails pace which will get you nowhere on the track. You want it all to peak just before the corner. The track length, cam choice, gearing... all enter into it.
Sorry for the novel
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1/3 mile moderately banked D shaped oval. I'm already hitting 6500 rpms going into the corners with 5.29 rear gears, 3-link IMCA mod. Changing over to a 4-link this winter and expecting to carry more momentum all the way around the track and projecting 6800 rpms into the corners. My other option would be different gears say 514's but I feel that would absolutely kill me on restarts and cornering??Comment
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!5 points on the ratio will not kill you. The hair that you lose will be made up by the quicker / flatter torque curve that a 230 duration cam will provide. The description of your track is more momentum than a stop and go type.Originally posted by ask0329 View PostGator EngineeringComment
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I just dont see the rpm getting up that much further. Maybe some of it though. And Dave is right on the gear. That gear should be in the hauler any way to try I think! lol. I have a high end virtual dyno and its liking the comp cam. Be sure to let the cam manufacturer help you decide on springs. May even ask them on the cam too. They could have one perfect for what your doing.
My advice is to do the cam swap with springs, get a gear ready to swap and take it with you, and get your 4-link done and worry more about getting your NEW setup right!Comment
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The more i think about this something seems off. Regardless of engine if I'm turning 6500 into the corners with 5.29's on a 3 link and obviously expect to turn more as a 4 link, lets say 6800-7K at most. a fellow driver is turning 7200 rpms going into the corners with 5.67 gears. Does not make sense that I could be potentialy be that close in rpms and such different gears. Both IMCA mods, same tires, both for 9" rears. Granted different engines but still........Comment
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