How high can the 420A engine rev safely on stock springs and retainers without worrying about valves floating or what not? Also, what is needed to get rid of the rev limiters ? (7200 and 7800 fuel/ignition cuts) would a msd ignition work? just wondering. Im rebuilding my engine and Im trying to decide what to do head wise. Originally i was going to get stainless valves, crower springs, retainers, pt cruiser lifters, rockers but someone said I should get cams and get port work done instead of getting the wprings, retainers and lifters since the stock ones are fine. anyone know?
i figure i may do rt2 since i can always get springs, retainers, lifter and such later on and the head would not have to be removed (at least i dont think it would) to put those in, where as getting it ported and polished would.
#58808, "RE: How high can engine rev safely?" In response to Reply # 2
The rocker arms can go up to 7200 rpms with no problems, any higher and they have the potential to break. Upgraded rockers from a PT cruiser (or blackdog racing rocker arms) solve that problem.
The stock valve springs and retainers can reportedly handle 8200 rpms on stock cams or mild cams, but I don't know if they can do that with the increased lift on agressive cams. I think the retainers would, but I'm not sure about teh springs.
Lifters should be fine to 8200 rpms as well. Lifters from a PT criuser have improved oiling, which is always better, but I don't remember anyone having problems with stock lifters. (it's not like the 4g63 lifters )
#58810, "RE: How high can engine rev safely?" In response to Reply # 0
>Also, what is needed to get rid of the rev limiters ? (7200 >and 7800 fuel/ignition cuts) would a msd ignition work? just >wondering.
there is no way to defeat the stock rev limiter without buying the AF/X computer or having a full standalone. although the MSD and the Crain units are highly effective, they are sitll just piggy-backs to the stock ECU.
in addition to everything else that has been said... unless you are turbocharged, you'd need some insane cams to make any real power up that high. something like the crane #18's, or in other words, the most aggressive and non-streetable camshaft that you can buy.
#58820, "RE: How high can engine rev safely?" In response to Reply # 4
Does the AFX ecu handle the 7200 fuel cut problem? I remember it pushing the ingition limit to 7800 but you still can't get that high without hitting fuel cut (7200). To my knowledge there is not anyone who yet has the ability to rev past the 7200 fuel cut, am I correct?
I edited to the wiki!
Originally posted by DR1665 NOTE TO SELF: Go commando to wedding. Scar the Irishman for life.
#58873, "RE: How high can engine rev safely?" In response to Reply # 5
yeah. supposely you can rev to 8200, according to what's written on Howell's site. but you're right, i haven't heard of anyone here who has actually done it.
#58917, "RE: How high can engine rev safely?" In response to Reply # 7
I remember Dino saying that the redline was 8200 but you still can't get there because of the fuel cut, so nobody will ever know till we find a way to beat the fuel cut.
I edited to the wiki!
Originally posted by DR1665 NOTE TO SELF: Go commando to wedding. Scar the Irishman for life.
#58924, "RE: How high can engine rev safely?" In response to Reply # 10
I went 1st,2nd,3rd,2nd today by accident and thought the rev limiter would kick in....I was wrong! Since I have the A/T Tach in there still I can only guess how much past 8000 it went I'm thinking 8300 or 8400 and no damage at all but I wouldn't want to do that all the time.
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