flatout

Any engine guys in here know how big of a cam I can go without encountering reversion? This would be for twin small block chevy's. If anyone has a cam grind recomendation that would be helpful. This is going to be a winter project cam heads and intake.

fastestbowtie

Well my experience with boats with reversion problems is very limited so all I can say about it is that this is the cam I have in my small block and have been fairly impressed with it so far: Crane Hydraulic Roller HR-284-2S-12 1G. It has 222/230 deg of duration at .050 and .509/.528 lift in/ex with 1.5 rockers. It is supposed to have a power band from like 2500-6000 but when my 355 was built back in 1995 (before I owned the boat, I just have the build sheets and dyno sheets from when it was done) it made 424 HP at 5500 rpms, and 445 ft/tq at 4800 rpms, also I can idle around in the no wake zones at a low 500 rpms with out it even trying to die. Also, I have no sign of reversion that I am aware of and it still uses stock style exhaust manifolds and risers (allthough it does only have through the transom exhaust with no mufflers).

traviss

I have had no reversion problems with my small block... have EMI exhaust with the long tube risers. Have ran these crane roller cams with 1.6 rockers.

Crane part#109831 which is, 222/230 .542/.563 lift 112 LSA

Crane part# 109841, which is 234/242,.574/.595 lift, 112 LSA

and now running a
Crane part# 118691 which is a Solid roller 250/258 duration, .598/.598 lift, 112 LSA.

No problems yet LOL!

Oh yeah.. the boat is for sale

fastestbowtie

The part# 109831 would be the same one I have except I still have the 1.5 rockers which gives the .509/.528 lift numbers. Traviss, what was the idle like with the larger 109841, and have you run any of these with stock type manifolds? I would like to upgrade to a set of headers, unfortunately, I can not justify $2,000.00 - $5,000.00 for a set of headers on a $10,000.00 boat. If I end up building a 383 I was debating on whether or not to move up to that larger cam or just add the 1.6 rockers to the one I have.

hillbilly24

Just switch to dry exhuast and don't worry about it

pullmytrigger

Bowtie - what heads are you running????

fastestbowtie

They are some cast iron Darts originally purchased in 1995... According to the build sheet they have 2.02 in 1.60 ex valves, but it does not specify which head it is (if there were more than one back then) or what size runners they have. I have not even had the valve covers off yet to see what the casting numbers are. One thing I did recently find out is that I also have a fluidamper, which was not listed on the build sheet.

BROWNIE

Our recommendation (Stainless Marine) is 224 dgrees at .050" maximum with aftermarket standard risers (short).
As the risers get longer, you can go with more and more cam, until you finally run it with no water whatsoever in the pipe. Send me your email address and I will forward the reversion page from our new website. [email protected]

flatout

I don't know if this will make a difference but I have stock manifolds with 3 inch spacer risers and straight through transom with no mufflers. I plan on doing the whole package at once heads intake and cam.

traviss

I can sell you my 383 and you get the boat free!!

max hp with a 383,109831 cam, 5250 rpm
Max hp with a 383, 109841 cam, around 5500 rpm
Max hp with a 383, 118691 cam, ballpark 6000 rpm


109841... it idled pretty good. i think I had it idling around 600 rpm if i remember right. No stock manifolds. First cam I used EMI's with the standard aluminum riser. the alst 2 cams were used with the EMI manifolds with stainless tube risers. Now I run the 118691 solid roller. Idles around 800-900 rpm. Only downside is i have to start it in gear.. saves the alpha