HippieCustoms

I hope this is an easy one for somone. I have a 92 5.7 in a wellcraft. Have some plans for the engine this winter, but would really like to find out what the stock cam specs are before I order a cam. Any help with this will be appreciated. Thanks, Hippie.

traviss

Tha only thing I could find in my books are these


GM part# 340284, Merc# 431-5943
flat tappet- 200/212 duration, .400/.410 lift


Merc#431-811658
Roller - 197/207 duration, .430/.450 lift

HippieCustoms

Thanks, although, ouch, what a wimpy grind. Definately has to go. I was hoping I could gain alittle by going with a set of 1.6 roller rockers, but that cam is so small, why bother. I'll get a good grind and then just run the 1.5 rollers. Was thinking about the xm262h by comp. Any input would be appreciated.

traviss

What are the specs on that cam?



There is a book you should pick up.

"small block chevy marine performance"
Author Dennis moore.

It will tell you anything you need to know about your stock motor and what to use for modifications.

He use to be on the board but I haven't seen him in a while.


Travis

cuda

I used a Crane Cam #113941 in the engine I'm building. I haven't finished it yet, so I can't comment on the performance.

HippieCustoms

specs on the xm262h- 218/224 @ .050 duration
462/477 lift
112 lsa
If I do end up going with this cam, I will run the 1.5 crane gold self alinging rockers for center bolt valve covers. Thanks again. I will look into picking up that book.. Hippie.

mcollinstn

I'd say the XM268 will be a good cam for a 350 with pocket-ported heads, an AirGap intake, and a large flame arrestor on top of the rejetted Quadrajet.

Reasonably inexpensive ordeal.
Good luck

Pat McPherson

The XM268 is close to the cam that Merc. used in the 280TRS and 300 Tempest.
Sorry, I can't seem to find the spec. from the last one I built.
I can say that changing the cam, and rejetting the carb, I gained about 400rpm and 4mph in a 20' Donzi with a 270HP/350mag...

HippieCustoms

Well let me share my plans with you guys. right now the boat has an edelbrock performer intake on it with a velocity stack flame arrestor and stock exhaust manifolds going through the hull. Boat runs 53mph according to my gps. Engine is turning right at 4,500 r's with a 19 pitch cleaver. I have a set of stainless marine high torque manifolds with ss risers to go on it. I am getting a complete msd ignition including 6al box. 1.5 roller rockers and the xm262h cam kit with matched springs. After I do these things, what do you guys think I can expect? Thanks for all the input.....Hippie.

jafo

I would seriously consider putting heads into your budget- using the light cast stock heads will hinder any flow increases you hoped for with cam, exhaust, intake, and re-jetting of the carb. Vortecs or World Products heads will give you a substantial increase power over the stockers.
Although MSD makes good ignition components, you really won't get any substantial power increase for your money--the Thunderbolt IV is an excellent all-around high energy system for the SBC. Put your money into the heads.
Jim