kingrich

I am in the process of installing a 1996-2000 model (GM 3/4 -1 tonne truck) 5.7 L GM new longblock in my 20 ft 1997 Wellcraft . I intend on mainly skiiing and cruising. I would like to know if the stock vortec L31 cam# 10241264 specs are going to be close enough to marine cam specs to use.

Last engine was 200 HP 1996 5.7 L (without vortec heads) and 2 barrel and was quite suitable before I Ouch! cracked the block and heads(froze - I know!!). Going to edelbrock vortec manifold, edelbrock 650 cfm carb, electric fuel pump and possibly harmonic balancer??? The crate engine vortec balancer is 8" dia. while my old marine 5.7 had a 6 3/4" dia. Is this because the vortec has a different lower assembly that requires the larger balancer or can I put the smaller balancer on my new vortec? Flywheel/coupler, starter & waterpump are all the same off my old marinized 5.7 L engine. Is the stock cam close enough for my needs and does everything look like it will work. Your feedback is greatly appreciated as I would like to complete in time for the boating season.

Rick


96 L31 camshaft profile, P/N 10241264
Intake:
Opening_________Closing____________Duration
.004 14 BTDC____.004 61.5 ABDC_____255°
.050 13 ATDC____.050 22.5 ABDC_____190°
Inlet centerline 106.25°
Max lift .275 x 1.5 ratio .412

Exhaust:
.004 62_________.004 24 ATDC_______266°
.050 31.5_______.050 16 BTDC_______195°
Exhaust centerline 115.75 degrees
Max lift .281 x 1.5 ratio .423
Lobe seperation 111°
--------------------------------------------

S-24

Change it to Crane 104224, it would really make a difference,
with Vortec Air-Gap intake, do not use the performer, you will get much more with the Air-Gap. There is dyno sheet in OSO
dyno room of 385hp/350. It run`s from 600rpm idle to 5400rpm. Nothing special, stock vortec heads, and little bit bigger cam 109821. But use 104224, and you`ll get it done
without machine shop. Just what I learned from here.

Mike

kingrich

Thanks for the info guys. I guess I just wanted to know if the stock vortec cam was close enough to do want I want. I am prepared to change cams if necessary. Do you know if I need any other mods with the crane cam such as springs, pushrods etc. or would I need to talk to cam manufacturer about that. I am a backyard mechanic with far less experience then most on this site but could probably handle the above. I am intending on using the air gap vortec manifold with edelbrock 600 cfm. Waiting to purchase until I get some more feedback.

Thanks Rick

S-24

Buy crane #10309-1 spring & retainer kit. It fits without modifications, I believe stock push rods work, though I would
use crane 10621-16. No need to change rocker arms, or studs, my machinist had to really make work to get the studs
out, when I changed to screw-in`s.

Mike