mill9876

Im in need of some one to tell me a good size of the cam and carb needed for my build up of the 454 so here is what I have so far

SCAT
crankshaft 4.25
forged I beams 6.135
flat top forged pistons .030 over
9.0-1 compression
cast iron 336781 heads with 2.25I 1.88E
edelbrock rpm air gap
looking for cam size
looking for carb size

this is a gen 6 roller cam block and has stock manifolds and quick silver through hall exhaust
I am now looking in to EMI thunder exhaust after reading the posts can any one tell me if this exhaust will flow good for this set up
any help would be very appreciated thanks guys

picklenjim

If it's a mark 4 this cam.
http://www.summitracing.com/parts/CRN-139011/

This carb.
http://www.jegs.com/i/Holley/510/0-9...oductId=743728

1BIGJIM

iTrader: (1)

One of the biggest factors for a cam is
WHAT exhaust do you have or plan on having?

mill9876

sorry its a gen6 with a roller cam and im runing stock manifolds with quick silver through hall exhaust on a 1997 baja 202 islander

Griff

With stock Merc exhaust, you are severly limiting the cam choice and ability to make more power. You can really only use slightly more than a stock magnum cam or you will get water reversion.

picklenjim

This is the cam for the Gen 6.
http://www.summitracing.com/parts/CRN-168731/
As mentioned exhaust will be a big factor.

pantera232

I have similar set up with approx .6 lift cam setup...

What horsepower do you think he will see with this setup?

I run a 750 dp holly carb, if i dont ease into the top end it stutters occasionally but thats prop a fuel pump concern..

I had to add 10" pipes welded onto my risers with a stainless marine exhaust bc of reversion.

mill9876

looking in to EMI exhaust

jeffswav

Get the exhaust with long risers.
Your compresion will be lower than 9 to 1, more like 8.7 to 1. I have 8.9 to 1 and I have 489 with flat tops and 110cc chambers. A crane 731 would be good, or get a custom roller from RMbuilder. You may want to use 2.19 valves, you will want to do a good job on bowl blending with bigger valves. Here are the head specs 336781.....73-85...oval...OPEN...454, 118cc chamber, 256/114cc ports

Budman II

iTrader: (1)

What Jeff said. Additionally, make sure you get the heads cc'd. There can be quite a bit of variance on chamber size. I have a set of 781's that cc'd at 124 cc's. This would drop you to around 8.5:1 CR. To get back up, you may have to mill heads and deck block, and/or run a thinner head gasket.

If you are going to run the 2.25 valves on a 4.25 bore, it woudl be a good idea to bore notch the top of the cylinders to unshroud the valves.