New Guy Here with some questions Re: Chev 350 and Exhaust

[Beech2000]

Wow replace manifolds and risers every 3 years?

I've priced them and unless you know where to puchase cheaper it seems $1000 USD is the norm for SBC. Ouch.

know of better resource for risers and manifolds?

[Beech2000]

Wow, replace exhaust manifolds and risers every 3 years?

I've priced them for the SBC and $600.00 USD for all 4 pieces seems to be the norm.

Is there a cheaper resorce for them?

[Beech2000]

Mis comfaluation on first reply

[Galaxie_406]

Let's talk about the manifolds first, the manifolds have been replaced, when not really sure, it was done prior to my obtaining the boat. The manifolds are Barr with the later model casting numbers, flanges looked excellent with no rust over and the manifolds have actually been dry for quite a few years and did not have much water jacket rust or buildup. I did not pressure test the manifolds, I did build the block off plate but I really think the cam was the culprit on this and the local speed and marine also said that the cam was wrong for the application. Maybe this is a gamble, but I will test the boat in water and pull the risers after the test and take a look for any water indication.

[Beech2000]

So what Cam did you replace the ISKY with?

What are the specs?

Still scared to much cam in my 5.7

[Galaxie_406]

Actually I replaced a Predator grind with the Isky cam as it came with the rebuilt Marine engine I picked up for $250 and it has a Forged Crank. Now it appears there are 2 variations of this cam Part Number# 201264 one for the street and one for Marine Part Number 201264/271-12 which I did not see the 271-12 stamped with 201264 part number but I may have missed it. But never the less they are two different cams.

Here's specs on the marine http://www.iskycams.com/pdfcatalog/2004-05/page164.pdf

Here's specs on the 210264
http://store.summitracing.com/partde...art=ISK-201264

One thing (Very Important) is that running a Sterndrive will require a very smooth and low idle to keep from crashing into gear.

[Beech2000]

Great thanks.

Looks similure to mine except for a little less lift.

Thanks for the reply

[RMSOSF]

Wow, that is a flat cam..... I prefer to see more duration on the exhaust side than the intake. Seems to me that cam will bottleneck the engine.

[Galaxie_406]

It might, but my last cam I think caused the problem with sucking up the exhaust water.

xxxxxxxxxxxxxxxIntake Exhaust
Duration @.050 214 224
Lobe lift .295 .310
Lobe separation 107 117