Hibbs

79Formula - Thanks for the data point that is helpful.

What were you running for rocker arms and valve springs? I am looking at a set of roller rockers but want to find something that will fit under the stock center bolt valve covers?

Also - I am not sure what you mean by "open center port" for the Vortecs. Could you help me there?

79formula

http://www.2quicknovas.com/vortec.jpg The middle hole goes nowhere. I ran stock springs. The machinist told me they were good to .500". I was also running stock rockers. The boat ran awesome, was super reliable. I would recommend that build to anybody. Great bang for the buck. I estimate 400-410 based off the speed i got and magazine builds.

79formula

Heres a few articles I used for reference.
http://www.hotrod.com/how-to/engine/...k-chevy-build/
http://www.superchevy.com/how-to/678...cam-355-build/
http://www.superchevy.com/how-to/490...e-roller-cams/

Hibbs

Thanks for the links.. those are great and I'll read them over the weekend.

The set of rebuilt Vortecs I purchased have been drilled and tapped with 3/8 studs installed and have upgraded valve springs which I was under the impression I would need for possibly the 262 cam but definitely a 270. I may just end up going with the stock rockers (or just a roller tip rocker) and that would solve any clearance issues with the center bolt valve covers.

Just to clarify... was your 355 running a roller cam?

Thanks again for the info!

79formula

I ran the xtreme marine 262 flat cam.

airjunky

Building jet boats feeds my kids .exceeding 5000 rpm pump shaft straightness and bowl bushing fitment ect become critical .don't start cutting below a b cut to make things right .you might be suprised what a 750 carb will go on that 350 if you can somehow get it to pull 5000 rpm with cast exhaust and a b impeller .which will prob involve 1100 rpm idle speeds and animated docking manuvers .,but possible

airjunky

Late friday nite , beer , pizza and horribly demented phone . But I'm going boat from massachusetts and berk jc pump .beefy hull layout for a short boat .your going to need power to beat a modern stingray with a alpha and a 220 Vortec fast burn v6 but it has b

FIXX

Hibbs,,i run the 270 xm cam.your gonna need it with the b impeller...it has vary strong low and midrange power and thats what you want with a jet pump..if you did not do the machine work yet look up the bee hive springs for the vortec heads,you wont have to machine them..im running the roller cam springs that came with my cylinder heads which has a little more pressure but thats ok because it keeps me from floating the valves..you may also want to use a crower stainless steel rocker,,a little more money but they are bullet proof...get the 270 xm cam and advance it 4* ,that will make it a stump puller and that is also what you need in a jet..low and midrange power..

Hibbs

airjunky - Thanks for the info and I didn't expect to find a jet drive guys on here.. sweet! I'm not expecting the boat to be a screamer but it will be different, low budget, and should be a lot of fun to build. I was able to pick up an Energized Jacuzzi YJ that was totally rebuild for dirt cheap. It is perfect shape but it has an AA impeller in it so from what I've read that isn't going to work well with a 350 hp small block. Base on the charts I've seen they tell me I should be going with a b/c. That is whey I'm currently thinking that way.




FIXX - I'm cool with going with the 270 XM cam if the general consensus is that it will benefit me even if I don't think this motor will see much more that 5200 or 5300 rpm. What are you running for compression? Do you think I will benefit if I am only 9:1? My only other question would then be around potential problems with exhaust. The EMP system look different from the stock system I'm running... I definitely don't want to run into any reversion issues.

My heads are done so the the guy I bought them from already had the spring bases machined and stronger valve springs installed.

Jonesyfxr

Do yourself a favor and buy the Alex's spring kit for Vortec heads. They make the process simple and it's a kit that comes in being budget friendly too!!

http://www.alexsparts.com/valve-spri...d-flat-tappet/

Hope this helps!!

Looks like a nice project and can't wait to see the final results.