SBC Built, now looking for jet recommendations
 

Hi all,

I am new here, thats not to say that i havent been lurking for a long time.I am just really good at searching and finding the answer i need :-)

However it seems my "googlefu" is off or something today.

Here's the deal, I have a 1980 Bahner mini day cruiser with an Alpha drive. For those not familiar it is a 21' "mini day" cruiser and a shallow vee/low freeboard boat. With the original motor (305) and a stainless 19pitch 3 blade it ran around 55 on GPS. I built a vortec headed sbc and actually got upwards of 70 (once).

Long story short, when I built that engine i cut corners and it ended up biting me, grenaded the engine a couple of months ago. Fast Forward to today, i built another SBC with the specs as follows:

STD Bore (350 CI)
Promaxx performance (same as patriot) Vortec Heads (setup for up to 600" roller lift)
Edelbrock Performer intake
SpeedPro Flat top pistons
10.02:1 Static Compression
Eagle Rods and Crank
7+ quart pan and High pressure/standard volume pump
Crane 109831 cam (222/230 509/528) (543/563 with 1.6's)
Full roller valve train with 1.6 rockers
Comp Magnum Pushrods
Holley Marine 750DP carb
Mercruiser "dry joint" manifolds and through transom exhaust (below waterline)
eBay HEI dist

For the most part everything is "middle" end and some higher end stuff. But the plan with this engine is for it to be a good Family cruiser with some balls if i want to get on it pretty hard.

Got the motor together, fired it off and sounds great, but it runs just OK.

I bought the carb, and did use it on the previous 350 i had built, but i hate Carburators and do not understand them at all. If it was EFI, no problem i would have this thing dialed in in not time.

From some google searching, this cam/setup seems to be pretty familiar. I was hoping some of you wouldnt mind sharing some jetting/powervalve recommendations? Currently im at 71/83 and it has a pretty nasty flatspot when revving from idle to WOT. I also am running a 6.5PV.

Any ideas or advice?

thank you for your time

You sure it's not your Ebay distributor/module/coil ? A lot of standard 'good' HEI's give up the ghost over 4k.

When is this flat spot most previlant ? Was it at same point as old engine build up ?

I was afraid of that, so this just arrived at my work.

http://img.photobucket.com/albums/v6...psqrmpxrmk.jpg

MSD 6a box, MSD Blaster2 coil, Summit billet Distirubtor

The flat spot is if i try to rev wide open from idle on the trailer. Havent had the boat out yet

and just cause i think its pretty
http://img.photobucket.com/albums/v6...psrdh5bii2.jpg

How can you tune anything - other than timing curve - with no load ?

Speaking of which, what is your base timing + total timing (rpm+degrees) ?

Plan to get it on the water this Saturday, but even with no load, it should rev cleanly and be relatively snappy on the trailer. It is not, just stumbles and even backfired at one point. Im obviously leaning towards ignition.

with the HEI had it set at 32* total. i dont know what the initial was but according to the spring kit it brings full advance in by 2000. I set timing at 3200.

BTW: looks like you have a spreadbore Edelbrock intake. Do you happen to have the square sealing plate to seal your squarebore carb to it ?

Decent total to start with. Initial with your cam will probably like somewhere around 12 or so degrees. You have such light springs in there your initial may have already started before your idle speed.

With cold water and intake, it may take a few minutes for your motor to idle and rev well. just as a heads up.

But yeh, a ****ty ignition will make a motor run like crap load or no load.

Do you have a provision on your exhaust for an o2 sensor to use an AF gauge? It's the only way to tune a carb these days. Many manufacturers are making adaptor plates to use sensor in their exhaust.

http://i622.photobucket.com/albums/t...14A38C8B00.png

Does anyone have any experience with a D.U.I. Distributor? One came on my boat and I'm wondering if it's a weak link.

its the edelbrock 2116 intake. Setup for both spread and square bores

http://www.edelbrock.com/automotive/...ds/sb/2116.jpg

At this point, im blaming the ignition. I just wanted some guide lines for jetting recommendations. I did tear the carb down, and clean/rebuild it. Replaced the PV with a new one and new jets. I really dont think its a carb issue.

This new distributor is a mechanical advance one. If i can lock it out i will lock it out at around 32 degrees and go from there.

FYI, i also tried a demon 850 (i know WAY to big but i had it laying around) and had more or less the same issues just worse