I know a guy that runs a 250 blower with a 850 on a mostly stock 502. It's low boost, maybe 4 lbs and it runs like a stocker only about 10 miles an hour faster. Good luck, it looks like you're on the right path.
Sounds like your popping accurs as soon as the secondary opens in the carb, which if what they say is true regarding the boost referenced PV, maybe that's it!
I had two problems like this in a NA boat a few years ago... Up to 3500 the boat ran perfect, over that it popped. In one instance there was a piece of metal shaving stuck in the needle/seat, in the second case the coil was bad.
They were Holleys. Not sure of the jet sizes. Doubt if he knows either, his mech. set it up.
Well, I got it in the water this evening with the boost referenced PV vacuum line hooked up; how should I say this?
A quote from the move Days of Thunder comes to mind......"Don't touch a thing Harry, she's perfect!!!!!!!"
This is the best these engines have every performed!!!
Ok, here are the facts:
- Twin 454's, 9:1 compression
- 250 Blowers from the Blower Shop set-up for max 4lbs of boost
- Single 850 Barry Grant Demon blower preped carbs with boost references 4.5 power valve with #98 jets in the proimary and #100 in the secondary.
- Initial timing set at 16 with Thunderbolt pack for anothr 14 degrees producing 30 degree total.
- 130 gph, 9 psi mechanical fuel pumps into Aeromotice regulators, 1/2 inch lines all the way back into the tanks
Pulled the nubmer 7 plug after streching her legs up to 5200 rpm, looks a bit rich but I think I'm going to leave it for now. After about 20 minutes of runing between 4000 to 5200 rpm, she never popped once!!!
Like I said, "don't touch a thing HArry, she's perfect. Hope someone finds this information usefull in the future.... believe me, it was costly getting here.
Thanks to eveyone that responded with input.... it was all helpful and I really appreciate everyone of them.
PS: Even got to meet Mark from Precision Marine while at the ramp this evening. Thanks for taking the time to speak with me Mark about my set-up. Your comments put my mind at ease regarding the use of the 850's on this application. Look forward to seeing you on the Tickfaw run this weekend.
Are you sure about the timing???????
A 14* advance V6 module usually does not give 14* on advance on V8. More like 10*. Check your timing at full advance around 3000rpms. You may still have some HP to gain with a simple timing adjustment.
Glad its running good for you.
Hey al what pressure are you running after the regs into the carbs?
Also sorry what is teh pressure at idle and how far if any does it drop at WOT (wide open throttle)
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