Reply With QuoteI've got the holley 950 commander system and so far it's done really well. I have the wide band O2 up grade with it. Those systems are bank fire EFI which is all you need for N/A. Give me your email and I'll send you some pics of it.
If you have a river trip in the future let me know and I'll spend a couple hours getting it dialed for you. Carbs are easy, wives are another thing altogether. No charge, I love a challenge.
Floored you are very kind.
I have decided that a new Holley 3310 780 vacuum secondary will be the first test. I believe the 850 Demon was too much all along, but it came on the boat when I bought it. With about 40 hours on the motor I have spent maybe 30 seconds at full throttle. I like to cruise and go slow, along with being safe and having fun with friends (kids too) in our boat. My next project is to quiet the noise down. I have an injected hydro and a blown injected hydro for all my speed needs and desire to screw with things. I want my cruiser to be like my vehicles, reliable and quite. One day a good programmable EFI system will make its way there.
I've got the holley 950 commander system and so far it's done really well. I have the wide band O2 up grade with it. Those systems are bank fire EFI which is all you need for N/A. Give me your email and I'll send you some pics of it.
Thats what I run,3310-3, and it works well for everything I do.
I'm concerned you may have a size missmatch going on. I'm running a 454 but with large oval port heads and a 700 Holley.
The 850 combined with the larger ports may have your port airstream velocity so low that it is causing you problems. Those Rectangular port heads work great at high-rpm's but cause trouble at lower revs because mixture velocity falls below a certain point and fuel drops out of the airstream, puddling in the manifold. I'd probably first give some effort to the power-valve tuning that was advised and then, if I was still dumping it, I'd drop down to a 750 or even less. I would also consider trying to "patch up" the port-runner hugeness with a vac-seccondary carb if you want something as big as an 800+.
I've done some computer-dyno comparisons on my 454 (less mild than she was stock but still 8.5:1 and cammed to .565" lift) and a larger carb gains me virtually nothing (except more gas consumption). If I was peaking my RPM's out close to 6,000, maybe, but I am only topping out arround 5K.
All the ideas I have. Best of luck.what is your engine combo?? i just got done putting together a pair of 454's for sterndrive, w/ stainless marine exhaust, mild(268/272 dur, 540 lift)comp cams, large oval port heads, edelbrock performer intakes, brc roller rockers and am currently running q-jets but am getting ready to switch to holley 750's, is your combo similar, and what is your power output?
I'm getting rid of the 850 Demon carb. I'm looking at another Holley 850 with a choke, a TBI, or EFI. Its a rectangular port BBC with mild parts in it. I'm not going to go forced induction..... Just want something easy to start and runs fine. The demon did great in everything besides off idle acceleration. I could finesse it enough at the right engine temps and conditions, but outside of those, it stumbled everytime. I even went with the experts specially made manual of the BG Demon. I got a race boat to screw with, so I have no patience for this one. (especially when theres 4 adults and 6 kids in the boat that stumbles off idle.)
I think (from my experience) that that carburetor is too large for your engine to get the crisp off idle response. does it have "down leg" boosters? or "annular boosters". If down leg, send it to demon to have it converted to annular boosters. They will create a better low speed vacuum signal and will help your situation. A 750 demon might be better. Demon carbs are "head and shoulders" above Holley IMHO.
Dave
what is your engine combo?? i just got done putting together a pair of 454's for sterndrive, w/ stainless marine exhaust, mild(268/272 dur, 540 lift)comp cams, large oval port heads, edelbrock performer intakes, brc roller rockers and am currently running q-jets but am getting ready to switch to holley 750's, is your combo similar, and what is your power output?
454, 2-bolt clean bores, cast crank & pistons (8.5 to 1), stock rods
Large port oval heads, 122cc open-chambers, 2.06/1.76 (the small big-block valves)
Isky cam & superlifters and matching springs (flat tappets) .565" lift, 280* duration, 1.7:1 rockers 3/8" pishrods & guides installed straight (custom ground 4* adv).
Edelbrock Performer RPM Air Gap 2.0 manifold
700 CFM 4150 style Holley mech seccondary carb, jetted pri 66 / sec 76 w 6.5 PV in Pri only.
K&N Filtercharger 14" element air cleaner
Niccson log exhausts (soon to become Lightning headers & 4" outlets thru-hull)
Acording to all I can see in Desktop Dyno, JP Calc, crossed with the tach on my boat (& test tools), Berk A $ 4800 RPM in a fairly tight drive with a good loader:
355 to 350 HP @ 5000 to 5500 (nice & flat) Torque, 400 to 412 to 398 from 3000 to 4500 RPM, still holding 373 @ 5,000.
Next year looks even better with headers (418 @ 5000, 421 @ 5500 torque, 461 @ 3500, 465 @ 4000, 460 @ 4500) and the following year a porting should reach me to arround 470 HP @ 5500, torque 472/482/485/475 @ 3500 to 5000.
That should run me an A at 5300 RPM, right in the heart of her power.
Kurtis -
I just built a 489 solid roller motor and the 750 I have is too small. I have a marine edelbrock 750 and a holley vac secondary holley. You could try both.
Since you are in Phx, maybe we could get together and try a few different arrangements.
I am looking for an 850 holley or BG
Shoot me a call, this could be interesting, lots of options, we'll take the gps and see what both boats like.
Tony
623-376-0366
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