carb spacers

[383man]

Re: carb spacers

I use a 4 hole Phenolic spacer under the 850 carb on my Holley Street Dominator single plane intake. I went with the 1" four hole because it would still let the carb fit under the hood and I figured it might help the low end. I have only run it with it but I can tell you it really helped it starting in real hot weather. If it sat for 10 minutes in real hot weather it would flood real easy if you touched the gas. But after I put the spacer on I had no problems at all with that as it lifted the carb bowls up away from the hot intake. Ron

[Freiburger]

Re: carb spacers

You're at the track a lot...so go do a back-to-back with that 4-hole and an open spacer. My guess is either it makes no difference at all or the open spacer picks up a little mph.

BTW, carb spacers can affect signal to the carb and change jetting requirements, too.

[runawy 9]

Re: carb spacers

I've tried the 4-hole and open and found that the 4-hole spacer gave the car better part throttle manners I guess from having a bettter signal. The open spacer did pick up almost two tenths and three mph in the eighth mile but the 60 foot dropped a whole tenth.

[smallblockjay]

Re: carb spacers

I've tried the 4-hole and open and found that the 4-hole spacer gave the car better part throttle manners I guess from having a bettter signal. The open spacer did pick up almost two tenths and three mph in the eighth mile but the 60 foot dropped a whole tenth.

Although I don't dyno my motor, and most people don't, this was my assumption. I put a four-hole on mine expecting that it would help keep a good signal to the carb on the bottom. Might not be a real big deal on a 12 second street car, but I run a motor that is potentially an 11-12 second motor in a 6000 pound truck. My focus as it sits is trying to keep throttle response and keep it "jumping" when I stick it quick. As it is, this motor is lazy in this truck until close to 2000 RPM. I'd be interested in a test of spacers on an every day motor, especially part throttle. But the only real test is on the street in your car. I felt a difference when I finally got the spacer out of there and put the carb on the intake. Took a while to find a vaccum fitting that is only 1/2 inch tall.

[DanStokes]

Re: carb spacers

David -
I suggest that you find a non-inertial dyno to do this testing (Mustang, newer Dynojet w/PAU, etc). This will give you the real part-throttle results you're looking for. Don't believe me? Ask Scott.

Dan

I think tapered combos tend to help single-planes if you want more signal in the midrange, but it really depends.

Keith Wilson talked me into a great test that I've never done, but that I want to...and that we could do here at CJTV. That would be to do PART THROTTLE testing. That could be done on the dyno with a throttle stop or with a very repeatable car and driver at a short road course. Useless for drag racing, but pretty interesting for street/open-track testing.

[Doug Odom]

Re: carb spacers

Just ran 2 sbc LSR motors on the dyno last month. A 300 inch and a 400 inch motor with a Holley. Both made the most power with a 2 inch spacer. Top inch is 4 hole and bottom inch is open. Its an old NASCAR thing that they outlawed years ago but it did help the 18 degree heads I run now.
Doug Odom in big ditch

[Freiburger]

Re: carb spacers

Jay and runawy: It's my guess that some squirter or squiter-cam tuning would get back te 60-foot, then you'd be even quicker still.

Dan: I think the real world is more real than a Dynojet, though perhaps not as easily repeatable.

Doug: Those step spacers work, but in my experience, the tapered combos are even better. Pick up one from Wilson and give it a shot.

[smallblockjay]

Re: carb spacers

Jay and runawy: It's my guess that some squirter or squiter-cam tuning would get back te 60-foot, then you'd be even quicker still.

Dan: I think the real world is more real than a Dynojet, though perhaps not as easily repeatable.

Doug: Those step spacers work, but in my experience, the tapered combos are even better. Pick up one from Wilson and give it a shot.

While I agree that my motor could use some carb tuning, I think more of my issue is running an RPM intake and 230-236 at .050 cam in a 6000 pound vehicle. I have done some tuning to my carb, but not on the pump cam. I have tuned it with squirters. The motor actually hits hard when I mat it. But if it hooks, which isn't likely, it will pull fairly hard, but you can feel it really start to pull at about 1800. After that, the revs go to 6500 pretty quick and it's time to hit the Megashifter.

While I haven't run it in a timed 1/4, I'd be confident it will run in the 14's. Not all that impressive, but in a car that weighs 2000 pounds less??????????? That's were I get the 12 second motor assumption. This truck won't run 12's without a couple hundred more HP.

And I've heard a lot of great things about Wilson spacers and tapered spacers. For what I do, I think carb on the manifold is close enough. If it needs a spacer to make that much of a difference, it is the wrong manifold and/or needs more plenum. Unless your trying to dig ever last pony out of it.

Just my opinion.

[Freiburger]

Re: carb spacers

IMO, a 230/236 and an RPM is not a problem in a heavy vehicle...but if you can "feel it really start to pull at 1800," does that mean the converter actually stalls at LESS than 1800? That would be a problem.

[10secvega]

Re: carb spacers

I've personally found that this 1/2 inch plate makes the most power and throttle response. ;D

[BillBallinger Sr]

Re: carb spacers

I am running a ported Holley Street Dominator single plane on my 390 FE in my truck. It seems happiest with a two inch four hole spacer, and a 1 inch open phenolic under that. So that's 3 inches of spacer, but the phenolic one doesn't seem to do much but keeps the carburetor from getting hot.

With the heads I have on the engine it revs to 7000 RPMs very cleanly, even though the cam should be done at 6000, but it is a solid and I'm running the lash a little bit tight. I've tried it every way, flat on the intake, on the 1 inch open spacer,the 2 inch four hole alone, and the 2 inch four hole plus the 1 inch open and it seems to like it best. Very responsive down low in no flat spots anywhere in the power band in any gear, and this is in a 4800 pound 4x4 truck. Knock on wood, it's never been stuck where it didn't require at least a tractor to pull it out. ;D

[smallblockjay]

Re: carb spacers

IMO, a 230/236 and an RPM is not a problem in a heavy vehicle...but if you can "feel it really start to pull at 1800," does that mean the converter actually stalls at LESS than 1800? That would be a problem.

Converter does seem really tight to me, though I wouldn't have thought it would be. It's a B&M Holeshot.