Moparts

holley carb set-up for footbrake

Posted By: Dan Brewer

holley carb set-up for footbrake - 10/05/10 12:23 AM

830 dp currently with a power valve in the front 80 jets. Rear blocked with 88's, jet ext and notched float. Has a bog when you launch at 2000. Not real sure what direction to go to try to get it out.
446" 12.5 CR .620"cam. 5200 convert.
Engine has 9-10" vac idle in gear w/4.5 power valve.
Any suggestions? What other info might you need?
Thanks for any help.
Posted By: one bad fish

Re: holley carb set-up for footbrake - 10/05/10 12:29 AM

squirters check em u should put 40 front and back
Posted By: Dan Brewer

Re: holley carb set-up for footbrake - 10/05/10 12:38 AM

They are 28, I assume this was stock. 30cc pumps enough? I'll give that a try.
Posted By: one bad fish

Re: holley carb set-up for footbrake - 10/05/10 12:39 AM

it wil get rid of the stumble
Posted By: maximum entropy

Re: holley carb set-up for footbrake - 10/05/10 12:53 AM

if the air is good you may need to try 50cc pumps front and rear. holley used to recommend this on all double pumper drag race apps, and many times it is required.
Posted By: abodiesonly1

Re: holley carb set-up for footbrake - 10/05/10 01:03 AM

The larger squirters and a little pump cam tuning should fix it. Also installing a 50cc pump on the secondary side.
Posted By: Locomotion

Re: holley carb set-up for footbrake - 10/05/10 01:17 AM

When I ran a power valve, it was about 1.5 - 2 #'s below vacuum at idle. But I had since taken it out and squared the jetting. One less thing to worry about.

The .040" squirters are a big jump, but a good idea. Depends how bad your bog is. If the bog is "initial" you may not need 50cc pumps. Pump cam adjustments/changes may help, if it's even needed. A 50cc pump will basically extend the duration of the squirt creating a too rich condition through the launch. Squirter size determines the initial fuel volume dumped in to cover up the vacuum signal drop when the throttle is slammed open.

Continued fine-tuning squirter size and pump cams can help 60' times more.
Posted By: roadhazard

Re: holley carb set-up for footbrake - 10/05/10 01:23 AM

Dan

I have 28 squirters in my Dominator
Been up in the 40's to get away from a bog myself but didn't help

What's your initial timing at?


Edit; you have 9-10" with a .620 cam what cam is that
Posted By: Dan Brewer

Re: holley carb set-up for footbrake - 10/05/10 01:33 AM

Hi Greg-
I have crank trigger locked around 34. Its been awhile since I have checke where I had it. Just took the crossram off and never had any poblems w/stock 3705's.
The cam is made by Hughes, I would have to find the cam card. Between 2-3K on the conv I have 12".

PS-new .015 gaskets are working out great!
Posted By: one bad fish

Re: holley carb set-up for footbrake - 10/05/10 01:52 AM

Quote:

Dan

I have 28 squirters in my Dominator
Been up in the 40's to get away from a bog myself but didn't help

What's your initial timing at ?
40 degrees bu i have a small block

Edit; you have 9-10" with a .620 cam what cam is that

Posted By: Labratt

Re: holley carb set-up for footbrake - 10/05/10 01:57 AM

WOW! That IS a LOT of vacuum for a .620 lift cam! Must not have all that much duration!
Posted By: YO7_A66

Re: holley carb set-up for footbrake - 10/05/10 02:22 AM

""Has a bog when you launch at 2000.""

Try moving your primary pump cam to position #2. This will delay the shot. You are wasting some of the pump shot from the cam while bringing up the rpms to 2000. Delay the cam to see if the bog gets better.
Some pump cams have three holes for this purpose. My Demon had three holes on the pink cams to delay the shot.
Posted By: Quicktree

Re: holley carb set-up for footbrake - 10/05/10 02:28 AM

one thing I see is the power valve is to small with that vac. it should be around 7-8 instead of 4.5. what pump cam do you have?
Posted By: Locomotion

Re: holley carb set-up for footbrake - 10/05/10 02:32 AM

Quote:

one thing I see is the power valve is to small with that vac. it should be around 7-8 instead of 4.5. what pump cam do you have?



"Late", not "small". Flow is the same regardless of #.
Posted By: Quicktree

Re: holley carb set-up for footbrake - 10/05/10 02:36 AM

Quote:

Quote:

one thing I see is the power valve is to small with that vac. it should be around 7-8 instead of 4.5. what pump cam do you have?



"Late", not "small". Flow is the same regardless of #.

thats what I was talking about. being late could cause the stumble
Posted By: Cab_Burge

Re: holley carb set-up for footbrake - 10/05/10 02:41 AM

Does your 830 DP have annular boosters? If so or if not either way try some # 35 or # 37 size squirter in front and back first, the 28 will probally work real well when it is hot and humid, save them. I have removed more 50 CC pumps from Holley DP than I have installed them on, it is very easy to make the car bog by having to little pump squirt or to big pump squirt You need enough pump squirt to make the transition from either the idle or transition circuit at that low RPM, probally the transition circuit. I have seen cars that are on the primary main circiut at or above 2300 RPM against the converter and didn't need much pumnp shot from there to launch wellMy message is don't spend money that you don't need to, squirters are a lot cheaper than 50 CC pumnps
Posted By: Triple Threat

Re: holley carb set-up for footbrake - 10/05/10 02:53 AM

Even on my little engine I run a 35 in the rear.
Posted By: Dan Brewer

Re: holley carb set-up for footbrake - 10/05/10 03:36 AM

Annular boosters, the pump cams are white. I have a pr of 37 squirters so I can try them. I always thought that you divide the idle vac by 2 and that is a good starting point for the pv's I haven't been to the track yet but I do have 80' of new concrete that is getting broke in proper. Thanks for all the input, I have some things to try now.
Posted By: Quicktree

Re: holley carb set-up for footbrake - 10/05/10 03:41 AM

Quote:

Annular boosters, the pump cams are white. I have a pr of 37 squirters so I can try them. I always thought that you divide the idle vac by 2 and that is a good starting point for the pv's I haven't been to the track yet but I do have 80' of new concrete that is getting broke in proper. Thanks for all the input, I have some things to try now.

you may get away with the dividing thing on a stock street car but it doesn't work well with performance combo's. also try a more aggressive cam like a brown or blue if the bigger squirters don't work. I myself like the 50cc pumps. you can use a smaller squirter.
Posted By: Dan Brewer

Re: holley carb set-up for footbrake - 10/06/10 03:13 AM

-Update-

So I switched the squiters from 28 to 37's. I had them so I gave them a try. Seems to have fixed the problem. Flashing the conv in high or launching the car feels great. I have some other pv's and cams on the way so I can tinker with them. Going to the track thurs for the real results. Anyone want to take a guess if the single 4 will be quicker/slower than the mw crossram and carters in similar air?

Thanks again for the help/suggestions.
Posted By: roadhazard

Re: holley carb set-up for footbrake - 10/06/10 02:07 PM

Glad to see you have a change in the positive direction Dan.

The track will be the true test, it always finds the weak spot.

Single 4 over the Cross Ram anyday

Glad things are working out with gaskets

Greg
Posted By: Cab_Burge

Re: holley carb set-up for footbrake - 10/06/10 05:29 PM

Quote:

-Update-

Going to the track thurs for the real results. Anyone want to take a guess if the single 4 will be quicker/slower than the mw crossram and carters in similar air?

Thanks again for the help/suggestions.

Glad to here that the simple things helped As far as my thoughts on the single versus the two carbs and cross ram intake, unless the carters where not close on the tune up and the new single four is dead on I think the crossram will be faster, not by a large amount but better I have a freind who removed a stock 426 M.W crossram with two Holley 650 and installed a Indy two piece bathtub intake for the M.W. SR heads with two Eddy 750 Carbs and picked up a bunch at the track Better intake and bigger carbs equalled faster and quicker Let us know Friday after the testing
Posted By: Dan Brewer

Re: holley carb set-up for footbrake - 10/08/10 03:37 AM

Just got home and was supprised that the single 4 was just a tad better than it has ever been in the 1/8th after a couple jet changes. Car was .01-.02 better 60'. MPH picked up .9 with jet change 2nd run. More jet 3rd run picked up .4 for a best of 1.563 4.649 7.25@94.61 mph. Best I can find in similar air was 7.28 This is at a race weight of 3825#. Crossram still looks better under the hood.
Posted By: Cab_Burge

Re: holley carb set-up for footbrake - 10/08/10 03:44 AM

Quote:

Crossram still looks better under the hood.

Posted By: Dan Brewer

Re: holley carb set-up for footbrake - 10/08/10 03:49 AM

I am going to put this engine in another car for next year and just wanted to try to get it figured out before it got pulled. I'm gonna put my more street friendly motor back in with the crossram.
Posted By: roadhazard

Re: holley carb set-up for footbrake - 10/08/10 02:10 PM

Dan, I'm not suprised at all the single 4 made more power. The more power you make the more the single 4 will leave the cross ram behind.

What single 4 do you have?

Certainly like the looks of the cross ram though
Posted By: Dan Brewer

Re: holley carb set-up for footbrake - 10/08/10 05:43 PM

The intake is the 337 mopar intake. Heads have never been touched and the intake ports on this intake are quite a bit smaller than the heads. I'm sure there is room for improvement. Next time I have the heads off I'll match the ports. I have accesss to a 950 HP carb, I might give that a try. Any thoughts? I shift at 5800 and it goes through 1/4 at 6000-6100.
Posted By: Cab_Burge

Re: holley carb set-up for footbrake - 10/09/10 04:25 AM

Quote:

The intake is the 337 mopar intake. Heads have never been touched and the intake ports on this intake are quite a bit smaller than the heads. I'm sure there is room for improvement. Next time I have the heads off I'll match the ports. I have accesss to a 950 HP carb, I might give that a try. Any thoughts? I shift at 5800 and it goes through 1/4 at 6000-6100.

Next time your at the track try shifting it at 6100 or 6200 or higher and let the motor grunt longer in high gear at the lower RPMs nearer to the peak torque RPMs
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