Holley calibration information needed

Posted By: Moparmal

Holley calibration information needed - 02/16/14 11:36 PM

Went to the track the 1st time with my my Pro Systems 750 Holley.

Currently its running a 50cc front shooter and 30cc rear shooter - both new diaphrams.

The car hooked fine..but my 60ft was still about 1/10th under where I think it should be...(Best was 1.84)

It feels "soggy" at launch..and there was no difference between a launch at 800rpm and at 2500

So here's my questions -

What is the recommended set up for dual pump shooters?

- should they be the same size..or should the primary be smaller than the sec?

What effect does it have swapping the small one and the big one from primary side to secondary side?

Can I run a 30cc diaphragm on a 50cc cam? What effect would this have?

Please bear with me - I'm not seeking "tuning" advice for this motor - its not far off being jetted correctly....but I don't understand how the twin pump shooter configuration is supposed to be set up.....

Posted By: Brian Hafliger

Re: Holley calibration information needed - 02/17/14 12:43 AM

Quote:

Went to the track the 1st time with my my Pro Systems 750 Holley.

Currently its running a 50cc front shooter and 30cc rear shooter - both new diaphrams.

The car hooked fine..but my 60ft was still about 1/10th under where I think it should be...(Best was 1.84)

It feels "soggy" at launch..and there was no difference between a launch at 800rpm and at 2500

So here's my questions -

What is the recommended set up for dual pump shooters?

- should they be the same size..or should the primary be smaller than the sec?

What effect does it have swapping the small one and the big one from primary side to secondary side?

Can I run a 30cc diaphragm on a 50cc cam? What effect would this have?

Please bear with me - I'm not seeking "tuning" advice for this motor - its not far off being jetted correctly....but I don't understand how the twin pump shooter configuration is supposed to be set up.....

I'm not a fan of ProSystems...that said I think the larger pump should be on the secondary side as that's the side that most times has to cover the "hole" made by going to WOT.
I start my holleys with Blue cams, and then go up on the squirters until there is no hesitation or your 60ft. is at it's best.
With 4 corner idle, you need to make sure the secondaries are cracked open some so there is a signal to the idle circuit and the Main circuit once it starts to move.
Also, make sure the idle mixture screws aren't set too lean...they will have an affect on going to WOT and the "hole" that's created by that sudden change in depression.
Brian

Posted By: Cab_Burge

Re: Holley calibration information needed - 02/17/14 02:46 AM

I never been a fan of the 50 CC pumps on any Holley carb., no matter what size

I have changed the rear 50 CC pump to a 30 CC pump and ended up with better 60 ft times on a bracket 440 motor with a Holley 800 D.P. carb.

I did the same thing on a SS style Hemi motor with a stock crossram that had dual 750 D.P. carbs with 50 CC pumps on the rear, we changed them to 30 CC pumps(you have to change the pump arm also

) and put in 31 squirters to get the best 60 ft. times that day at that track

I would adjust the accelerator pump arms like Holley says to and go from there

You can slow the 60 ft. times down with to much accerator pump shot is what I'm trying to say

Posted By: BIGS

Re: Holley calibration information needed - 02/17/14 02:53 AM

Like cab said......Run 30s front and rear......would be nice to get some light pump springs for under the 30cc diaphrams as they do a nice job of getting the complete 30cc spray.....I would say 33-35 squirters square and all should be good....Jesse

Posted By: Leigh

Re: Holley calibration information needed - 02/17/14 03:28 AM

Properly sized discharge nozzles and discharge timing, won't care what size supply diaphragm supplies it. That's been my experience.

Posted By: Moparmal

Re: Holley calibration information needed - 02/17/14 03:47 AM

What you guys are suggesting makes sense compared to what Im feeling thru the seat of the pants..

Seems like Ive gone from not having enough pump shot with the Eddie Thunder to having too much.

Ill change the front shooter to 30cc and see if it improves at the track

Thx for your help

Posted By: 383man

Re: Holley calibration information needed - 02/17/14 04:59 AM

Just curious as does the car seem to hesitate or bog ? Or just kinda a down on power feeling ? Ron

Posted By: Moparmal

Re: Holley calibration information needed - 02/17/14 07:32 AM

Just a "down on power" felling over the first 30 yards or so...Once its winding out it pulls well...

Posted By: Mr.Yuck

Re: Holley calibration information needed - 02/17/14 04:24 PM

what is the engine specs? Did you change anything else in the carb?

Posted By: rt66jim

Re: Holley calibration information needed - 02/17/14 06:34 PM

A Holley tech at a Nat'l event told me to increase squirter size. Until the sixty foot slowed down. Then back-up to the previous size. I.E. 33 to 35 and 60' slowed. Go back to 33.

I have had success using this method. Jim

Posted By: Moparmal

Re: Holley calibration information needed - 02/17/14 11:07 PM

So changing squirter size is not the same as changing the diaghram?

So which should I change...the 50cc diaphram and cam......or the shooter?

Posted By: rt66jim

Re: Holley calibration information needed - 02/18/14 12:29 AM

I would try different size squirters first if you have or can borrow them.

Posted By: Cab_Burge

Re: Holley calibration information needed - 02/18/14 05:27 AM

Quote:

So changing squirter size is not the same as changing the diaghram?

So which should I change...the 50cc diaphram and cam......or the shooter?

When you change the squirters you end up changing how long the fuel squirts through them, not how much by volume, just the time it squirts out

If you enlarge the squiter isze it will stop squirting sooner than when it has smaller squirters in it. If you want to reduce the volume used per stroke on the accelerator pump circuit change from the larger pump,50 CC, to the smaller 30 CC pump

Holley, for what ever reasons, uses ten stroke on each pump to distingish(SP?) the differences between the 30 CC and the 50 cc pumps, it is not pumping 30 CC or 50 CC per pump shot

Posted By: Moparmal

Re: Holley calibration information needed - 02/18/14 11:21 AM

Cheers Cab

This thing has 40th front and rear squirters...which is probably a little large for my purposes?

My main question is that b4 I change anything...would I have more luck with the 50cc pump on the primaries or secondaries?

Or do I just swap them over and suck it and see?

Posted By: Mr.Yuck

Re: Holley calibration information needed - 02/18/14 03:23 PM

Quote:

Cheers Cab

This thing has 40th front and rear squirters...which is probably a little large for my purposes?

My main question is that b4 I change anything...would I have more luck with the 50cc pump on the primaries or secondaries?

Or do I just swap them over and suck it and see?

wow 40 seems like too much unless you have a 500 inch motor. If you are running the 5.7 in your sig I'd try 31's and go up from there.

Posted By: Dodgem

Re: Holley calibration information needed - 02/18/14 05:35 PM

Larger than needed jets can also bring the 60 foot numbers down!.

and with big cams like my timing all in by 1200?

Posted By: Monte_Smith

Re: Holley calibration information needed - 02/18/14 05:54 PM

My experience with Pro-Systems, is that every one I have ever seen was extremely RICH down low. That coupled with big squirters, explains the "soft" feeling down low. It's just rich

Monte

Posted By: Thumperdart

Re: Holley calibration information needed - 02/18/14 06:05 PM

A lot of holleys in general are fat from what I`ve seen and my car runs cleaner and faster w/28 squirters and jetted/set up leaner on the idle and cruise circuit. If you can`t read plugs a wide band is your friend. Years ago Cab told me this; there`s 3-circuits on a carb(2-circuit) idle, cruise and wot so we`d set up the idle circuit first and read the plug idle only then make necessary changes. Then we`d work on the cruise circuit driving on primaries only and read the plugs then finally wot. Took a lot of work but w/out a wide band I don`t see any other way and although it`s not perfect, it`s a great reference tool and now my plugs look like the wide band indicated. Slightly rich at idle and cruise and nice at wot..........

Posted By: 383man

Re: Holley calibration information needed - 02/18/14 11:23 PM

Just curious as you said it really doesn't stumble so I was wondering about the converter you are using. Not to tight is it ? Ron

Posted By: MR_P_BODY

Re: Holley calibration information needed - 02/19/14 12:24 AM

Quote:

Cheers Cab

This thing has 40th front and rear squirters...which is probably a little large for my purposes?

My main question is that b4 I change anything...would I have more luck with the 50cc pump on the primaries or secondaries?

Or do I just swap them over and suck it and see?

The largest squirters I have ever used was a 36 and
that was too much... I have a 850 with dual 50cc
pumps on it.. the pumps just have the volume.. the
squirters tell it how much to shoot but with 50cc
it will go much longer if needed

Posted By: Moparmal

Re: Holley calibration information needed - 02/19/14 01:49 AM

Ok ..thx all for the input.

Ill look at smaller squirters and see what that does.

I may also swap the 50cc from sec to prim and see what effect that has.

Converter is 3800
Baby hyd roller cam...218/227@.50
Gears 3.91 - weight 3650 with me in it

I have a wide band AF gauge..what should it read when I nail it?

At wot at 6000 its reading around 12.8 which has proved to be perfect at the track....

Just not sure what it should read when the squirters come into play at launch.

Posted By: MR_P_BODY

Re: Holley calibration information needed - 02/19/14 03:44 AM

Quote:

Ok ..thx all for the input.

Ill look at smaller squirters and see what that does.

I may also swap the 50cc from sec to prim and see what effect that has.

Converter is 3800
Baby hyd roller cam...218/227@.50
Gears 3.91 - weight 3650 with me in it

I have a wide band AF gauge..what should it read when I nail it?

At wot at 6000 its reading around 12.8 which has proved to be perfect at the track....

Just not sure what it should read when the squirters come into play at launch.

If your gonna run a 50cc pump you want it on the rear...
a 30cc in most cases will work in front... I put a
50cc on the front of mine because thats what I had
in the trailer to fix a leaking pump... it works fine
but I never got around to changing it.... if you get
down to a realistic squirter size the 30cc in front
should be fined
EDIT
on the hit, it will go fat but pretty quick it should
come back to that 12.8 range or a bit fatter and
drop to the 12.8

Posted By: Moparmal

Re: Holley calibration information needed - 02/22/14 05:27 AM

U were spot on Mr P!!

UPDATE - Swapped the 50cc pump to the secondaries and the 30cc to the primaries -

Improved 2/10ths 0-60 on the Gtec (4.11) without turning tyres.

Then I did the "rubber" test.......improved a full twenty yards - both runs on MT Drag Radials LOL!!

Posted By: MR_P_BODY

Re: Holley calibration information needed - 02/22/14 05:47 AM

Quote:

U were spot on Mr P!!

UPDATE - Swapped the 50cc pump to the secondaries and the 30cc to the primaries -

Improved 2/10ths 0-60 on the Gtec (4.11) without turning tyres.

Then I did the "rubber" test.......improved a full twenty yards - both runs on MT Drag Radials LOL!!

Cool... finish tweaking it in to get the best MPH
in the 1/4

Posted By: Mr.Yuck

Re: Holley calibration information needed - 02/22/14 04:37 PM

Quote:

U were spot on Mr P!!

UPDATE - Swapped the 50cc pump to the secondaries and the 30cc to the primaries -

Improved 2/10ths 0-60 on the Gtec (4.11) without turning tyres.

Then I did the "rubber" test.......improved a full twenty yards - both runs on MT Drag Radials LOL!!

did you drop down on the squirter as well?

Posted By: Moparmal

Re: Holley calibration information needed - 02/23/14 09:26 AM

Quote:

Quote:

U were spot on Mr P!!

UPDATE - Swapped the 50cc pump to the secondaries and the 30cc to the primaries -

Improved 2/10ths 0-60 on the Gtec (4.11) without turning tyres.

Then I did the "rubber" test.......improved a full twenty yards - both runs on MT Drag Radials LOL!!

did you drop down on the squirter as well?

My .034th squirters arrive tomorrow...so it'll be good to see what differences they make