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Re: Another Carb question... [Re: Thumperdart] #2414858
12/07/17 07:17 PM
12/07/17 07:17 PM
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Bradenton, FL
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Benforsp Offline OP
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Originally Posted By Thumperdart
You have to to in order to have a base tune and to know what needs to be changed to bring it around to your cars needs...........no other way........ thumbs


Thumper,

What all is involved in this and what specialty tools are needed?

Re: Another Carb question... [Re: Benforsp] #2414883
12/07/17 08:04 PM
12/07/17 08:04 PM
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We need to talk, too much to type..........


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
Re: Another Carb question... [Re: Thumperdart] #2414904
12/07/17 08:32 PM
12/07/17 08:32 PM
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Val-haul-ass... eventually
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Originally Posted By Thumperdart
We need to talk, too much to type.......... with one finger

haha

Re: Another Carb question... [Re: Benforsp] #2414948
12/07/17 10:16 PM
12/07/17 10:16 PM
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So. Burlington, Vt.
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fast68plymouth Offline
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Quote:

-> 440-ish cubes with "big" heads that work better on 500+"
-> moderate CR
-> 260+ at .050" street roller
-> limited stall speed
-> street-tuned(?) carb w/ 1.56 venturi & downleg boosters


Those are my thoughts as well.

1.56 venturi downleg carbs can be a real challenge to "tune the bog out of".

IMO, I think a main body swap to something with a smaller venturi would ultimately yield better results(I'd probably use a 1.400 x 1.750)....... But if I were trying to work around that combo, I would expect to have to run fairly large squirters, and probably a 50cc pump/cam on the secondary side, and I would absolutely ditch the 2.5 pv.
You want to get a head start on the main circuit enrichment when going to wot...... It would get a 6.5 if I were messing with it.

There is a lot of plenum and runner volume in that combo, and not a lot of cubes generating signal.......... It's going to need a lot of help(pump shot) to give the motor something to work with until the main circuit is activated.

Not what you asked, but there is some performance left on the table with that cam, in that combo.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Another Carb question... [Re: Benforsp] #2414956
12/07/17 10:34 PM
12/07/17 10:34 PM
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Palm City, FL
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whats the fuel pressure set to...

Re: Another Carb question... [Re: BradH] #2414966
12/07/17 10:52 PM
12/07/17 10:52 PM
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Originally Posted By BradH
Originally Posted By Thumperdart
We need to talk, too much to type.......... with one finger

haha


You know me too well...............lol


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
Re: Another Carb question... [Re: fast68plymouth] #2415165
12/08/17 12:19 PM
12/08/17 12:19 PM
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Bradenton, FL
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Benforsp Offline OP
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Originally Posted By fast68plymouth
Quote:

-> 440-ish cubes with "big" heads that work better on 500+"
-> moderate CR
-> 260+ at .050" street roller
-> limited stall speed
-> street-tuned(?) carb w/ 1.56 venturi & downleg boosters


Those are my thoughts as well.

1.56 venturi downleg carbs can be a real challenge to "tune the bog out of".

IMO, I think a main body swap to something with a smaller venturi would ultimately yield better results(I'd probably use a 1.400 x 1.750)....... But if I were trying to work around that combo, I would expect to have to run fairly large squirters, and probably a 50cc pump/cam on the secondary side, and I would absolutely ditch the 2.5 pv.
You want to get a head start on the main circuit enrichment when going to wot...... It would get a 6.5 if I were messing with it.

There is a lot of plenum and runner volume in that combo, and not a lot of cubes generating signal.......... It's going to need a lot of help(pump shot) to give the motor something to work with until the main circuit is activated.

Not what you asked, but there is some performance left on the table with that cam, in that combo.


Fast,

The carb had 6.5's in it and I can put them back in no sweat. I knew the cam was pretty big but had talked to some folks and they suggested it would be suitable, but I would consider other options, what might you advise?

Re: Another Carb question... [Re: Dadodgekid] #2415169
12/08/17 12:24 PM
12/08/17 12:24 PM
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Bradenton, FL
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Originally Posted By Dadodgekid
whats the fuel pressure set to...


Kid,

The fuel pressure is 6.5-7 PSI. I run an electric pump with a return style fuel system with -8 lines.

Re: Another Carb question... [Re: Benforsp] #2415212
12/08/17 01:48 PM
12/08/17 01:48 PM
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So. Burlington, Vt.
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fast68plymouth Offline
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It would require a conversation before I would recommend any other cam, but I think getting rid of some seat timing would be a step in the right direction.

You said "pv's"....... If you're still running one in the secondary side, remove it and replace with a plug....... And jet up accordingly(around 8 sizes).


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Another Carb question... [Re: Benforsp] #2415239
12/08/17 02:30 PM
12/08/17 02:30 PM
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Originally Posted By Benforsp
Originally Posted By Dadodgekid
whats the fuel pressure set to...


Kid,

The fuel pressure is 6.5-7 PSI. I run an electric pump with a return style fuel system with -8 lines.


Still waiting for a call...........lower the pressure to 5.5 max IF you run .120 needle n seats which you should....... callme


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
Re: Another Carb question... [Re: Benforsp] #2415277
12/08/17 03:53 PM
12/08/17 03:53 PM
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Bend,OR USA
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Originally Posted By Benforsp
Originally Posted By BradH
You still haven't given any details of the cam or the carb's current tune. That doesn't make it any easier to try and help.

The 0-82951 is the "Street HP", right? Check the actual venturi diameter and see if it's 1.38" or 1.56" I've seen conflicting specs, depending upon when the carb was made I guess. The tune would likely vary quite a bit depending upon which size it is.

I have no first-hand experience w/ the "Street HP" stuff. I'd hope that they're "flexible" enough to be tuned to work w/ your combination.


http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=739&sb=1

Installed straight up with 1.6 ratio rockers to bring the lift up.
Cam Detail....

Did you degree the cam or did you install it with the dots "straight up" ? If not degreed you should do that now twocents
I would advance it so the intake lobes are from 107 to 105 max lift after top dead center up
I've ran a very similar cam (260@.050 int., 266@.050 ex. ground on a 108 LC installed two degrees advanced on the intake lobes)) Comp solid roller with 1.6 ratio rockers, no bog even with a six pack set up after I had to sort it out.
I had another bracket motor with a Holley 80496 950 HP on a TM7 intake with ported 906 heads and a bigger Crane solid roller and it never bogged ever, that cam was advanced 4 degrees work

Last edited by Cab_Burge; 12/08/17 03:54 PM.

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Re: Another Carb question... [Re: Cab_Burge] #2415298
12/08/17 04:46 PM
12/08/17 04:46 PM
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Bradenton, FL
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Benforsp Offline OP
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Originally Posted By Cab_Burge
Originally Posted By Benforsp
Originally Posted By BradH
You still haven't given any details of the cam or the carb's current tune. That doesn't make it any easier to try and help.

The 0-82951 is the "Street HP", right? Check the actual venturi diameter and see if it's 1.38" or 1.56" I've seen conflicting specs, depending upon when the carb was made I guess. The tune would likely vary quite a bit depending upon which size it is.

I have no first-hand experience w/ the "Street HP" stuff. I'd hope that they're "flexible" enough to be tuned to work w/ your combination.


http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=739&sb=1

Installed straight up with 1.6 ratio rockers to bring the lift up.
Cam Detail....

Did you degree the cam or did you install it with the dots "straight up" ? If not degreed you should do that now twocents
I would advance it so the intake lobes are from 107 to 105 max lift after top dead center up
I've ran a very similar cam (260@.050 int., 266@.050 ex. ground on a 108 LC installed two degrees advanced on the intake lobes)) Comp solid roller with 1.6 ratio rockers, no bog even with a six pack set up after I had to sort it out.
I had another bracket motor with a Holley 80496 950 HP on a TM7 intake with ported 906 heads and a bigger Crane solid roller and it never bogged ever, that cam was advanced 4 degrees work


Cab,

I had thought about installing it advanced and regret not doing so at this point. The cam was degreed.

Re: Another Carb question... [Re: Benforsp] #2415303
12/08/17 04:54 PM
12/08/17 04:54 PM
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Originally Posted By Benforsp
Originally Posted By Thumperdart
You have to to in order to have a base tune and to know what needs to be changed to bring it around to your cars needs...........no other way........ thumbs


Thumper,

What all is involved in this and what specialty tools are needed?

How much carb tuning experience do you really have? It sounds like you may be in over your head.

Re: Another Carb question... [Re: Thumperdart] #2415304
12/08/17 04:57 PM
12/08/17 04:57 PM
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Posts: 153
Bradenton, FL
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Benforsp Offline OP
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Originally Posted By Thumperdart
Originally Posted By Benforsp
Originally Posted By Dadodgekid
whats the fuel pressure set to...


Kid,

The fuel pressure is 6.5-7 PSI. I run an electric pump with a return style fuel system with -8 lines.


Still waiting for a call...........lower the pressure to 5.5 max IF you run .120 needle n seats which you should....... callme


I tried! No Answer.

Re: Another Carb question... [Re: Benforsp] #2415327
12/08/17 05:47 PM
12/08/17 05:47 PM
Joined: Jan 2003
Posts: 14,478
So. Burlington, Vt.
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fast68plymouth Offline
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Quote:
I had thought about installing it advanced and regret not doing so at this point. The cam was degreed.


If the cam was installed as per the cam card in the link you posted, then it's installed 4deg advanced.
The advance is ground into the cam.

Advancing it "more" isn't going to cure your problem.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Another Carb question... [Re: Benforsp] #2415653
12/09/17 11:15 AM
12/09/17 11:15 AM
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Harleysville, PA USA
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Tommy D Offline
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It was mentioned earlier to check the float levels. I did not see a response where that was checked. Where do you run the float level?

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