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#2383259 - 10/06/17 11:15 PM Re: 408 help needed [Re: Mirada 408]
rb446 Offline
member

Registered: 10/17/15
Posts: 169
Loc: UK
Blue pump on my '69 440 brkt car, 850DP, stock 906 heads, best 11.2@118, made just 1 NA run with new 2.14/1.81 ported 906's with HS rockers, no other changes, 10.7@125....people give those pumps away for free these days don't they?
_________________________
1969 'Cuda 446ci, best 9.96@133.9 in 1990
1971 340 'Cuda, best 11.01@122.8 in 1987

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#2383278 - 10/07/17 12:38 AM Re: 408 help needed [Re: Guitar Jones]
Cab_Burge Offline
Too Many Posts

Registered: 08/23/03
Posts: 29377
Loc: Bend,OR USA
Originally Posted By Guitar Jones
Two carbs in that kind of application actually require less fuel flow to keep up because the jets are smaller. I know sounds weird.

If the motor makes more power with two carbs., and what Mopar V8 doesn't, it has to use more fuel, correct work
It takes X amount of fuel to make each HP, increase the HP output and the fuel consumption has to increase to make that power shruggy
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Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

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#2383300 - 10/07/17 03:09 AM Re: 408 help needed [Re: Cab_Burge]
Guitar Jones Offline
master

Registered: 12/18/09
Posts: 8746
Loc: in a cattle trailer down by th...
Originally Posted By Cab_Burge
Originally Posted By Guitar Jones
Two carbs in that kind of application actually require less fuel flow to keep up because the jets are smaller. I know sounds weird.

If the motor makes more power with two carbs., and what Mopar V8 doesn't, it has to use more fuel, correct work
It takes X amount of fuel to make each HP, increase the HP output and the fuel consumption has to increase to make that power shruggy


True but you now have 4 float bowls each using less fuel than just two. If the systems flow was near or at capacity with two bowls it should be slightly less taxed with 4 bowls. Its not necessarily the pump either. Where you could get by feeding each carb on a tunnel ram with 5/16 line you may need 3/8 or 1/2 for a single carb.

I know my 2 BG 750's use a lot.


Edited by Guitar Jones (10/07/17 03:48 AM)
_________________________
W5 408 cid, 1.324, 6.155 @ 110.34, 9.756 @ 134.67 with a broken converter hub. Oh yeah, it's all Mopar too, 904 trans and an 8.75 rear!!

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#2383313 - 10/07/17 08:00 AM Re: 408 help needed [Re: Guitar Jones]
B1MAXX Offline
mopar

Registered: 05/07/05
Posts: 666
Loc: Apollo, PA.
Originally Posted By Guitar Jones
Two carbs in that kind of application actually require less fuel flow to keep up because the jets are smaller. I know sounds weird.


2 750'S jetted square with 8 #79 jets and no power valve is .052 sq.in total jet area.

a single 1050 jetted 88 square no power valve is .034 sq. in. total jet area.

you also have to keep 4 bowls at set level...all comes down to total jet restriction.


Edited by B1MAXX (10/07/17 08:06 AM)

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#2383327 - 10/07/17 08:50 AM Re: 408 help needed [Re: Cab_Burge]
MR_P_BODY Offline
Master

Registered: 06/13/03
Posts: 50192
Loc: Romeo MI
Originally Posted By Cab_Burge
Originally Posted By Guitar Jones
Two carbs in that kind of application actually require less fuel flow to keep up because the jets are smaller. I know sounds weird.

If the motor makes more power with two carbs., and what Mopar V8 doesn't, it has to use more fuel, correct work
It takes X amount of fuel to make each HP, increase the HP output and the fuel consumption has to increase to make that power shruggy


Rule of thumb is it takes .5 lbs of fuel for
every HP
wave
_________________________

W-9 8.94 @ 151 NOW ON E-85
Mike "Raff"...(180)Watching over us
CAR IS FOR SALE

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#2383343 - 10/07/17 09:30 AM Re: 408 help needed [Re: Mirada 408]
Guitar Jones Offline
master

Registered: 12/18/09
Posts: 8746
Loc: in a cattle trailer down by th...
I guess I stated incorrectly. What I meant was each carb of a tunnel ram application uses less fuel than a single carb would. TR carbs don't typically use a power valve either. Some carbs have PV's in both the front and rear and the size of the PV orifice must also be taken into consideration. They are not all the same. So 4 bowls don't empty nearly as fast as 2 will. While you should be able to maintain the fuel bowls full all the way through a pass it could get by with less by the end of the pass. You could be giving up some MPH that way and never know it.

Sorry for the confusion.

Either way none of this is helping the OP, we still don't know what he has for a fuel system. Anytime I hear someone say their car is nosing over at higher RPM's my first thought is fuel supply, second thought is valve float.

BTW I feed my carbs with blue pumps, one for each carb with -8 to the regulators and -6 at the bowls.
_________________________
W5 408 cid, 1.324, 6.155 @ 110.34, 9.756 @ 134.67 with a broken converter hub. Oh yeah, it's all Mopar too, 904 trans and an 8.75 rear!!

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#2383382 - 10/07/17 11:06 AM Re: 408 help needed [Re: Mirada 408]
fast68plymouth Offline
I Live Here

Registered: 01/20/03
Posts: 10221
Loc: So. Burlington, Vt.
I went 10.60's @3670lbs with a Carter mech fuel pump, a $4 wix fuel filter, and the rest of the original 5/16" fuel line from the tank to the pump.

It doesn't take hardly anything for a fuel system to run deep into the 11's.

The only way I can see this really being the issue for the lack of performance in the OP's combo is if there is just a straight up "problem" with what he's running.

A Summit mech pump(used with a moly coated eccentric) with the rest of the plumbing all stock would be enough for his goals........ Provided the line isn't kinked somewhere and the pick-up sock isn't plugged.
_________________________
68 Plymouth Satellite, 383, stock 906's, 3550lbs, 11.18 @ 123, 1.51 60' PRH is a Comp Cams W/D......competitive pricing on entire line. Custom cams available. ** dealer for Indy Cylinder Heads **

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#2383433 - 10/07/17 12:37 PM Re: 408 help needed [Re: fast68plymouth]
Guitar Jones Offline
master

Registered: 12/18/09
Posts: 8746
Loc: in a cattle trailer down by th...
What gets me is he says the ET didn't change at all. You would think something would change for better or worse. That's what makes me think there is something wrong with the fuel system. There was probably more in the original combo but something is holding it back and what ever that was it's also limiting the new combo.

And I have never been able to squeeze those kind of numbers out of a nearly stock fuel system. laugh2 The heat here is probably a factor in that though.

I tend to over build my fuel systems just so I know there is enough. I used those same two blue pumps and 3/8 lines when I ran a single 950 with each pump feeding one bowl.
_________________________
W5 408 cid, 1.324, 6.155 @ 110.34, 9.756 @ 134.67 with a broken converter hub. Oh yeah, it's all Mopar too, 904 trans and an 8.75 rear!!

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#2383435 - 10/07/17 12:44 PM Re: 408 help needed [Re: Mirada 408]
Guitar Jones Offline
master

Registered: 12/18/09
Posts: 8746
Loc: in a cattle trailer down by th...
Just thinking, he didn't say whose converter was in it either did he? There are plenty of crappy converters out there. I had a Hughes in my Duster then bought a Turbo Action and picked up 7 tenths. Apples to oranges I know, the Hughes was a 9.5 inch and the T/A was an 8 inch. Still goes to show what the correct converter can do.
_________________________
W5 408 cid, 1.324, 6.155 @ 110.34, 9.756 @ 134.67 with a broken converter hub. Oh yeah, it's all Mopar too, 904 trans and an 8.75 rear!!

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#2383456 - 10/07/17 01:58 PM Re: 408 help needed [Re: Mirada 408]
fast68plymouth Offline
I Live Here

Registered: 01/20/03
Posts: 10221
Loc: So. Burlington, Vt.
IMO, the converter is way way up on the list of things that need to be "right".

When my friend was racing his gto as a bracket car, running low 11's at around 120mph, he thought maybe it was time to upgrade from the factory fuel line and Carter street/strip mechanical pump.

He went with a Mallory 140 pump/regulator, matching filter, and upgraded to a 1/2" line from pick-up to regulator.
Then 2 #6 lines to the carb.

Zero difference in performance.

I'm not advocating the use of marginal fuel systems...... But at the same time, you only need what you need...... And having more fuel system capacity than that won't improve your ET.


_________________________
68 Plymouth Satellite, 383, stock 906's, 3550lbs, 11.18 @ 123, 1.51 60' PRH is a Comp Cams W/D......competitive pricing on entire line. Custom cams available. ** dealer for Indy Cylinder Heads **

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#2383574 - 10/07/17 06:56 PM Re: 408 help needed [Re: Cab_Burge]
gregsdart Offline
master

Registered: 01/21/03
Posts: 8060
Loc: Frostbitefalls (Rocky&Bullwink...
Originally Posted By Cab_Burge
Originally Posted By Guitar Jones
Two carbs in that kind of application actually require less fuel flow to keep up because the jets are smaller. I know sounds weird.

If the motor makes more power with two carbs., and what Mopar V8 doesn't, it has to use more fuel, correct work
It takes X amount of fuel to make each HP, increase the HP output and the fuel consumption has to increase to make that power shruggy

The deal with feeding a tunnelram is you can do it with a lot less pressure because you are feeding the bowls with four needle and seats, twice as much area for flow. I bet it is also better as far as not aireating the fuel in the bowls as well , If you keep the pressure down some. I ran a tunnelram many years ago and got away with 3.5 psi. That is all one blue pump and the junk I had would deliver in the traps. More pressure from a second pump didn't change the mph.


Edited by gregsdart (10/07/17 07:05 PM)
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GREG
Educated at SHK U
Measure with yardstick
mark with chalk
cut with torch!



528 cubic inch alky injected 440-1 wedge, 3055 race weight.
8.779 at 153.16 mph. 1.289 60 ft. density altitude 1617 feet. Best 60 ft 1.24

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#2383793 - 10/08/17 09:48 AM Re: 408 help needed [Re: gregsdart]
B1MAXX Offline
mopar

Registered: 05/07/05
Posts: 666
Loc: Apollo, PA.
I wonder how much if at all that the cnc portwork opened up the chamber. Could it be that the compression ratio was dropped. I had a pair of B1BS heads ported, the chamber went from 65cc to 85cc. To the OP was there chamber work done? If so how much? If this was already covered someone say so. I didn't read all 6 pages.

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#2384076 - 10/08/17 06:10 PM Re: 408 help needed [Re: Mirada 408]
Mirada 408 Offline
member

Registered: 08/10/15
Posts: 14
Loc: West Virginia
Fuel System consists of stock tank, original lines 5/16, Holley Blue pump and regulator run with 7lbs pressure. Never thought of pick-up sock, so good call on that. The converter is a PTC. Heads got milled so that i wouldn't lose compression.

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