4bbL vs weber or stack for max hp from 302

Ross Nicol

GT40s Supporter
Gordon- will you dyno your motor when you fit the new stack manifold to it? Be interesting to compare torque and HP between the IDAs and the new individual runners. The Motec guys here reckon they get better figures with IR than 4bbl but I'm a sceptic until proof comes from good sources.
Ross
 
I will dyno it once the manifold is finished.
am having an intake with 52mm t-bodies made for the 306. It's the only way the numbers will make sence at 9000 revs.
 

Sandy

Gulf GT40
Lifetime Supporter
I have had a couple of head/engine folks say that the Victor Jr. is highly mismatched port to port and the Super Vic is better (But bigger). The manifold that Ron has was highly recommended (Parker Funnel Web) but would not fit on the Mustang or the GT40 or I would run one due to height. Gordon, very interested to see how things run out on the Dyno.

Sandy
 
Gordon,

I have a victor Jr. on my GT40 with a Elderbrock 600cfm carb - seems to hesitate (buck) a little when accelerating from 2-4000 rpm. How would a Holley 750 double pumper work on the Victory Jr?

John
:pepper:
 

Sandy

Gulf GT40
Lifetime Supporter
John -

Likely the carb is not set up right. The Edelbrock carbs are the old Carter AFB's which are a bit simple of a carb and IMHO harder to get working then a Holley. The Size of the carb is also not likely your problem, and depends on your engine capabilities, a 600cfm-750cfm holley might be fine, but a few things will determine that, cam/rpm potential, cubic inches, etc.

Sandy
 

Russ Noble

GT40s Supporter
Lifetime Supporter
So John, is this a new OTB carb or secondhand? What jets and needles are you running? What happens under 2000 rpm? Is the hesitation just an initial stumble when you floor the pedal or does it run rough all the way through to 4000rpm?

I am no expert but I have found my 500 Edelbrock on a Rover V8 very tolerant to a range of engine capacities, 215 to 300 ci, single and dual plane manifolds and mild to not so mild cams. Always runs well with OTB jets etc, just needs small changes to optimize everything.

I don't have any experience with Holleys but the Edelbrock does not seem difficult to deal with if you follow their supplied handbook and apply needle and jet changes diligently using their reference graphs. These are also available online.

Are you sure it's your carb, and not something silly like the cam timing set incorrectly etc?

Cheers
 
John, I need to know your engine specs to be able to answer your questions.
I will always use a holley over the Edelbrock carbs on a Ford.
 
Russ and Gordon,

My engine is a 350 Chevy engine with an Isky roller cam - has about 300 miles on the engine so it is not broken in.

Cam specs are: Intake : duration - 280 degree
open - 32 before TDC
close - 68 after BDC
cam lift - .350
valve lift - .525
valve lash - .020


Cam specs are: Exhaust: duration - 280 degree
open - 68 before TDC
close - 32 after BDC
cam lift -.350
valve lift - .525
valve lash - .020

Overlap 64 degrees:

The carb is a Elderbrock 600 cfm P/N 2290-1405
primary jets - .100
sec - .095

The manifold is a Victor Jr.

It seems to pull alright up to 2K RPM but kind of bucks and jerks between 2 - 4K in second gear. I'm running a 930 Porsche transaxle but don't know the gear ratios.

What do you thinK?

John
:pepper:
 

Randy V

Admin
Lifetime Supporter
John - at 300 miles, your engine is already broken in. Bucking / surging is usually a lean condition or potentially an ignition issue.. That's not a lot of carburetor for the engine you are running. It would probably perform a little better with a 700-750 CFM carb with that camshaft.
 
John - at 300 miles, your engine is already broken in. Bucking / surging is usually a lean condition or potentially an ignition issue.. That's not a lot of carburetor for the engine you are running. It would probably perform a little better with a 700-750 CFM carb with that camshaft.
Thanks Randy,

I just picked up a Holley double pumper 750cm to put on - I'll keep you posted on the results!

John
:pepper:
 
Just bringing this thread alive again,
I'm thinking of using a victor junior super EFi manifold and 4 barrel 1200 CFM throttle body on my DRB. Apart from not knowing if it will fit under the hatch, Am I making a big mistake using this set up? and is anyone running one of these manifold with success?
I'm thinking of buying this stuff from Summit racing.com can anyone recomend other web shops to purchase from?
 

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Hi Dave -

I've setup a couple of cars with these on. GTD40 (SB302Ford) and GTD R42 (SB383Chevy). Both ran Motec M48 on sequential injection and gave good results, plus, they have a good idle speed control valve which makes easy idle.:) Quite low in profile too so if deck room is an issue, they'll help there too.
 

Ross Nicol

GT40s Supporter
Hi Dave
I've got a Motec setup as in your pics, for sale, if your interested.It was on my current motor when I purchased it. I've got no idea what it's worth but I'm sure I can be competitive compared to new one from Summit.
Ross
 
Dave,
My original system was similar to what you have described.

1000cfm throttle body on victor jr manifold. The whole package came from EFI hardware in Melbourne. It was very competetively priced and really good package in operation. In some ways it was preferable over the 8 stack system. It certainly had a higher power output than 8 stacks.

If you haven't called them it is worth the call. The other bonus is that they are at least within Oz so freight and duty wont stack up the costs.

Photo attached of the original setup on my car.
 

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Hey Rick / Ross
I can get the manifold from Victoria Performance warehouse for $700 AU
and the 4 barrel from Summit for $500 AU.
So Ross if you're interested in selling your set-up PM me with a price and I will consider it.
Cheers Guys.
 
Old thread, new live...
Single Holley, dual Holley or Quad Webers... Performance wise.
Quad Webers do look cool and sounds cool but mk2's came with singe quad & dual quad Holleys.

Sinare also available for smalblock Winsor 302 engines.

Normaly you would use a ( Calculated) 600cfm Holley on a 302 engine..
So what carb size Holley, single & dual and what carb size Weber, IDF or 48IDA if you can take hands on it..

Here's the theory in simple terms.A typical Weber 48IDA / or similar sized stack flows about 330 cfm per barrel.While the sum total of all 8 barrels is over 2600cfm, the important difference is that each cylinder can only draw from 1 330 cfm barrel.With a 4BBL on a single plane manifold each cylinder has access to 4 barrels, reducing restriction during peak flow and increasing high speed horsepower.
 
Old thread, new live...
Single Holley, dual Holley or Quad Webers... Performance wise.
Quad Webers do look cool and sounds cool but mk2's came with singe quad & dual quad Holleys.

Sinare also available for smalblock Winsor 302 engines.

Normaly you would use a ( Calculated) 600cfm Holley on a 302 engine..
So what carb size Holley, single & dual and what carb size Weber, IDF or 48IDA if you can take hands on it..
Thought that info you quoted from Ross looked familiar, My thoughts have not changed.
 
Ford went with the GT program from quad Webers, to single Holley to dual Holley.
Imo from UK induction (Weber) to US induction (Holley) to dual Holley (probably to simulate quad Webers).

This topic as is is aged and Ill guess outdated as there must be more info by now. Thats why I reopened this topic.

Holley 600 dp or vc vs Weber 48IDA or Holley 780(single pump/double squirt) as used on the GT's vs quad 48 IDA.
I assume most use a Holley 600 vc these days on a 302 in their GT40 but I might be wrong.

SAE papers show an improvement from single Holley 780 to dual Holley on the GT program.
 
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