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Help selecting a carb by mcguiver3
Started on: 01-16-2014 04:34 PM
Replies: 12 (165 views)
Last post by: Arns85GT on 01-16-2014 09:23 PM
mcguiver3
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Report this Post01-16-2014 04:34 PM Click Here to See the Profile for mcguiver3Send a Private Message to mcguiver3Edit/Delete MessageReply w/QuoteDirect Link to This Post
Ok members here is my problem............
My son has built himself an 88 race car with a really warmed over 3.4 and has it carbed.
The issue is I believe he has the wrong carb installed.
The current one is a Holly 550 4 barrel, Street Eliminator from Summit.
The car runs great but starves at mid corner on long sweepers.
Floats are adjusted to spec.
I am not a carb guy.
Any recommendations? Anyone in CT that's good with this stuff?
Need to sort it out before April if possible.
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Csjag
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Report this Post01-16-2014 04:37 PM Click Here to See the Profile for CsjagSend a Private Message to CsjagEdit/Delete MessageReply w/QuoteDirect Link to This Post
Could it be that the fuel pump isn't pumping enough?
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Patrick
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Report this Post01-16-2014 04:43 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by mcguiver3:

The car runs great but starves at mid corner on long sweepers.
Floats are adjusted to spec.


I suspect this has to do with the fact the carb is mounted on transversely mounted engine, and the carb/floats may have originally been designed to be used on a longitudinal mounted drivetrain... but I know that doesn't help you any.
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conan469
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Report this Post01-16-2014 04:57 PM Click Here to See the Profile for conan469Click Here to visit conan469's HomePageSend a Private Message to conan469Edit/Delete MessageReply w/QuoteDirect Link to This Post
larger carb would be of no help.
you need to look into modified float bowl setups.
they make a set of jet extensions for drag racing to keep them in the fuel on hard launches.
this might help
they also make/used to make float bowl foam inserts to slow down fuel slosh.
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mcguiver3
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Report this Post01-16-2014 05:08 PM Click Here to See the Profile for mcguiver3Send a Private Message to mcguiver3Edit/Delete MessageReply w/QuoteDirect Link to This Post
Fuel pressure is 5 psi
I fabricated a mounting plate that rotates the unit 90 deg. so it faces F/R
And it sits level.
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trotterlg
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Report this Post01-16-2014 05:19 PM Click Here to See the Profile for trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
I did a carbed 3100 and changed how the carb sat, I think that is your problem. Larry

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2.5
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Report this Post01-16-2014 05:27 PM Click Here to See the Profile for 2.5Send a Private Message to 2.5Edit/Delete MessageReply w/QuoteDirect Link to This Post
There are "off road" carbs made for bouncing and leaning, etc without slosh. Could look into that too.
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mcguiver3
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Report this Post01-16-2014 05:30 PM Click Here to See the Profile for mcguiver3Send a Private Message to mcguiver3Edit/Delete MessageReply w/QuoteDirect Link to This Post
Larry,
The carb does sit front-to-back.
I do think it's float related, pick-ups need to be extended?
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HarryG
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Report this Post01-16-2014 05:41 PM Click Here to See the Profile for HarryGSend a Private Message to HarryGEdit/Delete MessageReply w/QuoteDirect Link to This Post
Which fuel pump is he using?
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trotterlg
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Report this Post01-16-2014 06:05 PM Click Here to See the Profile for trotterlgSend a Private Message to trotterlgEdit/Delete MessageReply w/QuoteDirect Link to This Post
Does it starve out turning both directions?
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mcguiver3
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Report this Post01-16-2014 07:59 PM Click Here to See the Profile for mcguiver3Send a Private Message to mcguiver3Edit/Delete MessageReply w/QuoteDirect Link to This Post
Fuel pump is an in line unit rated for 4-9 PSI and is what the carb requires for volume.
It appears to be only in right hand corners.
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cmechmann
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Report this Post01-16-2014 08:30 PM Click Here to See the Profile for cmechmannSend a Private Message to cmechmannEdit/Delete MessageReply w/QuoteDirect Link to This Post
Sounds like it may be a venting problem. Is there anything covering the vent ports to the bowls? Sometimes poor designed snorkles or air cleaner assemblies can cover the vent ports. That of course if it is using ventury ports. newer style carbs will have ports that have plumbing to canister/evap system and use a tube at the bowls to be connected to hoses going to the charcoal canister. If it is that design make sure you have no restrictions in your vent plumbing.
Also on Holleys, I've found it better to use a running drip setting at the bowl screws on the sides of the bowls rather than using height measurement. Remove side bowl screw, start up, loosen top lock screw, adjust height nut till fuel just starts to drip, tighten lock screw, repeat for rear bowl.
Holleys work great when you need a lot of fuel and CFMs but under 300hp not really needed. Found stock type carbs to work better in that range. Especially when it comes to getting emissions down.
I am biased towards Quadrajets. Have not had a problem with them, when you know where to make the right adjustments.
Quadrajets had received a bad rep. Setting the rear bowl spring load properly is important. Too mant try to release the spring load to get the secondaries to open sooner, only resulting in bogging down. Adjusting the rear metering rods and opening angles can make those carbs work for many different applications.
Dual jets were used extensively on front wheel drives. They are practically the same front two Barrels as a Quardrajet.
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Arns85GT
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Report this Post01-16-2014 09:23 PM Click Here to See the Profile for Arns85GTSend a Private Message to Arns85GTEdit/Delete MessageReply w/QuoteDirect Link to This Post
I've been running a Holley carb on a Fiero for a few years.

The standard Holley has side mounted floats. You can tell if your model has side mounts because the float bowls are rectangular.

Center hung models will not fail in the corners.

More importantly the 550 is allot of air for 3.4 engines. I would not use over a 450 ci. on that engine.

I'm using a 500 cfm on 4.9 L It is the 2 barrel, center float.

If you already have a center float, you have a richness problem, Holley custom shop gives you a 1-800 in the booklet that came with it.

If I haven't answered you question, they likely can. Good luck with it.

Arn
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