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Phenolic Carb Spacers for Victor LS1 EFI

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Old 04-09-2006, 07:58 AM   #1
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Default Phenolic Carb Spacers for Victor LS1 EFI

I am putting together a new combo, so I need help deciding how thick of a carb spacer the motor needs. If I remember correctly carb'd 350's liked 2" spacers.

Brief over view:
347 LS1
Scat 6.125
Mahle 3.905 -4cc
Stock crank
Accufab 4150 style throttle body
Victor Jr. EFI port matched to "Cleaned up" stock heads
T-Rex
TH-350
4,600 stall
4.56
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Old 04-09-2006, 09:23 AM   #2
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No one has any idea?
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Old 04-09-2006, 09:30 AM   #3
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Every engine combination is different. You'll want to experiment. Some power from the tall carb spacers may be from fuel distribution and signal (4 hole) instead of just the added plenum volume. Obviously this isn't an issue with your setup. The air straightening effect of a spacer can be a benifit for you so just get 2 or 3 and try them out at the track.
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Old 04-10-2006, 12:50 AM   #4
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Carb spacers tend to increase plenum volume with the open ones. Some will also send a stronger vacuum signal to the boosters in a carb'd application, like a 4 hole spacer.

an open spacer might work if you need more plenum volume. Looks like it's experimentation time for you.
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Old 04-10-2006, 07:09 AM   #5
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This will also depend on the size of the carb. Smaller carbs tend to like the taller spacer because the air fuel mixture comes through it with a greater velocity and the taller spacers give it a larger area to make the transition into the runners. There are also some spacers out there that are making even more power than standard spacers. Check these out: http://www.sdpc2000.com/catalog/1852...or-Spacers.htm
They are expensive, but on an offshore boating forum I visit there are a few builders that swear they are worth 15 hp or more and in every case I have seen where they tried them they have been. Granted we are talking about large cubic inch, carbed, 600+ HP big blocks. I am not sure how much you would gain with EFI, if any, especialy if you are using port type injection where only air will be passing through the T/B.
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Old 04-11-2006, 11:53 PM   #6
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That will take quite a bit of cutting and fabing to look decent.

Good luck with your experiment.
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Old 04-13-2006, 12:01 AM   #7
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Phenolic is a used as a carb spacer for its insulation properties, to keep heat away from the carb and fuel. It is tough to machine and the dust is toxic or irritating. Since there's no fuel in your throttle body, you could just use an aluminum spacer. For the price of 1 phenolic you can get 2 different size aluminum. Virtually no difference in performance between the 2 materials on an EFI motor.

Jim
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Old 04-13-2006, 11:35 AM   #8
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Quote:
Originally Posted by stevemilz
I am putting together a new combo, so I need help deciding how thick of a carb spacer the motor needs. If I remember correctly carb'd 350's liked 2" spacers.

Brief over view:
347 LS1
Scat 6.125
Mahle 3.905 -4cc
Stock crank
Accufab 4150 style throttle body
Victor Jr. EFI port matched to "Cleaned up" stock heads
T-Rex
TH-350
4,600 stall
4.56
Thoughts:

If you are trying for more power than the LSx or FAST folded hands manifold, you might look carefully at intake tuning on the Vic. The long runners are about 7.25 long and the short ones about 4.5 in. long. I don't think a cam designed for the OEM/FAST manifold will be ideal. IMO, the short/long runners ask for different valve timing for the inner cylinders from what the outer cylinders like. That's doable for a reasonable price.

High end engines like Nextel Cup treat each cylinder as a separate "engine" as far as valve timing goes. Treating an LS1 with the Vic manifold as 2 V4s on a common crank might prove worthwhile.

Plenum size on the Vic is about 35-40 cubic inches, which might be smaller than you need. An open 4150 spacer is about 12 cu. in. per inch of height.

Good luck.
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Old 04-16-2006, 02:51 AM   #9
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Quote:
Originally Posted by Old SStroker
Plenum size on the Vic is about 35-40 cubic inches, which might be smaller than you need. An open 4150 spacer is about 12 cu. in. per inch of height.
How big is the plenum on the LS6? Or the LQ4/9 truck manifold? Anyone know?
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