Author Topic: GT350 Holley carb auto vs. 4 Spd differences  (Read 375 times)

Corey Bowcutt

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GT350 Holley carb auto vs. 4 Spd differences
« on: November 24, 2021, 06:02:10 PM »
Can any one tell me the difference between the Holley 4bbl used with auto vs. manual transmission on 1968 GT350?

Corey

Drew Pojedinec

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Re: GT350 Holley carb auto vs. 4 Spd differences
« Reply #1 on: November 24, 2021, 06:48:47 PM »
I’m not 100% of which ones you are talking about…. But honestly, there is very little if any difference.
With some it is a tony difference, like .01 in a bleed to make a slightly richer idle for an auto.

Corey Bowcutt

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Re: GT350 Holley carb auto vs. 4 Spd differences
« Reply #2 on: November 24, 2021, 08:11:53 PM »
Drew, on thecoralsnake.com Pete lists the Holley for auto as S8MS-A and for 4spd S8MS-C. I need a 4sp carb but know someone selling an auto so I am just trying to determine if it will work for me.
Corey

Drew Pojedinec

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Re: GT350 Holley carb auto vs. 4 Spd differences
« Reply #3 on: November 24, 2021, 08:18:44 PM »
Ok. Now that I know which ones, I’ll check my calibration info and notes when I get back to the shop friday, but they take the same blocks, if I remember airbleeds are the same (will check). Might just be a different airbleed or something external like a dashpot… I suspect you could use either without any insurmountable issue.

6s1640

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Re: GT350 Holley carb auto vs. 4 Spd differences
« Reply #4 on: November 24, 2021, 09:50:03 PM »
Hi Corey,

I am also confused.  According to Mustangtek, the features that make each carb appear to be identical.  See attached image from Mustangtek.

I recommend checking an alternate source to see if the info is the same or different.

Cory
« Last Edit: November 24, 2021, 09:53:34 PM by 6s1640 »

Corey Bowcutt

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Re: GT350 Holley carb auto vs. 4 Spd differences
« Reply #5 on: November 24, 2021, 10:07:08 PM »
Cory, thank you for posting that. It is very interresting.

Drew, look forward to seeing what you find.

Corey

shelbydoug

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Re: GT350 Holley carb auto vs. 4 Spd differences
« Reply #6 on: November 24, 2021, 10:31:34 PM »
I'd like to hear the difference also but isn't it that one is an automatic choke and the other manual?
68 GT350 Lives Matter!

CharlesTurner

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Re: GT350 Holley carb auto vs. 4 Spd differences
« Reply #7 on: November 24, 2021, 11:02:51 PM »
I'd like to hear the difference also but isn't it that one is an automatic choke and the other manual?

They were both auto choke for '68.

Probably minor idle circuit differences or something like that as Drew mentioned.
Charles Turner
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TLea

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Re: GT350 Holley carb auto vs. 4 Spd differences
« Reply #8 on: November 25, 2021, 10:15:29 AM »
Very minor differences in the idle circuits. The bottom line is if you’re going to spend that much money you should probably get the right one for your car otherwise a $400 universal holley at AutoZone will work just as well