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Carburetor purchase help

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70power

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Discussion starter · #1 ·
Looking for a new carb purchase. Currently have a Quik Fuel HR680 VS, auto choke. Off the shelf the 680 came with 70 front jet and 74 rear jet. During dyno the car ran lean so the jets were changed to 74 front and 80 rear. Car ran correct then.

Carb has a crack in the body. Leaking fuel.

My set up is 454, 291 Heads, Tremec 5, 3.31’s out back. 420/480 wheel dyno.

I’ve talked to Holley and Summit for a replacement. Not much help..

Should I stay with vacuum secondary, should I try a 750?

My buddy said he’d sell me a Holley 850 VS part number 12366996. He didn’t use it on his 502 crate install.

Suggestions on a couple of choices?
 
#3 ·
If you can get a deal on the 850 I would go for it. Vacuum secondary carburetors are quite versatile because they open only as much as the engine can handle and if you ever go to a higher HP combination you’ll be fine. 750 is a great fit for you now I would prefer a 4150 (metering block in the back) vs the 4160 which has a metering plate in the back with vacuum secondary.
 
#6 ·
396325 said:
If you can get a deal on the 850 I would go for it. Vacuum secondary carburetors are quite versatile because they open only as much as the engine can handle and if you ever go to a higher HP combination you’ll be fine. 750 is a great fit for you now I would prefer a 4150 (metering block in the back) vs the 4160 which has a metering plate in the back with vacuum secondary.
Click to expand...
Agree with this - if you can get a deal on it, it’s worth tuning.

Another option - you say your main body is cracked. You could just get a replacement main body and rebuild it.
 
#9 ·
70power said:
Looking for a new carb purchase. Currently have a Quik Fuel HR680 VS, auto choke. Off the shelf the 680 came with 70 front jet and 74 rear jet. During dyno the car ran lean so the jets were changed to 74 front and 80 rear. Car ran correct then.

Carb has a crack in the body. Leaking fuel.

My set up is 454, 291 Heads, Tremec 5, 3.31’s out back. 420/480 wheel dyno.

I’ve talked to Holley and Summit for a replacement. Not much help..

Should I stay with vacuum secondary, should I try a 750?

My buddy said he’d sell me a Holley 850 VS part number 12366996. He didn’t use it on his 502 crate install.

Suggestions on a couple of choices?
Click to expand...
I have a 1970 Chevelle SS 396 with the 402 CID motori am running a Edelbrock Air GAp intake and a Holley 750 Ultra double pumper. I also am running a Tremec TKX with .68 Over-drive. i switched out the OEM 3:31 limited slip rear end to a 3:73 limited slip.I am running an electric choke, it works well.
Doug
 
Discussion starter · #10 ·
Thanks all,
I've narrowed it down to a couple.

  • 750 Holley electric choke VS, 4160, part 80508S, $460
  • 750 Holley electric choke MS, 4150, part 4779SAE, $669
  • 750 Quick Fuel HR-750, electric choke, MS, 4150, part HR-750, $700

But, I’m going to buy my buddy’s new 850 as mentioned above. Brand new and still in the box. Looks like I’ll get a steal on it for an engine stand I have and a $100 bill.. I’ll probably set aside until I order a MJ variant. I don’t plan on that until this current motor goes..



Image



I’ve found a price on a new base plate for my 680. The cost is $165. I also need a new rear bowel kit. Around another $100. So, I’ll keep my 680 for parts or rebuild later.

So, in the end I might have 2 spares. Worse things in life.

But before I pull a new 750 purchase I’m going to reach out to Phil as Leo mentioned.
 
Discussion starter · #15 ·
Okay, after talking with quite a few. I bought the Holley 750, electric choke, VS. Model # 80508S. 4160 type.

On a whim, I went to Parks Auto here in SC. They had one in stock. I got it for $440 out the door.

Dialed her in today, choke okay, minor bleeds adjustment, maybe 1/8 turn each side. Vacuum rolling around 16. She’s eating again and seat of pants is fantastic. No smoke and no pinging. I’m running 18 initial 38 all in with 94 non ethanol. Spun it too 5200 today and it loved it.

Thanks all..
 
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swampy 6x6
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