Carb adapter help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Bisblue · 03-23-2018, 01:04 AM

Hey folks,

A friend gave me a holley 2 barrel and adapter that fits my 292, kind of.

Even with a fat gasket, I'm bottoming out with the bolts coming out of the intake manifold. See poor quality night pictures. Any ideas? Anyone know where to find replacement bolts so I can try and cut them down if need be?

Thanks in advance for the help.

**'68OrangeSunshine** · 03-23-2018, 02:14 AM

Looks like you will have to remove these OEM studs with vice-grips, and find some other studs that have deeper threading.
What CFM is the 2-Bbl Holley?

B Myers · 03-23-2018, 08:03 AM

I think with the interference you might have to remove the studs and use bolts.

B Myers · 03-23-2018, 08:05 AM

Also the studs are threaded into the intake so they will screw out.

Bisblue · 03-23-2018, 10:26 AM

Not sure on the cfm, the 1 barrel was acting up and the holley was free from a friend to try. The holley came off of a dodge 360/400.
Anyone know the size/thread pattern of the studs?

Troy Sr · 03-23-2018, 10:32 AM

You can just go to the Hardware store and buy a piece of threaded rod with the same threads and cut to the length you need. It doesn't look like you can get a bolt in the hole with the interference.

jfnar · 03-23-2018, 10:49 AM

I think you need a different adapter. Take a look at this video and fast forward to about the 5 minute mark. https://www.youtube.com/watch?v=x-UfzjIAOXo

Bisblue · 03-23-2018, 11:11 AM

Thanks for the heads up, I ordered something similar and the bolt pattern was too narrow. Also the difference between free and 50 bucks for the one I've got. I'll get some shorter studs, and see if it works, they're 1.50 each, if not I'll look again for the right adapter that's wider.

jfnar · 03-23-2018, 12:13 PM

I bought an adapter at O'Reilly's. I'll look tonight and see if I can find the pn. I don't think it was very expensive.

Bisblue · 03-23-2018, 12:21 PM

Thanks,
mine is a 2 15/16 pattern. The transdapt 2041 is 40 bucks on amazon. Even the shortest studs I can buy are too long. I might just suck it up and get the right adapter.

**'68OrangeSunshine** · 03-25-2018, 02:09 AM

At one time, I was going to use a similar Offenhauser 5710 [2-into-1] adapter on my stock intake to put a Holley/Weber 5210, progressive-linked 2 Bbl on my 292. I had the same problem, that the adapter holes needed to be hogged out quite a bit to fit the GM L6 manifold pattern.
I was told by ''helpful speed shop owners" that the 5210 didn't have enough CFMs to power my .030-over-bored 292. So I bought an Offy 5416 4 Bbl intake, a Holley #8007 390 CFM 4 Bbl, and Clifford Headers.
I have no regrets, but researching lately, I found out that the stock Monojet flows about 250 CFM [GM was never CFM-specific about carbs, like Carter, Holley and Edelbrock]. The Holley/Weber 5200/5210 flowed about 280 CFM. So it might have been an improvement.
Buying the Big Boy toys, 40 years ago made me a bigger boy, I guess. Except for the 390 Holley, I still run that gear on my current 292 L6 engine in the same truck.

Bisblue · 03-25-2018, 10:19 AM

Thanks for the info Orange,
I've got a 283 I'm gonna throw in it. Mainly I got a free 2 barrel and was having issues with my monojet, so looking for a fix for a couple months, until I get the 283 ready to go in. I broke down and ordered the correct transdapt adapter, we'll see how it goes.

03-23-2018, 01:04 AM	#1
Bisblue Registered User Join Date: Apr 2017 Location: Las Vegas Posts: 65	Carb adapter help Hey folks, A friend gave me a holley 2 barrel and adapter that fits my 292, kind of. Even with a fat gasket, I'm bottoming out with the bolts coming out of the intake manifold. See poor quality night pictures. Any ideas? Anyone know where to find replacement bolts so I can try and cut them down if need be? Thanks in advance for the help. Attached Images

03-23-2018, 02:14 AM	#2
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,019	Re: Carb adapter help Looks like you will have to remove these OEM studs with vice-grips, and find some other studs that have deeper threading. What CFM is the 2-Bbl Holley? __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.

03-23-2018, 08:03 AM	#3
B Myers Registered User Join Date: Feb 2016 Location: Murphysboro Illinois Posts: 119	Re: Carb adapter help I think with the interference you might have to remove the studs and use bolts.

03-23-2018, 08:05 AM	#4
B Myers Registered User Join Date: Feb 2016 Location: Murphysboro Illinois Posts: 119	Re: Carb adapter help Also the studs are threaded into the intake so they will screw out.

03-23-2018, 10:26 AM	#5
Bisblue Registered User Join Date: Apr 2017 Location: Las Vegas Posts: 65	Re: Carb adapter help Not sure on the cfm, the 1 barrel was acting up and the holley was free from a friend to try. The holley came off of a dodge 360/400. Anyone know the size/thread pattern of the studs? Last edited by Bisblue; 03-23-2018 at 10:44 AM.

03-23-2018, 10:32 AM	#6
Troy Sr Registered User Join Date: Nov 2013 Location: Antioch, Ca. Posts: 442	Re: Carb adapter help You can just go to the Hardware store and buy a piece of threaded rod with the same threads and cut to the length you need. It doesn't look like you can get a bolt in the hole with the interference. __________________ Take Care Troy

03-23-2018, 10:49 AM	#7
jfnar Registered User Join Date: Jul 2009 Location: Jonesboro, AR Posts: 410	Re: Carb adapter help I think you need a different adapter. Take a look at this video and fast forward to about the 5 minute mark. https://www.youtube.com/watch?v=x-UfzjIAOXo

03-23-2018, 11:11 AM	#8
Bisblue Registered User Join Date: Apr 2017 Location: Las Vegas Posts: 65	Re: Carb adapter help Thanks for the heads up, I ordered something similar and the bolt pattern was too narrow. Also the difference between free and 50 bucks for the one I've got. I'll get some shorter studs, and see if it works, they're 1.50 each, if not I'll look again for the right adapter that's wider. Last edited by Bisblue; 03-23-2018 at 11:17 AM.

03-23-2018, 12:13 PM	#9
jfnar Registered User Join Date: Jul 2009 Location: Jonesboro, AR Posts: 410	Re: Carb adapter help I bought an adapter at O'Reilly's. I'll look tonight and see if I can find the pn. I don't think it was very expensive.

03-23-2018, 12:21 PM	#10
Bisblue Registered User Join Date: Apr 2017 Location: Las Vegas Posts: 65	Re: Carb adapter help Thanks, mine is a 2 15/16 pattern. The transdapt 2041 is 40 bucks on amazon. Even the shortest studs I can buy are too long. I might just suck it up and get the right adapter. Last edited by Bisblue; 03-23-2018 at 05:30 PM.

03-25-2018, 02:09 AM	#11
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,019	Re: Carb adapter help At one time, I was going to use a similar Offenhauser 5710 [2-into-1] adapter on my stock intake to put a Holley/Weber 5210, progressive-linked 2 Bbl on my 292. I had the same problem, that the adapter holes needed to be hogged out quite a bit to fit the GM L6 manifold pattern. I was told by ''helpful speed shop owners" that the 5210 didn't have enough CFMs to power my .030-over-bored 292. So I bought an Offy 5416 4 Bbl intake, a Holley #8007 390 CFM 4 Bbl, and Clifford Headers. I have no regrets, but researching lately, I found out that the stock Monojet flows about 250 CFM [GM was never CFM-specific about carbs, like Carter, Holley and Edelbrock]. The Holley/Weber 5200/5210 flowed about 280 CFM. So it might have been an improvement. Buying the Big Boy toys, 40 years ago made me a bigger boy, I guess. Except for the 390 Holley, I still run that gear on my current 292 L6 engine in the same truck. Attached Images __________________ Every 25 years I like to rebuild that 292, whether it needs it or not. Last edited by '68OrangeSunshine; 03-25-2018 at 02:19 AM.

03-25-2018, 10:19 AM	#12
Bisblue Registered User Join Date: Apr 2017 Location: Las Vegas Posts: 65	Re: Carb adapter help Thanks for the info Orange, I've got a 283 I'm gonna throw in it. Mainly I got a free 2 barrel and was having issues with my monojet, so looking for a fix for a couple months, until I get the 283 ready to go in. I broke down and ordered the correct transdapt adapter, we'll see how it goes.



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