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Alternate carb choices?
Posted by: mmak116 ()
Date: January 06, 2018 09:46AM

Anyone ever successfully use any combination of Rochester B series or other alternate (zenith, stromberg, etc) carbs? I plan to use a set of modified 102 or 110 heads with larger valves from American Flat 6 and OT-20 cam for my 64 coupe. Of course I am concerned with making the most of the mods. What machining to the intake logs or carb pads was required - minimal? major? Results?
Any information on anyones experiences, good or bad, would be appreciated.



Edited 1 time(s). Last edit at 01/06/2018 01:23PM by MattNall.

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Re: alrernate carb choices
Posted by: MattNall ()
Date: January 06, 2018 10:40AM

We've seen a few Solex's used.... But the HV's are good for most....and can be bored and modified to 1-1/2" throttle plates





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Alternate carb choices?
Posted by: Frank DuVal ()
Date: January 06, 2018 03:52PM

I second stick with HVs and get them bored out to a larger size if needed. Should not need to go to 1 1/2 for street use. Several machinists do this modification.

Back in the 70s, when Pintos and Vegas were all around, there were adapters to mount those Weber Holley clones (5200 series) giving two barrels per head.

Are you getting the second mount installed on each head?

Frank DuVal

Fredericksburg, VA

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Re: Alternate carb choices?
Posted by: chris ()
Date: January 06, 2018 03:58PM

Frank DuVal Wrote:
-------------------------------------------------------
> I second stick with HVs and get them bored out to
> a larger size if needed. Should not need to go to
> 1 1/2 for street use. Several machinists do this
> modification.
>
> Back in the 70s, when Pintos and Vegas were all
> around, there were adapters to mount those Weber
> Holley clones (5200 series) giving two barrels per
> head.
>
> Are you getting the second mount installed on each
> head?

Believe it or not, but I think Offenhauser still offers the Holley 5200/Rochester 2GC adapter (Clark's maybe too?) but it only goes to one opening on the head.
[www.offyparts.com]

'65 Monza 4 door
4 speed
110hp
Gardner, KS

Heart of America Corvair Owners Association

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Re: Alternate carb choices?
Posted by: American Mel ()
Date: January 06, 2018 04:48PM

chris Wrote:

>
> Believe it or not, but I think Offenhauser still
> offers the Holley 5200/Rochester 2GC adapter
> (Clark's maybe too?) but it only goes to one
> opening on the head.
> [www.offyparts.com]
> _id/959?osCsid=af9c3df3882e0c17b7a45d512c8db9f1

Cool, looks like they still make the 2 carb manifold replacement also.

.
-----------------------------------------------
WA. state, 1 mile south of the Canadian border,
I am not at the end of the world, but you can see it from here.
'66 Monza Coupe - 4spd, 140 Daily driver beater
'67 Monza Vert. - PG, 140 Daily driver beater

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Re: Alternate carb choices?
Posted by: mmak116 ()
Date: January 07, 2018 06:35AM

I’m on the fence about adding the second carb pad on each head. Looking for opinions on what works best for performance taking into account this will be a street car strictly for driving enjoyment. I’m not racing every stoplight to stoplight but as a motorsport enthusiast,I enjoy spirited driving. What will give the best performance for the modified heads and cam? Will one modified HV on each side provide enough flow? Are there other carbs (one on each head) that will provide enough flow and performance to take advantage of the heads and cam? The center mounted two barrel option looks like an option especially if synchronization is not an issue but is this enough flow?
Opinions please.
Thanks for your input.

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Re: Alternate carb choices?
Posted by: 65CrownV8 ()
Date: January 07, 2018 06:52AM

IMHO thr HVs can provide as much flow as the heads can handle. If you're looking for more flow, look to modify the exhaust side first. Angle port exhaust, headers and port work will do more for the fun factor than anything you can do on the intake side.

George Jones - East Orlando, FL
'65 Monza V8 Convertible - 355/4-spd Posi - TT015
'66 Monza Coupe - 95/PG
'67 Monza Coupe 140/4-spd/Posi, A/C
COrvaiR Society of America (CORSA), Central Florida Corvair Club, Tidewater Corvair Club, V8 Registry

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Re: Alternate carb choices?
Posted by: Shaker455 ()
Date: January 07, 2018 07:02AM

mmak116 Wrote:
-------------------------------------------------------
> Anyone ever successfully use any combination of
> Rochester B series or other alternate (zenith,
> stromberg, etc) carbs? I plan to use a set of
> modified 102 or 110 heads with larger valves from
> American Flat 6 and OT-20 cam for my 64 coupe. Of
> course I am concerned with making the most of the
> mods. What machining to the intake logs or carb
> pads was required - minimal? major? Results?
> Any information on anyones experiences, good or
> bad, would be appreciated.

I'm working closely with Tom K on his 40mm weber 2bbl's.
I have his heads, intake & Weber set up to test and modify to fit our apps.
I'm a machinist and a carb builder/ modifier.

Jeff
Granite State NH

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Re: Alternate carb choices?
Posted by: mmak116 ()
Date: January 07, 2018 07:59AM

Thanks for all of the input. My heads will be going to Tom soon and I need to get the rest sorted out. As far as exhaust goes, I was leaning toward 140 exhaust tubes. Is the Weber you’re working on with Tom the IDF or the DG/DV(Holley 5200)?

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Re: Alternate carb choices?
Posted by: Shaker455 ()
Date: January 07, 2018 08:27AM

It's the IDF,
He did ask me about the Holley 5200
I build custom Holley's also so we are going to explore best carb options as well.

Jeff
Granite State NH

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Re: Alternate carb choices?
Posted by: mmak116 ()
Date: January 07, 2018 08:32AM

Thanks Jeff! I’ll PM you when the time comes to further discuss the Weber and Holley options. Any other input from others is also welcome.

Michael

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Re: Alternate carb choices?
Posted by: Shaker455 ()
Date: January 07, 2018 08:45AM

Be happy to hear from you Michael

Jeff
Granite State NH

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Re: Alternate carb choices?
Posted by: MattNall ()
Date: January 07, 2018 09:23AM

American Mel Wrote:
-------------------------------------------------------

> Cool, looks like they still make the 2 carb
> manifold replacement also.


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Re: Alternate carb choices?
Posted by: mmak116 ()
Date: January 07, 2018 09:45AM

I saw those Offy manifolds on eBay, just wasn’t sure if the plenum was a different size (not sure if the 140HP big valve and small valve heads intake plenum sizs and volumes were the same). Looks like the pads on them are rotated too. Anyone use them before or can confirm if they will also fit the small valve heads?

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Re: Alternate carb choices?
Posted by: MattNall ()
Date: January 07, 2018 09:51AM

That's what they were made for!! Pre- 1965!! no 140's!

Bill Thomas used them on a 1960 in 1960..





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Alternate carb choices?
Posted by: mmak116 ()
Date: January 07, 2018 09:58AM

Thanks Matt! Yet another option to consider.

Michael

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Re: Alternate carb choices?
Posted by: Shaker455 ()
Date: January 07, 2018 10:04AM

Tom makes his own pads from billet aluminum

Jeff
Granite State NH

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Re: Alternate carb choices?
Posted by: MattNall ()
Date: January 07, 2018 10:40AM

chris Wrote:
-------------------------------------------------------

> Believe it or not, but I think Offenhauser still
> offers the Holley 5200/Rochester 2GC adapter
> (Clark's maybe too?) but it only goes to one
> opening on the head.
==============================================================

Using any carb that is feeding an intake port SMALLER is a total waste of time....

And to add to your thoughts of improving power... Ask Tom!!

Our Exhaust ports are the restriction!! Not the carbs! He'll add 140 tubes [ larger ] Why not go for the angle port exhaust mod?







MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Alternate carb choices?
Posted by: v8vair ()
Date: January 07, 2018 11:09AM

The Slant tube gains you very little. The stock 140 tube is more than enough. I only did the slant tube on my first set of heads because " every racer does it" We were able to get the stock tube to flow better than most slant tubes numbers ive seen.
Headers are your friend.
Reeves right now has the fastest Lap time around Road Atlanta with a 2.7,Webbers and stock 140 exhaust tubes, Heads done properly, you dont need large slant tubes especially for the street.
Ray Sedman told me this a few years ago but i had to have them, then we did a comparison on a Super Flow 600 bench, and he was right.
Mike

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Re: Alternate carb choices?
Posted by: MattNall ()
Date: January 07, 2018 11:13AM

Interesting! Never remember hearing that before from someone with a flow bench!

Now I know why Tom Kn. doesn't talk up the Slants... all these years I thought my $$ / labor frugality cost me power!! gg





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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