What is it ? Holley 4 bbl DP (?)

[MattH]

It seems big, secondary butterflies are so big that they foul the Offy 360 manifold when open, and the studs touch the fuel bowls.

Can anyone identify or recognise what this is. I think it is a double pumper from the way the butterflies operate but I am a complete novice on 4 barrels, having been brough up on Strombergs and SU's.

[Pete]

It is a DP.

You need to check the LIST number on the air horn.

I think that is a later carb where they attempted to improve economy by making the primaries very small, and making the secondaries very big to maintain performance.

[Blue]

Holley carbs designed for universal applications have all 4 butterflys equally sized. What you have there is a spreadbore carb (small primarys/ large secondaries) designed to be a direct replacement for a Chevy application using a quadrajet carb I believe. It is a double pumper ( though again not the regular style) and the number stamped into the choke horn will identify the size. Is this on Mandys truck?

[MattH]

Holley carbs designed for universal applications have all 4 butterflys equally sized. What you have there is a spreadbore carb (small primarys/ large secondaries) designed to be a direct replacement for a Chevy application using a quadrajet carb I believe. It is a double pumper ( though again not the regular style) and the number stamped into the choke horn will identify the size. Is this on Mandys truck?

No this isnt on Mandie's truck, this is a carb I had as an option to put on the Challenger, but have found (see other thread in workshop) that it wont fit on the Offenhauser 360 intake due to the Bananarama! the fue bowls and the butterflies touching the sides of the ports of the inlet when fully open.
Therefore I'm putting the Carter AFB on the Challenger is it fits and bolts on OK.
Not very scientific but I'll put it on and see if it is an improvement over the 2 barrel. Bish says it will be better fuel economy as well as more power.

Mandie's truck has an Edelbrock performer manifold and an Edelbrock carb. That has MUCH bigger inlet ports from the carb so the Holley would fit on that potentially.

[MattH]

So I found the number on the choke horn, LIST -6210-3 1262.

Internet seems to say its a 650CFM spread bore Double Pumper.

[Pete]

Sounds about right - you can even buy adapter plates to make fitment easier...

[Blue]

Size is ok, that might work well on the Challenger if you can get it to fit.

[MattH]

Size is ok, that might work well on the Challenger if you can get it to fit.

I assume I'd need to install some sort of riser or spacer so the studs don't foul the fuel bowls.

[Pete]

Size is ok, that might work well on the Challenger if you can get it to fit.

I assume I'd need to install some sort of riser or spacer so the studs don't foul the fuel bowls.

I / We have one in stock if you need it to bolt a Spreadbore to 4150 pattern... (or I have a waste paper bin if that helps....)

[lemans-tom]

Model 4165 - dble pumper, Model 4175 vac sec (IIRC)
Quadrajet replacements - hence the small/large butterflies

[MrNorm]

Yes that could be an interesting choice on the Challenger...as said, you'll need a spreadbore to squarebore adaptor which not only will assist in clearing the linkage but also allow the secondaries to open without fouling. Inherently I like the idea of a spreadbore, you get better fuel economy cruising on the small primaries but when you need the power those large secondaries kick in. I don't know whether that airflap on the secondaries is a choke or an airvalve to open the secondaries. With a secondary accelerator pump like that has, I 'm going to guess that the key to getting that carb performing well would be to secondaries opening well, via the pump shot and whatever else it uses if that is an air valve. Then you would get the benefits of a spreadbore. If you get it wrong you might have a thirsty bogger........!!

[lemans-tom]

The flap is the choke.
You would generally have some sort of air related opening on vac secs.
This is a d/p so its going to be mechanical opening.
Getting the #2 accel shot tuned is going to be key