Hello, This might be a dumb question but does anyone have the bolt pattern for a carburetor to intake. Intake is off a 67 400 but mounted on a 455 engine now. Looking to get a new carb and one of the places is asking for the bolt pattern. I've seen several posts on what carburetor's everyone likes. This is a street use 69 442 with a rebuilt 455 very mild cam, right now I'm looking at Holly carbs

Any help would be greatly appreciated

 

There are really only two applicable bolt patterns for 4bbl carbs, the spread bore pattern as used on the stock Qjet carb and the square bore pattern as used on the Holley. They do not interchange, however some carbs (like the E-brock) come with both and can often be used on either intake. The problem is more than the bolt pattern - it's the size of the throttle bores.

This is your stock carb pattern:



This is a Holley:



Personally, for a mild street car, I think you'll be a lot happier with a correct Qjet than a one-size-fits-none Holley. The Holley carbs are set up for Chevy motors and unless you have the skill and patience to tune it for your application, you'll have less than optimal performance.

 

IF you use a Qjet make sure you have it rebuilt with new throttle shaft bushings and a heli-coiled fuel inlet. This could be one of the few drawbacks of going with a Qjet. The carburetors are all so old now that they pretty much all require this repair.

As far as Holleys are concerned, I run a Summit carburetor on my 71 98. It's a clone of a Holley 4010 and uses all of the Holley parts. It runs like a champ but as Joe said you have to know how to set it up to dial it in (then again that could be said for any carburetor).

 

I have some Olds 455 Quadrajets on hand I could custom build for you if you are interested.
http://www.quadrajetpower.com/online...6sort%3Dnormal

 

Thanks everyone for the comments. I know the Q-jets were designed for the Olds and I have the 7040251 on it now but I'm sure it isn't set up or tuned correctly. My first plan is to see if I can find someone local to take a look at that is experienced with them. If it needs too much or won't tune then I may try a Holly. I want to thank you for the offers on the Q-jets but right now I'm going this route. One of the troubling things is on cold starts or after the car sits for a day or even overnight. I have to crank the crap out of it until it starts. Probably 3 or 4; 5 to 8 second cranks then it pops off. Tried an initial pedal push, then the pump action etc. It could be losing prime and was thinking of adding a check valve between the fuel pump and carb. Anyone have this problem or try the check valve option?

 

You can put this check valve in your filter and it will prevent the carb from draining to the pump.
http://www.quadrajetpower.com/online...ory%3D20893446

Fuel wells could be leaking but most don't have this problem. Some certainly do.

 

I'd like to understand how fuel in the bowl can climb uphill to the needle and seat and drain out of the carb.

To the OP: The real problem is evaporation of the fuel when the car isn't driven daily. Coupled with weak or deteriorating fuel pump valves caused by age or ethanol, the pump takes a while to replenish the fuel in the bowl. A new carb won't fix this problem.

 

It's magic!
OP asked for check valve. I have those.
If a windowed needle/seat is used it is well below the fuel level in the bowl, if float is set correctly. This greatly contributes to the evaporation issue that is common, and complicated since Quadrajet bowl is small and Olds float is large.

 

Have you tried looking down the carb before starting, while operating the linkage, to see if it actually sprays 2 solid streams of fuel and sets the choke properly? Everything else is pure speculation on what your problem is.

 

x2

I have heard of leaky fuel bowls on Q-jets. I thought it was a rather common problem; regardless, it can be fixed during the rebuild more easily than throttle plate bushings or fuel inlet threads. Just use gasoline resistant epoxy to seal the bottom of the fuel bowl where the leak is (usually directly below the jets).

 

It really isn't common. The 66-67 Qjets with the pressed-in sheet metal cap plugs had this problem. Qjets since 1968 have used spun-in aluminum plugs that are FAR less prone to leakage. Unfortunately, ever since Doug Roe wrote about it, everyone thinks it's a problem.

In any case, there's a very simple test. Take the carb off the car and prop it up over a piece of paper. Fill the float bowl through the vent. Leave it overnight. If there's no sign of gas on the paper in the morning, the plugs don't leak.

 

That's a good idea.

I've heard you can also look in the intake manifold and see marks where the fuel weeps from the carb and hits the intake. I don't know if it's true though...

 

Unfortunately, every intake I've seen has fuel stains under the carb just from normal use.

 

Yeah, I know my intake is pretty dirty and stained. That's because I'm lazy though.

 

Wow I never knew what that was for?