Need a good carb for built 403.

[Bri guy]

Got a olds 403 that's been bored to 425. Has a edelbrock rpm intake and edelbrock 1406 carb. Has mild Cam, roller rockers and some other stuff. I can post the build sheet if necessary. But previous owner claims it gets around 400hp and around 475 torque. Rear end is 7.5 inch, not sure on the ratio. Don't know the rear ends gearing but it could be a 3.08 or 2.7? 4 speed transmission with overdrive.

 

[Bri guy]

Got a olds 403 that's been bored to 425. Has a edelbrock rpm intake and edelbrock 1406 carb. Has mild Cam, roller rockers and some other stuff. I can post the build sheet if necessary. But previous owner claims it gets around 400hp and around 475 torque. Rear end is 7.5 inch, not sure on the ratio. Don't know the rear ends gearing but it could be a 3.08 or 2.7? 4 speed transmission with overdrive.

 

[QS442]

How about the good ol 800cfm quadrajet from off a 403? I had them on a few 403s. I have a core if you are interested.

 

[L92 OLDS]

Agreed. I have a similar 403 build and use a good 800cfm Q jet. It's the best performing carb I have had on it.

I would be concerned about the "bored to 425" comment. Are you sure about that? 403's don't have enough steel to bore safely past .040 - .050" without over heating issues.

 

[81cutlass]

I see the engine was built in Dysart, I am in Wloo/Cedar falls if the car is still sorta local.

I have a quadrajet off my 455 somewhere (it might be back home in MN) if you are looking for a spread bore carb, I wouldn't mind getting rid of it.
Another option if you still have a spreadbore intake is a spreadbore holley if you want the slightly easier tuning of a holley and parts.

However, a 1406 is a square bore. I'd stay with the edelbrock (if you have to) or go standard 1450/1460 series holley. A vacuum secondary carb is going to be better on an auto heavier street car.

Qjets are good for performance and economy if you have a good builder but if you already have a square bore intake I would stay with square bore and go 1460 holley. Easy to tune, good parts, every carb shop can do them.

 

[QS442]

Agreed. I have a similar 403 build and use a good 800cfm Q jet. It's the best performing carb I have had on it.

I would be concerned about the "bored to 425" comment. Are you sure about that? 403's don't have enough steel to bore safely past .040 - .050" without over heating issues.

Yea, are you sure about the 425? I see the pistons say "405" KB's .024 ?????

 

[Michael Watts]

An 800 CFM carb will handle most anything as long as it is tuned properly.

 

[Bri guy]

Honestly I'm not quite sure. He told me it was bored slightly and was calling it a 425. As far as the carb, I was kinda hoping for suggestions for what size/brand I should be looking for.i don't think my 1406 is up to par. Also should I keep the rpm intake or get something else? I won't use the car on a track, just wanting a strong runner

 

[Bri guy]

I live in waterloo. And the carb is a square bore.

 

[Bri guy]

Car runs good. Doesn't overheat. She takes the beating I give it. But seems like it should have more potential as far as power