qjet or distibutor issues on 455

[wskirvin]

first thing i would do is get total timing set right without vacuum advance you will have to turn throttle screw up with no vacuum advance hooked up. initial timing doesn't mean much on a non stock engine. i start at 30 degrees full advance run wide open throttle. keep bumping it up 2 degrees until you hear denotation or loose power then back it off a couple of degrees. After that hook vacuum advance to full manifold adjust throttle screw. drive around at cruising speed and if you can adjust vacuum advance canister do the same thing as the full timing bump up around 2 degrees until you loose power or hear denotation. then back off a couple of degrees. if it is a pontiac engine you should have around 32-36 for total timing without vacuum advance and 12 more with vacuum. after that make sure you have the right size metering rods and jets in carburetor. cliff ruggles quadrajet book is great on how to set one up. after that you can set the idle mixture screws. quadrajets are in my opinion the best carburetor but can be time consuming to set up right.

It's an Olds 455. Now question about the timing. how are you figuring out exactly what degree you are at? my timing tab only goes to 12. it is the original one that came on the 455 with a points distributor. I have looked and cannot seem to find a timing tape for the factory Olds balancer that is correct. Every one that i have found have actually been for a larger diameter balancer. i have been kicking around getting a new distributor anyways just to make sure exactly what i have and i'm not guessing how much advance it has. my timing light is an older one that doesnt have a digital readout of the exact degrees either.

 

[pontiacgp]

Since the guy who rebuilt it put in the wrong float I'm wondering if the carburetor has some main rods designed for a quadrajet 1976 and up. They are .040 shorter than the rods in a 1970 quadrajet. If I were you I'd find an 800 cfm 76 quadrajet, they are a much better design than the 1970 version.

 

[GPNX]

It's an Olds 455. Now question about the timing. how are you figuring out exactly what degree you are at? my timing tab only goes to 12. it is the original one that came on the 455 with a points distributor. I have looked and cannot seem to find a timing tape for the factory Olds balancer that is correct. Every one that i have found have actually been for a larger diameter balancer. i have been kicking around getting a new distributor anyways just to make sure exactly what i have and i'm not guessing how much advance it has. my timing light is an older one that doesnt have a digital readout of the exact degrees either.

you would need a timing light that you can set up for total timing. i have personally only worked on pontiac and chevy engines so if i was you i would do some research and google a good starting point for oldsmobile 455 for a total timing number to start with. did you have the engine rebuilt. if you did you could talk to the person that rebuilt it and see what he recommends for timing values also.

 

[fleming442]

Total timing on an Olds is similar to other makes- 34-36*. the difference is the initial that needs to be higher- 16-20*, thus limiting the curve range.

 

[GPNX]

Since the guy who rebuilt it put in the wrong float I'm wondering if the carburetor has some main rods designed for a quadrajet 1976 and up. They are .040 shorter than the rods in a 1970 quadrajet. If I were you I'd find an 800 cfm 76 quadrajet, they are a much better design than the 1970 version.

How would the float be wrong? I've worked on quite a few quadrajets and any float will work as long as it floats in the bowl and you have the depth set right.

 

[wskirvin]

How would the float be wrong? I've worked on quite a few quadrajets and any float will work as long as it floats in the bowl and you have the depth set right.

I personally did not see it, the shop that went through it for me last week said that the float was actually hitting the metering rods but i did not personally see it. i'm going to send it to everyday performance and just let them do it. just sucks spending more money on a carb that was supposed to be "rebuilt" already

 

[GPNX]

Since the guy who rebuilt it put in the wrong float I'm wondering if the carburetor has some main rods designed for a quadrajet 1976 and up. They are .040 shorter than the rods in a 1970 quadrajet. If I were you I'd find an 800 cfm 76 quadrajet, they are a much better design than the 1970 version.

The 76 design might be a little better adjusting. but the 70 will work just fine. the only difference is in the 70 one you have to get the metering rods and jets exact. and the 76 you can adjust a little bit with that apt screw. cliff ruggles quadrajet book is a good source to learn from.

 

[pontiacgp]

How would the float be wrong? I've worked on quite a few quadrajets and any float will work as long as it floats in the bowl and you have the depth set right.

I don't know how the float could be wrong but that was posted in the first post in this thread so I take the posters word on it. Here are two quadrajet floats with visible differences in the length

 

[GPNX]

I personally did not see it, the shop that went through it for me last week said that the float was actually hitting the metering rods but i did not personally see it. i'm going to send it to everyday performance and just let them do it. just sucks spending more money on a carb that was supposed to be "rebuilt" already

More than likely it is probably rebuilt right to stock specs. You will have to fine tune it on the motor to get it running right. Which means taking it apart resetting float and changing jets and metering rods. Then changing secondary rods and when the secondaries open. If your going to keep the carburetor i would by the book. Doing it yourself is a lot cheaper and you know what you have then.

 

[wskirvin]

i actually just bought a copy online so ill definitly be reading through it. I went back through my pictures and found the numbers on the carb. they are 7042251 re 3511. so if i've looked it up right on carburetors unlimited, this is actually a 1972 not a 70. but not sure if i should stop messing with this and try to find a better carb or if this will work with the correct parts.