[nas t eh]

In the early 80s I rebuilt the the 455 in my TA.
At that time H-O Racing would sell you kits for your distributor and carb to resolve the inherent issues with the stock pieces and tune them to your combination. You just had to tell them what you had.

I bought a brand new SR 1973 455SD 4 speed carb from GM and put the kit in it back then. While I never got the car to the track to test it, I thought the set up ran very well on the street.

Back then using a 1970 455 4 bolt block the motor was build as a close to a SD 455 shortblock as I could get and I had hand ported(using H-O’s booklet) a set of 1972 400/4bbl heads, with a port matched torquer intake and a cheap set of headers. The cam was a CompCam HE SFT one, I think they called it a HE 264?, but I remember it was not a very big cam at all for a solid lifter one. I added 1:65 ratio rockerarms to it.

From what I remember the carb kit came with new metering rods,new jets, a new accelerator pump and stuff(screws and epoxy) to repair the leaky well seals on a Rochester. I put it all in.

Now I’ve changed the top end with a set of Butler 290cfm D-port E heads and a much larger solid roller cam speced by Butler to match the heads.( I don’t remember the exact numbers but it was very similar to the Road Paver SD performance sells) I’m still using the same intake and carb and cheap headers. The car is not finished enough to get on the street, but I did get the carb cleaned out and a new accelerator pump in it. The motor starts well and idles great, seems to have a good response to the throttle. but has not been run down the road.

The points in the distributor have now been replaced with a Petronix kit , I’ve since read that they can be troublesome but I’m hoping for the best.

So the question is what are the chances that the jetting/ metering rods speced by HO all those years ago will be fairly close to what the motor needs now?

A second question what are the chances the distributor springs and weights speced back then are good now too?

[Cliff R]

Not nearly enough information to provide much assistance.

Carb number, jet size, primary metering rods size, secondary rods, would help. So would compression ratio, head flow, and specs from the cam card.

Probably best to get it on the road and do some testing. Idling well is a good thing, and hopefully full control with the idle mixture screws. The SD carbs were pretty generous there so it may be OK. Test light part throttle, heavy part throttle and full throttle. If things are off some it will let you know, then go back and address the areas where it needs help.

The HO accuracy kits for the Q-jets for the most part were pretty decent, but every Pontiac carburetor part number will have different requirements as there were many different models. These days we spec out tuning kits for all Pontiac Q-jets based on the carb number, how the factory set it up, and where it is going to be used.

What you do have doing for you is that the Super Duty units, both originals and SR's are very generous for idle fuel, a bit lean at part throttle, and not to bad for WOT without any work done to them.......Cliff

[nas t eh]

Thanks Cliff, I’ll hopefully get it finished up soon, then see how it drives.

If there are issues, I’ll get gather the details and ask again.