Takid455

stock '56 88 w/ 2bbl on 324. carb cleaned & rebuilt. seems to be working fine for piratical purposes. all passageways are clear.

Have surge/ stumble at constant cruise. clears up w/ increased throttle. hard accel once off idle is strong. Leads me to believe it is lean. Jets are #62. will try to partially close choke to see if there is a difference. DO know that todays fuels contain more alky than yesterdays thus requirement for more fuel.

Are all Rochester jets the same. I have a bunch from the 70's 4bbl Qjets.

oldcutlass

It could be your timing also.

Takid455

Timing is next. While it is probably not a perfect curve, the stumble still occurs in the upper RPM range when the timing curve is all 'in'.

this is the next step. I'll spin it on the machine to see where were are and go from there. I am guessing 34-36 deg all in by 2600-2800 is where 324's run happy?

Jet question answered:

NO. While they all interchange , they flow differently and some have long / short tapers and different lead angles (60 & 90).

They are available down to 38 jet.

2cg will have a 60 deg short tapper (typical) jet. Going to try 63 & 64 jets.

cliffs has what you need. Used him for my Pontiac stuff
http://cliffshighperformance.com/

oldsmobum

I had the same problem on mine, same motor and carb. I found out the vacuum advance diapragm on the distributor was torn, so its a double whammy improper timing/vacuum leak. Put a vacuum gauge on it and see if it will hold. After you have checked that and the timing, you can assume its the carb. The only issue I had with my carb was an off idle stumble I could not get rid of, even after rebuilding it at home with a kit. I eventually got it professionally rebuilt by JET Performance, and all my drivability issues were gone.