Deanoko Posted May 29, 2011 Share Posted May 29, 2011 After a thorough/correct Rochester 4jet carb rebuild and tuneup I'm getting just about 13MPG around town and some freeway. I'm figuring that is about as good as it's ever going to get. The car runs great! Anyone with other opinions / experience and advice?Thanks!Deano K. Link to comment Share on other sites More sharing options...
Jim Cannon Posted May 30, 2011 Share Posted May 30, 2011 After a thorough/correct Rochester 4jet carb rebuild and tuneup I'm getting just about 13MPG around town and some freeway. I'm figuring that is about as good as it's ever going to get. The car runs great! Anyone with other opinions / experience and advice?Thanks!Deano K.The correct carb for the '63 Riv is a Carter AFB.Regardless of the carb, the 13 you are experiencing is about all you will get. You can accelerate really slowly and help out on the MPG, but where's the fun in that when you have so many HP under the hood, wanting to show off!PS - Do I have your '63 in my database? Link to comment Share on other sites More sharing options...
Guest jpb76@sbcglobal.net Posted May 30, 2011 Share Posted May 30, 2011 Deanoko,I too have a rochester 4jet gc on a 1964 buick wildcat, I rebuilt the carb and it is now flooding out the motor. did you rebuild yours' or did you have someone else do it. if you did it you self i could use some advice. thanks Link to comment Share on other sites More sharing options...
gungeey Posted May 30, 2011 Share Posted May 30, 2011 Deanoko, 13mpg kicking around is decent mileage on these cars, you're right in the ballpark of what a properly running Riv should be getting...also, I think the statement regarding your carb being incorrect for your '63 was a typo on Jim's part...clearly there are many original Rivis running around with that same Rochester.. Link to comment Share on other sites More sharing options...
Deanoko Posted May 30, 2011 Author Share Posted May 30, 2011 Thanks for the replies. That's what I figured but didn't know if I should be shooting for 15 or higher.I had a friend rebuild it to spec. The biggest problem was with most gasket kits not having the correct internal gaskets. The PO or someone had an incorrect gasket which was blocking a couple internal vacuum circuits.Proper float level is is important and might be the cause of your flooding issue.My 63 Buick shop manual shows a chapter for Carter AFB and a chapter for Rochester 4jet pertaining to the 4700 series. I believe mine is original. Plus my body number and engine number match.Yes it is in the data base.Thanks,Deano Link to comment Share on other sites More sharing options...
RivNut Posted May 30, 2011 Share Posted May 30, 2011 My '63 came with the Rochester 4GC as the OE carb. I switched to an AFB for two reasons:1) I had rebuilt AFB's before and was familiar with them, and 2) the AFB has no gaskets lower than the float level - hence it's not prone to leaking.I didn't notice any difference in performance or mileage between the two carbs. AFB carbs (A for aluminum) require a stainless heat shield between the carb and the intake to keep the exhaust crossover gasses from corroding the base of the carb (aluminum) whereas the base of the 4GC is cast iron and doesn't require the stainless heat shield.Ed Link to comment Share on other sites More sharing options...
JZRIV Posted May 30, 2011 Share Posted May 30, 2011 Having the distributor set up properly is also important. Where is your timing set and how much total advance, mechanical + vacuum do you have? Link to comment Share on other sites More sharing options...
Guest rivguff Posted May 31, 2011 Share Posted May 31, 2011 Sounds about right. I never got more than 15 mpg under ideal highway conditions.Jerome Link to comment Share on other sites More sharing options...
Guest Robert Ricci Posted June 11, 2011 Share Posted June 11, 2011 Hi, just did a mileage test on my 1963 with a 401. Thats is the ballpark gas mileage. Bob Link to comment Share on other sites More sharing options...
cobravii Posted June 11, 2011 Share Posted June 11, 2011 13 MPG!!!!! OMG!!!What do you think I'll get with a dual quad 425 Electra ?!?!?!? Link to comment Share on other sites More sharing options...
Guest REX STALLION Posted June 11, 2011 Share Posted June 11, 2011 How many SMILES per gallon? Link to comment Share on other sites More sharing options...
Guest Kingoftheroad Posted June 12, 2011 Share Posted June 12, 2011 Wow, 13 mpg is better then I would've expected. I use to have a boattail years ago and the best mpg I got was 11 mpg in mixed driving, if I remember correctly. That was when gas was affordable ... Link to comment Share on other sites More sharing options...
Dales90 Posted June 12, 2011 Share Posted June 12, 2011 Hi,Back in the day, that is to say when higher octane was available, I had a 61 Electra 225 convert with a 401 Carter. I assume that car was heavier than a first gen Riv.After a tune up, new points, condenser, rotor, and timing reset, fresh air filter, and anything else I could attempt to give it a chance to give best mpg, I drove approx 165 miles at 55 mph cross country, and got that magic 20 mpg at the destiniation.Best I've ever gotten, never to be duplicated.Dale Link to comment Share on other sites More sharing options...
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