Any ideas on this? How would you think it would run? If you've read my other posts regarding my project, you'll know i'm already running the carb, but it wont stay below 2K RPM..it just wants to rev like mad. Any thoughts?





I've seen 650s on stock ports before...so I know it can be done...doesnt mean it was running well, but it was running...

Are the jets in the holley allowing too much fuel to enter the system, my guess is yes that they are too big and its flooding the engine at a low RPM. It revs like mad i think because there is soo much fuel but at a higher rev it can burn off any extra. check your A/F's I'd say try to get it to like 12.5 so your some what rich but somewhat lean so you can make the most power. Down size your jets this may take a few hours to find the right combination but i think it will pay off.

I'm running the #64, smallest jets in a normal holley kit. I think this is related to some kind of vac leak. I believe the idle is going to be high, around 2.5K or so..maybe a lil less...and I would be fine w/ that as I'm just trying to use it to move the car around while doing body work.

give it a street port. if your in the long island new york area i can help. I got rb street port templates that are race proven.

I'm building the bridged motor right now... thats why i went w/ the 650 instead of trying to locate a stock manifold and rebuild the stock carb... just figured i'd get my setup up and running before swapping the motor. Gives me a chance to get my fuel cell, pump, fpr and lines all run and setup, etc

cool mine is fuel injected but carbs are much simpler and better to work with im considering a convert.

650 on a 12a..hmm . Too big for a 12a, even a bridged one.



How much vacuum are you drawing?



You should be on your idle circuit, your main jets dont have an effect on idle.



Your idle mixture is determined by the mixture screws on your metering blocks. You should start them at about 1-1/2 turns loose. Adjust until you get maximum vac pressure. Dont tighten them hard, you will damage em.

Is there an echo in here?.

It's all good man... it's been mostly sorted out now. A 650 on a stock 12A isn't too big at all, mazda used to run them on stock port 12As in the late 80s during their GTU events, etc... very common, ask racing beat about it... i've used them for a lot a Q&A during this build...



Basically it just took getting the squirter set right, rebuilt the carb (using non-stock gaskets this time, lol) and getting all the settings right.



I'm moving soon, so for now the car sits, but I'll have it tuned in after I have a new garage for it, lol.. i probably wont even bother tuning the stock port motor, it runs good enough now to drive around the house and neighborhood..which is all i needed. I'll swap the BP motor in later and start tuning from there...