Thread: new qtf 600 cfm

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I love it when someone pays big bucks for dyno and they run there test carb instead of the customers carb that will be used on the engine-whats the point??
Craig-------- if you want, I will guide you thru checking out and setting up your carb and ignition----just let me know-If you need referances on me??? you can do a search but you better have a case of beer and lots of time to read them----

alright main jets probably won't get me on the idle circuit, with the screws all the way in and manifold vac pulled off it idles smooth turn the screws out one turn it bogs. plug the vac, line it still idles but very rich. i read about drilling holes in the butterfly's as a last resort.

With idle mixture screws all the way in it should die not run better. The incorrect power valve can cause this, and a vacuum leak will. If in doubt about the power valve put a new one in, there usually less than 10 bucks. With your vacuum at 12 inches or less, I would drop down to a #5 or 4.5 power valve anyway.

OK------first choice-can you return the carb??? It sounds totally messed up and might be a return from someone previous and then sold to you-----

Power valve-suggest rated at half your idle vacume--with 10in you need to go to a 4.5-----main jets primary Holley carbs should be within a couple numbers of the carbs cfm rating-you got a 600cfm-try 58 to 62 primary.
Do the accelerator pumps have there check valves in the float bowls and the needle under the squirter nozzle? what size number on the squirter and are pumps 30 or 50 cc?

Is your carb built to street or race specs? supercharger blowthru or suck thru?

Take base plate off carb and turn upside down------back off the primary idle speed screw til clearance for stop(blades should be completely shut. Set sec screw til blades shut completely and the idle transfer hole looks like a little square( .022 slotx .022 open looks square) now set primary idle same place

reassemble carb making sure all gaskets are correct and proper for the holes and passages

check gasket imprint for base plate to manifold for imprint proving correct

use a piece of safty wire to tie around the advance spring tabs in the dist to lock out advance-----set crank to 12-18 degrees btdc and turn dist til the reluctor rib lines exactly with the middle of the sensor-----

turn idle mixture screws out 1 3/4 turns-prime carb ( you are running gasoline but what octane/etc/ethonal in Cal)

start engine and it will idle at 850 -----------

BTW, Jerry's offer to help you is very generous, his knowledge and experience is at the top.
The Keeling & Clayton story continues

thanks for the link--------I've read that several times and always look at the pics

going to try that tomorrow after work, thanks

If you get the proper ignition timing in the motor, manifold vacuum will improve. The cam is not that radical, so you will not have to drill the primary throttle blades. Stop lookin' all over the net and do what we're tellin' you to do. I'm bettin' you won't need any more than about 16 at the crank, with a total of 34, all in by 2800. Those double pumpers always come out of the box pig rich, so adjust for the proper idle slot like Jerry said (and I said), lean out on the jets and see where you are. NOTHING GOOD IS GOING TO COME OF THIS UNTIL YOU GET THE IGNITION TIMING SQUARED AWAY. Buy the piston stop, get TDC nailed down on your damper, install a timing tape and put the right timing in the motor. Then work on the carb.

"Cam is cs1105r". Yep, same specs I gave in post 5.

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Originally Posted by craig akiyama

the engine was built at jms in irwindale. it was dinenod?

This engine should have come with all timing specs from the builder. I suggest you stop guessing, purchase a timing light and set the timing to the engine builders specs.

QFT carb if new should of been built to engine specs---------return it--------if returning it directly to QFT , give them your engine specs , gear ratios, type of driving you want to do---should be a runner out of the box-------of course tho, if it was a return to some supplier, from someone else that had messed it up and wasn't happy with it, you then just bought a pig in a poke-------sorta like same circumstances that they dynode your engine without your carb on it. probably because they don't know how to tune----------

like tech ins.1 said when i changed timing vac came up to 16 in. @800 i got the light i need a tape for the dampener still. primary jets are 68 secondary's 74, throttle plates were closed on secondary's already. gaskets looked proper air bleeds sec. inside 31 outside 39 on primary inside 31 outside 70 didn't mess with excel. pump yet. i can find no compleat specs on this carb, like a parts list of out of the box components. jms supplied the carb. i don't have a recite, but i'll have to look into that, i'd rather just try to figure this thing out,

Go up lakwood bl. to the 5 fwy no. get off an Atlantic bl turn right go about 3 blocks turn left go about 500 feet on the right you will see bill's garage dyno tuning talk to bill ask him how much to fix this mess he is sharp haven't seen him for along time tell I sen't ya I was his snap on dealer almost 30 years ago and him and his son were students of mine at chaffey col. auto emissions extension school or go an face book bills garage dyno tuning

Primary air bleeds---check them out---are yours the screw in type??if so , suggest changing the primary outside to around .070--------or temp change sec ones to pri see if the idle changes

yes they are 70,s outside 31 inside and they are changeable secondary side has 39's outside 31 inside. had to order a timing tape at autozone, takes two days

i'm working on timing issue,waiting for tape, i want to re jet while i got it apart,qtf says step at 2 sizes at a time,primary's are 68,i think i can get jets at pep boys for holly's that i heard will work, do the secondary's also need to be changed at this time?