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View Full Version : dual carb tuners??????



Squirtcha?
05-06-2004, 07:32 PM
She's coming along, slow but sure. I should be able to fire it up this weekend. Trying to figure out a good baseline for jetting. The carbs are 660 center squirters w/ mechanical secondaries. I've changed out the meter plates for a set of blocks so I can jet all four corners. Stock jetting in the primaries is a 76. According to the Holley book, the metering blocks would've been the equivalent of 76's. Do you think running 76's in the primaries and secondaries would be a good place to start when running two carbs?
Keep in mind I'd much rather run fat than lean (of course). Thanks for your time and any suggestions you may have.
Oh yeah, the motor is a BBF 460 bored .030 over, running headers and the cam is a 244 duration .570 lift hydraulic flat tappet, Edelbrock aluminum heads (small chamber). DD says it's about 492 hp @ 5500 rpm when running the single carb and supposedly the tunnelram and 1320 cfm should take me to 535 hp at 5500 rpm.
Don't know if any of that is pertinent, but thought I'd mention it.
http://www.jetheaven.us/photopost/data/500/19big.jpg
It may not go any faster, but it don't look like grandma's ski boat anymore.
My son, aka mini me, aka goober, aka PIA thinks the scoop is cool. He wouldn't let me send it back. Oh well...........what the hell.

Nucking futs
05-06-2004, 09:55 PM
Hey dan looks great,Give lakesonly a pm he is really good with jetting those engines.He just gaind some mph just by changing jets and some good fuel.Oops I wonder if i just gave up his secret,sorry lakes

Blown 472
05-06-2004, 10:53 PM
You have to consider now you are putting more air to the motor so you are going to want to run more fuel, how are your plug reading skills? and seat of the pants tuning? if you are cruising and it feels like it is surging or trailer hitching then it is too lean.

Squirtcha?
05-07-2004, 10:01 PM
If I were the nervous type, I'd say I pissed somebody off (or maybe everybody). Nobody's got any tips, hints, scraps of wisdom for ol Dan?
Went to the carb shop today and bought eight 76 jets. Holley's are notorious for being pretty close when box stock so I'll give that a whirl.
Since nobody saw fit to give me an idea, I was forced to come up with my own. OH NO!
:frown:

Danhercules
05-07-2004, 11:34 PM
Well Squircha, If info is what you want,then that is what I will give you. I never said it was correct info.
I got 70 on the pri's and 74 on the seconds. I am running fat. She still runs good. Now that I have my new cam and such in , she is still running fat. I am gonna take some new plugs and read them this weekend at Freeboard Challanged. I wish I could help ya, you have helped me in the past.

screamdreambrad
05-07-2004, 11:43 PM
dan 76's may be ok. did you take the power valves out? i don't think you need to jet it square if you didn't. should be plenty though. just go easy on it, til you get a plug check. brad

Duane HTP
05-08-2004, 07:09 PM
Squirtcha read your PM

DORIGHT
05-09-2004, 08:28 AM
Squirt
I think your all right with the 76 as a STARTING point with square jetting.
By the way 660 center squirters dont have power valve's
I belive im in the same neiborhood with my two on the BB in my Bahner.
My experianc with the things have been if you go to big it will run like its running out of gas when to big, Poping cutting out ect.
although it will start and idle, Very confusing to some acts like ignition problem.
Make sure float levals are good before you start any other adjustments.
Plug reading is a must when you start leaning it down!
try to get a golden tan if you can or dare im on the fat side myself as I have been known to add additives of an unpopulare type on rare ocasions (Nitro propane)
Also It is absolutly critical that they are cleaned in some carb dip before you start playing with them, unless they are brand new.
I have been running mine for years and find that dipping them every year is best.
For some resone they have been more tempremental than other carbs I have run in the past about wanting to be clean Just my experiance.
Email me if you need help

Blown 472
05-09-2004, 09:36 AM
Originally posted by DORIGHT
Squirt
I think your all right with the 76 as a STARTING point with square jetting.
By the way 660 center squirters dont have power valve's
I belive im in the same neiborhood with my two on the BB in my Bahner.
My experianc with the things have been if you go to big it will run like its running out of gas when to big, Poping cutting out ect.
although it will start and idle, Very confusing to some acts like ignition problem.
Make sure float levals are good before you start any other adjustments.
Plug reading is a must when you start leaning it down!
try to get a golden tan if you can or dare im on the fat side myself as I have been known to add additives of an unpopulare type on rare ocasions (Nitro propane)
Also It is absolutly critical that they are cleaned in some carb dip before you start playing with them, unless they are brand new.
I have been running mine for years and find that dipping them every year is best.
For some resone they have been more tempremental than other carbs I have run in the past about wanting to be clean Just my experiance.
Email me if you need help
Nitro propane?? what is it and where do you get it?

bottom feeder
05-09-2004, 09:56 AM
Blown
Nitropropane is one of the other Nitro based chemicals. The need a much lower level of oxygen to light and burn. Thus you can jam much more fuel in the cyclinder with the same air. You Should be able to aquire it at most chemical firms. Be ware ! Really voilent stuff. I will look later seams like 10 jets up for 1% cant remember now.
Bottom feeder

bottom feeder
05-09-2004, 10:19 AM
Squitcha
Hey man you running a air cleaner under that air scooper? I have been building some air pans for the diferant scoops the use the flat K&N filters.
Bottom Feeder

Squirtcha?
05-09-2004, 11:17 AM
Thanks for all the input fellas. That's some good stuff. Don't think I'll be messing with nitropropane so we can disregard that part.
Duane and Lakes, the PM's were good too, and for the mostpart reaffirmed some of the stuff I was aware of. I was primarily looking for jetting info, and although I realize no two will be the same, I was just looking for a reasonable starting point. I have a fair selection of jets going to the fat side so if I need to jet the secondaries fatter, that's not a problem. I believe I have 80's, 82's and 84's.
I bought the carbs and TR used. When I kitted/rebuilt the carbs they had the stock metering plates in the secondaries and 65's in the primaries. I thought that seemed a little on the lean side, so I went with the box stock 76's to get things rolling.
Need to pick up some -3AN for the nitrous and connect the solenoids and she should be good to go. No nitrous of course, until I know I got her tuned to run well on just the motor.
Thanks again all
Dan (almost ready to roll) Squirtcha?
At least that's what my lead mechanic tells me.
http://www.jetheaven.us/photopost/data/500/19ready_to_roll.jpg

Blown 472
05-09-2004, 12:45 PM
Originally posted by bottom feeder
Blown
Nitropropane is one of the other Nitro based chemicals. The need a much lower level of oxygen to light and burn. Thus you can jam much more fuel in the cyclinder with the same air. You Should be able to aquire it at most chemical firms. Be ware ! Really voilent stuff. I will look later seams like 10 jets up for 1% cant remember now.
Bottom feeder
Is this something you mix in with the gas??