How do I adjust the idle mixtures on 4 corner dominators ?
 

I been doing so much diesel stuff I forget how to set carbs ! I have to set up a friends new blower motors and can't remember how to adjust the 4 corner idle mixtures on the dominators . They are 510 inch ,250 blowers , with single 1050 carbs . Can someone refresh me on this ? Thanks , JOE

carb talk ...
 

Hi ya Boot,
On a 4 corner carb start out with the engine off. Next turn each air fuel screw in until it bottoms out (SOFTLY), do not force when running in. Turn each crew out 1 to 1 1/2 turns. Start the engine. If it will not idle on its own, turn each screw out a 1/4 turn more. do this until it will idle on its own. Once the engine is up to temp. rev it up a few times between 3000-4000 rpm, see if it will come back to an idle with out a stumble. If not back out 1/8 turn again on all crews. Do the rev up test again until it doesnt stumble when returning to an idle.

Then adjust with the boat in the water. At an idle put boat in gear, see if it idles. If not out some more on the air fuel screws. Just an 1/8 at a time. If the rpm isnt high enough you must raise the idle screws in 1/16 to an 1/8 on each side, primary and secondary until you get your idle speed where you want it. If you need any more advice feel free to call the shop.

Pwrbt33- John
Offshore Performance
410-827-0200 x-1

I THOUGHT YOU WHERE WORKING ON YOUR BOAT, GET MOVING NEW YORK IS 3 WEEKS AWAY ROCK AND ROLL. GOT THE BOAT RUNS AWSOME,LIKE THE TRUCK. SEA YA SCOTT

remember to set timming and float before doing this . ajust the float in the water.

Thank you Pwrbt33- John ! Thats what I thought ,but you forget a lot in a years time when you have other things on the brain !
:crazy: What is the best way to get rid of , or what causes, blower surge ? My 588's with 8-71's and dual dominators serge quite a bit when you take them out of gear . You can tune it out with mixture adjustments but some times it comes back depending on what you are doing . Any ideas ? Thanks !

outer37, Glad to hear you got your new beast going ! :cool: It must be great ! I am actualy working on my boat too . Between everything else ...... My exhaust problem wasn't as bad as thought . Just the stainless spacers leaking between the manifolds and risers . Have to weld them up . THen check out the motors and hopefully put them back in . Sounds simple ..........:rolleyes:

Strip Poker 388, Thanks , That does help to do it before beating my head against the wall !

Thanks all ! JOE

Hi ya Joe,
One way you can help blower surge is to raise the air bleed jets if your carb has removable jets. You might want to go up about 5 numbers at a time and then you can go out on your air fuel ratio. We have a few Cobra 1200's around here and they actually idle pretty good. Some do want to hunt when out of gear though, but once they go into gear they lay right around a steady 900- 1000 rpm.Some people use boost referencing and some do it by the air bleeds.
You also want to make sure that your primary and secondary butterflies are open equal amounts. If you sometimes open the primary more, it will cause this problem as well. The air fuel on a blower carb will be done in smaller increments than a natural carb. As you are aware blowers are sensitive to adjustments.
One thing is for sure, CABS WILL DRIVE A PERSON TO DRINK VERY HEAVILY !!!! See if this helps and let me know.

Pwrbt33-John S.
Offshore Performance
410-827-0200 x-1 :D

on mine i wanted it to surge so i could put in gear on the down cycle. the up cycle it would go up to 1400 rpm. but i was running 12 psi of boost though.

use heavy springs on the distributor advance, or lock the timing. This will keep the timing from advancing on the upswing and aggravating the surge.

Lots of good advise hear !;)

As soon as I quit helping everyone else and put my motors back in , I'll try it ............ Thanks , JOE

Well, here's how things go in my world . Started my buddys engines , brought them to temp, sounds great , set timing ,shut down , checked throttle plate postions front and back , restarted , started setting mixtures ,,,,,,,,,,,, things started getting worse ! Surging more and more ! Get it to go away , comes back ! :mad: Motor starts to sound rough , motor starts to feel rough , ,,,,,, motor starts to make ticking sounds , shut it down ........ MAshed the tips of the push rods !!! :hothead: Called engine builder who had been out twice already to corect valve train problems ........ Explaned to him ,IN DETAIL , how we felt ! No boating this weekend .