dominator carb question
 

idles ok when it warms up, but when I stick it in gear it drops from 800rpm to 400 and dies, how do I adjust the air screws to keep it from stalling under load.

1. make sure your power valves are not opening when the vacuum drops going into gear.

2. try a slightly richer mixture at idle.

3. Add some timing at idle.

Get a can of carb. cleaner and clean out the air bleeds. Use the little red straw to force the cleaner through them. Then make sure the front & rear throttle plates are open the same amount. Then adjust your idle mixture the same amount screwing them out makes it richer.

These are fresh rebuilt, on fresh engines, when you put it in gear the rpms drop so far it dies, im wondering about how to get the idle air screws adjusted right.

theres really no magical setting on the idle mix screws, you just kinda give the engine what it wants. How far out from seated are the screws now? 800RPM in neutral might be a little low for a modified setup. You may wanna try 900-1000RPM warmed up in neutral.

What do you have for ignition setup? With a healthy cammed dominator carb'd engine, sometimes its very hard to get them to idle worth a crap if you have the typical mercruiser 10* base timing setting.

Sounds like it's lean at idle. Where are the idle mixture screws set at now? Turn them counter clockwise to richen it up.

Did you change anything in the engine? cam, compression.

put a timing light on it..see if advance is falling off causing it to stall...can seem like a carb issue...

I will say this i was leary of these engines as most of you have seen me ask several questions but it was at 85mph and climbing still when it got a little loose feeling and the trim was not working correctly, and my indicators are screwed way up, but she ran better than i thought.

not a carb issue, its all about timing johnny. slam it into gear and jab the throttle forward fast enough it wont die.. problem solved and youre welcome

There is a slot inside the throttle bores. The secondary throttle plates should be set open .020 (pretty sure that is the correct number!). The adjustment is on the bottom so the carb has to come off.

The likely issue is you are having to open the throttle blades too far into the transfer slots to get 650-800 RPM in gear and 1000 RPM +/- in neutral. You will likely have to drill 1-2 small holes (or drill and tap for a small jet or IAB) in the top of the carb to allow more air vs. opening the throttle blades more. The easy way to check the RPM spread is by idleing in gear and while using a digital tach to adjust the throttle blades (carb linkage) to get the lowest RPM without stalling. Now shift to neutral and see where the idle goes. It it goes much above 1000 RPM (likely) you will need to drill a hole in the top of the carb in introduce air so you can reduce the opening of the throttle blades. This is a common Dominator trick and is now standard on Holley's newest generation of 2 & 3 circuit billet Dominators.

if you need to turn the idle mixture screws out more than 2 turns you probibally need larger idle air bleeds providing the timing is good,check it with an advance lite,you might need to lock out the distributor.

Burn my eye's!! i never go futher than 3/4 turn..anything over 1 turn and its all fuel..they like to load the engine with fuel over 1 turn unless you have a really big blower on top :P

That's actually backwards. Larger air bleeds would make it leaner, requiring you to turn the mixture screws out further.

Lots of timing and a little bit richer, as others have said, are the best bet.

when i set my quickfuel carbs up they told me the larger air bleed wll cause the carb to pull more fuel;they were right as it worked,im no carb expert,just stating what the experts at quickfuel told me.

haxby,i just looked it up,you are correct,i had it backwards.

timing should be at 36? and andy that's what I did with the blower motors , but im a little rusty and these were more bi polar, if you know what I mean.:eekdrop:

I was having the same problems, Make sure your throttle plates are even and within the small transfer slots or you will lose idle mixture control. If you need more are than that, start with 1/8 holes on the inboard side of your secondaries. The best thing I can recommend is to lock your distributor, I'm running 34 degrees, but I'm also at 10.1:1 compression. I had power valves that were fully open at idle and didn't notice a difference. I've been told that you won't pull fuel through the PV circuit until you get enough air velocity.

if does not like to idle, might have to lock dist and set timing around 30 and see how that works...cleans the idle up...

running crane ignition, screwed with the timing still falls off at idle, then other engine acts like timing is off . if I set it like the other it starts like its got a low battery, back it back off its fine at this point im going to run it. then address this over the layup period. makes me sick to spend all these hours and all this money only to look like a fool big cool ass boat that runs when it wants to.

tell us more on the engine ? also putting a vacume gauge on to ck it at idle will help, what dist are you running ? does your ign box have a start retard built in ? depending on the cam/heads etc, run lots of timing to get to idle in gear decently...how does it idle @ 30 deg ? what RPM does it idle at ?

what did these end up making for HP ? have you gone any faster then 85 yet? what props? I have a very similar set up '98 side by side 540's 630ish HP, motors are currently out for freshening..

it ran 85 on gps against the limiter, trim was not workin correct would not trim out under power, as far as power 625hp seemed like it ran good 28p b1s need 30s i think 90 is in the future.(or a cruiser) tired of wrenching .