Carb tunning question
#1
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Thread Starter
Carb tunning question
I have a new quickfuel 850 carb. Its on my rebuilt 509.
Everything is good except when i shift into gear it idles to low. I have the idle at 800, but when in gear it drops to 400 ish and is hard to stay running. In order to get a decent idle in gear i have to turn the idle up to over 1000 in neutral.
I have set the floats so they are half way up tje sight glass. All 4 mixture screws are out 1 1/2 turns from full seated
i know enough to ne dangerous when it comes to carbs. Is there any more i can do?
Everything is good except when i shift into gear it idles to low. I have the idle at 800, but when in gear it drops to 400 ish and is hard to stay running. In order to get a decent idle in gear i have to turn the idle up to over 1000 in neutral.
I have set the floats so they are half way up tje sight glass. All 4 mixture screws are out 1 1/2 turns from full seated
i know enough to ne dangerous when it comes to carbs. Is there any more i can do?
#4
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iTrader: (1)
What are your timing specs ?
#5
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Thanks for the replies
i originally tried 2 turns out on all 4 corners then backed each in 1/2 a turn. Didnt seem to make a difference if anything its maybe a little better at 1 1/2
timing is set at 34 all in. I didnt really mess with initial just let fall where it did but i believe its around 12 at idle.
The boat does seem to be running on the rich side. I noticed black soot on the transom the last few times out but my floats were still high so i blamed it on that and the fuel is from june 1 (87 non ethanol) due to the motor issues and being outta comission. Motor came out after i filled the tank. Lol. Teying to work it back down.
i originally tried 2 turns out on all 4 corners then backed each in 1/2 a turn. Didnt seem to make a difference if anything its maybe a little better at 1 1/2
timing is set at 34 all in. I didnt really mess with initial just let fall where it did but i believe its around 12 at idle.
The boat does seem to be running on the rich side. I noticed black soot on the transom the last few times out but my floats were still high so i blamed it on that and the fuel is from june 1 (87 non ethanol) due to the motor issues and being outta comission. Motor came out after i filled the tank. Lol. Teying to work it back down.
#6
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If you can tune your distributor to get more timing at idle it will help clean up a nasty rich lame idle associated with bigger cams. Try to get idle timing up around 20-24*. If you have an MSD distributor you change the stop bushing to achieve this.
Last edited by picklenjim; 08-22-2017 at 02:26 PM.
#7
Platinum Member
Platinum Member
See if Holly offers a marine carb in your CFM range. In our experience with Holley Marine Dominators, they solved 15+ years of jacking around trying to get the automotive Dominators carbs to idle in gear.
#9
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as said, look at timing at idle in gear, see if its backing off, either running full locked, if starting not a issue, or limited advance so you can run more base helps a lot
#10
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Thread Starter
Thanks. Im gonna send the distributor back to msd over the winter to get rebuilt so ill look at locking it oit when i get it back
for now ill make it work till winter.
for now ill make it work till winter.