340 timing need some advice on rufff timing

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chubsgts

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i have a mild built 340 10 1/2 motor stock carb elc ing med purp cam
x heads stock intake not a crazy motor just nice mild car

book says 5 degrees i set it to that ran like crap i went to 10 seems better but this car is a straight dog i think my wife's cavalier is faster lol
ive done all i can think of.

set vacuum at carb adjusted the air fuel messed with the timing i ask what should i set it at because the book may be way off of what these motors like and some one may chime into say 15 or 20 will get me closer.

i caped the advance didn't see any real difference then one time the car came alive ran super hard then pulled in drive way and the idel was way off running at like 300 rpm what the hell was that all about cracked it open and then it was fine cars got me pulling my hair our

also no spark knock at 10 degrees ether

i know there are a ton a variables but im just fishing for fresh ideals

no vacuum leaks ether almost every thing is brand new minus the dizzy and box carb was just redone

im running ngk plugs also dont think it will matter but maybe
 
well... as much timing as it will start with 'warmed up' is where I recommend the initial should be, then around 30-35* total, of corse you wan to experiment with driving it at diff total settings.

once you dial the initial..you'll need to limit the mechanical advance so it still gives only the necessary amount of advance afterwards.


one thing you should check as well is the balancer marks against actual tdc 'piston stop'
the balancer may have slipped on the hub and is fooling you on where the timing really is...
 
balancer is good i set it at tdc #1 when i pulled the dizzy and it was at 0 on tab


guess ill go warm here up and throw more timing in here
 
cranked more timing in seems to be better tab only reads to 10 degrees

im guessing
im at like 25 lol if the increments are spaced the same further from zero u go
then thats how i come up with 25 car is not spark knocking and still starting fine guess ill go try more lol

also when try to launch the car falls on it face i can not seem to get it to torque up like it should for a hole shoot so fig more timing and keep trying to launch the car till it runs good and will still starts
car is starting to pull good when i do down shift and stick it so guess im getting some where
 
Either buy a timing tape for your balancer or a dial back timing light. This will allow you to see what the timing is set at.
Another thing, Did you degree the cam in??
 
no the motor was all ready in the car was just rebuilt before i got the car so didnt fig i would tear it down it ran pretty good before but it all ways had mood swings.
after i bought it last summer i noticed it some time run like hell other times just lay over
fig it was carb car had been inside a garage for 15 years with minimal starting time.

had carb done seems alot better but i still have issues some where sense the mood swing is back gonna go try to get a timing tape now dont know if it will help much i have just been slowly cranking here round till the idel stops going up and she starts knocking just found that point.
im gonna go hook my vacuum up and take here for a ride
 
What type of dizzy do you have. If it is a stock unit you are probably looking at 28 to 30 degrees built into it (mechanical). Do not guess with this. Agree with jefflock. You need a dial back light & some timing tape especially if you don't know specs on dizzy. You never want your total(initial plus mechanical) minus the vacumn advance to be much over 40 degrees & definately under 45.

Oldschoolcuda
 
the mood swing is back
Click to expand...

Hmmm
Mechanical advance sticking or bushing bad?.......broken/stretched spring?

Take your Dist. cap off and see if the rotor will move back and forth.
Can you fill the spring tension, does it return back all the way by it's self?
smooth feeling or sticky?
 
Hillbilly timing tape.

HillbillyTimingtape002.jpg


Roll the balancer timing mark to 10* before TDC on timing cover and mark balancer at 5* after, 15* spread. Roll the new mark to 10* BTDC and mark balancer at 5* after.

You now have marks on the balancer for 0, 15 and 30 degrees BTDC.

It's not uncommon for 340's to want 20* of initial timing. You might want to toss the factory timing specs in the garbage, they aren't set up for best performance. You've also changed things some, that throws a wrench in things.

Basic idea with car at idle speed you want, turn the distributor giving more advance, if the engine picks up RPM, it wants the advance. reset idle to where you want and repeat. You'll reach a point where it won't speed up much at all, you found where the engine likes initial timing level. As long as it will start when warm, not kicking back on starter or straining you then need to work on the mechanical curve in the distributor.
 
stock dizzy

im gonna go check the springs and all that ill update soon on what i found

and yes stock specs where so far off car didnt even want to run
i found that 20 was about where it started to be happy now ill try and get a tape and go for it again to final tune i did get it to the point of spark knock then backed it off so
im sure im close but like i said car just still is not building the power it should when i hammer it.
not down shifting ether inless i pull it down and ive adjusted the linkages 3 times not sure whats up there.
the slotted down shift linkage is resting again the throttle pin to so it has to be in the middel shaft i would guess
 
just popped the cap rotor turns one way 1/2" or so then stops and returns so spring should be good rotor wont spin the other way but thats normal or motor would have to crank backwerds

thru vacuum pump on the advance i watched that pull in and return when i released it

one thing im not sure on is the shaft of the dizzy i can pull it up like 1/4" not sure if thats saying bushing are shot or normal

thanks again guys

im also thinking i may throw my other ing box on during next test drive
just to see if it has any thing to do with that
 
pulled a few plugs just to have a look whitish carb board color so burn should be pretty good also making condensation off the tail pipes i was told thats very good for a carbed car no sure if thats tru or not
 
Hi, I have the same problem I have a 340 ci mild purple shaft summit 600 cfm carb and mechanical advance mopar electronic distributor does any body have any idea where the base timing should be ? and what should be the maximum ad vanced timing thanks guys
 
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