340 not pulling the way it should

[nivvy]

i had the stiffest springs in and we changed them to lighter ones. yes i definately have roller rockers but have not checked my lash yet.
 i know exactly what you mean as far as expecting to much from the car, i did not build this engine, i'm taking the guys word but when you add 14* total timing and there is no change i would have to say there is s :pullinghair:omething wrong. 

what color springs and what color bushing do you have in there now??? im no saying what oldschool posted is wrong in anyway but sounds like you have timing issues to start...

[leanburn]

i believe light silver on both, we had silver blue and went to the next softest wich is silver. i beleive i ended up with the blue stopper.
but i don't think the springs are the issue, as i was saying i gained 14* of total timing after i got the weights moving freely and didn't change a thing.

[Oldschool]

Sometimes a significant vacuum leak will make an engine not accept tuning inputs correctly.  Also, a loose timing chain will make the timing mark "jump" around when you put the light on it.          

[nivvy]

i believe light silver on both, we had silver blue and went to the next softest wich is silver. i beleive i ended up with the blue stopper.
but i don't think the springs are the issue, as i was saying i gained 14* of total timing after i got the weights moving freely and didn't change a thing.

okay... I put both light silvers in my 499 and all my junk is new... and I was getting some spuratic readngs... I am running the blue/silver combo with the black bushing.... if you are running silver / silver and blue bushing your are gonna have 21* of mechancal advance and all you timing will come in about 1800 range... go out and set your timing at 36* at 3000 rpm then check your initial is at 15*.... make sure you clamp the dist. clamp down tight enough after setting total timng... also see if your timing is coming in at about 1800 rpm...

but yea chain stretch etc. is an option also...

[leanburn]

if i had a bad enough vacuum leak to effect timing would it run like crap? this thing runs great, starts awsome, no bog, ect.
is this something i can check with a vacuum gauge?

[nivvy]

if i had a bad enough vacuum leak to effect timing would it run like crap? this thing runs great, starts awsome, no bog, ect.
is this something i can check with a vacuum gauge?

If it runs good through all rpms and no sputtering I would look elsewhere like oldschool mentioned...

[nivvy]

what ignition system r u running.... what timing light did you use.... dial back timing lights can give false timing issues with multispark ignitions... ask me how i know.... 

[leanburn]

it's a msd box with a msd distributor and yes i was useing a dial back light. i'll try another light tomorrow.

[nivvy]

I bought the flaming river 1 wire battery power timing light... i love it........ summit sells them... dial back light - that would explain you erratic timing.....

[Aussie Challenger]

  I think you might have to go back to basics, like Oldschool said a loose timing chain causes the ignition timing to alter but also the cam timing will alter drastically. The chain can be checked very easily by setting the timing mark up at zero on the balancer and rotating the crank backwards and noting how many degrees it moves before you feel the cam turn.
  Those cam timing numbers don't make much sense, you might have to check the timing with a degree wheel and dial indicator. CP has an article on this board about the importance of setting your cam up properly.   

[moper]

The pressure readings are good for the cam and "advertised" static ratio. I don't think it's timing chain issues, or degreeing. Who ported the heads? I've seen soem good builds ruined by morons with sanding rolls playing head guru. I think I would stick it ona  chassis dyno before you spend dime one. Have them use the A/F sensor to set the carb up. What trans type, gearing and convertor are in the car? How are you staging it? If you make changes and they have no effect, the thing has a problem. Whether it's an easy one like timing or carb or the brakes are dragging, or you're not really getting 100% full throttle, or a harder to ifx issue like port volume too large for your rpm window, carb too large (that Demon when compared "apples to aplles" to the old Holley sizing that are dry flowed is closer to 840cfm), or the valve geometry is way off... That's hard to say until we know all the facts. I would agree, you got an issue or issues.

[jeryst]

If you changing the springs had absolutely no effect, then the problem has to be occurring before you get any benefit that the springs would provide.

Is this an automatic, or manual?

[Moparal]

Wish we new what converter and gear he has.  With a stall speed converter. He should flash right up there, the timing advance would be wide open, and the engine would sing. So If he is set at 35 degrees or so full advance then the distributor is just sending juice to the plugs like it's suposed to. You may have a bad coverter or not enough gear. My distributor is locked full advance after 2k, I use a timing retard to back it off 4 degress on the top end. This way I can start the engine, then it's advanced to full, then when I am in 3rd I have a dial for the retard setting. It helps mph.

But just an engine doesnt make a race car. Your 60 ft tells me you got something else wrong.  I am positive a converter will cause 60 ft issues if it isnt right.  Some converters cost over a grand and some are 295. An example would be run your car with a stock vert, then install and vert made for your car through a dyno sheet,gear, and weight chart. Could be more then a second off your times.  Pull the trans and vert out of your other car and try it in this car, running the same gear as both cars. See what you get.

If you got spark going to the plugs and the advance is set to full, then at some degree the engine is done advancing and the car should be running at peak.  Curving the distributor in the advance is more for street use. When racing, set it full advanced and locked, then mash the pedal and go for the win light.  It's got to idle, and it's got to run wide open full advance. Anything after that is behind the engine or weight.

[leanburn]

it's a 3000 stall with 4:11's and 26.5'' tires.
even if my stall was bad, wouldn't i still see a change when adding over 10* of timing.

[jeryst]

Any chance you can try another distributor? Is it possible that the timing advance is not working at all?