Engine set up

[GoldDuster340]

I have a 340 with a mild pupleshaft 484 lift cam, electronic ignition, headers aluminum intake Holley 600 dbl pump.

After setting the timing with a light and vacuum removed and plugged the engine seems to idle best at about 12 deg on the before marks of the timing marks on balancer. If i bring it down to 0 degrees it runs rough

this normal for this engine set up?

 

[oldkimmer]

.........With the 484 it will run fairly choppy even with 12 d adv.........leave the vacc adv plugged and set total timing 2 35 or 36 d total at approx 2500 rpm.....u may need 2 recurve ur dist to get the best curve 4 u, u could also try removing the heavy spring .....kim.........

 

[green1]

My purple, 70 340, adv 10.5 comp ratio, won't idle under 20 degrees initial. Just mod your dist.

 

[Guitar Jones]

If it runs best at 12* then leave it there. As long as it doesn't ping it should be fine. Most any engine will not run well at 0*, there has to be some lead time to get the fuel burning.

 

[GoldDuster340]

If it runs best at 12* then leave it there. As long as it doesn't ping it should be fine. Most any engine will not run well at 0*, there has to be some lead time to get the fuel burning.

Yes i just wanted to make sure. I new it would be advanced just wasn't sure how much with the mild cam it seems to idle fairly well but until i get it on the street for a test drive then i can do some final tweaking.

I tried advancing it to like 20 and it seem to idle better around 12 or 15

I also will be hooking up my tack tomorrow so i can check it at other rpms as kimmer said

thanks for all the help guys this place is a huge learning curve and very informative 8)

 

[GoldDuster340]

.........With the 484 it will run fairly choppy even with 12 d adv.........leave the vacc adv plugged and set total timing 2 35 or 36 d total at approx 2500 rpm.....u may need 2 recurve ur dist to get the best curve 4 u, u could also try removing the heavy spring .....kim.........

I digress i just read my cam card this is the 474 lift cam 280 dur
Im also using the mopar performance electronic distributer kit and 10:1 comp in the block

see learning curve hahaha

 

[green1]

It want's big initial, just have to limit mech, in the dist. I bought a Mallory, and it is fairly simple, they even include spacers, to set total.
If I set mine below 18, it will just slowly die (8 vacuum, with 2.5 powervalve.) 650 carb.

 

[GoldDuster340]

It want's big initial, just have to limit mech, in the dist. I bought a Mallory, and it is fairly simple, they even include spacers, to set total.
If I set mine below 18, it will just slowly die (8 vacuum, with 2.5 powervalve.) 650 carb.

what do you mean limit the initial? this is changing the springs in the distributor?

it starts ok at about 950 rpms, but I'm getting a bit of a stumble or rough idle occasionally,i must be at least 30 degrees advanced the timing the mark is under the water pump so i need to get timing tape since my light does not have advance feature.