I am in the process of dialing in the timing on a 318 I dropped in my belvedere I have it at 16 degrees.

1. Is that to much?

2. Does detination sound like little cha cha cha cha sound once you get to a certain RPM

it seems to run real well at 15, 16 and 17 degrees.

any info would be great


Thanks

 

16 deg is a bit much. detination.. sounds like glass breaking in the cylinders.(high pitched tink) manly happends when your lugging an engine. sounds like you could be a tooth off on your timing chain? bout 10 deg .. what year is your engine?

 

the motor is a 79 casting with 9.6 to 1 compression pistons , i did a little porting to the heads, i have a mild comp cam, and am running an edelbrock intake and carb.

I installed the timing set straight up when i put it together. i had the timing at 13 degrees and it was sluggish i bumped it to 15 and it ran great i was expirementing with the timing and it just got better with the advanced timing ( all the way to 17)but i am not sure if the motor is detonating or not i have a small sound that kinda sounds like a small exhaust leak when i punch it in third gear.

don't want to do any damage but want good performance.

 

just in third gear? detination can happen in any (all) gear/s.

 

That is the only time that i heard any kind of noise other than the exhaust and a little valve tapping that i seem to have.

I have read that some of the balancers on the 70's motors can be off quite a bit so maybe that is it.

Is the noise loud where you couldn't mistake it ?, because the noise i was hearing was pretty faint maybe sounded like a little bit of an exhaust leak tapping i don't want to do any damage but i want to get this thing dialed in.

if I keep it in 1st gear and drop the pedal I should here it correct?

 

lugging gives you a cha cha cha
detonation sounds like metal shaking

 

well what im trying to say is if you lug an engine and hammer the throttle down you will hear it detionate...if it will detionate. its a good thing that you are concerned about it. if its bad enough you can lose the crank. i dont know what your funds are like but a shop can test for detionation.

 

back the timing down to 15
if it still pings, goes back down
this is your initial timing right?

 

Yeah my initial timing at 1000 rpm with the vacume advance disconnected and vacuume port plugged is at 15

I bumped it up to 17 and it ran even better, but i just am not sure if i am advancing it to much.

I put it back to 15 and it runs well.

I am going to step it up again tomorrow and see if i notice any noises now that i have a little better grasp on the sound it would be making if it was detonating.

I have read tons of stuff that say that the balancers can shift due to old age and give a false reading.

I want to step it up until i hear that detonation sound and then back it off a couple of degrees, but it is hard when youhave never heard that noise before and the exhaust is pretty loud.

Thanks i will keep you guys informed on what happens, any more ideas are welcomed

thanks

 

you are an automatic right?
what is your idle speed?

 

Yes, Automatic 904 a

idle speed in neutral about 1000/950, when it is in gear it is around 750, 800

I am timing at 1000, I am pretty sure that is what the manual say to time at

Am I way off?

 

no, I think your ok. The curve doesn't come in to around 1500 rpm.

 

i am going to play with it again this afternoon. I am going to take it up maybe to 18 and see if i can hear anything , i almost want to advance it enough to hear the "glass breaking " sound so i know what to look out for.

Thanks for all the help i will let youknow what i find out

Thanks again

 

Here is what i found out. i played with the timing and brought it up all the way to 19 degrees. On heavy exceleration under load i heard a small amount of noise definitely from the engine some place, i am still not sure if it is detonation or something else. I only heard it when i was under load and it would let up after i took my foot of the gas.

i moved it back down to 17 and it seems to run really well , starts right up, has good acceleration, idles well and when i get on it i don't think that i hear anything.

I checked my plugs and they look really nice, just a hair off white nice and clean.

so i am going to run it that way for a while

thanks everyone for the help

Luke