Thread: ignition timing?

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hi all, first thanks to eery body that helped with my carb problem.

Next chevy 350 9.5 comp ratio, small cam 204-214, my question is the timing what shoud it be set at. i'm not realy familiar with advance and retard i have only had DIS ignition. is advance before or after TDC? i was told to set it at 12 degrees so i did 12 deg, before and the motor seems very hard to turn over like the starter struggles ( ihave a high tork starter) it starts but runs rough, 12deg is at the end of my scal should i go more before TDC or less?

Thanks

You have too much advance in it. Yes adv. is before TDC. While it's running retard it till it sounds right and see where the timing is at. Set it to factory
specs for starters.

Advancing the timing would be turning the distributor counter clockwise? I am using a mallory unilight it has a shutter wheel , there are windows on the wheel one on each side of the rotor when setting distributor up i used the window before the rotor (looking at it from the front) should i be using the window after the rotor? i cant seem to get it to 8 deg. the distributor it self wont turn that far (vacuum advance pot not hitting anything just wont go). now whe it's runing and i turn it counter clock wise it starts to sound better, if i move it clock wise even a little bit the whole motor shakes pretty bad.

there is a slew of posts on the site on this topic. Check out the search engine. Also remember that a specific setting suggested is to get you in the ballpark. Every motor has a different happy spot when it comes to timing and the specific parts combination. Also check out the threads on timing with a vac gauge and checking with a light. Good Luck to ya.

Chevy rotor turns clockwise, so turning the dist counterclockwise will advance the timng. You should be able to see that with your timing light.

Do you have the vacuum line disconnected and plugged?

yes, vacuum line pluged. Ifound out that with edelbrock performer cam it says not to use a lae model timing chain set because they are machined retarded, my machine shop put the bottom end together, how would i know if he used a late model timing chain? if he did couldint i advance the distributor to compensate for this?

my machine shop put the bottom end together, how would i know if he used a late model timing chain?

Ask him? Unless there were specific instructions AND he read them, he probably used a standard timing set.

if he did couldint i advance the distributor to compensate for this?

Cam timing and spark timing are two different things. Cam timing affects the opening and closing of valves with respect to TDC. Spark timing affects the firing of the spark plug with respect to TDC.

First, you need to find true TDC to make sure that you don't have the wrong timing pointer or a slipped harmonic damper. A $10 piston stop, a piece of masking tape and a pencil are all you need for that.

Then, you need to look at the dist. I had a Unilite, and I could turn it 360 degrees. I don't understand what's keeping yours from turning.

Do you have it wired correctly? (1-8-4-3-6-5-7-2 clockwise)

Originally Posted by Motown

hi all, first thanks to eery body that helped with my carb problem.

Next chevy 350 9.5 comp ratio, small cam 204-214, my question is the timing what shoud it be set at. i'm not realy familiar with advance and retard i have only had DIS ignition. is advance before or after TDC? i was told to set it at 12 degrees so i did 12 deg, before and the motor seems very hard to turn over like the starter struggles ( ihave a high tork starter) it starts but runs rough, 12deg is at the end of my scal should i go more before TDC or less?

Thanks

I would look more at total timing than initial timing.
I would also try and have all your timing out by 2,800-3,000 rpms.

ok, at TDC rotor faces number 1 on cap, timing tab and balencer line up at 0. i started the motor set it at 12 deg adanced runs rough and hard to turn over like starter strains, (brand new high tork starter 12.5 volts to lead)advance it a littlemore statrts to smooth out, if i retard any motor shakes realy bad, if i keep advancing to smooth out idle then i cant start it back up like the motor is to tight.any ideas?

By the way Henry i love your car,, is that a 33?

Wild stab in the dark here......Camshaft is possibly off one tooth on the chain. Get brave at this point and pull the timing cover to look at it. Other ways to check, but at this point, simpilest way to be sure. Weird possibilities from mis-machined timing gears or somebody at the cam grinder had a few too many margaritas for lunch messed up. I don't feel that's the problem though. If the cam is off (probably too advanced), this will cause the symptoms you describe.

Motown,

33/34 . . . with 'glass replicas, who can tell? It's titled as a '34.

Based on what you describe, I would pull the timing cover. Maybe wasted time, maybe not. It's not hard to miss it by a tooth - even by someone who does it every day. I would also install Edelbrock's timing chain & gears straight up. They may be recommending that in order to sell parts, but I doubt it.

Not sure on the year it is some where between 1969-1979 driver side dip stick, i'm going to check vacuum now if not good i'm pulling timing cover.

From the discussion on temporary forum, it appears that the dist was set at #6 TDC vice #1 TDC

Denny,

Yep, the dot-to-dot and 12 o'clock high discussion pretty much told the tale.

Thanks guys, i installed the edelbrock timing chain, this time made sure bolth were at 12 o clock at TDC, motor runs a lot better. Funny thing though, when installing the gears i had to actualy rotate the cam shaft about a 1/8th of an inch clockwise to get the new cam gear on, the hole for the pin on the front of the cam is different on the other timing set.

Thanks again for all your help !!!