chevy 383 ignition timing?

[sam priem]

a buddy of mine has a mid 80’s half ton chevy pickup 4×4 with a bored over 350. he had a knocking in the enigne (not mechanical, more like spark knock) so he replaced the cap and rotor. he asked me what it could be but i couldnt tell him much. im thinkin the ignition timing is advanced a little to far (thats what it sounds like anyways). i have a timing light and i’ve adjusted timing on a few vehicles but not an old chevy 350. does anyone know how many degrees BTDC it should be at? or if anyone has some input on what else the problem could be?

Topic

[619DioFan]

With the vacuum advance disconnected and idle around 700 set the base timing at 4-5 degrees before tdc. if the motor is running an after market cam you may need to play with the timing to get it right but around 5 degrees should be good. if it has a points dizzy make sure the dwell angle is also set right. the small block in my 69 chevelle with a mild cam , edelbrock manifold and edelbrock carb seemed happy at 5 degrees btdc.

[Roy French]

Hey Sam, I always set them for 32 degrees total advance. That means you rev it up to around 2000 rpm when you are fully mechanically advanced and set it. It helps if you have a timing light with a knob to set the advance. If you don’t have one you use a special tape with the graduations marked on it attached to the harmonic balancer. I haven’t seen the tape lately, but you used to be able to get it at auto parts stores.
A bored out 350 doesn’t make a 383. You have to change the crank also to increase the stroke. If that’s what he has it will be a rocket when it’s running right.

[sam priem]

we got it figured out. the timing was a little too high causin the knock. i backed it off a bit (dont remember to what) but its running WAY better. and yes it has a stroker cam in it. i forgot to say that. hes also got an aftermarket cam so i just backed it off little by little till i got it to a point where the engine was happy again. problem solved. thanks for the inputs.

[EricTheCarGuy]

Thanks for the update. Yea with those modifications you need to play with the timing a bit to get things right. Glad you found the ‘sweet spot’. Thanks for keeping us up to date and for using the ETCG forum.

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