Sbc 350 timing issues maybe

[jserrato714]

Good to be back on here. Been a while fellas. So I got a new project finally.I Rebuilt a sbc 350 bored .040 , stock heads, summit racing k1102 cam, hei, 1405 edelbrock, aluminum intake. The engine fires and idled pretty good I think. I checked my timing and it is at -4 after tdc. So I unpluged the vac advance of distributor and tried to advance it to maybe 12 btdc but it just stays where its at. Again car idles fine. I give it gas while parked and the engine responds as it should no boggin. I put it in gear and it idles fine as well. The engine runs around 190 at the temp gauge. I used my temp gun and the hottest part of the engine is the intake at 201 after 20 minutes of idling. From reading up on timing on here it sounds like its a bad thing anytime the engine ignition timing is set on after tdc. Please relieve my stress level as I dont want to ruin this fresh block. Thanks

[kwmech]

Try a different timing light?

[jserrato714]

Its an old school craftsman gun. It crossed my mind that it could be bad. Its about 20 plus years old.

[Greasey Harley]

Originally Posted by jserrato714

.... I checked my timing and it is at -4 after tdc. So I unpluged the vac advance of distributor and tried to advance it to maybe 12 btdc but it just stays where its at. .... Thanks

This seems wrong.
Just to clarify:
With the VA disconnected, you physically turned the distributor counter-clockwise and your timing didn't change?

[jserrato714]

At first it changed to 8 btdc...but then it dropped down to 4 atdc. Wait a sec. I moved the idle screw while at 8 btdc to lower rpms.. Might that be the issue as my idle is maybe 1k after messing with the idle adjustment?

[Greasey Harley]

Set the timing with the idle as low as possible. Mechanical advance can start activating at fairly low RPM's (as low as 750ish sometimes)
I can't tell you what to set it to, as all engines are a bit different.
Set the timing with the Vac. Adv. disconnected.
Turn the idle back up a touch after you get your timing set.

Advance it as much as you can get away with without it pinging.
Start at 10btdc take it out and drive it, get on it a bit if there's no pinging try 12btdc
then 14, 15, 16, and so on.
Do these tests with the vacuum advance disconnected.
When you start getting detonation, back it off a couple degrees and that's where it will run. (at least without recurving the dizzy)
Then reattach the vac adv and drive it again.

If it likes it, leave it there.
If not ...recalculate.

[jserrato714]

Sounds good. I will try 1st thing tomorrow. Thanks for the help peeps.

[johnsrob]

Jserrato,

I would check your distributor, Yes sir, I know you have HEI make sure the distributor is the non-locked out kind or hasn't been locked out. How you check is, remove the cap and see if the rotor moves a certain direction but snaps back to the original position. There are springs and weights under the rotor for your advance curve. There is possibility you might have a locked - out distributor. this is going to be the constant timing all the time. I had similar problem before, checked it with a timing light and that is when I found out. changed my distributor and I was in business. I was able to put 34 degrees. disconnect the Vacuum advance when the setting timing.

good luck my friend.

[jserrato714]

My distributor is a duralast gold bdlg-gm08. I thought all rotors move manually and spring back when you let go of the rotor.

[toolboxchev]

Check and follow this: https://www.crankshaftcoalition.com/...EI_distributor

Every engine will be different due to the exact parts used in the rebuild. Follow the instructions on timing and set to your preferences.

My mostly stock truck with a one step above stock cam, 76cc heads, HEI, 1405 carb likes the following.

First I added silver step up springs in the carb. Call Edelbrock tech. Of course I use a vac guage to set the idle mixtures.

16 intial
22 mechanical
36-40 all in.

Some say this is too much yet I have low compression heads and no pinging. Today's fuel from the pump 87 octane likes a lot of advance.

[rpmerf]

I usually set it by reving the engine up until it stops advancing, and set it around 34-36*. That way, you do not have to worry about what your mechanical advance is doing at idle. Then set the vacuum advance to add about 10-12*. If it pings due to the vacuum advance, it will be during cold cruise (choke on, > 2K RPM, high vacuum).

Less advance is safer, but you lose a LOT of power if it is too far out. As long as it is close, you should be fine. It's too much advance that will destroy an engine.

[weq92f]

Originally Posted by rpmerf

I usually set it by reving the engine up until it stops advancing, and set it around 34-36*. ...

I like this way too...just let the initial value fall where it may by setting total timing and being done with it.

My preference is tune-n-test as noted above by Greasey Harley but you really need some quiet exhaust and a good ear to get that right without going too far.

-klb

[Chris_oz]

Originally Posted by rpmerf

I usually set it by reving the engine up until it stops advancing, and set it around 34-36*. That way, you do not have to worry about what your mechanical advance is doing at idle. Then set the vacuum advance to add about 10-12*. If it pings due to the vacuum advance, it will be during cold cruise (choke on, > 2K RPM, high vacuum).

Less advance is safer, but you lose a LOT of power if it is too far out. As long as it is close, you should be fine. It's too much advance that will destroy an engine.

This is a great way of getting around a distributor that is flogged out and maybe advancing very early in RPM.

It works well and is a great tip.

[68 P.O.S.]

The first thing you have to do is get your timing right, then you can move on to other things if needed. The easiest way to set total timing when you don't know the strength of the advance springs in the dizzy, is to remove them. This ensures two things; the weights will fully advance (I go to 1500 rpm) and you won't have to hold the engine at 4K rpm to time it with your head under the hood. The ears like that better. Replace those springs with some from Crane Cams; one blue one silver and it will be spot on. I always set my timing to 36 degrees and my initial falls at 14. This shows my dizzy has 22 degrees of advance in it, just where it needs to be. How much does yours have? Also, will your old school timing light even go to 36 degrees? You may need a timing tape in order to set total timing correctly.