Setting Timing and Vacuum on 390FE

[KPace1955]

Gentleman, My question concerns my initial timing is set at 12 Degrees. Starts up great every time, but top end drops off at 3500 rpms. I have Eldebrock Heads and Intake with 600cfm carb (vacuum) stock cam. I put on the vacuum guage on the manifold and noticed I only had 6lbs. So I upped the timing to 20 Degrees and now have 20lbs of vacuum at idle and it runs great up to 5500 rpms. The problem not is after it runs a while up to temperature and I shut it off it will not restart. It sounds like the starter has nothing left in it. After about a 1/2 hour it cools down and starts right up. Bottom line, I like the engine above 3500rpms but when the timing is at 12 degrees it start all the time. Thoughts?????? Starter?? Distributor vacuum works.

[sparky72]

Are you running headers?

[KPace1955]

No I'm not. I use too and that had a big effect on the starter when hot.

[sargentrs]

Might try some heat shield/insulation wrap on the starter?

[sparky72]

Yeah, try the head shield over the starter. You could then try a high torque starter. Some people will install a switch that disables ignition until the starter gets up to speed to fix issues like this, too.

Out of curiosity, how much total advance do you have now? You might want to look into recurving your distributor to give you the total you want without excessive initial.

Another thing - 6 inches of vacuum at idle is really, really low, especially with a stock cam. There is probably something going on there that large amounts of initial advance (and the faster idle that comes with it) are simply covering up. What was your idle speed when you were getting 6 inches of vacuum? If it was in the ballpark (500-700rpm, I would say) but your vacuum was that low, I would start looking for a vacuum leak.

[DuckRyder]

You could try a hi torque starter or heat shield... but IMO your starting issue is a result of something else.

First do some checking.

6inHG is very little vacuum
20inHG is a lot of vacuum

Are you sure these numbers are correct.

Do you have a way to check total advance vs initial (dial back timing light, timing tape)

Step one is verify the marks on the balancer... (even if its only TDC)

Must say E heads and a stock cam is an odd build too...

[My427stang]

Duck is giving you very good advice

1 - Verify your timing marks
2 - Verify your timing curve and recurve if needed (best 100-150 you will ever spend)
3 - Lack of headers, even with a stock cam is a power sucker up top
4 - FE starters typically don't die with heat unless it's extreme, there is no solenoid to fail like a Chevy. I'd likely get a set of ceramic coated, however, realize with Edel heads, you'll have to verify that the headers are flange seal, not welded ring, as a truck header has a different port location than the CJ style Edelbrocks. FPA makes them, big bucks, but you could even reflange and coat a cheap set, I believe you can just flip the flanges upside down if handy with a welder

You numbers do seem odd that you would lose so much vacuum at 12 BTDC, my guess is your balancer slipped, or something else is causing a bad reading.

Also, always make sure you are setting timing with vacuum advance disconnected and plugged

[brkdncr]

If your starter is getting to hot, a common solution is to get a mini-starter and a starter insulation wrap.. I’m doing this on my 390 while it’s out, and will then do it on my 430 MEL that has the exact issue you’re describing.

Another possibility is a combination of a tight engine and poor wiring or a failing starter solenoid.