timing?

[tim21391]

what would i time it at what degrees? 402 big block.. puttin hei dist. in it.. dont know what to time it at..

[prostreetC-10]

I'd start in the 16-18 degree mark and see how she does. My BBC's like a lot of initial advance. Do you have a light that will show you total advance?? You want around 36 total and the light will help you know how much mechanical is built into the distributor. If it's the old strobe light....it won't help you with that.

[jim zag]

Depends on how big your camshaft is. You need to put enough initial timing in it to get the idle as smooth as you like. Too much initial and it will not start. Total mechanical advance 32 to 36 degrees. Big blocks are more sensitive to DETONATION so listen for spark knock!!!!

[tim21391]

one guy says 16-18 other says 32-36.. im confused haha

[prostreetC-10]

Oh my....this gets complicated. 16-18 is INITIAL timing and 32-36 is total timing which is initial timing set by you and the built in timing built into the distributor.....I bet you are really confused now!

[prostreetC-10]

You need built in advance because your distributor has to "catch up" as the motor increases in rpms.....it actually falls behind from idle.

I charge $75 and hour for phone support!! lol Just Kidding.

[Werewolf]

Idly, 16 to 18 good for a 396 big block too?

I checked mine after replacing the carb, as the truck seemed to be running at 0, or even retarded. It was at 10 degrees, so I upped it to 14 and thought that to be high, although the truck sounds and runs a lot better.

I know 350's of the era took 8 degrees base with points. This is a 396 with HEI and a mild cam.

My vacuum advance leaks down, so I've got an adjustable with new springs coming from Summit.

[prostreetC-10]

[QUOTE=Werewolf;3378909] although the truck sounds and runs a lot better.

QUOTE]


And the question was??????? ;o)

A lot to most of the performace chips out there advance your timing. The reason the factory likes to retard the motor is for their EPA emissions and gas mileage sticker. They will run a little cleaner retarded and ROB POWER!!!!

Zero degrees is way too retarded for a big block or any motor. You need 16-18 and then to drop your idle at the carb. You will have a lot more low end driveability if you run in these ranges. I also love the timing lights that show when and how much your motor advances. They are not cheap though.

[prostreetC-10]

What do you mean your vacuum advance leaks down???

[mclairmo]

Remember that you have initial timing, total timing with the vacuum advance disconnected and then total timing with the vacuum advance hooked up. You set the intial with the vacuum advance plugged, then see what the total is with the vacuum advance still plugged and then see what the total advance is with the vacuum advance hooked up again. If you need the total mechanical advance to be less or to come in earlier, you will have to switch to lighter springs and install a mechanical advance bushing that limits the amount of advance. If you need to reduce the amount of vacuum advance, you can try adjusting the vaccum can on it now or buy an adjustable unit. MSD has great info on their website on how to time your ignition.

[Werewolf]

Yeah, I'm aware of all this; I'm just used to going by book values for timing. But, as I said, even 10 degrees seemed retarded for this engine.

The plunger in my vacuum advance canister leaks. When you apply a vacuum gauge to it, it won't hold vacuum. It draws enough to advance the timing a little, but likely does not advance as far as it should. So .. I'm replacing it.

[tim21391]

Its still not right?