DasBaldDog

Hello,

Quick introduction. I recently purchased a 1972 Cutlass with a rebuilt 455 out of a 1973.

My main quandry comes from trying to time the engine with a roll-back (dialback) timing light.

My wife runs the throttle up to 3400 rpms and I set the distro (with the vaccum advance pulled and plugged) to 36* BTDC.


Then the weird part. I tell her to drop the throttle and I notice that the timing mark on the dampner is only a few degrees off (just barely off the timing notch on the dampner).

I adjust the dial and find out that at the 1100 or so rpms at Idle in Park, that we are sitting at an initial timing of roughly 28*.


Umm.... what?

The engine does not seem to ping, knock, etc..... It has a really rough cold start.... but no pinging/knocking while driving at this setting....

BTW: Supposedly is late 70's Delco-Remy HEI....


Can anyone tell me what to start checking?

Thank you in advance.




BTW: I know very little about the car from the person I purchased it from. I know that it has a 280/290 and 500/510 cam (I know jack about cams... so please don't ask... All I know is that these are the numbers listed on the "To Do" list of the engine re-builder). Has a Holley 4150 Street Avenger 770 Carb, Edelbrock Performer Olds 455 intake. Pistons are "10.25:1" according to the build sheet and was supposedly bored .030 over.

TH400 transmission and 3.90 rear end gears. Anything I'm leaving out?

Octania

Not unusual for an HEI

You can get easy starting and great throttle response by hooking the vacuum to a manifold source. No vacuum = retarded timing while cranking, then vacuum at idle advances the timing to 20 or so, then your aftermarket kit can get you the other 16 you seek by mechanical.

A good idea to pull the dist'r, dismantle, refresh the "grease", and set the mechanical advance to your liking.

http://www.realoldspower.com/phpBB2/...ic.php?t=84851

DasBaldDog

Wait, its normal for an HEI to have a base timing of 28?!



My process, please check this to make sure its correct.

1. Warm up Car
2. Pull and plug off Vacuum Advance
3. Run throttle up to 3400 rpms
4. Adjust timing on HEI to 36*
5. Let off throttle and return to idle (1100 rpms in Park)
6. Check Base Timing (It's 28*)

Sorry if I sound incredulous but this seems VERY VERY wrong.



What "aftermarket kit" are you referring to?

MDchanic

No, it's normal for HEI to have a base timing of 24°, and 28° isn't that different from 24° in the world of stock production variations.

If you need a little more mechanical advance for easier starting, then get an HEI recurve kit (Moroso, Mr. Gasket, etc.), and, while you're installing it, give the distributor a good clean and lube, as Octania said.



One light and one medium spring seems to work well for most people, but you should try a few combinations.

- Eric

DasBaldDog

Ahhh, I see. Sorry, was missing some or the connecting points (no pun).


Do I need an Olds specific kit or will any GM Delco-Remy based kit work? Is there one brand more trusted than others?


I definitely need to dial back the initial.... when you try and start her warm, its like asking Kate Moss to push a M1 Abrams.

MDchanic

Any HEI kit is fine.

I don't have a brand preference, but others might.

With only 8°, there is a chance you may need to mess around a bit with the parts, but I suspect you'll get enough range out of the parts in the kit.

Don't forget that the central plate is held on by two tiny C-clips, which will be invisible.

And I know what you mean about Kate - she was useless pushing the 6-by out of a ditch that time.

- Eric

olds 307 and 403

What rpm is your idle set at? I have an HEI that needs 25 base for 36 total at 3000. I bet your advance is hanging up.

DeltaPace77

I agree with the mechanical advance mechinism hanging up, as quite common for grease on the advance shaft to get gummy over the years. Good idea pulling the dizzy, disassemble it, and clean all the old grease out of it. Then relube it with new grease, before you put it back together.