Distributor curving?

[dphipps]

So I have access to a syncrograph and all sorts of springs and weights, so I plan on making the most of it while I can.

I have a 229 ('81). Does anyone have any ideas if these motors like a specific curve? If not I guess I'll just play around and see if it does anything.

 

[dphipps]

Anyone?

Or if anyone has a picture of the timing tab, that would be nice. I can't read mine at all so a picture of the marks would be nice to find.

 

[mhamilton]

Isn't '81 a computer controlled distributor?

Anyway, I have found the best curve for these is the factory one. The way they have these set up, the vacuum advance does most of the work. The mechanical advance comes in pretty late, over 1200 rpm, and just adds a few degrees of timing. More than that and you'll get knocking with the 305/229 engines. Also loose a lot of smoothness and economy.

The timing tab should be standard SBC, but I'll take a look and see if there's a picture in the FSM later.

 

[dphipps]

Hey, thanks for the reply.

My car is Canadian so there's no computer control. It is just a plain old GM HEI unit. Or atleast I think it is... I haven't actually had it out yet but I'm fairly sure it isn't.

The more I read into it I think I will just keep the stock curve, but I still plan on pulling it out and servicing it and checking it out on the machine to make sure it's working properly.

I found a 4.3 timing cover and checked the tab and if that is the same as 3.8 then my timing is out a few degrees atleast, but a picture would still be appreciated just in case it is something different (which I doubt it is).

 

[mhamilton]

Ah, okay, yours will be a standard HEI.

It would be worth checking. I had endless problems with my HEI trying to keep the stock curve. The OE springs were very heavy to keep the spark from advancing too quickly, but they wear out quickly and over-advance the timing.

I found this on Google, it's what should be there on yours: http://media.photobucket.com/image/SBC%20timing%20tab/pyroryan/base.jpg

The "point" closest to the passenger side is 12* BTDC, next point is 8*, etc.

 

[dphipps]

It is different than an SBC one, but thanks anyways.

But from what I can tell, lowest 'valley' is 0 degrees, then each 'peak' and 'valley' after that are spaced 2 deg apart for any chev.

All this came about from checking the timing, and having a hard time reading the tab. I was told (I didn't get a chance to look) but when it was being revved , it wasn't advancing at all.

It runs fine so I can't see that, I think I might have to take a look with the light and see for myself.