250 engine timing

[jfw432]

Hey guys, new here and just bought a 79 C-10 with a straight 6 250. I've been looking all over the web and it sounds like timing on these engines should be fairly straight forward. From what I can tell, there are supposed to be sawtooth marks on the timing cover. However, this truck has no timing marks from what I can tell.

Here's where I am... I disconnected the vacuum advance and the engine sounded more like 1500rpms vs 2500rpms (no tach here) and barely running. It looks like the timing marks should be on the timing cover on the drivers side of the engine. I've cleaned all the goop down to bare metal on the timing cover and it looks like there is a nice flat section on the cover with absolutely nothing on it. From what I can tell, passenger side is advance (BTDC) and drivers side is retarded (ATDC). The engine was timed way on the drivers side and ran very poorly especially when cold. It basically required that 2500ish rpms to stay running.

I did what I believe to be advancing the timing until it's a little past center of the flat spot on the timing cover on the passenger side. Had to lower the idle screw significantly. I kept adjusting until it sounded like the engine rpms quit going up and then tightened the distributor back down.

Does this sound reasonable or is there a better way to ensure the timing is correct? Or am I missing something entirely?

[cadillac_al]

I'm pretty sure there are numbers on that timing tab. Of course they are pretty hard to see but they should be there. When standing on the passenger side the timing mark will come towards you when you advance it.

[greg64]

Does the timing tab ( driver's side, attached to timing gear cover) have notches in it? Each of the notches represents so many degrees. I think peak- to-peak is 2 or 4 deg ( from memory) . Did you find the notch in the balancer?

Sounds like your timing is retarded to me.

[jfw432]

If you're talking about numbers on a sawtooth style tab, that tab is what I can't actually find. If it is still on the engine somewhere, where is it located?

I do see the notch on the harmonic balancer.

[greg64]

If you look at this picture, you'll see the timing tab attached to the timing cover (orange)

[jfw432]

Forgive me for being ignorant but I don't see any orange on the engine itself and I'm guessing that yellow arrow has nothing to do with what we're talking about here?

Is the blue circle the area you're talking about?

[greg64]

Yup, you got it, the blue circle you drew. Sorry, I just grabbed that picture from another post.

[jfw432]

Ok thanks. Well unfortunately there is nothing there but bare metal.

I think I've got the timing close but I'd like to know that it is right and not just close. It starts really easily when warm and runs well without pinging. It doesn't want to be shifted into gear for the first minute or so but after that it's golden.

JEGS sells timing tabs but just says they are applicable to a lot of cars and trucks. Are the tabs all the same?

[geezer#99]

No the tabs aren't all the same. Those ones from JEGS are for a sbc which could have a larger balancer.
All you need is a pointer and a digital timing light.
The pointer you can make yourself. Find a nice close bolt to mount a homemade point from. A 1/2 inch wide piece of flat iron can be made into a pointer.
Find true tdc #1 by using a piston stop, line up your pointer with the mark on the balancer and then set your timing.
A digital light works perfect for this or a dial back light will work too.

[lilpoindexter]

On my '78 250 I confirmed the timing tab was still accurate (the harmonic balancer hadn't moved)...and it seemed like It tolerated a lot of advance...I think the sticker said 8 degrees btdc, but at 14 btdc it ran better.

[cadillac_al]

On my 76 250 the timing tab is on the passenger side. Weird. Try looking on the other side for the heck of it.

[jfw432]

I thought the 292's were on the passenger side. Either way... I think with the ideas here, I can find TDC and make a mark on the timing cover and then measure and make marks on the harmonic balancer based on 360 degrees. A digital timing light would be easier but honestly I don't have a need for something that sophisticated 99% of the time and they aren't cheap.

Thanks for all the help.

[geezer#99]

Here's a link on finding tdc. The info is for a sbc but still works on a six banger.
http://www.crankshaftcoalition.com/w...op_dead_center