This again.... 4bbl on a 318 with a 2bbl

[PRH]

I haven’t read every post, but am I correct in assuming the engine is stock for the vehicle?
If so, a reasonable starting point for timing/idle speed would be whatever the factory settings are(unless the timing is really low, like zero or something after TDC, in which case I’d try 4-5btdc).
Of course, if the distributor has some sort of performance curve in it, just disregard this post.

 

[abcdefghii]

I haven’t read every post, but am I correct in assuming the engine is stock for the vehicle?

Correct.... No modifications to the engine other than the distributor, carb and intake manifold. It's had other changes, but nothing directly related to the engine (exhaust, electric in tank fuel pump).

Factory sticker says 16° at 650rpm.

 

[Mattax]

Factory sticker says 16° at 650rpm.

That's interesting
What year ?

Can you post a pic of the sticker?

I'm guessing from your 1st post the truck is a later 70s or 80s.
Once catalytic converters were being used, the retarded initial timing used for emissions at idle wasn't needed anymore.
So in many ways the entire timing curve looks more like would be seen before emissions controls of the late 60s.

 

[RustyRatRod]

Yeah, and I assume I'm using it correctly, but going to just make certain before I do anything more.



Hopefully that's good, the balancer was replaced in October when I replaced the timing chain etc.

I did not, but only because I had noticed the steam from the engine. When I next have time to work on it, I'll start adjusting that down and watching the timing.

It was (is) definitely a good place to start, as I wrote previously the whine fires up almost instantly where it's currently set.

I think at this point what you should do here is verify top dead center. Since everything is based off that, it's really important that it's right. You need a piston stop to find it accurately. That way, if the balancer is mismarked, OR if you have a mismatched group of parts like say an early timing cover for instance where you need a late one, or vice versa.

 

[abcdefghii]

That's interesting
What year ?

Can you post a pic of the sticker?

I'm guessing from your 1st post the truck is a later 70s or 80s.
Once catalytic converters were being used, the retarded initial timing used for emissions at idle wasn't needed anymore.

1981... I believe from the factory it would have had a cat, but it's long gone. Here's a picture of the sticker:

I think at this point what you should do here is verify top dead center. Since everything is based off that, it's really important that it's right.

I did that yesterday, but used a cork and rotated the engine over until that popped out, then used a straw and some tape like a flag, rotated until that stopped moving upwards. I do have a piston stop, if I need to verify again I'll use that.

 

[PRH]

Not to overload you with info, but since it has an aftermarket distributor, I’d probably try setting the “total timing”, and then see where the timing at idle lands, and if that’s reasonable, I’d go with it.

For total timing, you set the upper limit for how far the mechanical advance can go.
I’d start out at 33-35*(vacuum disconnected)…….. at whatever rpm it takes to get there.
Most performance distributors will reach full advance before 4000.
Then see what the timing is when it idles back down.
You’d like to have it end up somewhere between around 5 and 18.

Then start playing with the idle speed screw and mixture screws.

 

[Mattax]

I disagree with you on that Duane. First because its a truck and presumably a street vehicle not a race set up. Second we know nothing about this distributor so why take a chance. I think its safer, and more productive first getting the idle established. Then check the timing at higher rpm, especially between 1400 and 2000 rpm. Then check at some a higher rpms. What happens between 1400 rpm and 2600 or so will dictate how well it will play with the vacuum advance.

 

[RustyRatRod]

1981... I believe from the factory it would have had a cat, but it's long gone. Here's a picture of the sticker:

View attachment 1716516189


I did that yesterday, but used a cork and rotated the engine over until that popped out, then used a straw and some tape like a flag, rotated until that stopped moving upwards. I do have a piston stop, if I need to verify again I'll use that.

And how did the timing mark correlate?

 

[Mattax]

Found Sun tune up cards for 1979 passenger casrs with 318 2 bbl and 4 bbl.
Both have 16 BTC and both used Electronic Spark Control (ECS).

Not that it really changes anything. Initial somewhere around 10 BTC is still a good starting point, and timing above idle should follow something like the 273 4 bbl (non emissions). Weight of vehicle and gearing will play into this. That's why I was looking for what the factory was doing.

 

[PRH]

I think its safer, and more productive first getting the idle established.

I won’t argue with that.

If either you or I were doing it, we’d have the timing curve mapped out in short order, then decide where to set the timing(as a starting point).

 

[abcdefghii]

Right about 16° and 650-700rpm.



Starts up nicely. I'll have to either temporarily move my tach or get an assistant to help mapping a timing curve.

But, for a miserable rainy day, I'll take this progress.

 

[PRH]

It’s amazing what can happen when a few screws get turned.

 

[abcdefghii]

It’s amazing what can happen when a few screws get turned.

And no small thanks to everyone helping with my possibly incredibly simple questions!

Which I'm sure to be back with more once I start working on a timing curve and get the truck out for a drive.

 

[318willrun]

Right about 16° and 650-700rpm.



Starts up nicely. I'll have to either temporarily move my tach or get an assistant to help mapping a timing curve.

But, for a miserable rainy day, I'll take this progress.

experience is a teacher....