360 Questions.. pardon my ignorance.

[CoolDave]

Gotchya. Just my personal advice, but I would disable and remove the OSAC valve.

Its gone, vacuum hooked direct from carb to distributor.

Came here because I have pretty much the same truck, same setup. '74 D200 truck, 360, Holley 2210. My setup runs PERFECT, so I wanted to let you in on where I ended up with it, starting with square transfer slots:

10 degrees initial, limited to 33 all in
Ported vacuum advance
mix screws 2.25 turns out.

This equals a 700rpm idle.

For what it's worth.

Ok that sounds like I’m not far off. How did you limit the all in timing? What port on your 2210 is your advance hooked to? I feel if I bump up my base timing from 5 up to 10 I’d probably be in the vicinity of 650-700rpm for idle.

 

[RustyRatRod]

Its gone, vacuum hooked direct from carb to distributor.

Probably a good idea. Even if it was in working order, it's just less to go wrong.

 

[volaredon]

The "osac" port on the carb IS the (ported) vac advance port.

 

[TT5.9mag]

Forget about the vacuum advance for now. Plug the damn port and get a base tune up in the poor thing. Then worry about vacuum advance.

 

[CoolDave]

Forget about the vacuum advance for now. Plug the damn port and get a base tune up in the poor thing. Then worry about vacuum advance.

So what’s your basic method then? It seems everyone has an opinion on what’s “correct”.

Carb is set to a baseline 2.5 turns on the idle mix screws, idle speed screw is set to achieve a square transfer slot. Initial timing is 5 degrees at 650rpm (on the last step of fast idle cam, shop manual calls for TDC). Once it comes off that cam to regular curb idle it wants to stall unless I give it a little throttle.

So where would YOU go from there?

 

[TT5.9mag]

So what’s your basic method then? It seems everyone has an opinion on what’s “correct”.

Carb is set to a baseline 2.5 turns on the idle mix screws, idle speed screw is set to achieve a square transfer slot. Initial timing is 5 degrees at 650rpm (on the last step of fast idle cam, shop manual calls for TDC). Once it comes off that cam to regular curb idle it wants to stall unless I give it a little throttle.

So where would YOU go from there?

Give the engine what it wants, stop worrying about trying to hit a specific number or target for timing, turns of idle mixture screws ect. Don’t be afraid to adjust the idle speed screw a little from a square transfer slot either way, give it the idle timing it needs to maintain a smooth idle and not slam in to gear, and make sure to limit the total timing once you establish what it wants for initial if it’s above what the distributor was originally curved for. And the best piece of advice I’ll give is this, once you set one thing, don’t be afraid to re do it once you change something else. All of these adjustments can affect each other.

 

[RustyRatRod]

You need a vacuum gauge. You can use that to zoom right in on the air screw adjustment and to see where the engine wants the timing to be.

 

[CoolDave]

Give the engine what it wants, stop worrying about trying to hit a specific number or target for timing, turns of idle mixture screws ect. Don’t be afraid to adjust the idle speed screw a little from a square transfer slot either way, give it the idle timing it needs to maintain a smooth idle and not slam in to gear, and make sure to limit the total timing once you establish what it wants for initial if it’s above what the distributor was originally curved for. And the best piece of advice I’ll give is this, once you set one thing, don’t be afraid to re do it once you change something else. All of these adjustments can affect each other.

I’m expecting to set things a few times and tinker a lot. So questions about the process..

With it stumbling at hot idle should I first adjust the speed screw or the base timing?

Once base idle is established do I adjust the mixture screws for best idle/vacuum before bringing the vacuum can back in?

After all that, I confirm my total timing and limit the distributor weights if necessary?

You need a vacuum gauge. You can use that to zoom right in on the air screw adjustment and to see where the engine wants the timing to be.

I have a gauge, I used it in an initial setup where I got the truck running OK from a non-starter when it came home. Now I’m to the point with the truck I’m really digging in and doing the proper process to actually start driving and using it.

 

[RustyRatRod]

I’m expecting to set things a few times and tinker a lot. So questions about the process..

With it stumbling at hot idle should I first adjust the speed screw or the base timing?

Once base idle is established do I adjust the mixture screws for best idle/vacuum before bringing the vacuum can back in?

After all that, I confirm my total timing and limit the distributor weights if necessary?


I have a gauge, I used it in an initial setup where I got the truck running OK from a non-starter when it came home. Now I’m to the point with the truck I’m really digging in and doing the proper process to actually start driving and using it.

You should continue using the vacuum gauge.