Timing Question

[Hawker7]

I have a 350 crate motor that is all stock running a edelbrock1406 carb, and a HEI Skip White distributor. When I first set the timing I had it set at 12 degrees initial and while it idled OK, it would stumble when trying to accelerate. I then advanced the timing till it would run decent and now it is at 24 degrees initial. Also, the total advance timing is 40 degrees at 2,000 RPM’s. Something seems way off. When I first set the motor up I did verify that TDC was 0 degrees on the timing tab. Any ideas? David

[mclairmo]

New or old balancer? Verify it has not slipped. Are these numbers with the vacuum advance can plugged or not?

[69GMCLonghorn]

Originally Posted by Hawker7

I have a 350 crate motor that is all stock running a edelbrock1406 carb, and a HEI Skip White distributor. When I first set the timing I had it set at 12 degrees initial and while it idled OK, it would stumble when trying to accelerate. I then advanced the timing till it would run decent and now it is at 24 degrees initial. Also, the total advance timing is 40 degrees at 2,000 RPM’s. Something seems way off. When I first set the motor up I did verify that TDC was 0 degrees on the timing tab. Any ideas? David

That is very possible. I have a 350 with a mild cam in it. I had a hot rod builder out here go through and re-arch the distributor and time it properly for the cam. The base timing was off the scale! I'm guessing almost 30°!! Total advance was around 43 - 44°. Oh, and NO vacuum advance!! All centrifugal... When he did that, my low end probably tripled in power, the mileage went up about 10 - 12% and it ran better than you could imagine. With no choke, I could get in it when it was around freezing, pump the gas once, start it and it ran!

So I'm not saying yours IS correct, but it MAY be correct.

[Hawker7]

Originally Posted by mclairmo

New or old balancer? Verify it has not slipped. Are these numbers with the vacuum advance can plugged or not?

New balancer from Summitt. This is with the vacuum plugged.

[Hawker7]

Originally Posted by 69GMCLonghorn

That is very possible. I have a 350 with a mild cam in it. I had a hot rod builder out here go through and re-arch the distributor and time it properly for the cam. The base timing was off the scale! I'm guessing almost 30°!! Total advance was around 43 - 44°. Oh, and NO vacuum advance!! All centrifugal... When he did that, my low end probably tripled in power, the mileage went up about 10 - 12% and it ran better than you could imagine. With no choke, I could get in it when it was around freezing, pump the gas once, start it and it ran!

So I'm not saying yours IS correct, but it MAY be correct.

It does start up with just a tap of the starter and runs nice. Since I only have 50 miles on the motor I have not ran it hard so I can't say for sure how much power it has.

[Mertz]

I set mine up for 14 base and 37 with mechanical and a total of 55 at 3000 rpm. It seems to work the best at that setting. I have a MSD ready to run distributor that I had to change the springs and bushing to get it to 37. Vacuum advance is not adjustable. I am also running an Edelbrock carb and EPS manifold with a 1" spacer.

[LONGHAIR]

37 degrees of centrifugal timing seems a bit out-there? but then so does running w/o vacuum advance on a street vehicle.

(All of that initial advance would be required to make it run w/o having the vacuum advance connected).....but it doen't make it right.

The only reason to run w/o vacuum advance is in a totally wide open throttle situation like drag racing.

When I first set the timing I had it set at 12 degrees initial and while it idled OK, it would stumble when trying to accelerate.

Assuming that the distributor is working properly...there is no real reason to look at the timing as the source of your stumble. The timing is "close enough" for timing to not be your problem, it is more likely carburetion/fuel. The timing may not be perfect, but it has to be off pretty badly to cause this kind of thing.

[Mertz]

Actually that is base and mechanical for a total of 37. It would be 23 mechanical. I am also running my vacuum advance off manifold vacuum. The truck runs great. I never have a problem starting. It normally starts with the first touch of the key. Power is good but found more by changing the rods in the carb but it was using to much gas. I am now trying a quadajet to try to imporve my mileage but I think I have a warped stock aluminum egr manifold because it is not running right. It falls flat on its face when I lay on the throttle with a Jet Stage 2 and doesn't do much better with a stock Q-jet. I am going to try the Edelbrock on the manifold to confirm it is not the carb.

[Hawker7]

Originally Posted by LONGHAIR

37 degrees of centrifugal timing seems a bit out-there? but then so does running w/o vacuum advance on a street vehicle.

(All of that initial advance would be required to make it run w/o having the vacuum advance connected).....but it doen't make it right.

The only reason to run w/o vacuum advance is in a totally wide open throttle situation like drag racing.



Assuming that the distributor is working properly...there is no real reason to look at the timing as the source of your stumble. The timing is "close enough" for timing to not be your problem, it is more likely carburetion/fuel. The timing may not be perfect, but it has to be off pretty badly to cause this kind of thing.

I'm not running it with no vacuum advance. Only to time it.

[highperf4x4]

All of these timing numbers are off the scale.

You shouldn't be running more than 37 degrees TOTAL advance at 3000rpm.

My base advance is 10 degrees without vacum. Even with Super Unleaded I get a ping if I try to advance it any further.

When you set your initial timing with the vacum advance disconnected and plugged off are you sure your engine is idling around 800-1000 rpm?
If not then you're getting some mechanical advance unless your springs are extremely stiff.

I'd run it down to a machine/performance shop and let someone set the timing for you with an inductive timing light. Or cough up about 300.00 and get your own.

[69 longhorn]

I like to shoot for about a 34 degree TOTAL @ 3000 rpms (vac can unhooked & plugged) on a 9.5- 10 to 1 pump fuel engine. Add 10 to 12 degrees vac advance, & you are in the ball park. some like a little more, some a little less, depending on the combo(comp ratio,cam ,ect). a lot of those old small blocks will pull tween 48-52 degrees (no load, with the vac can hooked up), with no problems. if it spark rattles @ part throttle. it has too much vac advance....spark rattle @ WOT , too much initial/mechanical advance. best of luck,crazyAl

[unclewatts]

Do you have a vacuum gauge? Ported vacuum should be about 20" at 3500RPM. If it's much lower or the gauge needle wiggles at idle, then you have a problem.

[LONGHAIR]

Originally Posted by Hawker7

I'm not running it with no vacuum advance. Only to time it.

Sorry, I didn't mean to confuse, I was refering to 69GMCLonghorn about the lack of vacuum advance.
You are correct in timing w/ the vacuum advance disconnected.

Originally Posted by Mertz

Actually that is base and mechanical for a total of 37. It would be 23 mechanical. I am also running my vacuum advance off manifold vacuum.

Well an initial setting of 14 plus 23 centrifugal would indeed total 37, I missed it in the wording.....I was confused by the "total" of 55...? I am assuming that this would be the "theoretical" vacuum added?....because it won't. These things really don't "just add up" The odds of you traveling down the road @ 3000 RPM and still having enough vacuum to pull in the advance are pretty slim. About the only time that happens is when you sharply close the throttle....you might make it happen "free-revving" in the garage, but it won't happen under the load of moving the truck.

Originally Posted by Mertz

I set mine up for 14 base and 37 with mechanical and a total of 55 at 3000 rpm.

[Richard H.]

Hawker, I have the same set up in my '55 and had the same issue.
Final result 11+ initial and got the metering kit for the 1406 and used the smallest rods I could use without changing the jets , at least that was my sweet spot. Also changed the primary pump setting.
It just wasn't getting enough fuel.

[Hawker7]

Originally Posted by Richard H.

Hawker, I have the same set up in my '55 and had the same issue.
Final result 11+ initial and got the metering kit for the 1406 and used the smallest rods I could use without changing the jets , at least that was my sweet spot. Also changed the primary pump setting.
It just wasn't getting enough fuel.

How hard is it to change the rods? Also, how do you change the primary pump setting?

[Richard H.]

Changing the rods and the pump setting are simple. You can get the manual off of edelbrocks site. The primary pump only has two settings and is on the right front.
This should help...
http://www.edelbrock.com/automotive_...ers_manual.pdf
Have fun

[jablack]

What kind of heads are you using? If you have vortec heads you have to use the right spark plug or the timing will be like that.

[Hawker7]

Originally Posted by jablack

What kind of heads are you using? If you have vortec heads you have to use the right spark plug or the timing will be like that.

They are the stock heads that came on the 260 crate motor.

[Hawker7]

Originally Posted by Richard H.

Hawker, I have the same set up in my '55 and had the same issue.
Final result 11+ initial and got the metering kit for the 1406 and used the smallest rods I could use without changing the jets , at least that was my sweet spot. Also changed the primary pump setting.
It just wasn't getting enough fuel.

you were right on. Got the kit and went with small rods and orange springs and it was night and day difference. What hole are you running primary pump setting? Mine has 3 and I currently have it on the one in the middle.

[dznucks]

What calibration point are you at on the calibration chart?

[Richard H.]

I don't remember which hole but whatever dumps the most fuel. You may be good where your at ,mine is a 290 hp with headers. Glad you got it.

[mtdave2]

Originally Posted by jablack

What kind of heads are you using? If you have vortec heads you have to use the right spark plug or the timing will be like that.

? why is the vortec differeant?

[jablack]

the spark plug is different. the threaded part is longer. If you use the regular plugs you have to run the timing up to get it to run decent.

[mtdave2]

huh, well, this may be my prob. i was planning on getting some new plugs tomorrow. i called jegs to ask what plug was recomended for the head i bought. i am having timing issues. had to advance the hell out of the timing like you said.. perhaps the plugs will help