Having some more issues.

[Cobain03]

i think im having vacuum and timing problems.

what should the timing be set at while in park? what is the correct way to check and change timing? do you also have to check "total" timing? how do you do this?

as far as vacuum goes, say your sitting in park, you shift to reverse to back out, the pedal is REAL hard. you have to really get into it to get the sucker to stop. But say once you take off in drive and give it a couple of revs, the pedal is great. what causes this? whats the fix?

 

[ForceFed70]

1st off... you should be measuring vacum with a vacum guage, not the feal of your brake pedal. It's these kind of things that send people in the total wrong direction...maybe your brake booster is wearing out?

Timing...

Your base timing should be somewhere in the 10 to 14* range. This is at idle with the vacum advance disconnected (remove and plug hose).

Total timing shouldn't need to be checked unless you are running into a problem with pinging (and your base timing is correct) or you are having a problem with low power at higher RPM.

 

[Cobain03]

the vac. advance hose, you saying pull the hosee off the dist. and plug it?

also, i will be buying a vacuum gauge. what should it read?

 

[ForceFed70]

the vac. advance hose, you saying pull the hosee off the dist. and plug it?

Yes, that's exactly it.

also, i will be buying a vacuum gauge. what should it read?

Good question. It depends on your cam and idle RPM. High performance cam's will have much less vacum at idle when compared to a regular cam.

It's been a long time since I measured mine, but it was around 60KPa at 850 RPM(sorry, not sure what this is in inches of water/mercury). See my sig for cam details.

 

[Cobain03]

my cam specs are in my sig. i was told that this was not a big cam in any way

 

[68keyblr]

I had my carb rebuilt by Pony carbs. They sent a video showing how to set the initial timing. They recommend setting your initial timing using a vacuum gauge instead of a timing light...basically you set the idle at 1,000 RPM and then rotate the distributor around until you achieve max vacuum. The point at which you have the max vacuum reading is where you tighten down your distributor bolt.

I gave it a try and my car has never run better

 

[iskwezm]

I had my carb rebuilt by Pony carbs. They sent a video showing how to set the initial timing. They recommend setting your initial timing using a vacuum gauge instead of a timing light...basically you set the idle at 1,000 RPM and then rotate the distributor around until you achieve max vacuum. The point at which you have the max vacuum reading is where you tighten down your distributor bolt.

I gave it a try and my car has never run better

i've heard of that for carb settings, but never timing...............learn something new

 

[D.Hearne]

I had my carb rebuilt by Pony carbs. They sent a video showing how to set the initial timing. They recommend setting your initial timing using a vacuum gauge instead of a timing light...basically you set the idle at 1,000 RPM and then rotate the distributor around until you achieve max vacuum. The point at which you have the max vacuum reading is where you tighten down your distributor bolt.

I gave it a try and my car has never run better

Only drawback to that method, is you have no idea what the total timing is. Yea, it's optimal for idling, but how many of us idle around town and on the freeway ? And once you've done this and you get it out on the road and the thing pings like mad, what do you do then, if you've got a tankful of 93 octane Premium gas ? ( answer: you go back and back off the initial timing or run race gas) Optimal timing is only determined by how much you want the engine to do,combined with how much you want to spend on fuel, and how high of an octane rating your engine needs to begin with to run without pinging at the lowest timing setting it'll run at.

 

[ForceFed70]

I had my carb rebuilt by Pony carbs. They sent a video showing how to set the initial timing. They recommend setting your initial timing using a vacuum gauge instead of a timing light...basically you set the idle at 1,000 RPM and then rotate the distributor around until you achieve max vacuum. The point at which you have the max vacuum reading is where you tighten down your distributor bolt.

I gave it a try and my car has never run better

Ummm...are you sure you wern't setting the idle mixture this way and not the timing?

Why would a carb company send you information on how to set your timing? This method sounds way wrong to me...

 

[68keyblr]

Ummm...are you sure you wern't setting the idle mixture this way and not the timing?

Why would a carb company send you information on how to set your timing? This method sounds way wrong to me...

Well, I hope I didn't get the distributor bolt confused with the idle screw....or maybe I was messing with the Halogen fluid?

Pony carbs provides a complete installation and tuning video with their carbs because they don't want to field a million support calls from customers that hook up their new carb and don't get the performance they are expecting. Timing is a critical factor in performance and many people confuse timing problems with carb problems.

It makes perfect sense to set the timing with a vacuum gauge - you want the initial timing set where the engine is pulling the strongest at idle speed. You can also do it with a tach for that matter.

Pony carbs recommends AGAINST using a timing light for setting the timing, because they argue that most harmonic balancers on 40 year old cars have slipped over the years and you are not getting an accurate reading. Take that for what it's worth.

All I'm saying is that I followed their procedure and the engine has never run better. As it turned out, the total timing came out about right too - barely starting to ping under full throttle.

 

[Cobain03]

ok heres the deal. we got the car running smooth and strong. it feels that i've gained (or picked back up which evr way you see it) a bunch of power. BUT, i have a miss around 1000 rpms. i've checked the plug wires too and i have good spark.

thoughts?

 

[ForceFed70]

Well, I hope I didn't get the distributor bolt confused with the idle screw....or maybe I was messing with the Halogen fluid?

Pony carbs provides a complete installation and tuning video with their carbs because they don't want to field a million support calls from customers that hook up their new carb and don't get the performance they are expecting. Timing is a critical factor in performance and many people confuse timing problems with carb problems.

It makes perfect sense to set the timing with a vacuum gauge - you want the initial timing set where the engine is pulling the strongest at idle speed. You can also do it with a tach for that matter.

Pony carbs recommends AGAINST using a timing light for setting the timing, because they argue that most harmonic balancers on 40 year old cars have slipped over the years and you are not getting an accurate reading. Take that for what it's worth.

All I'm saying is that I followed their procedure and the engine has never run better. As it turned out, the total timing came out about right too - barely starting to ping under full throttle.

Lol.. I suppose it does make some sense. I just happen to know that if I were to use this method, my timing at idle would be nearly 18*. Thus causing bad pinging during driving. I could back off the mechanical and vacum advance to compensate..and the engine would probably run great... but that's not what most people would want to do. That much timing with a higher compression engine could also cause some big starting problems...

 

[wild70stang]

For vacuum gauges, I went to Ebaymotors. For using the gauge heres the site.

http://www.centuryperformance.com/vacuum.asp

 

[ForceFed70]

ok heres the deal. we got the car running smooth and strong. it feels that i've gained (or picked back up which evr way you see it) a bunch of power. BUT, i have a miss around 1000 rpms. i've checked the plug wires too and i have good spark.

thoughts?

Have you checked for vacum leaks? Try spraying carb cleaner around the base of your carb and around the intake manifold gaskets.

 

[jbuening]

I'm running a Comp Cams XE262H cam in my 351w and i get 15 in Hg at idle. This isn't a big cam either, but is lower than the normal 18 in Hg for stock motors. The needle should be fairly still otherwise you have problems like a vacuum leak or your valvetrain needs adjustment.

As far as the Pony Carbs instructions, here is a discussion and another link in there about this method. Personally, I use the timing light. Is your dizzy stock or aftermarket? If it isn't stock, then just setting the base to 10-14° could throw your total timing way off. Some have 20° mechanical and some have more/less, so you would have to adjust your base setting accordingly.