carb issues

[rwhite65]

82gt-
They both have great knowledge and have helped me in the past.

My knowledge of these is still elementary, so I need all the help I can get.
Ryan

[82 GT]

Originally Posted by rwhite65

82gt-
They both have great knowledge and have helped me in the past.

Ryan

I agree 100% I couldn't agree more.

[PKRWUD]

Holley knows their stuff, believe me. They tend to tune for the average car, though. You seem to be losing power at the end of your run, which is often because the PV closes too soon. I'm not guaranteeing the 8.5 PV will be a miracle cure, but it should be better. If it's too much, you'll run extremely rich at idle.

Ryan-
Sorry about causing you to lose traction.

The cams all act differently, and in all the Holley books I've ever read, none of them recommended the green cam, but it's still my favorite. And now you know why. Books are great, but experience is invaluable.

Your vacuum numbers sound better than they did before (8" at idle couldn't be correct if the mixture and timing were on), and by answering my hypothetical question, I can say with confidence that you don't have a vacuum leak (if you did, the engine would stall during a panic breaking condition).

Now that you have the single best tool for working on engines, use it to adjust your idle mixture, and make sure you're on the money. As far as your vibration, I'm thinking you should be looking at your tranny/convertor.

[~The Jester~]

Oh wow! Time to defend myself I guess! LOL

Last YEAR (Ryan!) when this was brought up, it was presented to me as an "off idle" stumble, so my first thought was squirters. Now it comes up as a partial throttle problem, and I'm gonna go with everyone else, and point the finger at the power valve. I'd just yank it and be done, but that's just me.

PKRWD, nothing at all personal here bro, I value each and every one of your posts. But this one I think we need to have a discussion on. The adjustment on the accelerator pump cam CAN'T be 0.000" for the simple reason that at WOT, you'll rupture the diaphragm on the accelerator pump. Remember, that's all mechanical linkage, and there's no room for errors, or "over run". Like I said, nothing personal, I'm just looking to learn something here!

Am I missin' something?

[PKRWUD]

Originally Posted by ~The Jester~

PKRWD, nothing at all personal here bro, I value each and every one of your posts. But this one I think we need to have a discussion on. The adjustment on the accelerator pump cam CAN'T be 0.000" for the simple reason that at WOT, you'll rupture the diaphragm on the accelerator pump. Remember, that's all mechanical linkage, and there's no room for errors, or "over run". Like I said, nothing personal, I'm just looking to learn something here!

Am I missin' something?

Nothing personal taken! This is a common area of misunderstanding when it comes to Holley carbs. First of all, you won't rupture the diaphragm no matter how badly it's adjusted, thanks to it's design. That's why there is a little spring around the screw and nut you adjust it with. Even when you bottom out the pump housing lever, the spring inside the pump will experience coil bind before the diaphragm would rupture. The worst thing that can happen from adjusting the linkage too tight is that you won't get the full 30cc shot of fuel. The perfect adjustment is zero clearance, but most people don't seem to be able to adjust it to zero, so actual clearance is recommended in their literature. But believe me, zero clearance will give you the best possible results.

[rwhite65]

Ok, so it is at all possible that the power valve, needing to be slightly smaller then it is now, would cause the shutter I still have?

I have a Holley book coming (thanks Brian) so I should be a little more educated on this by some time next week.

PKRWUD-
I know you think tranny/converter...which I will look at, I am just not sure at this point what in those two pieces may be the cause of this. The converter is suppose to be pretty stout, not saying it still couldn't fail though.

Thanks all, we are half way there!
Ryan

[PKRWUD]

It just sounds more like a possible issue with the convertor lock up than a carb issue, but it's really hard to tell online.

On a side note, I think a 3.5 PV will only hurt your performance, but I'm interested to know if it solves your problem.

[~The Jester~]

<---- Thinking, taking this all in.

I'll be back later.

[Rev]

I had that low rpm cruising stumble once. Since the carb is running almost entirely off of the idle/transition circuit at those low cruising rpms, the idle being set too lean will cause a stumble sometimes under those conditions. How many turns out are your idle mixture screws out from the closed position? I had to richen mine a little more to get rid of the stumble but then it was a little rich at idle. I eventually had to open up the low speed or idle bleeds to get everything just right.

Rev

[rwhite65]

Originally Posted by Rev

I had that low rpm cruising stumble once. Since the carb is running almost entirely off of the idle/transition circuit at those low cruising rpms, the idle being set too lean will cause a stumble sometimes under those conditions. How many turns out are your idle mixture screws out from the closed position? I had to richen mine a little more to get rid of the stumble but then it was a little rich at idle. I eventually had to open up the low speed or idle bleeds to get everything just right.

Rev

I really don’t know what it is set at, I will check it tom and see what I find. It could be the converter, but I am hoping not right now.

PKRWUD-
I didn’t mean to say I wondered about installing the 3.5 power valve. According to Holley’s way of thinking, the 5.5 would be what my vacuum in gear called for.

Ryan

[rwhite65]

Looks like I had another hidden issue. I noticed a small tapping noise coming from the driver's side bank of cylinders today when I was going to a buddy’s house to adjust the idle mixture screws.

The tapping noise sounded like plastic on metal, not the sound I have heard from detonation in the past. The noise got louder, and the car finally started to lose power. I was able to get it home, where I realized my distributor hold down was lose , so I am not sure if the distributor was moving or not. The wires look good, and appear to be seated on the plugs.

The one odd thing I noticed was when it started to run crappy and rough, I went behind the car and could hear a serious change in my exhaust sound. The car actually sounded smoother and reminded me of what a Honda would sound like.

I believe I may have a bad plug, although they are only 1.5 years old. I have autolite 25's in it and hope to put some 24's in it tonight after work.

I will say this, I have pretty much eliminated the Trans and t.c. from the shutter problem now. I also had a slight backfire out the exhaust while I limped the car home, going down a pretty good sized hill.

Ryan

[82 GT]

Do you think it could be the U-joints causing the shutter...or maybe your carb. just needs rebuilt.
Out of curiousity, why are going to Autolite 24's instead of staying with the 25's? Are the 25's too hot a plug?

[rwhite65]

Originally Posted by 82 GT

Do you think it could be the U-joints causing the shutter...or maybe your carb. just needs rebuilt.
Out of curiousity, why are going to Autolite 24's instead of staying with the 25's? Are the 25's too hot a plug?

The carb was rebuilt either last summer or the summer before. I decided on the 24's because I cant leave anything alone, and thought I would try the hotter plug-which I was informed was the 24's.

[82 GT]

Uhh...I hate to tell you this but the 24's are a colder plug.
I know for a fact, at least for autolites, that a higher number means hotter plug. Hold the 24 and 25 next to each other and you will notice the 25 has a slightly longer reach into the combustion chamber. That's how you tell how a plug is hotter or colder than another.

[rwhite65]

Originally Posted by 82 GT

Uhh...I hate to tell you this but the 24's are a colder plug.
I know for a fact, at least for autolites, that a higher number means hotter plug. Hold the 24 and 25 next to each other and you will notice the 25 has a slightly longer reach into the combustion chamber. That's how you tell how a plug is hotter or colder than another.

Well, I guess thats what I get for goin to the auto parts store and leaving it up to them to give me the right ones.....lol....
Ryan

[PKRWUD]

Originally Posted by rwhite65

Looks like I had another hidden issue. I noticed a small tapping noise coming from the driver's side bank of cylinders today when I was going to a buddy’s house to adjust the idle mixture screws.

The tapping noise sounded like plastic on metal, not the sound I have heard from detonation in the past. The noise got louder, and the car finally started to lose power. I was able to get it home, where I realized my distributor hold down was lose , so I am not sure if the distributor was moving or not. The wires look good, and appear to be seated on the plugs.

The one odd thing I noticed was when it started to run crappy and rough, I went behind the car and could hear a serious change in my exhaust sound. The car actually sounded smoother and reminded me of what a Honda would sound like.

I believe I may have a bad plug, although they are only 1.5 years old. I have autolite 25's in it and hope to put some 24's in it tonight after work.

I will say this, I have pretty much eliminated the Trans and t.c. from the shutter problem now. I also had a slight backfire out the exhaust while I limped the car home, going down a pretty good sized hill.

Ryan

That all sounds like a timing issue, and if your distributor hold down was loose, I'd bet the farm that the distributor moved. Reset your timing, and all should be well again.

[rwhite65]

I reset the timing, still have the new issues. I thought the same thing. Now I am trying to decide what is causing the problem. The ignition is pretty simple on this thing....Mallory brain coil and a Mallory Unilite. The Unilite’s module has gone bad on me in the past.
Ryan

[PKRWUD]

Well, looks like I lose the farm. lol. It's been my experience for more than 20 years that Mallory makes junk. I will never buy another product of theirs, all though in all fairness, the coil in our sprint car is a Mallory, and it still works.

What is your timing set to? Had it changed?

[rwhite65]

Mallory was in the car when I bought it, otherwise I will never buy their stuff. I plan to put MSD in when this one goes bad.

I wish I could tell you where my timing was, but here is the thing. When I swapped in the new 91 5.0, but kept some of the early style front dress, meaning timing chain cover, alternator bracket, water pump, I haven’t been able to find a pointer that would work. Reason being the pointer that works with this set up is designed for the passenger side if I remember right and I needed one for the driver's side where the lower radiator hose was not in the way. I couldn’t find one that would work though so I made one for it, but I must of been off a little. Last time I tried checking it, I was WAY off (like way past 16 degrees). So to answer your question, it was timed by advancing it as much as I could, then I would shut the car off for a minute. I then backed it down a little at a time until it would "hot" start...then I locked it down there.

I will show some pictures just to clarify. Also on a side note, no matter where I put the timing, I can’t get it to run right now. This is more then a "timing" issue. Something definitely has failed.

Ryan

[rwhite65]

Well, the plugs still look new and all the wires were on good, so I am not sure where to go from here. I went ahead and put in the new plugs, and only found one slight burn/crack in one of the plug wires boots. The crack didn’t appear to be overly deep. I checked it with the car running and no lights on in the garage, no arcing that I could see or here.

I am in a wedding this weekend, so the rest of today and tomorrow is shot with that. I will put a timing light on it for you PRWUD, but I am sure it will say something crazy like 20* advanced. Anyhow, I am not sure what it is, the car gets so few of miles, I am really not sure what is causing my good sounding stang to sound like a dang Honda.
Ryan