1986 460 Smog Pump Delete

[Bullnose Gator]

Thanks for confirming. So Jeremy should be looking for ~10 BTDC, which is on the side of the scale with lines going all the way to 30 or 40 BTDC.

So I gave it a shot. To be clear, my scale is -10, 0, +10, +20, +30, and no marks after +30.

After getting it up to temp, I turned off the engine, pulled the vac hose off the distributor, and plugged it. I turned the engine on and turned the distributor slowly clockwise until it was at +10. It sounded much better. I went to +12 and it sounded like I crossed the line, because it started to back towards sounding bad again.

RPMs were right around 750-800. I turned it off, tightened the dist nut, stuck the the vac hose back on the dist nipple and cranked it back up. It didn't sound good. I checked timing and it was reading +33 deg. Idle still looked good.

Also, the vac gauge was pushing 23-25in throughout the process.

I can't mess with it anymore tonight, but I'm wondering if I have a vacuum leak or something. I can almost hear a faint "hiss" with the vac adv hose connected, and it seems like it might get more pronounced when I disconnect and plug it. If it's not in my head, it sounds like it may be coming from the right side of the carb/engine.

[viven44]

So I gave it a shot. To be clear, my scale is -10, 0, +10, +20, +30, and no marks after +30.

After getting it up to temp, I turned off the engine, pulled the vac hose off the distributor, and plugged it. I turned the engine on and turned the distributor slowly clockwise until it was at +10. It sounded much better. I went to +12 and it sounded like I crossed the line, because it started to back towards sounding bad again.

RPMs were right around 750-800. I turned it off, tightened the dist nut, stuck the the vac hose back on the dist nipple and cranked it back up. It didn't sound good. I checked timing and it was reading +33 deg. Idle still looked good.

Also, the vac gauge was pushing 23-25in throughout the process.

I can't mess with it anymore tonight, but I'm wondering if I have a vacuum leak or something. I can almost hear a faint "hiss" with the vac adv hose connected, and it seems like it might get more pronounced when I disconnect and plug it. If it's not in my head, it sounds like it may be coming from the right side of the carb/engine.

I recall you mentioning that vacuum advance pot was adjusted by you all the way clockwise with an allen wrench...? I think the total advance being at 33" is too much at idle... just back that off some... initial + vacuum advance at idle should be ~20-25 (I THINK).

and the hissing sound is normal (if its what i think it is).. thats just the carburetor pulling air.. if you haven't heard that until now, that would be somewhat abnormal in my limited experience..

[Bullnose Gator]

I recall you mentioning that vacuum advance pot was adjusted by you all the way clockwise with an allen wrench...? I think the total advance being at 33" is too much at idle... just back that off some... initial + vacuum advance at idle should be ~20-25 (I THINK).

and the hissing sound is normal (if its what i think it is).. thats just the carburetor pulling air.. if you haven't heard that until now, that would be somewhat abnormal in my limited experience..

Well, there definitely was a vacuum leak. While I was packing up tools for the night I took a closer look around the engine and saw that one of the vac plugs on the manifold tree had popped off. Doh! I also noticed that a couple of the original vag plugs that were on that tree were also brittle and a little leaky. I replaced them all with new, snugger fitting plugs.

I also opened the vac adv "can" a few turns, as suggested. Then I went back through the process again, but the results were nearly the same, readings wise.

Eventually, I settled it in at +10 deg BTDC, vac gauge read 24in, vac adv dist can turned left 8 full turns, idle at approximately 700 rpm. When I put the vac hose back on the dist the idle went up to 1000, and the timing went to +30. So I adjusted the idle screw a touch to 750 rpms. The timing dropped to 28 deg.

I runs a lot better than before, but I honestly don't know what "perfect" or as close to it as this old engine can get would sound like. I took it for a drive and it definitely has noticeably more "pep" than before, and drove great. It has a little bit of "glug-a-lug" to it, but not much, and the carb certainly needs a little more adjusting, but isn't far off.

I'm going to go ahead and replace the carb with a holley or edelbrock 600-650 just to be able to tune the idle mixture screws easily, as they are NOT easy to get at and adjust on the 4180. I'm also going to replace the egr spacer gasket while I'm at it, to make sure there's no vacuum leak there, and maybe get/make a plate to block off the egr port, since the egr valve is just sitting there doing nothing anyway.

So how does 28 deg initial timing sound? Is that going to do any engine damage that high?

[Bullnose Gator]

Well, there definitely was a vacuum leak. While I was packing up tools for the night I took a closer look around the engine and saw that one of the vac plugs on the manifold tree had popped off. Doh! I also noticed that a couple of the original vag plugs that were on that tree were also brittle and a little leaky. I replaced them all with new, snugger fitting plugs.

I also opened the vac adv "can" a few turns, as suggested. Then I went back through the process again, but the results were nearly the same, readings wise.

Eventually, I settled it in at +10 deg BTDC, vac gauge read 24in, vac adv dist can turned left 8 full turns, idle at approximately 700 rpm. When I put the vac hose back on the dist the idle went up to 1000, and the timing went to +30. So I adjusted the idle screw a touch to 750 rpms. The timing dropped to 28 deg.

I runs a lot better than before, but I honestly don't know what "perfect" or as close to it as this old engine can get would sound like. I took it for a drive and it definitely has noticeably more "pep" than before, and drove great. It has a little bit of "glug-a-lug" to it, but not much, and the carb certainly needs a little more adjusting, but isn't far off.

I'm going to go ahead and replace the carb with a holley or edelbrock 600-650 just to be able to tune the idle mixture screws easily, as they are NOT easy to get at and adjust on the 4180. I'm also going to replace the egr spacer gasket while I'm at it, to make sure there's no vacuum leak there, and maybe get/make a plate to block off the egr port, since the egr valve is just sitting there doing nothing anyway.

So how does 28 deg initial timing sound? Is that going to do any engine damage that high?

After all the help yall gave me, just wanted to share that this weekend I drove the truck back to my hometown, over 2 hrs away. 70mph for the bulk of it, and it drove great there and back. I even pushed it up to 90mph for .00048 seconds, before getting scared I'd blow something up lol, and that wasn't even fully to the floor. Never thought it could go that fast.

But I changed the oil right before the trip, and the fresh, probably too light weight (5W-30), oil made my RMS leak worse. I also determined that there's a small exhaust leak around the passenger side exhaust manifold/pipe.

Looks like I'll have an enging yanking party in my future, but I'll save all those questions for another post. Just wanted to thank yall for all of your patience and help!

[viven44]

After all the help yall gave me, just wanted to share that this weekend I drove the truck back to my hometown, over 2 hrs away. 70mph for the bulk of it, and it drove great there and back. I even pushed it up to 90mph for .00048 seconds, before getting scared I'd blow something up lol, and that wasn't even fully to the floor. Never thought it could go that fast.

But I changed the oil right before the trip, and the fresh, probably too light weight (5W-30), oil made my RMS leak worse. I also determined that there's a small exhaust leak around the passenger side exhaust manifold/pipe.

Looks like I'll have an enging yanking party in my future, but I'll save all those questions for another post. Just wanted to thank yall for all of your patience and help!

Hey that's great news! What rear end ratio do you have ? Assuming 3.55.... at 4.1, I can't imaging going 70mph the whole way!!

And if that RMS leak isn't too bad, live with it!! 460s leaking would be more common than not... so much so that someone came up with an idea for a single piece rear main seal. I don't even know how that is installed or works.....

[Bullnose Gator]

Hey that's great news! What rear end ratio do you have ? Assuming 3.55.... at 4.1, I can't imaging going 70mph the whole way!!

And if that RMS leak isn't too bad, live with it!! 460s leaking would be more common than not... so much so that someone came up with an idea for a single piece rear main seal. I don't even know how that is installed or works.....

I'd have to check, but I think it actually is a 4.10. Are you saying driving a 4.10 at 70 is bad? Please don't tell me I just broke something else lol!

The leak is pretty bad right now, especially right after driving it while the engine is hot. It's leaving appetizer plate sized stains wherever I park it for more than 30 minutes.

 

[viven44]

I'd have to check, but I think it actually is a 4.10. Are you saying driving a 4.10 at 70 is bad? Please don't tell me I just broke something else lol!

The leak is pretty bad right now, especially right after driving it while the engine is hot. It's leaving appetizer plate sized stains wherever I park it for more than 30 minutes.

Not at all!! What RPMs were you spinning at 70mph ? 3500rpm ?

I'm one of those guys that likes things below 3K RPM. Just afraid something might come loose

Baseless fear is all!

If you are losing a quart of oil every 200 miles due to leaks, I'd say get that leak addressed. If that is a quart every 500, maybe its live able.

[ArdWrknTrk]

Not at all!! What RPMs were you spinning at 70mph ? 3500rpm ?

I'm one of those guys that likes things below 3K RPM. Just afraid something might come loose

Baseless fear is all!

If you are losing a quart of oil every 200 miles due to leaks, I'd say get that leak addressed. If that is a quart every 500, maybe its live able.

I have 4.10's in my truck and used to have a T-19, so 1:1 in 4th with a 31-32" stock tire.

Don't worry about going 70.... or 100.

You'll run out of cam long before you float the valves.

My truck sees 5,500 often enough.

I would definitely run thicker oil, but that 5W number is measured at 0° (32°F) it's the #30 that concerns you.

You might consider 15W40 diesel oil. It's cheaper in bulk and has more detergent because of the extremely long oil change intervals found in most diesel trucks.

Down where you live the higher initial viscosity shouldn't ever be a problem.

 

[Bullnose Gator]

I have 4.10's in my truck and used to have a T-19, so 1:1 in 4th with a 31-32" stock tire.

Don't worry about going 70.... or 100.

You'll run out of cam long before you float the valves.

My truck sees 5,500 often enough.

I would definitely run thicker oil, but that 5W number is measured at 0° (32°F) it's the #30 that concerns you.

You might consider 15W40 diesel oil. It's cheaper in bulk and has more detergent because of the extremely long oil change intervals found in most diesel trucks.

Down where you live the higher initial viscosity shouldn't ever be a problem.

I was planning on trying 15W-40, so glad to hear that. At 70 it was at about 3,200 rpms, with 33" tires. I think they are stock because the speedometer is accurate.