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Username Post: Timing issues        (Topic#348923)
65_Impala 
Very Senior Member
Posts: 3928

Reg: 12-29-02
01-02-18 12:34 PM - Post#2719788    
    In response to malibu27

The PCV valve sucking that much oil would tell me you didn't have proper oil baffling for the valve.



 




malibu27 
Forum Newbie
Posts: 61
malibu27
Loc: Harrisonburg
Reg: 03-15-15
01-02-18 03:24 PM - Post#2719805    
    In response to 65_Impala

  • 65_Impala Said:
The PCV valve sucking that much oil would tell me you didn't have proper oil baffling for the valve.



The valve covers I have do have baffling. Don't know if it's the correct kind of baffling.

So I did the vac advance modification today just like the instructions said. I put the stop at .110 to give me 10 degrees of vac advance. Hooked it up to full manifold vac. I had 20* BTDC at idle. Took the truck for a drive and it's back to pinging at part throttle.

'83 chevy K20, 383, Scat Crank, Comp Cams 08-408-8, Etec 170's, sm465
'97 chevy 1500 Silverado, 350, 4L60E


 
65_Impala 
Very Senior Member
Posts: 3928

Reg: 12-29-02
01-02-18 03:33 PM - Post#2719807    
    In response to malibu27

Only having 10* of vacuum advance doesn't mean it will work. The vacuum where it is added matters too. I've also setup many engines with more than 10* of vacuum advance that worked fine.

Got a vacuum hand pump? Test the vacuum advance to see what vacuum it starts moving and what vacuum it's at full travel.





 
IgnitionMan 
Valued Contributor
Posts: 3220

Reg: 04-15-05
01-02-18 04:14 PM - Post#2719811    
    In response to 65_Impala

Is this one of the stock vacuum advances, or an adjustable like a Crane?? If stock, the actual vacuum rating of the advance could be a problem if it were too soft. If it is a stock vac adv, please post which numbers/letters are stamped on the mounting plate. I can ID it for vacuum/application.

There are only about 20 stock replacement vacuum advances for each, point and HEI distributors, all have different springs in them, to work with different vacuum ratings. And, different vacuum pulls use different actuation speeds to match the spring set inside them.

As far as the baffle to the PC valve, there is NO reason the baffle would control any PC valve function regarding vacuum, that is in the valve itself, in both the orifice size and spring loading, NOT THE BAFFLE. The baffle separates oils out of the air/oil mix, and allows the oil to flow back into the engine. To make the baffle hold oil to be sucked into the valve, it would have to be filled with oil, and act as a pool for the valve to pull into the valve and line.

Since you had the baffle, I'd have to say it is that there is NO free air allowed into the engine, as I outlined previously, NOT THE BAFFLE.

For the extreme simpleton that posted above, think of it as two straws in a soda cup, both at the top of the cup, closed to the cup, but open on their ends. Neither goes down into the soda. One is suction, one is vacuum. Now, when suction is added to one of the straws, air passes into the cup, aerates with the soda, passes through the baffle, where the main part of the soda is separated from the mix, and dropped back into the cup, and the vapor and air passes to the suction device, and is enjoyed by the sucker.

Now, do the same, but, close off the open air inlet to the straw, and suck as hard as you can, what you get is a lot more liquid soda, not allowed to separate in the baffle, and sucked into the sucker person.

Welcome to PCV-101.

I've said this before about the above poster, and I will say it yet again, I steadfastly refuse to engage in a battle of wits with a completely and totally unarmed person.



 
65_Impala 
Very Senior Member
Posts: 3928

Reg: 12-29-02
01-02-18 06:03 PM - Post#2719825    
    In response to IgnitionMan

Show us a picture of the baffle or at least a link to the valve cover that shows it.

Piss poor baffling is the only reason the PVC will suck the amount of oil you're saying it does. Just compare the little flat piece of tin on some aftermarket covers (ones that actually have one) vs the big baffle in stock GM covers and then still try to claim that aftermarket baffle works as well. You can fix the other cover to add a fresh air inlet, but it'll still be sucking oil from the improper baffle.

Hell, I remember plugging the fresh air inlet as a common simple fix on the old fox body Mustangs. Those EFI Winsor engines sucked oil badly enough many other people would remove the PVC and atmosphere vent the things to avoid the oil buildup in the intake.

The issue you'll most likely have without the fresh air inlet is not properly getting the gases out so the engine builds up gunk. Similar problems happen with simple valve cover vents. Remember the old GM road draft tubes that would actually suck the fumes out of the engine once driving down the road? It was an early fix to keep the engine vented before PCV systems.

I have no idea how no air inlet would make oil flow up...



 
IgnitionMan 
Valued Contributor
Posts: 3220

Reg: 04-15-05
01-02-18 09:31 PM - Post#2719845    
    In response to malibu27

Malibu, let me know, OFF BOARD, if I can help get you dialed in with the right advance can.

Until then, you might take a serration out of the vacuum stop, test, go again until the pinging stops.

In those 20 or so stock vacuum cans, are 20 or so differently set vacuum pull rates, all different. The Crane adjustable can has all 20 settings, and every one in between.

Crane is the only adjustable with the best, widest adjustment spread.

As I asked, what is on the advance mounting bar, please? Stock GM will have three sets of numbers, aftermarket stock replacements would use a letter-number code, like for the large coil in cap HEI, A-1, A-2, A-3, etc. Points cans use a first letter of B, B-1, B-2, etc.



 
models916 
Valued Contributor
Posts: 4701

Age: 66
Loc: Addison, IL
Reg: 05-28-10
01-03-18 05:01 AM - Post#2719858    
    In response to IgnitionMan

Grinding the weights and stiffening the springs will give you LESS or SLOWER advance. Vacuum advance only works at high vacuum like idle or part throttle at speed. When you nail the gas pedal, you turn off the vacuum advance.



 
malibu27 
Forum Newbie
Posts: 61
malibu27
Loc: Harrisonburg
Reg: 03-15-15
01-03-18 03:55 PM - Post#2719905    
    In response to models916

  • models916 Said:
Grinding the weights and stiffening the springs will give you LESS or SLOWER advance. Vacuum advance only works at high vacuum like idle or part throttle at speed. When you nail the gas pedal, you turn off the vacuum advance.



So if I remember right I actually did the grinding on the center metal piece, not the weights. I had never done it before and I was just experimenting. It seemed to work pretty good though.

At idle and WOT the truck is fine, no pinging. It's only at part throttle, 10-15 inches of vacuum that it pings.

'83 chevy K20, 383, Scat Crank, Comp Cams 08-408-8, Etec 170's, sm465
'97 chevy 1500 Silverado, 350, 4L60E


 
malibu27 
Forum Newbie
Posts: 61
malibu27
Loc: Harrisonburg
Reg: 03-15-15
01-03-18 04:00 PM - Post#2719907    
    In response to IgnitionMan

  • IgnitionMan Said:
Malibu, let me know, OFF BOARD, if I can help get you dialed in with the right advance can.

Until then, you might take a serration out of the vacuum stop, test, go again until the pinging stops.

In those 20 or so stock vacuum cans, are 20 or so differently set vacuum pull rates, all different. The Crane adjustable can has all 20 settings, and every one in between.

Crane is the only adjustable with the best, widest adjustment spread.

As I asked, what is on the advance mounting bar, please? Stock GM will have three sets of numbers, aftermarket stock replacements would use a letter-number code, like for the large coil in cap HEI, A-1, A-2, A-3, etc. Points cans use a first letter of B, B-1, B-2, etc.



Honestly, do I need vacuum advance at all. This is a weekend wood hauling, trailer pulling, fun having truck. Not a daily driver. I'm kind of tired of messing with the d@%! vacuum advance and PCV valve.

Here is a link to the valve covers I have. The pictures don't show the baffles but they do have them.
https://www.summitracing.com/parts/sum-440402



'83 chevy K20, 383, Scat Crank, Comp Cams 08-408-8, Etec 170's, sm465
'97 chevy 1500 Silverado, 350, 4L60E


 
65_Impala 
Very Senior Member
Posts: 3928

Reg: 12-29-02
01-03-18 08:50 PM - Post#2719937    
    In response to malibu27

No, you do not require the vacuum advance. It does help with keeping the plugs clean and with fuel economy but the engine will work just fine without it.

Did you verify the canister that came on the distributor isn't adjustable? If it happens to be, you should be able to fix it with a few turns of a hex wrench.

I can see there is something blocking the hole of the valve cover, but no indication of what it looks like on the back side. It does appear the plate is fairly close to the hole so the valve might be close to touching it when it's installed. If the plate shape and position allows the rockers/valvetrain to throw oil up onto the top of it, then some of that oil will easily be picked up as it flows around/past the end of the valve.





 
malibu27 
Forum Newbie
Posts: 61
malibu27
Loc: Harrisonburg
Reg: 03-15-15
01-04-18 03:05 PM - Post#2720013    
    In response to 65_Impala

  • 65_Impala Said:
No, you do not require the vacuum advance. It does help with keeping the plugs clean and with fuel economy but the engine will work just fine without it.

Did you verify the canister that came on the distributor isn't adjustable? If it happens to be, you should be able to fix it with a few turns of a hex wrench.

I can see there is something blocking the hole of the valve cover, but no indication of what it looks like on the back side. It does appear the plate is fairly close to the hole so the valve might be close to touching it when it's installed. If the plate shape and position allows the rockers/valvetrain to throw oil up onto the top of it, then some of that oil will easily be picked up as it flows around/past the end of the valve.





I'm petty sure the vac advance canister is adjustable because when i look down the hole it looks like there is a tiny Allen head in there. What does turning it do?

I'll pop a valve cover off and snap a picture of the baffle.


'83 chevy K20, 383, Scat Crank, Comp Cams 08-408-8, Etec 170's, sm465
'97 chevy 1500 Silverado, 350, 4L60E


 
65_Impala 
Very Senior Member
Posts: 3928

Reg: 12-29-02
01-04-18 04:10 PM - Post#2720024    
    In response to malibu27

The simple answer is to turn the screw counter clockwise one turn at a time and see if it helps.

Turning it counterclockwise makes it require more vacuum to pull in and advance the timing. So, adjusting it will cut back the total timing at part throttle when you are getting pinging.

Being a China distributor, there may be no info available specifically for that canister. But, it is possible that if you turn the screw too far counter clockwise that you can unscrew the adjuster out of the threads. Just saying to not go too crazy turning it.

If you want to try and avoid unscrewing the adjuster then first turn it clockwise till it bottoms while counting the turns. The, turn it back counterclockwise until it's back where it was. After that, don't turn it a total of more than about 10 turns counterclockwise from the bottomed out position. That should be safe enough to avoid unscrewing the adjuster. For example, if it started out 3 turns from bottoming out then don't turn it more than 7 turns further counterclockwise.

If you wanted to get really fancy, then you could also adjust it using a vacuum pump. But, it's not necessary to do it that way. You just need to be willing to go for a drive after each adjustment.

If adjusting it doesn't make a difference, then I'd change to a name brand adjustable canister.



 
malibu27 
Forum Newbie
Posts: 61
malibu27
Loc: Harrisonburg
Reg: 03-15-15
01-09-18 04:23 PM - Post#2720601    
    In response to 65_Impala

So i unhooked the vac advance again. I also installed the 50cc accelerator pump with the biggest nozzle holley offers which is a 50. Its still going lean when i hammer it and I'm under 2000rpms. If I'm over 2000rpms it does fine. Anyway to get more fuel at lower rpm?

'83 chevy K20, 383, Scat Crank, Comp Cams 08-408-8, Etec 170's, sm465
'97 chevy 1500 Silverado, 350, 4L60E


 
models916 
Valued Contributor
Posts: 4701

Age: 66
Loc: Addison, IL
Reg: 05-28-10
01-10-18 05:37 AM - Post#2720663    
    In response to malibu27

Holley power valve may not be operating correctly or be of the wrong vacuum setting and holding on to the lean stage too long. Cheap and easy to change out, available in a number of vacuum setting and just screw into the mid plate in front.



 
malibu27 
Forum Newbie
Posts: 61
malibu27
Loc: Harrisonburg
Reg: 03-15-15
01-10-18 06:20 AM - Post#2720667    
    In response to models916

I've got the 10.5 power valve and it is working because i can see it open up on my afr gauge. I'm tempted to change to bigger mains but it cruises perfectly at 14 on the afr gauge.

'83 chevy K20, 383, Scat Crank, Comp Cams 08-408-8, Etec 170's, sm465
'97 chevy 1500 Silverado, 350, 4L60E


 
models916 
Valued Contributor
Posts: 4701

Age: 66
Loc: Addison, IL
Reg: 05-28-10
01-10-18 06:29 AM - Post#2720668    
    In response to malibu27

Almost everything I have tuned on in the street hot rod range has gotten a 6.5. Worth a try?




 




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