Gain extra benefits by becoming a Supporting Member Click here find out how!
Classic Performance Products Classic Parts
Ciadella InteriorsAmerican Auto Wire Classic Industries
Chevs of the 40sDanchuk Catalog
Hellwig Products IncPerformance Rod & CustomEcklers AutoMotive
Nu-Relics Power WindowsRain Gear Wiper Systems
Impala Bob's Bob's Chevy Trucks Bob's Chevelle Parts Bob's Classic Chevy



 Page 2 of 2 <12
Username Post: Timing issues        (Topic#348923)
65_Impala 
Very Senior Member
Posts: 4021

Reg: 12-29-02
01-02-18 01:34 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: 66
malibu27
Loc: Harrisonburg
Reg: 03-15-15
01-02-18 04:24 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: 4021

Reg: 12-29-02
01-02-18 04:33 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: 3361

Reg: 04-15-05
01-02-18 05:14 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: 4021

Reg: 12-29-02
01-02-18 07:03 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: 3361

Reg: 04-15-05
01-02-18 10:31 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: 4781

Age: 67
Loc: Addison, IL
Reg: 05-28-10
01-03-18 06:01 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: 66
malibu27
Loc: Harrisonburg
Reg: 03-15-15
01-03-18 04:55 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: 66
malibu27
Loc: Harrisonburg
Reg: 03-15-15
01-03-18 05:00 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: 4021

Reg: 12-29-02
01-03-18 09:50 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: 66
malibu27
Loc: Harrisonburg
Reg: 03-15-15
01-04-18 04:05 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: 4021

Reg: 12-29-02
01-04-18 05:10 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: 66
malibu27
Loc: Harrisonburg
Reg: 03-15-15
01-09-18 05:23 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: 4781

Age: 67
Loc: Addison, IL
Reg: 05-28-10
01-10-18 06:37 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: 66
malibu27
Loc: Harrisonburg
Reg: 03-15-15
01-10-18 07:20 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: 4781

Age: 67
Loc: Addison, IL
Reg: 05-28-10
01-10-18 07:29 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?




 
malibu27 
Forum Newbie
Posts: 66
malibu27
Loc: Harrisonburg
Reg: 03-15-15
02-16-18 06:34 PM - Post#2724634    
    In response to models916

So I just wanted to update this thread by saying I switched over to Holley Sniper EFI with their Dual sync distributor and my truck has never run better. I picked up 50 horsepower and no more spark knocking. I have complete control over my fuel and spark curves now. Should have done it sooner. I will never waste time with a carb and mechanical HEI distributor again.

'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: 4021

Reg: 12-29-02
02-17-18 08:44 AM - Post#2724677    
    In response to malibu27

Good to hear. What you said about never going back is what almost every person who was willing to make the switch to EFI says. Not only will I only run EFI, I also will also only run electronically controlled automatics in any vehicles that will get an automatic.



 
IgnitionMan 
Valued Contributor
Posts: 3361

Reg: 04-15-05
02-17-18 09:14 AM - Post#2724679    
    In response to malibu27

You did the right thing going to the Holley system. I see people go through total hell in trying to get other systems dialed in, when the Holley EFI just plain works.

I am biased, though, I worked at Holley on Pro-Stock carbs for a few years. Their EFI department and techs are the best of the best, bar none.



 
malibu27 
Forum Newbie
Posts: 66
malibu27
Loc: Harrisonburg
Reg: 03-15-15
02-17-18 07:39 PM - Post#2724722    
    In response to IgnitionMan

Yes I thought about getting the Fitech but some of the reviews were bad and the Holley wasn't but another $100 or so. Plus the dual sync allows timing control. I don't think the fitech has timing control and that was a deal breaker for me. Why spend all that money on the fuel side and still have 30 year old timing technology?

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


 
IgnitionMan 
Valued Contributor
Posts: 3361

Reg: 04-15-05
02-18-18 09:18 AM - Post#2724750    
    In response to malibu27

You are right, today's EFI does need to also fully control the timing parameters as well as the fuel curves.

Carbureted engine, 30 years old timing methods, they work well, but not for sophisticated fuel injection.

I speak with more people really unhappy with their FiTech systems than all others combined. Just shows that over hype advertizing works, in the beginning, but the real story does eventually come about.



 
CNC BLOCKS N/E 
Senior Member
Posts: 974
CNC BLOCKS N/E
Loc: NORTH EAST
Reg: 12-12-03
02-18-18 01:06 PM - Post#2724778    
    In response to malibu27

  • malibu27 Said:
  • Shepherd Said:
With a set back timing lite you can check the advance curve at any point. If the heads are steel, 10.5 compression is tough to control detonation unless you have an aggressive cam.



I do have a set back timing light. I'll check the advance throughout the curve. The heads are aluminum.



Should not be using a dial back timing lite with MSD unless your using the MSD timing light or the French Grimmes lite.

https://www.chevytalk.org/fusionbb/showtopic.php?ti...






 
malibu27 
Forum Newbie
Posts: 66
malibu27
Loc: Harrisonburg
Reg: 03-15-15
02-18-18 06:54 PM - Post#2724808    
    In response to CNC BLOCKS N/E

Thanks but I don't need a timing light at all anymore. Sheeesh

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


 
IgnitionMan 
Valued Contributor
Posts: 3361

Reg: 04-15-05
02-19-18 01:45 AM - Post#2724828    
    In response to malibu27

I beg to differ, you do still need the light to set the firing reference point for the computer, and to check the curve the computer has, to reset the timing parameters in it as you adjust them.

This is one instance where a dial back light is beneficial.





 
0utlaw 
Very Senior Member
Posts: 2789
0utlaw
Loc: US East Coast
Reg: 09-10-02
02-19-18 03:55 AM - Post#2724837    
    In response to malibu27

I've read that MOST old school hi performance STREET ignitions need to have SOME vacuum advance...for cruising and gas mileage.(Not talking about a radical racecar driven on the street)
Vacuum advance should be called vacuum retard...when you step on the gas, vacuum goes nearer to zero and your spark retards to protect your motor. And it helps your motor to run COOLER. But, light throttle knock that you loose with the vacuum disconected is a good sign that you either need to adjust your can (adjustable can) or rework the vacuum advance so it advances LESS.

I have a similar setup on medium springs and I set my timing on 34 degrees at 3000 rpm. I, then installed a vacuum advance that I reworked to move about half-way. (I did this by spot welding a piece of steel to limit the travel on the bench.) Easy to do.
Basically experimenting...no scientific data to support.
So far...
No pinging or knock at all on high test and very responsive.



 
IgnitionMan 
Valued Contributor
Posts: 3361

Reg: 04-15-05
02-19-18 09:41 AM - Post#2724859    
    In response to 0utlaw

Actually, Ford got it right in naming 'vacuum advance', they called it a "load compensator device".

The points Outlaw made are right on target.



 
65_Impala 
Very Senior Member
Posts: 4021

Reg: 12-29-02
02-20-18 08:20 AM - Post#2724980    
    In response to CNC BLOCKS N/E

Good point on the MSD since the dual sync distributor needs an ignition box so there is most likely a multiple spark discharge box in use here.


Claims about computer controls and dial back lights are such a joke though. Any time a single spark worth of energy travels down a spark plug wire to the plug it is EXACTLY THE SAME between a computer controlled distributor/coil and a non-computer controlled distributor/coil. An inductive pickup put AROUND the plug wire will pick up the energy from EITHER type the EXACT SAME WAY. The inductive pickup has no clue what upstream controls are triggering the coil and causing that spark to be travelling down the wire.

If certain dial back lights don't work with a single spark ignition it's because the delay circuit in the light is JUNK, not because it's not being used on a computer controlled ignition. Same reason certain lights not working with a multiple spark CD ignition box - bad/wrong electronics inside for the application.







 
malibu27 
Forum Newbie
Posts: 66
malibu27
Loc: Harrisonburg
Reg: 03-15-15
02-25-18 02:28 PM - Post#2725558    
    In response to IgnitionMan

  • IgnitionMan Said:
I beg to differ, you do still need the light to set the firing reference point for the computer, and to check the curve the computer has, to reset the timing parameters in it as you adjust them.

This is one instance where a dial back light is beneficial.







Yes, i did use my timing light to do that. I don't need it anymore though.


'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: 66
malibu27
Loc: Harrisonburg
Reg: 03-15-15
02-25-18 02:41 PM - Post#2725562    
    In response to 0utlaw

  • 0utlaw Said:
I've read that MOST old school hi performance STREET ignitions need to have SOME vacuum advance...for cruising and gas mileage.(Not talking about a radical racecar driven on the street)
Vacuum advance should be called vacuum retard...when you step on the gas, vacuum goes nearer to zero and your spark retards to protect your motor. And it helps your motor to run COOLER. But, light throttle knock that you loose with the vacuum disconected is a good sign that you either need to adjust your can (adjustable can) or rework the vacuum advance so it advances LESS.

I have a similar setup on medium springs and I set my timing on 34 degrees at 3000 rpm. I, then installed a vacuum advance that I reworked to move about half-way. (I did this by spot welding a piece of steel to limit the travel on the bench.) Easy to do.
Basically experimenting...no scientific data to support.
So far...
No pinging or knock at all on high test and very responsive.



That's why i switched to efi and digitally controlled timing. No more experimenting. I can set my timing to whatever i want it at any rpm and any manifold air pressure. Right now i basically have 18* initial timing. 36* WOT timing. 44* cruising. With a few adjustments in the low rpm and high manifold air pressure range. Obviously all those blend together making a nice smooth graph. I love it! So much easier

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


 
Shepherd 
Frequent Contributor
Posts: 1335

Loc: Lake George, NY
Reg: 11-11-15
02-25-18 03:20 PM - Post#2725571    
    In response to 65_Impala

Actrons set back lite doesn't work with MSD.



 




 Page 2 of 2 <12
Icon Legend Permissions Topic Options
Report Post

Quote Post

Quick Reply

Print Topic

Email Topic

2129 Views
FusionBB
FusionBB™ Version 2.1
©2003-2006 InteractivePHP, Inc.
Execution time: 0.373 seconds.   Total Queries: 13   Zlib Compression is on.
All times are (GMT -0800) Pacific. Current time is 03:58 PM
Top