Notices
C3 Tech/Performance V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette

Timing Issue

 
Old 02-03-2019, 02:23 PM
  #1  
jeff42899
Junior Member
Thread Starter
 
jeff42899's Avatar
 
Member Since: Aug 2016
Location: Cleveland Ohio
Posts: 35
Thanked 1 Time in 1 Post
Default Timing Issue

I'm trying to get a new to me 1981 car running. It has a new 383 that the previous owner purchased and had installed. I've spoken to the engine builder and got all the specs on the motor. The shop is reputable and I really like the build. Unfortunately, it appears the previous owner really skimped on installing the engine. It runs, although very poorly, occasionally backfiring through the carb, especially when cold. I retarded the timing a little bit and the backfiring seems to have stopped. When I last had it running, I hit it with the timing light and the indicator wasn't anywhere near the notch in the dampener. Today I tried to start it and I can't get it to run. I bumped the engine over until the notch was near the indicator and pulled the distributor cap. The rotor is pointing exactly 180 from #1 wire. Anyone have some ideas? I think at this point I need to pull #1 plug, bump the engine until I get compression stroke and see where the rotor is at. That sound like a good place to start? Here are the rotor and timing marks. #1 is the first wire counterclockwise from the electronics plugs in the cap.




jeff42899 is offline  
Old 02-03-2019, 02:46 PM
  #2  
HeadsU.P.
CF Senior Member
 
HeadsU.P.'s Avatar
 
Member Since: Aug 2017
Location: Cool Northern Michigan
Posts: 2,001
Thanked 346 Times in 327 Posts
Default

If your timing mark refuses to show up within a reasonable distance of the timing cover point, perhaps you still have the Vac adv line hooked up.

As far as the rotor being 180* off, jog the key until the dampner mark comes around again. Now where is the rotor?

And holy crap. You have vacuum lines going everywhere. Where does the ported or timed vac line off of the metering block end up going?

But I like your intake, your carb, your valvecovers, your dizzy. Where is the fuel filter might I ask? Inside the junction with the fuel gauge?

Last edited by HeadsU.P.; 02-03-2019 at 03:27 PM.
HeadsU.P. is offline  
Old 02-03-2019, 03:06 PM
  #3  
jeff42899
Junior Member
Thread Starter
 
jeff42899's Avatar
 
Member Since: Aug 2016
Location: Cleveland Ohio
Posts: 35
Thanked 1 Time in 1 Post
Default

Originally Posted by HeadsU.P. View Post
If your timing mark refuses to show up within a reasonable distance of the timing cover point, perhaps you still have the Vac adv line hooked up.

As far as the rotor being 180* off, jog the key until the dampner mark comes around again. Now where is the rotor?

And holy crap. You have vacuum lines going everywhere. Where does the ported line off of the metering block end up going?

But I like your intake, your carb, your valvecovers, your dizzy. Where is the fuel filter might I ask? Inside the junction with the fuel gauge?
Must be in exhaust stroke. Duh. Vacuum lines are my next education. They are literally everywhere. Fuel filter is down by the pump. I'm going to verify tdc now and see where the rotor is pointing.
jeff42899 is offline  
Old 02-03-2019, 03:17 PM
  #4  
HeadsU.P.
CF Senior Member
 
HeadsU.P.'s Avatar
 
Member Since: Aug 2017
Location: Cool Northern Michigan
Posts: 2,001
Thanked 346 Times in 327 Posts
Default

You are close on the timing. No need to pull the dizzy. But you do need to pull the Vac on the dizzy and plug it off. If you have a dial-back light, shoot for about 34* BTDC. Then around 52* with Vac hooked up.

But before you do anything, double, triple check the firing order on the cap and follow the wire to the cylinder. Even 50 yr veterans have screwed this up once in a while.
HeadsU.P. is offline  
The Following User Says Thank You to HeadsU.P. For This Useful Post:
wadenelson (03-12-2019)
Old 02-03-2019, 03:17 PM
  #5  
stumpshot
CF Senior Member
 
Member Since: Sep 2011
Location: Humboldt county Ca
Posts: 398
Thanked 47 Times in 46 Posts
Default

Originally Posted by jeff42899 View Post
Must be in exhaust stroke. Duh. Vacuum lines are my next education. They are literally everywhere. Fuel filter is down by the pump. I'm going to verify tdc now and see where the rotor is pointing.
Pull the vac line at the distributor and plug it as suggested. Find TDC either on #1 or #6 and make sure the rotor is pointing at it. Worry about the vac lines once you get it to start and run. I'll look at my QFT and see which line is full vac to the distributor.

Last edited by stumpshot; 02-03-2019 at 03:17 PM.
stumpshot is offline  
Old 02-03-2019, 03:22 PM
  #6  
HeadsU.P.
CF Senior Member
 
HeadsU.P.'s Avatar
 
Member Since: Aug 2017
Location: Cool Northern Michigan
Posts: 2,001
Thanked 346 Times in 327 Posts
Default

Originally Posted by stumpshot View Post
Pull the vac line at the distributor and plug it as suggested. Find TDC either on #1 or #6 and make sure the rotor is pointing at it. Worry about the vac lines once you get it to start and run. I'll look at my QFT and see which line is full vac to the distributor.
It appears the dizzy is getting full Vac off of the front base of carb. Pick a hose, any hose. It goes somewhere.
I think QuickFuel has two Vac ports in the front, maybe?

Last edited by HeadsU.P.; 02-03-2019 at 03:25 PM.
HeadsU.P. is offline  
Old 02-03-2019, 03:35 PM
  #7  
stumpshot
CF Senior Member
 
Member Since: Sep 2011
Location: Humboldt county Ca
Posts: 398
Thanked 47 Times in 46 Posts
Default

Just chkd my QFT. Full vac is the outside , passanger side pipe. Inside is ported vac. Side pipe high on pass side is ported also.
Yes, check your wires. My dist starts with #1 being 2nd from the plug-in. Firing order:1,8,4,3,6,5,7,2. Driver bank plugs are 1 3 5 7, front to rear. Pass side: 2,4,6,8, front to rear.
stumpshot is offline  
Old 02-03-2019, 03:47 PM
  #8  
jeff42899
Junior Member
Thread Starter
 
jeff42899's Avatar
 
Member Since: Aug 2016
Location: Cleveland Ohio
Posts: 35
Thanked 1 Time in 1 Post
Default

Originally Posted by stumpshot View Post
Just chkd my QFT. Full vac is the outside , passanger side pipe. Inside is ported vac. Side pipe high on pass side is ported also.
Yes, check your wires. My dist starts with #1 being 2nd from the plug-in. Firing order:1,8,4,3,6,5,7,2. Driver bank plugs are 1 3 5 7, front to rear. Pass side: 2,4,6,8, front to rear.
Outside passenger goes to the distributor. I pulled it and plugged it. It appears at tdc the rotor points to the second plug like you state, #2, but I can't rotate it far enough to get it there before the vacuum hits the intake. I got it to run a little like that but no idle and puffing fuel out of the carb when it would die. I'm thinking I may move all the wires down one like yours is. Firing order is correct. I was hoping that was the issue.
jeff42899 is offline  
Old 02-03-2019, 03:49 PM
  #9  
HeadsU.P.
CF Senior Member
 
HeadsU.P.'s Avatar
 
Member Since: Aug 2017
Location: Cool Northern Michigan
Posts: 2,001
Thanked 346 Times in 327 Posts
Default

I have an aftermarket throttle / base plate under my Holley. It too has a ported and one full vac ports in the front. Plus the Holley has one on the metering block of course. Both ported or "timed" ports should be blocked off. It appears the O.P. has his timed vac line going to a wiper door or the HVAC or something? Depending on what yr this is? IDK
Transmission vac line is the steel line next to the dipstick.

Last edited by HeadsU.P.; 02-03-2019 at 05:24 PM.
HeadsU.P. is offline  
Old 02-03-2019, 04:36 PM
  #10  
stumpshot
CF Senior Member
 
Member Since: Sep 2011
Location: Humboldt county Ca
Posts: 398
Thanked 47 Times in 46 Posts
Default

Originally Posted by jeff42899 View Post
Outside passenger goes to the distributor. I pulled it and plugged it. It appears at tdc the rotor points to the second plug like you state, #2, but I can't rotate it far enough to get it there before the vacuum hits the intake. I got it to run a little like that but no idle and puffing fuel out of the carb when it would die. I'm thinking I may move all the wires down one like yours is. Firing order is correct. I was hoping that was the issue.
I would hop the wires around 1 slot as you said. Getting enough advance without hitting the manifold is a problem on these. You may need to pull all the wires to get the shortest/longest combo right unless all your wires are long.
You are on the right track! Take your time and check your plug wires twice. You are nearly there.

Last edited by stumpshot; 02-03-2019 at 04:37 PM.
stumpshot is offline  
Old 02-03-2019, 05:27 PM
  #11  
HeadsU.P.
CF Senior Member
 
HeadsU.P.'s Avatar
 
Member Since: Aug 2017
Location: Cool Northern Michigan
Posts: 2,001
Thanked 346 Times in 327 Posts
Default

"puffing fuel out the carb then it dies." Forget the timing. This is a whole new ballgame now.

You likely have a float sticking.
HeadsU.P. is offline  
Old 02-03-2019, 10:19 PM
  #12  
stumpshot
CF Senior Member
 
Member Since: Sep 2011
Location: Humboldt county Ca
Posts: 398
Thanked 47 Times in 46 Posts
Default


For what it's worth-- this is the orientation of my distributor. My #1 is the one with the boot pulled, 2nd clockwise from the plug-in. Not saying this is right but my 383 was set up by the builder and dynoed and the intake and dist were marked at 16. I've messed with the timing little but I always come back to the dyno marks. Runs best there.
stumpshot is offline  
Old 02-04-2019, 07:55 AM
  #13  
Jebbysan
CF Senior Member
 
Jebbysan's Avatar
 
Member Since: Mar 2012
Location: New Braunfels Texas
Posts: 3,077
Thanked 352 Times in 318 Posts
Default

Have buddy bump he engine over with your thumb on #1.....
When your thumb blows off.....that is around TDC #1.
See where your mark is.....if it is close.....use a breaker bar to turn the balancer bolt until you are closer or spot on.
Pull cap and see where the rotor is. Line it up exact then give it a slight nudge counter clockwise. Tighten distributor and start.
Use a dial back timing light to set total timing to 34-36 degrees or so......this number is different with different heads.
Don't worry about using a dial back light.......you do not have an ignition box, the number will be correct.
This needs to be done with vac advance disconnected. Once timed, hook it up to full manifold vacuum.
It should run good after this......if not......you have other problems.

Jebby
Jebbysan is offline  
The Following User Says Thank You to Jebbysan For This Useful Post:
lakerider57 (03-13-2019)
Old 03-11-2019, 08:11 PM
  #14  
jeff42899
Junior Member
Thread Starter
 
jeff42899's Avatar
 
Member Since: Aug 2016
Location: Cleveland Ohio
Posts: 35
Thanked 1 Time in 1 Post
Default

New developments on this. I figured I would start at the basics and changed the plugs. They looked terrible. I swapped them all out and the car started immediately. I unplugged and capped the vacuum line to the distributor and pulled out the timing light and the timing mark wasn't anywhere near the indicator. I advanced the timing light and at about 32 degrees the indicator lined up with the mark on the balancer. Does this make sense?
jeff42899 is offline  
Old 03-12-2019, 07:24 AM
  #15  
Jebbysan
CF Senior Member
 
Jebbysan's Avatar
 
Member Since: Mar 2012
Location: New Braunfels Texas
Posts: 3,077
Thanked 352 Times in 318 Posts
Default

Originally Posted by jeff42899 View Post
New developments on this. I figured I would start at the basics and changed the plugs. They looked terrible. I swapped them all out and the car started immediately. I unplugged and capped the vacuum line to the distributor and pulled out the timing light and the timing mark wasn't anywhere near the indicator. I advanced the timing light and at about 32 degrees the indicator lined up with the mark on the balancer. Does this make sense?
At what RPM? At 3000 it should be 34-36 degrees.....do not worry about idle timing unless it is some crazy number in the 20' or in the single digits.....

Jebby
Jebbysan is offline  
Old 03-12-2019, 07:43 AM
  #16  
jeff42899
Junior Member
Thread Starter
 
jeff42899's Avatar
 
Member Since: Aug 2016
Location: Cleveland Ohio
Posts: 35
Thanked 1 Time in 1 Post
Default

It's 32 degrees at idle. If it matters, it's a 383 with Scat internals, Dart Pro 1 200cc heads, Comp Cams 12-422-8 Duration 270/276, Lift .495/.502, Dart intake and QFT 750.
jeff42899 is offline  
Old 03-12-2019, 07:54 AM
  #17  
Jebbysan
CF Senior Member
 
Jebbysan's Avatar
 
Member Since: Mar 2012
Location: New Braunfels Texas
Posts: 3,077
Thanked 352 Times in 318 Posts
Default

Originally Posted by jeff42899 View Post
It's 32 degrees at idle. If it matters, it's a 383 with Scat internals, Dart Pro 1 200cc heads, Comp Cams 12-422-8 Duration 270/276, Lift .495/.502, Dart intake and QFT 750.
With vacuum advanced unplugged that is way too much....should be like 14-18 idle and 34-36 at 3000 rpm....the idle timing is no where near as important as the total timing....

Jebby
Jebbysan is offline  
Old 03-12-2019, 08:51 AM
  #18  
Bikespace
CF Senior Member
 
Bikespace's Avatar
 
Member Since: Mar 2017
Location: Vienna VA
Posts: 1,426
Thanked 222 Times in 207 Posts
Default

If you haven't already, email Lars and ask for his timing papers. Is your distributor timing fixed (no mechanical advance)? Perhaps your advance springs are missing. Do you get any additional advance at higher RPMs?
Bikespace is offline  
Old 03-12-2019, 10:24 AM
  #19  
jeff42899
Junior Member
Thread Starter
 
jeff42899's Avatar
 
Member Since: Aug 2016
Location: Cleveland Ohio
Posts: 35
Thanked 1 Time in 1 Post
Default

Originally Posted by Bikespace View Post
If you haven't already, email Lars and ask for his timing papers. Is your distributor timing fixed (no mechanical advance)? Perhaps your advance springs are missing. Do you get any additional advance at higher RPMs?
I have not emailed but I will. Thank you! I do get additional advance with increased RPM, so there must be a mechanical advance and springs, but that's a great place to look to see exactly what I have. The idle and throttle response were good without any backfiring, which I found strange at this high advance. Prior to the plug change I was getting a lot of backfiring through the carb, which is why I assumed I had a timing issue. I think tonight I will try to retard it down to 12-15 and see what it does. The plugs I removed were completely black and gapped a little higher (.050) than the ones I installed (.035). Here's the motor while being built.








jeff42899 is offline  
Old 03-12-2019, 10:27 AM
  #20  
Jebbysan
CF Senior Member
 
Jebbysan's Avatar
 
Member Since: Mar 2012
Location: New Braunfels Texas
Posts: 3,077
Thanked 352 Times in 318 Posts
Default

383 with Dart 180's and that cam will should be a mega torque beast......tire smoker.
Those heads with the fast burn chamber only want about 32-33 degrees total timing FYI.

Jebby

Last edited by Jebbysan; 03-12-2019 at 10:28 AM.
Jebbysan is offline  
The Following User Says Thank You to Jebbysan For This Useful Post:
jeff42899 (03-12-2019)

Thread Tools
Search this Thread
Quick Reply: Timing Issue


Sponsored Ads
Vendor Directory

Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: