Distributor / timing. Still running good. - Chevelle Tech
Troubleshooting Diagnosing problems done here.

 2Likes
  • 1 Post By Monkey
  • 1 Post By lucifershammer
 
LinkBack Thread Tools Search this Thread Display Modes
post #1 of 11 (permalink) Old Jun 29th, 20, 2:53 PM Thread Starter
 
Join Date: May 2020
Posts: 4
Angry Distributor / timing. Still running good.

Thanks for any help in advance.

I just bought a 1970 Chevelle with a 454 in it. The engine maybe has 100 miles on it. I took it to a shop for some brake work and to have an external vacuum pump installed because the car had no vacuum at idle.
The shop told me my timing is way off and that it should be between 15-30 degrees at TDC. I spoke with the engine builder and he said the cam was set to 0 when he installed it so it is not advanced. The car is running great and sounds great but the shop who checked the timing said the distributor is set at 56 degrees? They said the car would die if they tried to set the timing to where it should normally be.
Not sure if I should just leave it alone since its running good or make sure its corrected. Anyone with any clues as to why this is happening?
Timothy T Nichols is offline  
Sponsored Links
Advertisement
 
post #2 of 11 (permalink) Old Jun 29th, 20, 3:01 PM
Senior Tech Team
Steve
 
Join Date: Sep 2015
Location: Central MA
Posts: 1,612
Re: Distributor / timing. Still running good.

I'll ask some possibly silly questions...

How good is the shop? Are they used to working on older cars?

Where did they connect the timing light pickup to? If they connected it at the distributor where the number 1 cylinder spark plug wire is supposed to be, did they check that it actually goes to the number 1 cylinder?

If the distributor wires are off by one on the cap, they could have connected to the wrong cylinder spark plug wire, and what they are seeing is the previous cylinder firing and the mark on the balancer is showing way off.

Each wire is 45 degrees apart - so if your timing was at 11 degrees advanced, and they connected to the previous cylinder, you would see timing at 56 degrees advanced when that cylinder fires.

BTW - this is probably not the problem, but it has happened in the past (I've watched it happen live. )

Quote:
Originally Posted by Timothy T Nichols View Post
Thanks for any help in advance.

I just bought a 1970 Chevelle with a 454 in it. The engine maybe has 100 miles on it. I took it to a shop for some brake work and to have an external vacuum pump installed because the car had no vacuum at idle.
The shop told me my timing is way off and that it should be between 15-30 degrees at TDC. I spoke with the engine builder and he said the cam was set to 0 when he installed it so it is not advanced. The car is running great and sounds great but the shop who checked the timing said the distributor is set at 56 degrees? They said the car would die if they tried to set the timing to where it should normally be.
Not sure if I should just leave it alone since its running good or make sure its corrected. Anyone with any clues as to why this is happening?

1972 Chevelle, 454, 200-4r non-lockup, 12 bolt 3.73
1981 Camaro Z28, 355, TH350, 3.73
lucifershammer is online now  
post #3 of 11 (permalink) Old Jun 29th, 20, 3:15 PM Thread Starter
 
Join Date: May 2020
Posts: 4
Re: Distributor / timing. Still running good.

The shop is not bad actually. They do some work on classic cars but their specialty is BMW / Mercedes. I am having a hard time finding a good hot rod shop near my house where I live.

I have no idea where they connected the light. Unfortunately I was not there when this was done.
Timothy T Nichols is offline  
 
post #4 of 11 (permalink) Old Jun 30th, 20, 11:18 AM
Tech Team
Rhys
 
Join Date: Dec 2009
Location: Australia - Chicago
Posts: 82
Re: Distributor / timing. Still running good.

Make sure the balancer hasn't spun.
lucifershammer likes this.

Not smart enough to think of something funny.
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Monkey is offline  
post #5 of 11 (permalink) Old Jun 30th, 20, 11:38 AM
Senior Tech Team
 
Join Date: Apr 2012
Location: Yerington, Nevada
Posts: 2,270
Re: Distributor / timing. Still running good.

With that much timing in the engine, I'd figure the cam was back a tooth, engines that have cams retarded a tooth like loads of timing right from the start, and usually have very soft low end performance, with acceptable high rpm operation.

Any idea what compression ratio, lifter type, advertized overall cam duration, duration at .050, and what degree does the intake valve close at (do not need lift or other cam specs)?

What are your ignition specs, initial, idle, vacuum advance degrees (let me guess, there either isn't a vacuum advance, or it isn't connected, sounds like there isn't enough vacuum to run one anyway), and total timing (you say it is 56 degrees)?
Dave Ray is offline  
post #6 of 11 (permalink) Old Jun 30th, 20, 3:52 PM
Lifetime Premium Member
 
Join Date: Jul 2000
Location: Northeast New Jersey
Posts: 8,342
Garage
Re: Distributor / timing. Still running good.

It could be since they are mostly working with imports and BMW's that they aren't sure where to measure the vacuum.For any engine to be running at an idle and show 0 on the gauge would lead me to look for another place to measure vacuum.Its impossible to run an engine at idle with 0 vacuum.
4 to 10 inches of vacuum I could believe but zero ??? at idle ??? exactly where did they take that vacuum reading ?
If that shop hooked their gauge to a ported vacuum fitting it would show zero at idle and then as you gave it some RPM would then start to show vacuum readings.This is normal and probably what they did if they hooked up to the wrong fitting.
I wouldn't allow them to do any work on the engine if they don't see the mistake they made.

John
71 El Camino SS
406 SBC M21 3.31 12 bolt
"Quality is always remembered,long after the price is forgotten"
"I would rather have questions I can't answer than have answers I can't question" :R.Feynman
71350SS is offline  
post #7 of 11 (permalink) Old Jun 30th, 20, 4:29 PM Thread Starter
 
Join Date: May 2020
Posts: 4
Re: Distributor / timing. Still running good.

I called the shop and they let me know that at idle I had maybe 5 inches of vacuum at idle which is why I had the vacuum pump installed.
Timothy T Nichols is offline  
post #8 of 11 (permalink) Old Jun 30th, 20, 4:33 PM Thread Starter
 
Join Date: May 2020
Posts: 4
Re: Distributor / timing. Still running good.

Quote:
Originally Posted by Dave Ray View Post
With that much timing in the engine, I'd figure the cam was back a tooth, engines that have cams retarded a tooth like loads of timing right from the start, and usually have very soft low end performance, with acceptable high rpm operation.

Any idea what compression ratio, lifter type, advertized overall cam duration, duration at .050, and what degree does the intake valve close at (do not need lift or other cam specs)?

What are your ignition specs, initial, idle, vacuum advance degrees (let me guess, there either isn't a vacuum advance, or it isn't connected, sounds like there isn't enough vacuum to run one anyway), and total timing (you say it is 56 degrees)?
Cam specs Below

Engine Family:Chevrolet 396-454 c.i. 8 Cylinder (1967-1996)
RPM Operating Range:2,500-6,500
Grind Number:292H-10
Cam Type:Hydraulic Flat Tappet
Lifter Style:Hydraulic Flat Tappet
Camshaft Series:Magnum
Camshaft Gear Attachment:3-Bolt
Usage:Street/Strip
Valve Springs Required:Yes
Camshaft Material:Cast Iron
California Proposition 65:WARNING: Cancer and Reproductive Harm P65Warnings.ca.gov
Advertised Intake Duration:292
Advertised Exhaust Duration:292
Intake Duration at .050 Inch Lift:224
Exhaust Duration at .050 Inch Lift:224
Intake Valve Lift:0.55
Exhaust Valve Lift:0.55
Lobe Lift Intake:0.323
Lobe Lift Exhaust:0.323
Lobe Separation:110
Intake Centerline:106
Assembly Lubricant Included:Yes
Timothy T Nichols is offline  
post #9 of 11 (permalink) Old Jun 30th, 20, 5:03 PM
Lifetime Premium Member
 
Join Date: Jul 2000
Location: Northeast New Jersey
Posts: 8,342
Garage
Re: Distributor / timing. Still running good.

Quote:
Originally Posted by Timothy T Nichols View Post
I called the shop and they let me know that at idle I had maybe 5 inches of vacuum at idle which is why I had the vacuum pump installed.
Ok I can see it having 5" at idle.
After first marking the dist. so they can return it to where you felt it was running good.They should then check timing with vacuum hose to dist.unplugged and then try advancing the timing about 10 degrees at first.That should cause the idle RPM to increase and then after re-connecting the dist vac hose,they should lower the idle speed to around 850-950 in park/neutral & 700-750 in gear.
Then take it for a ride and see what they/you think how it runs.It should run better with the timing increased.As far as more detailed timing instructions perhaps Dave would help you out if he can?

John
71 El Camino SS
406 SBC M21 3.31 12 bolt
"Quality is always remembered,long after the price is forgotten"
"I would rather have questions I can't answer than have answers I can't question" :R.Feynman
71350SS is offline  
post #10 of 11 (permalink) Old Jun 30th, 20, 5:28 PM
Senior Tech Team
Steve
 
Join Date: Sep 2015
Location: Central MA
Posts: 1,612
Re: Distributor / timing. Still running good.

Also, where are you located? There might be someone local that could come help you check it out...
LeoP likes this.

1972 Chevelle, 454, 200-4r non-lockup, 12 bolt 3.73
1981 Camaro Z28, 355, TH350, 3.73
lucifershammer is online now  
post #11 of 11 (permalink) Old Jul 1st, 20, 8:57 PM
Senior Tech Team
 
Join Date: Apr 2012
Location: Yerington, Nevada
Posts: 2,270
Re: Distributor / timing. Still running good.

And, NOTHING ON THE IGNITION SYSTEM, NOR CURRENT TIMING SPECIFICATIONS.

That cam isn't that radical @ .050, I feel it should have between 8 and 12 in'hg idle vacuum.
Dave Ray is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevelle Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address. Note, you will be sent a confirmation request to this address.

Email Address:
OR

Log-in










Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome