Timing??
Thread Starter
Instructor
Joined: Jun 2019
Posts: 232
Likes: 14
Timing??
When timing, I know that you pull the vacuum and cap/plug for initial timing. My question is for total timing. Do you reconnect or leave the vacuum off? Do you run the rpms up until they stop increasing and then set to 34-36? Do you take rpms to 3000 añd then set?
Can someone please explain the proper procedure? TIA
Can someone please explain the proper procedure? TIA
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Pull vacuum hose and plug.
Bring up rpm's and note where the advance stops.
For iron heads, you are looking for the timing advance to stop at 36* at 3000 rpm.
Total advance is initial advance and mech'l advance.
Distributors have say 20* mech'l. So, set initial to 16* for a total of 36*.
If your total is higher than 3000 rpm, change to lighter springs in the distributor so the advance comes in quicker.
Most folks use manifold vacuum for the vacuum advance source and not the ported vacuum source.
Reconnect vacuum advance hose and adjust idle.........
If engine pings, reduce initial timing until ping is eliminated, use higher octane fue or limit vacuum advance.
Bring up rpm's and note where the advance stops.
For iron heads, you are looking for the timing advance to stop at 36* at 3000 rpm.
Total advance is initial advance and mech'l advance.
Distributors have say 20* mech'l. So, set initial to 16* for a total of 36*.
If your total is higher than 3000 rpm, change to lighter springs in the distributor so the advance comes in quicker.
Most folks use manifold vacuum for the vacuum advance source and not the ported vacuum source.
Reconnect vacuum advance hose and adjust idle.........
If engine pings, reduce initial timing until ping is eliminated, use higher octane fue or limit vacuum advance.
Race Director
Joined: May 2006
Posts: 18,689
Likes: 2,571
You can not use stock springs to set total timing.
You need to purchase a spring kit such as Mr Gasket 928G.
The bushing in the kit requires you to remove the distributor and then remove the main shaft.
Start with one silver and one black spring.
You need to purchase a spring kit such as Mr Gasket 928G.
The bushing in the kit requires you to remove the distributor and then remove the main shaft.
Start with one silver and one black spring.
Last edited by MelWff; Oct 4, 2019 at 11:36 AM.
Safety Car
Joined: Jan 2008
Posts: 3,794
Likes: 430
From: Aarhus, Denmark
Pull vacuum hose and plug.
Bring up rpm's and note where the advance stops.
For iron heads, you are looking for the timing advance to stop at 36* at 3000 rpm.
Total advance is initial advance and mech'l advance.
Distributors have say 20* mech'l. So, set initial to 16* for a total of 36*.
If your total is higher than 3000 rpm, change to lighter springs in the distributor so the advance comes in quicker.
Most folks use manifold vacuum for the vacuum advance source and not the ported vacuum source.
Reconnect vacuum advance hose and adjust idle.........
If engine pings, reduce initial timing until ping is eliminated, use higher octane fue or limit vacuum advance.
Bring up rpm's and note where the advance stops.
For iron heads, you are looking for the timing advance to stop at 36* at 3000 rpm.
Total advance is initial advance and mech'l advance.
Distributors have say 20* mech'l. So, set initial to 16* for a total of 36*.
If your total is higher than 3000 rpm, change to lighter springs in the distributor so the advance comes in quicker.
Most folks use manifold vacuum for the vacuum advance source and not the ported vacuum source.
Reconnect vacuum advance hose and adjust idle.........
If engine pings, reduce initial timing until ping is eliminated, use higher octane fue or limit vacuum advance.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,145
Likes: 9,278
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
the vacuum will bring it up to 48 thru 52 area. Its been written here that if you are getting up past 48 you should limit the vacuum advance to make sure you dont get above that point
Le Mans Master
Joined: Jun 2019
Posts: 7,649
Likes: 2,466
From: Indiana
I am starting to read and time my 79 L82..
CAUTION
just went to harbor freight and bought this
https://www.harborfreight.com/timing...SABEgIpS_D_BwE
great deal and made in taiwan excellent..i was thrilled especially throwing away my old timing light years ago.
this one also has advance ****...this the problem and i tried two...set at zero or below i got a rock solid 14 degrees vacuum plugged at idle...but when i adjust **** on gun so the balancer reads zero i was expecting 14 degrees...nope both guns read 24-25 degrees and full throttle like 58...what a shame.. so here i sit and ordeed this
should be here sunday and will update as i still have harbor freight #2 to verify..too bad..anyway watchout
also this new one has rpm as my tach is off... and i need to verify 900 rpm at idle for manual
CAUTION
just went to harbor freight and bought this
https://www.harborfreight.com/timing...SABEgIpS_D_BwE
great deal and made in taiwan excellent..i was thrilled especially throwing away my old timing light years ago.
this one also has advance ****...this the problem and i tried two...set at zero or below i got a rock solid 14 degrees vacuum plugged at idle...but when i adjust **** on gun so the balancer reads zero i was expecting 14 degrees...nope both guns read 24-25 degrees and full throttle like 58...what a shame.. so here i sit and ordeed this
should be here sunday and will update as i still have harbor freight #2 to verify..too bad..anyway watchout
also this new one has rpm as my tach is off... and i need to verify 900 rpm at idle for manual
Last edited by interpon; Oct 5, 2019 at 06:09 PM.
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,145
Likes: 9,278
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
I am starting to read and time my 79 L82..
CAUTION
just went to harbor freight and bought this
https://www.harborfreight.com/timing...SABEgIpS_D_BwE
great deal and made in taiwan excellent..i was thrilled especially throwing away my old timing light years ago.
this one also has advance ****...this the problem and i tried two...set at zero or below i got a rock solid 14 degrees vacuum plugged at idle...but when i adjust **** on gun so the balancer reads zero i was expecting 14 degrees...nope both guns read 24-25 degrees and full throttle like 58...what a shame.. so here i sit and ordeed this
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
should be here sunday and will update as i still have harbor freight #2 to verify..too bad..anyway watchout
also this new one has rpm as my tach is off... and i need to verify 900 rpm at idle for manual
CAUTION
just went to harbor freight and bought this
https://www.harborfreight.com/timing...SABEgIpS_D_BwE
great deal and made in taiwan excellent..i was thrilled especially throwing away my old timing light years ago.
this one also has advance ****...this the problem and i tried two...set at zero or below i got a rock solid 14 degrees vacuum plugged at idle...but when i adjust **** on gun so the balancer reads zero i was expecting 14 degrees...nope both guns read 24-25 degrees and full throttle like 58...what a shame.. so here i sit and ordeed this
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
should be here sunday and will update as i still have harbor freight #2 to verify..too bad..anyway watchout
also this new one has rpm as my tach is off... and i need to verify 900 rpm at idle for manual
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Le Mans Master
Joined: Jun 2019
Posts: 7,649
Likes: 2,466
From: Indiana
my car runs good..here are my numbers..never changed anything from owner..
initial timing harbor freight 14, innova 16
total timing vacuum plugged harbor freight 56...innova 34
vacuum hooked to carburetor advances about 10 degrees at idle..
all hooked up about 46 degrees timing..
harbor freight..forget it.
edit - my mechanical advance starts about 1500 and all in around 2500..never have detonation run 90 octane no ethanol
idle warmed and all hooked up i increased from 850 to 900. Dead cold choke about 1200..
tachometer dead on...must get hot later and under show rpm on my dash tachometer..
Good luck!
Last edited by interpon; Oct 6, 2019 at 04:33 PM.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
whatever happened to degreed dampers / timing tapes ? ... no shift, no creep, accurate.
Dinosaur's using an inductive SUN bought new in '77 ... replaced lamp once.
'though many times wish I had dial-back on old Harley ... mark on internal flywheel viewed thru a ~1/2" hole in crankcase.
Dinosaur's using an inductive SUN bought new in '77 ... replaced lamp once.
'though many times wish I had dial-back on old Harley ... mark on internal flywheel viewed thru a ~1/2" hole in crankcase.
Dr. Detroit
Joined: Mar 2012
Posts: 10,095
Likes: 4,024
From: New Braunfels Texas
Pull vacuum hose and plug.
Bring up rpm's and note where the advance stops.
For iron heads, you are looking for the timing advance to stop at 36* at 3000 rpm.
Total advance is initial advance and mech'l advance.
Distributors have say 20* mech'l. So, set initial to 16* for a total of 36*.
If your total is higher than 3000 rpm, change to lighter springs in the distributor so the advance comes in quicker.
Most folks use manifold vacuum for the vacuum advance source and not the ported vacuum source.
Reconnect vacuum advance hose and adjust idle.........
If engine pings, reduce initial timing until ping is eliminated, use higher octane fuel or limit vacuum advance.
Bring up rpm's and note where the advance stops.
For iron heads, you are looking for the timing advance to stop at 36* at 3000 rpm.
Total advance is initial advance and mech'l advance.
Distributors have say 20* mech'l. So, set initial to 16* for a total of 36*.
If your total is higher than 3000 rpm, change to lighter springs in the distributor so the advance comes in quicker.
Most folks use manifold vacuum for the vacuum advance source and not the ported vacuum source.
Reconnect vacuum advance hose and adjust idle.........
If engine pings, reduce initial timing until ping is eliminated, use higher octane fuel or limit vacuum advance.
Now at light throttle/light load cruising......you should have 48-50.......does that make sense? You cannot rev it in the driveway as there is no load......it will not pull vacuum at 3000rpm in park.
Jebby
Last edited by Jebbysan; Oct 7, 2019 at 01:01 PM.
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Yeah Jebb, I should have made it more clear that the car needed to be driven under light load to check for any pinging. 