Timing, how to
1967 Pedal Car Champion
Joined: Mar 2020
Posts: 8,946
Likes: 4,113
From: US-PNW
I agree with CKH, too bad you just missed the last character.
The three options seem to be:
CKH 1972 307 Powerglide 130 2 F A X/Apollo/Ventura
CKH 1973 350 m/t, 4 spd, NB2 L48 175 4 F A X/Chevelle/Monte
CKH 1974 350 m/t,3 & 4 spd, NB2 L48 160 4 F A X
Option 1 is 307ci, so hopefully not that.
So not a Corvette engine, but period appropriate.
https://nastyz28.com/gm-chevy-codes/...s-suffix-2.php
The three options seem to be:
CKH 1972 307 Powerglide 130 2 F A X/Apollo/Ventura
CKH 1973 350 m/t, 4 spd, NB2 L48 175 4 F A X/Chevelle/Monte
CKH 1974 350 m/t,3 & 4 spd, NB2 L48 160 4 F A X
Option 1 is 307ci, so hopefully not that.
So not a Corvette engine, but period appropriate.
https://nastyz28.com/gm-chevy-codes/...s-suffix-2.php
I'm not sure where the OP is getting the information that the timing tab at 12:00 used to be on earlier small blocks - just not in my knowledge bank of seeing a whole bunch of small block Chevy/Corvette C1,C2, & C3 engines over 40 years. This 12:00 tab was a new one on me!
Race Director
Joined: Mar 2017
Posts: 11,839
Likes: 4,455
From: Virginia
That's not a small, squarish pad. That's the long, narrow pad. Or, at least, it probably is. It's impossible to tell much of anything with all of these tightly cropped photos. How do we know the rest of the H wasn't stamped? Why crop that?
See my post above for a 77-82 engine with a 12 o'clock timing tab, which matches the GM corporate blue harmonic damper and timing cover.
Better photos would help. I'm done.
See my post above for a 77-82 engine with a 12 o'clock timing tab, which matches the GM corporate blue harmonic damper and timing cover.
Better photos would help. I'm done.
Thread Starter
Instructor
Joined: Oct 2021
Posts: 209
Likes: 33
That's not a small, squarish pad. That's the long, narrow pad. Or, at least, it probably is. It's impossible to tell much of anything with all of these tightly cropped photos. How do we know the rest of the H wasn't stamped? Why crop that?
See my post above for a 77-82 engine with a 12 o'clock timing tab, which matches the GM corporate blue harmonic damper and timing cover.
Better photos would help. I'm done.
See my post above for a 77-82 engine with a 12 o'clock timing tab, which matches the GM corporate blue harmonic damper and timing cover.
Better photos would help. I'm done.
Last edited by RubyRedMetallic; May 21, 2023 at 04:18 PM.
Intermediate
Joined: Jun 2020
Posts: 32
Likes: 1
From: Erie, PA
30 degree retarded was a guess because there are no retarded marks on the pointer plate. It has 0 to about 16 before top dead center, no retarded marks. 16 is a guess too because the plate is so high at 12oclock that you cant even see the other side of the plate. Stupid place to put this. Anyway, upon getting car home from buying it, I checked timeing and it was set roughly 2 inches on the retarded side, or drivers side of the 0 mark. Way down around 2 oclock. I was amazed it ran like that. Is now set to what I think is degrees, one line before 8 closer to 0, but again hard to see with the angle, so could be 7 or 5 as well. The 1/4 inch space between the marker and the balancer line makes it hard to get right with the angle. You cant really tell if its bang on the arrow since your view is 90degree angle off the marks. Almost putting my face into the alternator fan trying to see 12 oclock area. Very hard to see. Been giving me so much head ache I actually have been looking at replacing the whole motor with a new 4 bolt main one. I notice they have since gotten smarter and mover the indicators way over to the 2 oclock position so you can see it. Also noticed the new motors have the dipstick on the passenger side. mines on the drivers side. So not sure what motor I have other than its a 350, and its orange. lol. Anyway, my 30 number was a guess, it was at 2 oclock way far away from the timing plate. Ran horrible there, but didnt ping.
Thread Starter
Instructor
Joined: Oct 2021
Posts: 209
Likes: 33
I posted the plate already. The mark on the damper is a groove cut all the way across and is the only line on it. And as stated above, I did purchase a piston stop tool and used it to determine that groove is bang on. Used the 0 mark for reference, marked in both directions. The groove was exactly in between the marks. So what ever motor I have, (most likely the high performance since all the belts for the regular motor were too short,) it has the correct damper, and the plate as well. Even though it's at 12 o'clock. An observation I had for that is that 12 o'clock is actually 8 degrees before, so when timed to the manuals spec the groove is exactly at 12 o'clock. 0 is slightly before on drivers side. But the plate is at 12 o'clock, 8 is in the middle of the plate. Also, it's total timed to 36 degrees and at idle it lines up on 8, so I'm guessing spec is correct. The manual shows all other Motors at 12 idle. Guess the hp requires less timing, but ends up still at 36.
Drifting
Joined: Oct 2020
Posts: 1,565
Likes: 569
From: Wisconsin
You said you gapped the plugs to .035, per the manual, but that is for the original points style ignition. Is your new distributor points style or electronic? If electronic, you should be able to open the gap up to .045, like the newer C3’s with the HEI.
Thread Starter
Instructor
Joined: Oct 2021
Posts: 209
Likes: 33
Ok, I do have an electronic. Not an hei, the coil is seperate. But electronic. Would. 045 make it hotter? Seems I need hotter plugs. The Bosch ones I just put back in wer gapped way under. 035. I opened them up to that.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Drifting
Joined: Oct 2020
Posts: 1,565
Likes: 569
From: Wisconsin
If you are using the original coil, keep the .035 gap. HEI coils are up around 50-65k to get the bigger spark gap.
Thread Starter
Instructor
Joined: Oct 2021
Posts: 209
Likes: 33
Pics are for everyone asking. Found that engine #.
I just looked that up. It's a 69-79 corvette 370 motor! Is that horse power or torque. Says 350 torque on shifter thingy. That's great, now back to pinging. Should I open that gap up a bit, maybe not 45 but 40? Lol.
Last edited by RubyRedMetallic; May 21, 2023 at 11:17 PM.
Thread Starter
Instructor
Joined: Oct 2021
Posts: 209
Likes: 33
I seriously suggest you E-Mail Lars at V8fastcars@msn.com and get a copy of his timing paper. You are confused and believe that not only is your timing pointer in the wrong spot, but the balancer is spun as well. This needs to be verified before you can go any further.
Not one automobile built from the 50's to the 90's had a factory timing spec that was conducive to performance or efficiency....not a single one. They all had an emissions friendly timing spec.
The only way to set timing is with the total advance method. This is not spelled out in any manual and no manufacturer has a procedure for it.....but it is the way that ALL professional engine builders and tuners do it. Vacuum advance is unplugged for timing set.
Base/Initial timing is soley a product of total timing.....you do not drive at idle so initial timing is not important except as a reference. I have set timing on hundreds of 70's small blocks and they run best around 15 degrees of initial timing.....but that is becasue the total timing is 36...which is where most small blocks want to be. At 8 degrees of initial....your total will be about 28 degrees which lose a significant amount of performance and elevated coolant temps......
Get Lars paper to understand what timing is all about.....it is not that difficult but about 99% of people get it wrong as most were never taught correctly or refuse to believe the factory spec is wrong. Even into the 90's, all cars were timing soft.....one of the worst was the 5.0l Mustang LX/GT....which had a Ford spec of 0 degrees....if you move this to 7 degrees, the car will pickup a half second in the 1/4 mile.....huge. Computer controlled cars were all set at base timing because the computer controls total timing and it is impossible to check free revving the engine in park......so this adds to the confusion.
At any rate......no low compression engine will ping at 8 degrees base......even on 87 octane or lower.....so something is wrong.
The timing pointer should be at the 2 o'clock position.....but some early covers have the timing mark at 12 o'clock....which is a pain as no one to my knowledge makes a balancer that has the correct 12 o'clock style timing scribe.....so this is another potential screw up.......
Jebby
Not one automobile built from the 50's to the 90's had a factory timing spec that was conducive to performance or efficiency....not a single one. They all had an emissions friendly timing spec.
The only way to set timing is with the total advance method. This is not spelled out in any manual and no manufacturer has a procedure for it.....but it is the way that ALL professional engine builders and tuners do it. Vacuum advance is unplugged for timing set.
Base/Initial timing is soley a product of total timing.....you do not drive at idle so initial timing is not important except as a reference. I have set timing on hundreds of 70's small blocks and they run best around 15 degrees of initial timing.....but that is becasue the total timing is 36...which is where most small blocks want to be. At 8 degrees of initial....your total will be about 28 degrees which lose a significant amount of performance and elevated coolant temps......
Get Lars paper to understand what timing is all about.....it is not that difficult but about 99% of people get it wrong as most were never taught correctly or refuse to believe the factory spec is wrong. Even into the 90's, all cars were timing soft.....one of the worst was the 5.0l Mustang LX/GT....which had a Ford spec of 0 degrees....if you move this to 7 degrees, the car will pickup a half second in the 1/4 mile.....huge. Computer controlled cars were all set at base timing because the computer controls total timing and it is impossible to check free revving the engine in park......so this adds to the confusion.
At any rate......no low compression engine will ping at 8 degrees base......even on 87 octane or lower.....so something is wrong.
The timing pointer should be at the 2 o'clock position.....but some early covers have the timing mark at 12 o'clock....which is a pain as no one to my knowledge makes a balancer that has the correct 12 o'clock style timing scribe.....so this is another potential screw up.......
Jebby
Thread Starter
Instructor
Joined: Oct 2021
Posts: 209
Likes: 33
I've been reading up on this gap and coil stuff, want all your opinions before I go ahead. What I have read is that points and electronic make no difference when set up right. Coil makes difference and gap as well. What I learned is that if you have a stock coil up to 30k volts then you gap as high as .035. If you have a 45k like I have then you can go as high as .045. I know, you told me that. BUt what I also learned is that the gap dictates the voltage, not the coil. SO, if I have my 45k coil, but I gap to .035 like I have, then it will fire at 30k volts and not even use the other 15k volts. In fact it doesnt even build the 45k because it lets go at 30k. If I want to use all 45k then I have to open up the gap so it doesn't jump before it builds the 45k. So i've been wasting my time, and have to open up those plugs to match my coil. Whats your thoughts before I go ahead.
Thread Starter
Instructor
Joined: Oct 2021
Posts: 209
Likes: 33
I also just read that if I have the stock gap it can cause misfires and pinging because today's fuels need a wider gap to have enough molecules between the gap to facilitate proper burn. And not increasing the gap will cause pinging or misfire and carbon build up! I've been chasing the wrong issue. Opening gap
Dr. Detroit
Joined: Mar 2012
Posts: 10,091
Likes: 4,016
From: New Braunfels Texas
I also just read that if I have the stock gap it can cause misfires and pinging because today's fuels need a wider gap to have enough molecules between the gap to facilitate proper burn. And not increasing the gap will cause pinging or misfire and carbon build up! I've been chasing the wrong issue. Opening gap
It is impossible also for a low compression 350 to ping from carbon buildup under proper timing specs....the carbon would be so thick it would flake off and go out the exhaust....
And .010 + - gap is completely unnoticeable anywhere but idle....
Jebby
Race Director
Joined: Feb 2001
Posts: 11,053
Likes: 1,956
From: Grapevine Tx
2018 C3 of Year Finalist
2016 C3 of the Year Finalist
The casting date on my 72 is on the aft passenger side just before the bell housing. I can see it by looking from the top just behind the head.
According to my Corvette Black Book, you have a 70-72 LT-1 block. 3970010, date code on pax side will give you the year.
According to my Corvette Black Book, you have a 70-72 LT-1 block. 3970010, date code on pax side will give you the year.
Last edited by F4Gary; May 22, 2023 at 01:08 PM.
Drifting
Joined: Oct 2020
Posts: 1,565
Likes: 569
From: Wisconsin
Absolute bullshit. Pinging and/or detonation is caused by fuel and air igniting prematurely....not from not enough gap to "facilitate the burn".
It is impossible also for a low compression 350 to ping from carbon buildup under proper timing specs....the carbon would be so thick it would flake off and go out the exhaust....
And .010 + - gap is completely unnoticeable anywhere but idle....
Jebby
It is impossible also for a low compression 350 to ping from carbon buildup under proper timing specs....the carbon would be so thick it would flake off and go out the exhaust....
And .010 + - gap is completely unnoticeable anywhere but idle....
Jebby