Topic: timing chain and pan drop questions
in Forum: C3 Engines
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In the process of doing my timing chain. I got the balancer off (and water pump and all other accessories) and now I'm ready to drop the pan. My Haynes manual told me to set the engine at #1 TDC before pulling the balancer, but the pan drop procedure (I read it after I pulled the balancer
) says to rotate the engine such that the timing mark points straight down. What's up with that??? Do I need to rotate the engine? I would think I want it at #1 TDC to do the chain. Will there be clearance problems with the crank if I don't set the engine the way the Haynes manual says?
) says to rotate the engine such that the timing mark points straight down. What's up with that??? Do I need to rotate the engine? I would think I want it at #1 TDC to do the chain. Will there be clearance problems with the crank if I don't set the engine the way the Haynes manual says? Also, any advice on a timing set to use? It's just a stock L-48, so don't need anything fancy. I was just thinking of the basic true roller set from Summit or similar. Will there be any clearance problems with the stock cover? Thanks.
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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When the #1 piston is at TDC, the dot on the crank gear should be at 12 o'clock and the cam gear should be at 6 o'clock. Don't confuse the timing mark on the balancer with the timing mark on the gear set.
Also important to make sure you are at TDC on the compression stroke. If you have someone bump the motor while holding your thumb over the #1 spark plug hole, you'll get a strong gust of air blowing your thumb off the hole when she reaches TDC.
If the motor is relatively mild, a Cloyes or TRW double row set is plenty beefy...costs usually between $20 to $30...
Good luck
Paul
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A full/true roller is best, but not 100% necessary. My thoughts are do it once, and do it right. A roller will fit under the stock cover easily.
You can set the timing marks on the cam gear and crank gear pointing towards each other, and swap the chain/gear with no problems. As long as the engine isn't turned with the chain off, you're good. I think the manual wants the engine with the timing mark DOWN to make it easier to get the pan off past the crank throws, but on a Shark car, it's pretty much a straight down deal.
You can set the timing marks on the cam gear and crank gear pointing towards each other, and swap the chain/gear with no problems. As long as the engine isn't turned with the chain off, you're good. I think the manual wants the engine with the timing mark DOWN to make it easier to get the pan off past the crank throws, but on a Shark car, it's pretty much a straight down deal.
Joel Adams
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Thanks guys. Yep, I checked - on the oil pan procedure it specifically says, "Turn the crankshaft until the timing mark on the vibration damper is pointed straight down." (Step 9) Still doesn't make sense - it tells you to remove the crossover pipe (mine's already gone) and the idler arm and lower steering linkage (I'm assuming they're correct there - not much clearance) and starter. Once you remove all that stuff there's nothing blocking the path of the pan at all. I got the car up on stands tonight and the starter and flywheel cover off tonight. Will do the rest one night this week hopefully. Then it's putting everything back together.....
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Yup...drop the idle arm, and disconnect the linkage from the driver side, and you'll have plenty of room to drop the pan.
Ken(kstyer) changed the whole crankshaft in his car, with the engine still in the car, so dropping the pan isn't that tough of a job.
Ken(kstyer) changed the whole crankshaft in his car, with the engine still in the car, so dropping the pan isn't that tough of a job.
Joel Adams
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Agreed! Changing the crank in the car sounds like too much fun for me. I'll count my blessings if I can get this "simple" project put back together. Unfortunately, time is my main limiting factor these days.... Thanks for the help.
Dave
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
Lifetime MemberHOWELL, NJ - USA
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We're rootin for ya Dave!! You can do it!!! 
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Glad someone's rooting for me! So I got the pan off (dang, 2-bolt main - was hoping to get lucky) and now I have more questions.
I read a thread on here about whether both timing marks should be at 12:00 or if the cam sprocket should be at 6:00. The debate may go on....mine are both at 12:00. It sure looks like the factory chain and sprockets (nylon teeth on the cam sprocket) and I'm reasonably certain I am at TDC on #1 (rotor pointing at #1 and it looks like both valves are closed on #1 -- I also have the intake and valve covers off). Both at 12:00 seems like it's right for when I put the new set on, but it will make it harder to ensure the timing is correct. In fact, it looks like the cam sprocket may be a little shy of 12:00, more like 11:55 or so, but it's hard to tell from the side. Is it possible I am off a tooth? The chain is very loose on the passenger side. The crank sprocket looks like it is exactly at 12:00
So what is the best way to make sure the cam sprocket is at 12:00 exactly? Is there a good way to measure that? And if I do need to turn the cam do I just thread some bolts in and stick a crow bar in between them?
1976 Silver/Firethorn. L48, 4spd. Original 2 bolt, vortec heads, 9.4:1 CR, Speed Pro Cam: 224/224@0.050, 112 LSA, Eagle Steel Crank.
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Use a straight edge, and align it with the center of the crank, and cam, straight up and down. That will show you where the gears are.
The 12/6 debate will continue, of course, but I've always used the crank @ 12, cam @ 6...basically having the marks facing each other. It's easiest for me to see that the marks are spot on like that.
Don't know that you would need a crow bar to turn the cam, but a medium-sized screwdriver should do it, if needed.
The 12/6 debate will continue, of course, but I've always used the crank @ 12, cam @ 6...basically having the marks facing each other. It's easiest for me to see that the marks are spot on like that.
Don't know that you would need a crow bar to turn the cam, but a medium-sized screwdriver should do it, if needed.
Joel Adams
C3VR Lifetime Member #56
My Link
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
in Forum: C3 Engines
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