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Did you happen to take any pictures of your repair process, specifically of the rocker-arms, after setting the lifters? #1 TDC occurs right after the #1 intake valve closes, this can be witnessed with the valve cover off....you could verify rotor orientation and timing marks this way, since it's hard to rotate the engine by hand and keep your finger over the #1 plug hole. If you in fact started adjusting lifters on #6 TDC, instead of #1 TDC, but thought you were on #1 TDC....that would certainly cause issues!!! I would take the valve covers off (post pictures of the rocker-arm studs on both heads), rotate engine to #1 TDC (watching the #1 intake valve as it closes and stopping when the damper lines up on zero degrees), back-off all the rocker-arm nuts and start over on lifter adjustment! Don't overthink it, rotate the push rods back and forth while slowly tightening the nut, when it's right there, you'll feel/see it stopping the spin, clock your wrench and tighten it 1/2 - 3/4 turn more (I like 1/2). It's ultra important that you set the correct valves on #1 & #6 TDC positions (exhaust valves line up with the exhaust manifold branches), use a Sharpie or dab of assembly lube to mark the rockers that have been set as you do them, triple check before rotating to #6 TDC, mark those and verify, then rotate to #1 TDC again (verifying timing is at zero) NOW drop your distributor in (put the cap on and mark the base with a vertical line exactly where the #1 plug tower is at) and verify rotor position...keep trying until it's lined up perfectly (you'll likely have to use a long screw driver to rotate the oil pump shaft to compensate for the "twist" of the distributor gear as it engages), I would get the distributor installed properly....by hand, not by "bumping" the engine to get the oil pump shaft to be properly seated! Anyway, I know you said you were very thorough on the lifter adjusting, but you don't have to tear everything apart again, just take the valve covers off do it one more time, it ran great before you worked on it, undo what you did and 100% verify it's right, if you still have issues, then I would focus on the new injectors/fuel delivery and possibly the timing chain...but if you were on #6 and thought it was #1, or you were setting exhaust valves and thought they were intake valves...I am in NO way trying to insult your intelligence or abilities, just trying to help and from your description of what it's doing now, the above suggestions are what I would do if I could get my hands on it!!! Good luck, don't despair, your engine/compression isn't suddenly bad, you'll figure it out and next time you'll be the one giving pointers👍
edit: I'm curious about rocker-arm studs pictures, because I wanted to see how much thread is above the nut on each stud.
Last edited by '78CorvetteS.A.; Apr 10, 2024 at 06:30 AM.
Did you happen to take any pictures of your repair process, specifically of the rocker-arms, after setting the lifters? #1 TDC occurs right after the #1 intake valve closes, this can be witnessed with the valve cover off....you could verify rotor orientation and timing marks this way, since it's hard to rotate the engine by hand and keep your finger over the #1 plug hole. If you in fact started adjusting lifters on #6 TDC, instead of #1 TDC, but thought you were on #1 TDC....that would certainly cause issues!!! I would take the valve covers off (post pictures of the rocker-arm studs on both heads), rotate engine to #1 TDC (watching the #1 intake valve as it closes and stopping when the damper lines up on zero degrees), back-off all the rocker-arm nuts and start over on lifter adjustment! Don't overthink it, rotate the push rods back and forth while slowly tightening the nut, when it's right there, you'll feel/see it stopping the spin, clock your wrench and tighten it 1/2 - 3/4 turn more (I like 1/2). It's ultra important that you set the correct valves on #1 & #6 TDC positions (exhaust valves line up with the exhaust manifold branches), use a Sharpie or dab of assembly lube to mark the rockers that have been set as you do them, triple check before rotating to #6 TDC, mark those and verify, then rotate to #1 TDC again (verifying timing is at zero) NOW drop your distributor in (put the cap on and mark the base with a vertical line exactly where the #1 plug tower is at) and verify rotor position...keep trying until it's lined up perfectly (you'll likely have to use a long screw driver to rotate the oil pump shaft to compensate for the "twist" of the distributor gear as it engages), I would get the distributor installed properly....by hand, not by "bumping" the engine to get the oil pump shaft to be properly seated! Anyway, I know you said you were very thorough on the lifter adjusting, but you don't have to tear everything apart again, just take the valve covers off do it one more time, it ran great before you worked on it, undo what you did and 100% verify it's right, if you still have issues, then I would focus on the new injectors/fuel delivery and possibly the timing chain...but if you were on #6 and thought it was #1, or you were setting exhaust valves and thought they were intake valves...I am in NO way trying to insult your intelligence or abilities, just trying to help and from your description of what it's doing now, the above suggestions are what I would do if I could get my hands on it!!! Good luck, don't despair, your engine/compression isn't suddenly bad, you'll figure it out and next time you'll be the one giving pointers👍
edit: I'm curious about rocker-arm studs pictures, because I wanted to see how much thread is above the nut on each stud.
This is great advice, thank you! I will try to post pictures either tonight or tomorrow, my work schedule is kinda hectic right now. I thought when I set the lash, all of the studs looked to have roughly the same amount of thread showing, but I'll give it another try with your process and make sure it's perfect.
Sounds good, make sure to unhook the negative battery cable (good safety practice) and pull all the plugs again, they're wet...spray them with carb cleaner and let them dry while performing your work...make sure to put anti-seize on the spark plug threads when installing in aluminum heads...not a ton, just coat the threads lightly👍
Sounds good, make sure to unhook the negative battery cable (good safety practice) and pull all the plugs again, they're wet...spray them with carb cleaner and let them dry while performing your work...make sure to put anti-seize on the spark plug threads when installing in aluminum heads...not a ton, just coat the threads lightly👍
Sounds good, thanks for the extra tips. My 86 still has the iron heads, would you still put anti seize on them?
Sounds good, thanks for the extra tips. My 86 still has the iron heads, would you still put anti seize on them?
No, iron heads don't need it. That's interesting, I thought all the '86 convertibles got the aluminum heads...maybe some early ones didn't or your's have been changed/different engine!? Hmmmm!?
Yeah I was thinking the same thing. I think I'll try putting the old ones back and setting lash again, that way I have both bases covered for sure.
While you have the valve covers off, pls double-check the position of the rotor at #1 wire vs the rockers on #1 should both be up. I know it's very basic, but while you're in there a little extra verification wouldn't hurt. Belt and suspenders, ya know.
While you have the valve covers off, pls double-check the position of the rotor at #1 wire vs the rockers on #1 should both be up. I know it's very basic, but while you're in there a little extra verification wouldn't hurt. Belt and suspenders, ya know.
not sure where this thread's at - not going to read all 33 posts in detail, so i'll just add my 2-cents. i've adjusted hydraulic lifters for some 40 years w/o issues until one day murphy's law kicked in. #1 intake on my 85 drove me nuts as i was getting things a bit too tight. car started OK, but as the temp came up, thermal expansion kicked in - #1 intake would not fully close - car ran like schitt. anyway, LSS, started using a .0015 feeler gauge to set zero lash on the lifters vs the turn until resistant is felt thing. it's a little too subjective. the .0015 on the lash doesn't amount to a hill of beans on the overall lifter adjustment. once the ".0015 lash" is set, turn the adjuster 3/4 turn. set and forget. follow the cylinder sequence in your service manual.
to set the distributor and timing -- #1 TDC compression, timing marks at zero. set the slot on the oil pump shaft to the 5:30 position. the distributor cap has 4 screws - position the cap screws so they are parallel and perpendicular to the engine's centerline - the electrical connections will be positioned to the left. as you lower the distributor, position the rotor, pointing to the center of the LH valve cover's emblem - lower until the gears engage - a little wiggle-jiggle may be required. as you lower the distributor with the gears engage, the rotor will rotate CW and will end up pointing toward the #1 spark plug. with four distributor cap screws parallel and perpendicular to the engine's CL, you are at zero degrees (TDC #1 compression) on your timing. now, turn your distributor CCW two or three degrees - lock your distributor. at this point you should be at 4-6 degrees BTDC on your timing. so easy, even stevie wonder could do it -
all should be good - UNLESS you have other issues....
question - did you by chance remove (and reinstall) the distributor gear during any of this rebuild effort? just asking.
not sure where this thread is - not going to read all 33 posts in detail, so i'll just add my 2-cents. i've adjusted hydraulic lifters for some 40 years w/o issues until one day murphy's law kicked in. #1 intake on my 85 drove me nuts as i was getting things a bit too tight. car started OK, but as the temp came up, thermal expansion kicked in - #1 intake would not fully close - car ran like schitt. anyway, LSS, started using a .0015 feeler gauge to set zero lash on the lifters vs the turn until resistant is felt thing. it's a little too subjective. the .0015 on the lash doesn't amount to a hill of beans on the overall lifter adjustment. once the ".0015 lash is set, turn the adjuster 3/4 turn. it's set - just forget. follow the cylinder sequence in your service manual.
to set the distributor and timing -- #1 TDC compression, timing marks at zero. set the slot on the oil pump shaft to the 5:30 position. the distributor cap has 4 screws - position the cap screws so they are parallel and perpendicular to the engine's centerline - the electrical connections will be position to the left. as you lower the distributor, position the rotor, pointing to the center of the LH valve cover's emblem - lower until the gears engage - a little wiggle-jiggle may be requited. as you lower the distributor and the gears engage, the rotor will naturally rotate CW and will end up pointing toward the #1 spark plug. with four distributor cap screws parallel and perpendicular to the engine's CL, you are at zero degrees on your timing. now, turn your distributor CCW two or three degrees - lock your distributor. at this point you should be at 4-6 degrees BTDC on your timing.
all should be good - UNLESS you have other issues....
question - did you by chance remove (and reinstall) the distributor gear during any of this rebuild effort? just asking.
Very informative, I appreciate the expert advice! I will let you know how it goes. I did not remove the distributor gear from the distributor (I actually didn't even know you could do that lol)
Success!!!!!! You guys were totally right, I just needed to redo the valve lash! I didn't have any feeler gauges on hand, so I decided to go with the spin method. I ended up only tightening them down 1/2 turn this time instead of 3/4 turn. I reset my distributor, cleaned my plugs, said a couple prayers, turned the key and she fired right up! She's running rough, but I still gotta time it and plug in the maf sensor and hook up a few vacuum lines. Thanks for all the advice and help, I was about to give up, you guys are the best! Here's a couple pictures of the amount of thread I had on each lifter as requested:
