berettagtz Posted October 15, 2011 Report Share Posted October 15, 2011 Is there any timing marks on the camshaft sprockets on 95 3.4 dohc? Had to replace rear cyl head because of a crack in between valves which caused it to burn coolant. I put it back together and it doesnt run very good, pretty sure i messed up the cam timing on the rear head because i pulled all the spark plugs out and front plugs look good the back plugs are black with carbon. Just wondering how to set all the cams to zero then i can bump it up to tdc and put the belt back on. Ant ideas? Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted October 16, 2011 Report Share Posted October 16, 2011 There may be marks on them, but often can't be trusted. Honestly with the hold down tools, timing our cars isn't really that bad (especially yours, since the '95 has the newer cam sprockets that can come loose without removing the cam carrier first). Pull all your plugs to remove compression on the engine, and pull the cam covers. Put a ratchet on the crank pulley and slowly rotate the engine by hand until one bank has the cam flats up and put the hold down tools on that bank. Using a ratchet and a cam sprocket holder, loosen the cam sprockets so they can freewheel. Now rotate the engine until the other bank has the cam flats up and repeat the process. Now you've got the cams all loose and locked down in their proper positions, and you should be able to re-time your engine. Just be sure to accurately find TDC when re-timing and make sure you have proper belt tension. There may be some particulars about timing a '95 that I don't know since I think the sensors are different with OBD 1.5 vs. the '92 that I have, so hopefully someone can chime in on that. Basically though, all you need it to accurately find TDC, ensure enough belt tension, and tighten down one the sprockets on one bank (rear first I believe, someone please confirm). Remove the hold down tools on that bank, rotate the engine 360 degrees, and them lock down the sprockets on the other bank. Remove the hold down tools, and the car is now timed. Hopefully this helps, and others can fill in details about your model year that I don't know Quote Link to comment Share on other sites More sharing options...
GEN1Z34 Posted October 16, 2011 Report Share Posted October 16, 2011 (edited) The timing marks on the LQ1 sprockets were painted on @ the factory and are likely not visible anymore.. Some sprokets were marked with a groove @ the front of one sprocket tooth but there's no guarantee they are in the correct possition.. The cam sprokets have no splines and no key ways so it's always a bad idea to use the sprokets for timing referance.. You have to pull the cam covers and lock down the cams @ the flat spots provided in order to set the timing properly.. The top dead center mark for the harmonic balancer is here on the coolant diverter.. Edited October 16, 2011 by GEN1Z34 Quote Link to comment Share on other sites More sharing options...
berettagtz Posted October 16, 2011 Author Report Share Posted October 16, 2011 Cam flats? do i have to take the cam covers off to see the cam flats? What do they look like? Im used rebuilding small block chevys, way to many cams for me lol. I have a 3.4 out of a 92 lumina z34 on my shop floor that im thinking that i will look at the cam location on that at tdc and see if i can line it up the same on the 95 monte carlo. Wish me luck im guna need it thanx for the info!! Quote Link to comment Share on other sites More sharing options...
GEN1Z34 Posted October 16, 2011 Report Share Posted October 16, 2011 There may be marks on them, but often can't be trusted. Honestly with the hold down tools, timing our cars isn't really that bad (especially yours, since the '95 has the newer cam sprockets that can come loose without removing the cam carrier first). Pull all your plugs to remove compression on the engine, and pull the cam covers. Put a ratchet on the crank pulley and slowly rotate the engine by hand until one bank has the cam flats up and put the hold down tools on that bank. Using a ratchet and a cam sprocket holder, loosen the cam sprockets so they can freewheel. Now rotate the engine until the other bank has the cam flats up and repeat the process. Now you've got the cams all loose and locked down in their proper positions, and you should be able to re-time your engine. Just be sure to accurately find TDC when re-timing and make sure you have proper belt tension. There may be some particulars about timing a '95 that I don't know since I think the sensors are different with OBD 1.5 vs. the '92 that I have, so hopefully someone can chime in on that. Basically though, all you need it to accurately find TDC, ensure enough belt tension, and tighten down one the sprockets on one bank (rear first I believe, someone please confirm). Remove the hold down tools on that bank, rotate the engine 360 degrees, and them lock down the sprockets on the other bank. Remove the hold down tools, and the car is now timed. Hopefully this helps, and others can fill in details about your model year that I don't know You have most of it right.. No need to remove the carriers on older LQ1's. OBD1's don't have cam sensors but the OBD2 LQ1's use the same proceedure for setting timing.. Belt tension is ~30 ft lbs.. Quote Link to comment Share on other sites More sharing options...
GEN1Z34 Posted October 16, 2011 Report Share Posted October 16, 2011 (edited) Cam flats? do i have to take the cam covers off to see the cam flats? What do they look like? Im used rebuilding small block chevys, way to many cams for me lol. I have a 3.4 out of a 92 lumina z34 on my shop floor that im thinking that i will look at the cam location on that at tdc and see if i can line it up the same on the 95 monte carlo. Wish me luck im guna need it thanx for the info!! The cam flats are located on the cams in opening of the carrier in the first pic I posted. The rear or left bank (looking from the front of the engine) cam flats are @ the rear of the carrier.. Both carriers have an open bolt hole between the cams for the bolt on the lock down tool.. Edited October 16, 2011 by GEN1Z34 Quote Link to comment Share on other sites More sharing options...
berettagtz Posted October 16, 2011 Author Report Share Posted October 16, 2011 Ahhh ok the pic you have circled of the head is were the cam flat spots are, one bank up one bank down hope it works thanx!! Quote Link to comment Share on other sites More sharing options...
GEN1Z34 Posted October 16, 2011 Report Share Posted October 16, 2011 Ahhh ok the pic you have circled of the head is were the cam flat spots are, one bank up one bank down hope it works thanx!! No prob.. As Spider said it's really not as hard as you may have heard.. Just a pain in a cramped W engine bay.. Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted October 17, 2011 Report Share Posted October 17, 2011 You have most of it right.. No need to remove the carriers on older LQ1's. True. I should have clarified; if you want to get all the sprockets freewheeling, you need to pull the carrier as their isn't enought room to pull the rear most sprocket on earlier LQ1s. That is not required in order to time the motor, but it is more of a hassle to get an accurate time. Thanks GM. Quote Link to comment Share on other sites More sharing options...
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