240zchevyv8 Posted November 19, 2009 Share Posted November 19, 2009 Hello guys i need some advice from people who know chevy engines. Ill be as detailed as possible, my 240z has a 1962 327ci v8 installed. Im having a lot of trouble with what i think is a timing fault, the distrubutor has mallory electronic ignition in it, but no vacuum advance i cannot see where it was possibly ever fitted to the distrubutor. When first starting from cold car starts ok, but does not tick over very smoothly, as if it was slightly missing, i know the car has supposedly got a lopey cam but it doesnt sound or feel smooth, i know lopey cams could make it do this, but car seems to struggle to tick over mor than it should, also while driving on exceleration it is fine, but take my foot of the gas and the engine sort of stumbles, as if moving but i know nothing is loose, i have new plug leads fitted new timing chain and sprockets, ive just bought new spark plugs but not yet fitted them, but do not think this is the problem, i think it is the distrubutor that is at fault, but would not having a vacuum advance cause this type of problem, it is really annoying when car continually jerks when taking your foot of the gas, the fuel mixture and tick over speeds appear ok, it has a nearly new 600 cfm 1406 edelbrock 4bbl carburator, so do not suspect this, i put lead additives in the fuel because only unleaded is available here, i have adjusted the timing but cannot stop the car stumbling:cry2:, i would appreciate any advice because very few people in the uk understand chevys, i always wanted a 240z chevy v8 but its turning into a nightmare, i think the way forward is replace the distrubutor with a type with vacuum advance, or does the car not need it. regards 240z chevy v8 Quote Link to comment Share on other sites More sharing options...
rucus01 Posted November 19, 2009 Share Posted November 19, 2009 Hello guys i need some advice from people who know chevy engines. Ill be as detailed as possible, my 240z has a 1962 327ci v8 installed. Im having a lot of trouble with what i think is a timing fault, the distrubutor has mallory electronic ignition in it, but no vacuum advance i cannot see where it was possibly ever fitted to the distrubutor. When first starting from cold car starts ok, but does not tick over very smoothly, as if it was slightly missing, i know the car has supposedly got a lopey cam but it doesnt sound or feel smooth, i know lopey cams could make it do this, but car seems to struggle to tick over mor than it should, also while driving on exceleration it is fine, but take my foot of the gas and the engine sort of stumbles, as if moving but i know nothing is loose, i have new plug leads fitted new timing chain and sprockets, ive just bought new spark plugs but not yet fitted them, but do not think this is the problem, i think it is the distrubutor that is at fault, but would not having a vacuum advance cause this type of problem, it is really annoying when car continually jerks when taking your foot of the gas, the fuel mixture and tick over speeds appear ok, it has a nearly new 600 cfm 1406 edelbrock 4bbl carburator, so do not suspect this, i put lead additives in the fuel because only unleaded is available here, i have adjusted the timing but cannot stop the car stumbling:cry2:, i would appreciate any advice because very few people in the uk understand chevys, i always wanted a 240z chevy v8 but its turning into a nightmare, i think the way forward is replace the distrubutor with a type with vacuum advance, or does the car not need it. regards 240z chevy v8 There are a few things we will need to know in order to help you. First what cam is in it? You say it is lopey but what are the specs on it? If you cant find this can you provide a vacuum reading at idle? Have you read the plugs, do they show rich or lean? How much initial / total timing do you have on the engine? What kind of transmission / torque convertor is fitted to the motor? Jerking on decel sounds more like a transmission problem than an engine problem. Quote Link to comment Share on other sites More sharing options...
240zchevyv8 Posted November 20, 2009 Author Share Posted November 20, 2009 Hello ill answer what i can, i dont know what camshaft is in the car it came with it in and i have not stripped the engine, i have not got a device for reading the vacuum, as regards to the plugs they look fine a light greyish colour, as for timing thats a good one when i tried to set up the timing, i marked the harmonic balancer and 8 degree before mark and fired up the engine but the strobe light showed the line way above the 12 degree mark???, i attempted to bring the timing mark down by moving the distrubutor but the engine was strugling to run and would have stopped if i had took it to the 8 before mark, this confused me but i read somewhere that it is not uncommon to have a chevy set up 30 degree before top dead centre, so i assumed that this was set up that way, and also because it was running, when i changed the timing chain/gears the old chain was well stretched, i removed the old items and refitted the new ones without moving anything so thought that this should be ok, or am i wrong and now the timing is so far out im lucky the car runs, the gearbox is a t5 with no stall converter fitted, it came that way, car ran fine prior to removing engine to set it back further and striping front cover of to fit a new one this is when i noticed the timing chain wear, the problem i have to me is not gearbox related it changes gear fine no noises and is really smooth in operation, one thing i thought strange was when i refitted the plug leads on the distrubutor( i had not touched it at all before this), was that the number 1 cylinder in books shows it at a six oclock position or facing the radiator of the car, on my engine its at a eight oclock position, or has someone put the leads on wrong and i followed them:confused: i find this thought to obvious, because surely like this it would not run at all, i would appreciate your views on this regards heath. Quote Link to comment Share on other sites More sharing options...
rucus01 Posted November 20, 2009 Share Posted November 20, 2009 Hello ill answer what i can, i dont know what camshaft is in the car it came with it in and i have not stripped the engine, i have not got a device for reading the vacuum, as regards to the plugs they look fine a light greyish colour, as for timing thats a good one when i tried to set up the timing, i marked the harmonic balancer and 8 degree before mark and fired up the engine but the strobe light showed the line way above the 12 degree mark???, i attempted to bring the timing mark down by moving the distrubutor but the engine was strugling to run and would have stopped if i had took it to the 8 before mark, this confused me but i read somewhere that it is not uncommon to have a chevy set up 30 degree before top dead centre, so i assumed that this was set up that way, and also because it was running, when i changed the timing chain/gears the old chain was well stretched, i removed the old items and refitted the new ones without moving anything so thought that this should be ok, or am i wrong and now the timing is so far out im lucky the car runs, the gearbox is a t5 with no stall converter fitted, it came that way, car ran fine prior to removing engine to set it back further and striping front cover of to fit a new one this is when i noticed the timing chain wear, the problem i have to me is not gearbox related it changes gear fine no noises and is really smooth in operation, one thing i thought strange was when i refitted the plug leads on the distrubutor( i had not touched it at all before this), was that the number 1 cylinder in books shows it at a six oclock position or facing the radiator of the car, on my engine its at a eight oclock position, or has someone put the leads on wrong and i followed them:confused: i find this thought to obvious, because surely like this it would not run at all, i would appreciate your views on this regards heath. If your car has a hot cam its not uncommon for it to need a minimum of 18-20 BDC timing at idle. when the throttle blades are closed you will probably find it will run best in the 26-30 BDC range at idle. You need to set it where it idles best, then use a dialback gun to check it at 3500 rpm when it comes all in. Adjust the stop in the distributor so it limits your total timing to something around 35. As for the plug wire being in the wrong spot they probably just stabed it in a different location, this wont hurt anything but might make your plug runs a bit less neat. Quote Link to comment Share on other sites More sharing options...
jt1 Posted November 21, 2009 Share Posted November 21, 2009 Check the TDC mark on the balancer to make sure it's correct; Check your timing at idle and whenever all the mechanical advance is in; Make sure all the vac nipples on the eddy are capped. I don't think a lack of vac advance is causing your problem, something else isn't right. jt Quote Link to comment Share on other sites More sharing options...
240zchevyv8 Posted November 22, 2009 Author Share Posted November 22, 2009 Hello thank you for the advice, i worked on the car today and put car to top dead centre and looked at the harmonic balancer mark, it was virtually bang on 0, i then removed distrubutor cap cleaned all the terminals, and fitted new plugs gapped to 38 rotar arm was right over number 1 plug lead so i know that the timing was right, but when i took car out for a spin it still stumbled also when i stopped the car and came to restart it it srtuggled to turn over, meaning the timing was out, but nothing had moved, i checked timing and was at the 12 oclock position on the balancer and not at the 2 oclock position for 0 where it was set up, this would indicate at least a 30 degree before top dead centre, is it possible that when i changed the timing chain and sprockets, that the crank shaft timing is slightly out because i did not line up the holes like i should have done, meaning that the timing is in but the valves are not quite right i then adjust the timing using the distrubutor cap to bring it in line with the valves, then the timing is out, only slightly but enough to cause a slight back pressure hence stumbling, also could you explain what is an eddy is have not heard that terminology before, what im doing now is stripping down the front cover to check the correct alignment of the cam and crank:violin:i could now kick myself for not doing so first time, i would appreciate your views on this regards heath 240zchevyv8 Quote Link to comment Share on other sites More sharing options...
jt1 Posted November 22, 2009 Share Posted November 22, 2009 How are you finding TDC? Are you checking piston position, or going by the marks on the damper? Do you have the damper off now? If so, look and see if the keyway for the crank key lines up with the tdc mark. Are you using a stock timing cover pointer, or aftermarket? How are you checking ignition timing? "eddy" is slang for an edelbrock carb. It has nipples for vac lines to attach to it, usually a large one on the baseplate and a smaller one higher up. All these should be capped at this point. jt Quote Link to comment Share on other sites More sharing options...
240zchevyv8 Posted November 22, 2009 Author Share Posted November 22, 2009 UREKA:mparty: i think i may have found the problem upon taking the timing cover off, after setting top dead centre with number 1 piston at the top using a wire through the plug hole, i removed the harmonic balancer and the key way was facing the one oclock position which is correct, once i removed the cover saw that the crankshaft 0 mark facing straight up which was also correct, but the camshaft mark was also facing straight up meaning that the camshaft is 180 degrees out, but in my book it says on rare occasions camshaft sprockets are sometimes marked 180 degrees out??? i thought bloody hell how do i tell if mine is correct or mistamped, then it says note the position of the cam sprocket dowel if when the dots are aligned the dowel is opposite the position shown, then the sprocket has been marked wrongly, the way mine is now if i move it 180 degrees to line up the dots the dowel will be as shown in the rebuild book as correctly marked, meaning that it is running with the camshaft 180 degrees OUT is this possible:icon5::icon5:, this may explain the stumbling on de-exceleration exhaust gases trying to escape when the valve is closed, but how is it able to run and dont the valves hit the pistons on these cars if wrongly set up, ill also check for blanks on the carb i know i removed one from the rear of the block that went to the carb, but was told it did not do anything it was behind the distrubutor on the block going to the front of the carb do you know is it needed, or was i told correctly, i would appreciate your views on this regards heath 240zchevyv8 Quote Link to comment Share on other sites More sharing options...
jt1 Posted November 22, 2009 Share Posted November 22, 2009 Just rotate the crank one revolution. Then the marks will be correct. Just joking. It doesn't matter whether the cam dot is at the top or bottom. The line may not be needed, but the nipple on the carb needs to be capped. Track down the line and see what it goes to. Does the keyway in the damper hub line up with the mark on the damper? jt Quote Link to comment Share on other sites More sharing options...
240zchevyv8 Posted November 23, 2009 Author Share Posted November 23, 2009 Yes the keyway in the damper lines up with the timing mark, just curious when setting up the timing should i set the small bottom timing gear on 0 facing straight up, or move it to one of the other marks, there are several markings with various numbers from 2-12 before or after top dead centre facing straight up, could anyone explain in simple terms how to set up the timing correctly, and also does anyone know what effect power wise running the camshaft 180 degrees out will have on an engine regards heath 240zchevy v8. Quote Link to comment Share on other sites More sharing options...
Slow280 Posted November 30, 2009 Share Posted November 30, 2009 If the timing cover is still off, pull the cam gear off and see if you cant see any markings on the camshaft itself. IF there ARE markings, google it and get the cam specs. Sometimes, not always, you may need to degree your cam with a degree wheel. I never have, but I have never built anything TOO radical. The last one I did was a 292 302 duration 488 510. I didn't have to degree it and it runs great, but I also have almost 35 degrees of timing in it. Just an idea being thrown out there. Look at the cam, get some info. Quote Link to comment Share on other sites More sharing options...
240zchevyv8 Posted November 30, 2009 Author Share Posted November 30, 2009 Thank you slow 280 ill look at the cam tommorrow to see if any marks are visable, im going to check the timing first chance i get, to make sure everything is opening and closing as it should. I also think i have a few other items causing problems,these being no PCV valve on the engine block, i removed it before i took the engine out of the car, and it ran ok then, also the edelbrock carburator im sure that when i removed it there was not a conversion plate under it, but it was sat straight onto the inlet manifold, the dual plane type and not the 4 hole type, what effect would this have on running of the engine. i would appreciate your views on this regards heath Quote Link to comment Share on other sites More sharing options...
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