Hello all, new member and as you can tell I'm having touble with my cam timing. (1972 Datsun 240z motor) (cam is recut/ground) New chain and gears, lined #1 on cam gear and lined up on crank mark. Ran engine and alot of poping though the carbs, checked timing again and the chain has poped back 2 positions on the cam gear mark. When installing the chain the tensioners were tight to keep all the slack out of the chain. Went back in, retimed and tightened adjusters, now it still pops through the carbs and the timing has jumped back 1 on the cam gear. What am I missing, any help would be appreciated....Lee.
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Cam timing chain keeps jumping
- Thread starter Lee
- Start date
twoforty
Well-Known Forum User
Hi Lee
Having just finished putting my cylinder head back together I can tell you what I went through.
I thought I had the tensioner wedged but didn't realise it was meant stay like that even when fitting the sproket back on
My tensioner popped out, luckily I managed to get it back in using a long bar and pulling on the chain. I had to mess around a few times to get the timing right but ended up on position 3 as my head is 2mm short of standard.
Maybe your tensioner has come out? shine a torch down there and have a look, I doubt your chain could slip with it in place. Another thing is to only turn the crank clockwise when checking the timing as the slack may give a bad reading if you turn it backwards
Having just finished putting my cylinder head back together I can tell you what I went through.
I thought I had the tensioner wedged but didn't realise it was meant stay like that even when fitting the sproket back on
My tensioner popped out, luckily I managed to get it back in using a long bar and pulling on the chain. I had to mess around a few times to get the timing right but ended up on position 3 as my head is 2mm short of standard.Maybe your tensioner has come out? shine a torch down there and have a look, I doubt your chain could slip with it in place. Another thing is to only turn the crank clockwise when checking the timing as the slack may give a bad reading if you turn it backwards
Thanks for your help Two Forty
Good morning from Vancouver island Canada, thakks for your help on my timing delema. At work I make a couple wedges for the timing chain, lasts time the chain jumped I pulled the front off and alined up the marks again and then it did the same thing. Checked the bottom temsioner last night with a flash light and it's still in place, and supose the front has to come off again and re time once again. The chain is so tight just cant see what I'm missing. Well time to get a couple beers and start tearing the front off, wish me luck.
Good morning from Vancouver island Canada, thakks for your help on my timing delema. At work I make a couple wedges for the timing chain, lasts time the chain jumped I pulled the front off and alined up the marks again and then it did the same thing. Checked the bottom temsioner last night with a flash light and it's still in place, and supose the front has to come off again and re time once again. The chain is so tight just cant see what I'm missing. Well time to get a couple beers and start tearing the front off, wish me luck.
Nigel Brook
Well-Known Forum User
Sounds like something could be binding in the cam area. Is it a new cam? If so did you check to see if it was running freely in the cam towers? Are your tappet clearances right? Is it a mild or race cam.
Nigel Brook
Well-Known Forum User
It occurs to me that as you have had the front cover off a few times, have you got the ignition timing right? ie, the distributor drive in the right place?
Thanks Nigel for you help
Hi sorry took so long to get back, very buisy the last couple day's. The jump chain should now be solved, I was relying on the hydrolic tentioner to do most of the job. Now everything is nice and tight, should have it fired up in a couple of day's. Will let you know how it runs, take care.
Lee
Hi sorry took so long to get back, very buisy the last couple day's. The jump chain should now be solved, I was relying on the hydrolic tentioner to do most of the job. Now everything is nice and tight, should have it fired up in a couple of day's. Will let you know how it runs, take care.
Lee