Povi Posted December 24, 2022 Author Report Share Posted December 24, 2022 I see. So the fact this rattle occurs most at idle and lower rpm seems counter to that idea. Perhaps I pull the front cover off and have a much better look down there Quote Link to comment
datzenmike Posted December 24, 2022 Report Share Posted December 24, 2022 Well I don't know how much 6 pounds will add extra tension to the chain but 2 or less at idle might be more noisy. Besides, the tensioner won't make a chain quiet if the chain guide rubber is worn away 1 Quote Link to comment
Povi Posted February 9, 2023 Author Report Share Posted February 9, 2023 Okay FINALLY got the time/space/wherewithal to solve this. Good time to also clean 48 years of grime off the front of the engine since most of it's gotta come off anyway. Pulled the oil pan and hey presto, there's a chunk of the tight side guide sitting in the bottom of it - the top piece above the two bolt holes. Thank god it didn't travel anywhere further. Got the cover off and can see the tensioner has also popped out. I assume the broken piece made the chain slap around, possibly letting the tensioner spring out of its hole. Chain looks okay, nothing damaged, but have ordered a new guide set. Can I just pop that tensioner back in? If the face of it looks healthy? 1 Quote Link to comment
Stoffregen Motorsports Posted February 9, 2023 Report Share Posted February 9, 2023 The tensioner also needs to be soft. If the rubber on the face is rock-hard, it will eventually fail. Installing new guides is easy, but getting the geometry right isn't shown in any of the handbooks. Generally speaking, the guides need to be adjusted so that there are no high or low spots in the chain. They should be even with each other. Sometimes this means filing out a hole in the curved guide or adding a rubber washer behind the plunger on the tensioner so that the chain has a smooth transition. I notice from the pic that the rubber washer on the plunger is broken. This indicates that the plunger face is hard too. Quote Link to comment
Povi Posted February 9, 2023 Author Report Share Posted February 9, 2023 Okay, I'll grab a fresh tensioner too and make sure to have the guides contact the chain as smoothly as possible. Anything else I should look out for? I know the spring in the tensioner is gonna be quite strong, but are there any tricks there for packing it all back in? 1 Quote Link to comment
Crashtd420 Posted February 9, 2023 Report Share Posted February 9, 2023 8 hours ago, Povi said: Okay, I'll grab a fresh tensioner too and make sure to have the guides contact the chain as smoothly as possible. Anything else I should look out for? I know the spring in the tensioner is gonna be quite strong, but are there any tricks there for packing it all back in? Yes get a new tensioner. And the spring actually is not that strong, strong enough but they slide right back in.... The spring works with the oil pressure to keep it extended 1 Quote Link to comment
datzenmike Posted February 9, 2023 Report Share Posted February 9, 2023 The new guide(s) will remove a lot of slack in the chain. I found the spring quite stiff and awkward to stuff into the housing. It's all relative. Hold the tensioner in all the way (zap strap?) and push the right side guide all the way to the left in it's slots against the chain before tightening. If needed file the slots for added adjustment. A worn chain may need this. Then release the tensioner against it. I calculated the oil pressure assist on the tensioner and at 55 PSI it contributed about 8 pounds on the chain in addition to the spring. At idle this would be less than 4. Looks like a small hole on the top so I doubt it builds much pressure anyway and perhaps the oil is just to lubricate and any drips are for the chain and guide.. 1 Quote Link to comment
Povi Posted February 27, 2023 Author Report Share Posted February 27, 2023 Is it safe to assume that if this is how the chain is sitting with new guides and tensioner, it's very stretched and needs to be replaced? Quote Link to comment
banzai510(hainz) Posted February 27, 2023 Report Share Posted February 27, 2023 (edited) NO that not good!!!!!!!!!! this is good get your fingers in there and squeeze the tensioner and move the slack side guide to get a nice smooth arch. I sent my vid to you and you can watch. I notice thqt diffent brand tensioer fit better than others somtimes. Why I dont know but they look the same Edited February 27, 2023 by banzai510(hainz) Quote Link to comment
datzenmike Posted February 27, 2023 Report Share Posted February 27, 2023 You can oval or cut those holes out that hold the guide and then push to the right. Especially the top one. The slack is worsened by having the head milled down. 1 Quote Link to comment
Crashtd420 Posted February 27, 2023 Report Share Posted February 27, 2023 1 hour ago, datzenmike said: You can oval or cut those holes out that hold the guide and then push to the right. Especially the top one. The slack is worsened by having the head milled down. But isn't the chain tensioner too far out already? Something seems wrong to me... Quote Link to comment
Stoffregen Motorsports Posted February 27, 2023 Report Share Posted February 27, 2023 2 minutes ago, Crashtd420 said: But isn't the chain tensioner too far out already? Something seems wrong to me... The curved guide, You slot those holes to move the curved guide over to the middle, which will push the tensioner plunger back in. Looks to me like there may be some head savers involved here. That or a new timing chain. That is a lot of slack. Quote Link to comment
Crashtd420 Posted February 27, 2023 Report Share Posted February 27, 2023 2 minutes ago, Stoffregen Motorsports said: The curved guide, You slot those holes to move the curved guide over to the middle, which will push the tensioner plunger back in. Looks to me like there may be some head savers involved here. That or a new timing chain. That is a lot of slack. I think I get what you are saying.... Definitely needs some more attention... Quote Link to comment
banzai510(hainz) Posted February 27, 2023 Report Share Posted February 27, 2023 (edited) loosen the top of the slack side guid and then squeeze the tensioner IN then hope it come out better. Like I said before I had one where the tensioner want all the way in then I used a different brand and it would be butted up in the tensioner housing. I dont know if the pad was maybe slightly bigger. I did NOT have to slot the slack side guide. Edited February 27, 2023 by banzai510(hainz) Quote Link to comment
Povi Posted February 27, 2023 Author Report Share Posted February 27, 2023 I understand what the chain should be looking like, but no amount of sizing the guide holes will change the fact that the tensioner is that far out already. My question was, if that is the case, should I just replace the chain. It's a pretty worn and neglected car I'm not confident the head was ever milled in its lifetime so chain stretch would be my leading culprit for the amount of slack Quote Link to comment
datzenmike Posted February 27, 2023 Report Share Posted February 27, 2023 Get new set. Quote Link to comment
datzenmike Posted February 27, 2023 Report Share Posted February 27, 2023 Set precisely to TDC turning only clockwise to keep the tension on the tension side. No backing up other than to set up and try again. Now look at the top hole on the sprocket. You should see this... If the U shaped notch in the back of the cam sprocket is over to the right then worn chain and/or sprockets. Quote Link to comment
Povi Posted February 27, 2023 Author Report Share Posted February 27, 2023 Certainly looks the case. Have ordered a Japanese timing chain kit. Quote Link to comment
banzai510(hainz) Posted February 27, 2023 Report Share Posted February 27, 2023 (edited) to me that looks fine. Look like you HAVE set to #2 plus you can set it to 3 if you like also. IF YOU THINK STRETCH Edited February 27, 2023 by banzai510(hainz) Quote Link to comment
Povi Posted February 27, 2023 Author Report Share Posted February 27, 2023 Setting it to 3 will tighten the chain? Quote Link to comment
datzenmike Posted February 27, 2023 Report Share Posted February 27, 2023 No all it does is move the cam to bring it into timing with the crankshaft. 40 minutes ago, banzai510(hainz) said: to me that looks fine. Look like you HAVE set to #2 plus you can set it to 3 if you like also. IF YOU THINK STRETCH I think L18 and L16s were on 1 from the factory so this looks like good cam timing and on #2 so definitely it's been moved to correct for stretch. Quote Link to comment
Stoffregen Motorsports Posted February 28, 2023 Report Share Posted February 28, 2023 Or just moved to advance the cam a bit. Advance the cam for more torque. Retard the cam for higher RPM power. L motors like them advanced. Quote Link to comment
datzenmike Posted February 28, 2023 Report Share Posted February 28, 2023 This is perfectly timed on #2. Each number moved is 40, or the width of that etch mark. If it was on #1 (factory setting) the notch would be way off to the right and out from under the line. A 0.020" cut on the head (an almost impossible amount) is only 0.5mm. The head would be closer to the block by this amount. As the chain has two sides that's 1.0mm of introduced chain slack. Look at the chain in the picture and imagine it moving 1.0 mm. Now look down at the notch on a smaller diameter and imagine it moving about half that. I would think that head milling does not add significantly to the chain stretch. Quote Link to comment
Stoffregen Motorsports Posted February 28, 2023 Report Share Posted February 28, 2023 Sometimes the top and bottom of the head are milled, and maybe head savers were not installed. Just speculating. I feel that the chain is stretched beyond use. And I agree with you that a cut head is not likely the cause here. 1 Quote Link to comment
Povi Posted February 28, 2023 Author Report Share Posted February 28, 2023 Will be replacing the chain once it arrives. I also have to assume that it was running with the tensioner popped out like that for long enough that it accelerated the chain stretch also. the face of the old tensioner was super rutted by the chain. that would have placed additional tension on an already tired chain 1 Quote Link to comment
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