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Talk about engine building here. New products, tricky questions or showcase your work - If it's engine building related it's welcome here.
I have a 93 240sx with ka24de and got an osk timing kit for it due to dealer not having a full kit due to being discontinued. From what I have read this is supposed to be the OE kit. I have also read the tensioners and bolts supplied with kit have common failures so I was either going to get a tensioner from my Nissan dealer which last I checked they could get which was a year ago or go with a ratcheting one to eliminate known issue with chain slack on this engine. The group I am in on FB talks a lot about a guy that sells the mechanical ratcheting ones which keeps the chain tight which I have heard might be better for upgraded valve train which i do have upgraded cams and springs but nothing crazy. I am hesitant to go away from OE but have read people even have trouble with the OE tensioner and tac weld the caps in place, so they don't come apart on them. My question is should I go with the self-locking ratcheting style that keeps tension on at all times or try my luck with the OE which may or may not give me problems. Quick overview of build is 10:1 compression stage 2 cams with recommended springs from cam card. Turbo E85 build with all supporting mods with around 500whp and will be daily driven. I was reading ford is going away from ratcheting tensioner due to chain stretch issues, so I am getting info to go both ways. Thanks for all help and suggestions.
I'm not that familiar with the engine, let alone its tensioners.
Just to clarify, the hydraulic uses oil pressure exclusively, and the ratcheting option uses what to tension the chain - a spring, or...?
The hydraulic tensioners I am familiar with, on different engines, used a combination of hydraulic*, from the oil system pressuring them, to apply the basic tension, and an internal ratchet to prevent the tensioner from backing off and releasing the tension.
* or a spring for non-hydraulic.
The OE ones have a spring and use oil pressure and the ratcheting ones use oil pressure but have teeth cut into them so they never back off unless manually released. I am wondering if my upgraded valve train would make that much difference on first start ups and jumping a tooth when the tensioner is not pumped up. I have read this can be a problem with this engine as a whole.
Seth that's a great question and you've already essentially highlighted the pros and cons of each option. Neither is perfect.
The no maintenance nature of the hydraulic tensioner suits most people's desire to install it and be done with it.
I've not had issues using hydraulic unless the cam and valvetrain are rather extreme. Stage 2 and recommended springs could mean a variety of things so perhaps ask the valvetrain manufacturer which tensioner style they suggest, and if manual, how tight they want it set. If they can't tell you, that would be a bit of a red flag for me, but hopefully they'll have a solid answer so you'll feel confident how to proceed.
In principle, I'd go 100% for the ratchet option - but that's dependant on it being well designed.
With just a hydraulic and spring tensioning the chain there's the potential for a back-fire, or a reverse rotated engine as may happen when spun out and the car travels backwards, to slacken off the chain to the point where it could, potentially, jump a tooth on the leading camshaft, as the chain would be slackened off on that side.
Thank you guys for the input.