1HDT Valve Adjustment Advice

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May 23, 2019
WNY For Now
My 1HDT is currently out on the stand for a refresh. I checked the valves and all were quite tight. Exhaust were mostly around .30mm and intake were .10-.12mm for the most part. Not particularly surprising at 200k miles and likely never touched. Since they all need to be adjusted I plan on just removing the cam, doing the math, shuffle a few/order the rest, and replacing them all at once.

My question is: What should I aim for? The wide end of the spectrum or dead in the middle? I assume these tend to tighten up with age like most shim valves.
Out of curiosity, do you want to take the cam off because you haven't been able to track down the spring compression tool or something? Akella/Yan on here can mail you a kit with all the shims and sst for pretty cheap. It's like a 30 minute job if you have everything there.

Anyway, I did this in March and mine were all tight like yours but only about 110k miles on it. This is completely stock tuning, no mods. I was informed to aim for the wider half of the range or as close to middle as possible without going under. I do think the clearances are meant to only decrease over time so that seemed sensible to me. I also found that they were all equally out of spec, so I didn't end up needing a bunch of different shims for the job.
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It's not specifically a lack of the SST, it's just that the motor is out of the truck and I planned on doing ALL the seals, so cam gear is off, timing cover is off, etc. So not much father to go to just do them all at once. Next time, in 100k miles with the engine (hopefully) in the truck, I'll do it the traditional way. Lol.

Thanks for the advice on the adjustment size. I'll skew towards the high side of the range on all 12.


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