Valve clearances with aftermarket cams...

[jondee86]

As I'm in the process of re-shimming the valves on my smallport
to install some"mystery" cams, I was wondering if there is any strong
opinion on clearances ??

At a guess the cams are around 272 with 8.5 or so of lift. Stock cams
are speccedfor 0.15-0.25 inlet and 0.20-0.30 exhaust, but to utilise
existing shims I would preferto target 0.25 inlet and 0.30 exhaust,
rather than the conventional 0.20 and 0.25.

Anyone know of any downside to using slightly more clearance, other
than possiblya tiny bit more "tappet" noise ??

Cheers... jondee86

[QikStarlie]

all kelfords 4age cams spec .25 in and .30 exhaust, . so i'd go with that.

cant even remember what i used tbh. but would say i would have used the above specs

[matt dunn]

slightly more clearance = slightly less lift

other than that have stuck that type of head flicking the shims out,
but dont know if excessive valve clearance was an issue.


I know my 20V threw the buckets out when the clearance was too much !!

[jondee86]

Yeah... I saw that some of the aftermarket cam manufacturers spec
a bit more clearance. Used to be pretty much standard practice on
motorsport applications to run a bit more clearance. I've got two sets
of shims, so I will just juggle them around to get as close as I can to
standard specs.

Cheers... jondee86

[atmosports]

Normally they only flick the shims out if the base circle has been reduced too much(I.e reground stock cams), when that happens the shim has to be quite thick to get the clearances right & it either gets flicked out or tipper over & jams wiping a lobe off the cam or destroying a bucket. No problems with shim under bucket though, only when you use the stock setup with the shim on top between the cam & bucket. Not just a toyota issue, seen Nissan's etc do the same.

[jondee86]

These aren't regrinds, but the base circle is a few thou under standard.
Means I need a bunch of shims between 3.00 and 3.15 if I go for
0.20/0.25 setting, or 2.95 and 3.10 if set loose.

Just about all the shims I have here are under 3.00 so I'm going to
need a few of the thicker ones. So if anyone has a bunch of shims
doing nothing in the Wellington area, give me a holla. I'll be there
with my vernier, and we can talk trade goods

Cheers... jondee86

[DFECTED]

If the head is off drop it in to me and ill do it properly, could also work a deal on a 'race' type valve regrind and suface 021 858 081, just started up Custom Works with hayden parker x Import Enhancements and have a full engine reconditioning shop, will do deals for toyspeed members

[jondee86]

Thanks for the offer. Head is still on the engine, and I'm not
planning on pulling it at the moment.

Cheers... jondee86

[jondee86]

Ended up going with OEM clearances. Got it running, but wasn't keen
to start on my existing tune. Probably because the cams are just
installed to OEM timing. I have to degree them to find out where the
centrelines are, and then set to known values. Start off with 108/110
and try a few variations until it feels good

Cheers... jondee86