Austarion

Hey guys,
I've got all the rocker gear off to do stem seals, can i swap the standard cam with a camtech stage 2 i've got here without changing anything else? Or are there bearings etc i have to change? Have all the seals etc but while I'm this far into it I'll change the camshaft if it's a simple swap.

Cheers

David

there's no camshaft bearings in the head - so long as the can journals on the head aren't too scored it should be fine to put in the new camshaft, assuming that it's designed to work with the factory rocker gear etc. On my old 4G37 I swapped over the camshaft and roller rockers over, and all was well.

*edit* might be a good idea to use a engine assembly lubricant when assembling the head back together, a dry head probably wont get a decent oil supply to the cam for a few seconds on startup. Follow the running in procedure for the cam too (pretty important).

Cheers Phil, head is still on the block. What is the running in procedure for cam? different for each cam or the same.

Thanks again

Just hold it at about 3000 rpm for 5 mins

cheers

if it's a new cam the running in procedure is usually supplied with the cam spec sheet. if the cam isn't new then maybe the running in procedure isn't required.

*edit* sorry when I meant putting the head back together, I meant putting the cam back into the journals and bolting the rocker shafts and cam caps back down, to just use either engine oil or engine assembly grease.

An oil with a high amount of zinc is recomended for our flat tappet type cams.
Eg Penrite HPR range of oils.

any decent engine oil these days will do a good job. remember when our engines were designed and built there wasn't exactly any spectacular oils around, namely 30/40 multigrade SC, SD or SE grade if you were luckly. These days with SM grade 15W40 or 20W50, they offer more than enough protection for our engines. the sirius engines have good oiling to the camshafts, and I can't see them wearing out cam lobes and rocker gear anytime soon just by not using Penrite oils.

My old 4G37 with had 400,000+kms on it before I swapped over to roller rockers and the accompanying camshaft - there was no measurable wear on the lobes and rockers when they were pulled out, and they're the same setup as our 4G63s.

Your probably right.... I don't think that it makes a huge difference, but when I spoke to the guys from Camtech when I bought my stage 2 cam off them, they recommended Penrite HPR. The flat tappet cams have a huge amount of pressure at the contact surface and the zinc content is said to bond with the cam lobes and create a protective coating. Some new high tech oils have little or no zinc and hence reduced protection for our older application. The stage 2 cam will be operating at higher surface pressures due to the faster lift profile than a standard cam.
My 2c...

that is a fair call - I heard that the more modern the oil is the less zinc it has - yet zinc content isn't a factor in the oil grade testing, so an SM oil can be worse for your engine than a SF/SJ grade oil. But as far as I know it wasn't confirmed and the claim was dismissed by my oil rep.

on this subject on the net, unfortunately its all relevant to american and euro market, the oils sold on the australian market do generally have a high zinc content, as our vehicle fleet is on average a lot older than those markets.

All good info thanks, will get onto it tonight.

Use engine honey as well......Oil will take a little while to reach the cam on first startup.

Alspos wrote:Use engine honey as well......Oil will take a little while to reach the cam on first startup.

Yeah, some cams come with a paste or moly lube that you smear on the lobes for the first couple of revs before the oil gets there...

my custom JD houses a HKS rally cam ( custom re-grind ) best thing ive done :D