hardening cam and possibly followers
Turbo Mini Forums

good evening chaps

today i set the tappets on my daily drive mpi cooper. i built the engine aprox 30k ago. it has all of the usual mpi upgrades - bored +73, raised compression, ported head, sw5i cam, roller rockers


however when setting tappet on one of the inlet valves the spring compression was vastly less in comparison to the others. there is something amsiss here - my guess is that one of the cam lobes is quite badly worn. i have seen this before on my brothers old 1380

i doubt that the 1.5 roller rockers have helped matters. also the fact that im running unknown poundage double springs on the head.

the car runs well but does feel down on power to me compared to how it used to feel. i am going to restore the bodywork this summer, but later in the year i plan to take another look at the engine situation. minisport offer Tuftrideing prosess on crank/cam/other engine components.

im a bit diaspointed that such wear has happened after such little mileage. replacent billet sw5i cams are 250 plus, i am thinking about getting the cam and followers treated to help prevent this happening again. im also going to use the matched springs. has anyone else ever had a camshaft hardened or can anyone see any problems with this?

whilst the engine is out it will give me the opertunity to sort a small gearbox issue, decoke the head and fit some rimflo inlets that i have, check the bore and hone if needed - basically a check and rebuild.



cheers, dan

I dont really see why it would wear on just one and not all the others.

well it seems something in the valve train has worn. be it the cam lobe, follower, pushrod! my moneys on the cam, as stated i have seen a 286 with one of the lobes worn right down....

I wore out 1 lobe on a billet 296. Usually it will be because the follower isnt rotating in its guide due to a bit of debris. Being a Swifty cam speak to them - it wont be a quality issue.
What size gap are you setting at the rocker tip?

Edited by paul wiginton on 27th Mar, 2012.

I seriously doubt it!

Get the cam superfineshed and the followers dlc coated piper do the work to the cams and some Internet research should help you find a company that can do dlc coatings, also don't set your springs to more than 200lbs over the nose mine are 160 and 180 in/ex but my engine will probably never see 7k rpm

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[quote=fab,8th Oct, 2010]fuck off

Depending on the vintage of the SW5 it may well have lost a lobe or two.
The one I took out of the wife's GT (professionally built by a "name") had a millimetre missing on one of them...

Metric is for people who can't do fractions.

setting them to aprox 14thou. by the looks of the lack of spring compression it looks like its lost more than a mm. i am awaiting a quotation to get the next cam and followers treated to try to prevent this happening again. also i might have to consider resetting tappets to 16 thou in future? cheers, dan

The spec sheet for the replacement says .015" gap.

All new SW5s are billet instead of reground - wonder why !

Metric is for people who can't do fractions.

Please youtube search ZDDP thats your main culprit........... and as
paul wiginton states

I had a worn lobe on my 295 cam. One cylinder was down on compression, thinking the worst I assumed it was rings and built myself a turbo lump to go in its place, to later find it was just the cam.

Have you done a compression test?

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1/4mile in 13.2sec @ 111 terminal on 15psi

cheers for the input chaps. i think i may look at getting the cam and followers hardened, as well as some additive for the oil. i currently run on gtx which i know isnt specific to older engines but thought an oil of this name/quality would have offered a little bit more protection. also i did a compression test on the car a month or two ago - i cant remember the exact figures but two cylinders were the higher side of normal, two the lower side of normal. i put this down to butting the head together without having the valve seats recut after changing the guides - i just ran out of time and needed the car for work...

when i strip it next time i will inspect everything, change the cam/followers, change the 1st motion gear (as there is a slight crunch into 4th sometimes - the cone is worn), im also considering having the standard mpi flywheel lightened a bit. i also have some rimflow inlet valves, wiull change these along with the springs and get the valve seats sorted. cheers, dan

The cams and followers are hard enough. That's not the problem

I always pre-lube the cam with Graphogen. That means that if the engine sits for a few months then it will be OK during those first few turns of the engine when the lobes do not get any oil.

Also I don't fill the engine with oil until just before the first start. That way the cam gets oil from draining down the pushrod holes.

Then, when I first start the engine, I take it straight up to 2000rpm and leave it there for half an hour if possible.

Get the lube and start up right and your cam should be fine.

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