15 replies to this topic

[m1n1]

Stripped down my 1380 for inspection, asked questions in previous topic about wear in conrod shells.. now i'd like any input on wear on the cam followers.

in the 9 years of owning the engine, this is its fourth stripdown. (It was not making any bad noises i just damaged the gearbox)

first strip was damaged gearbox
second strip was me putting half moon seal on wrong way around..
this time its damaged 1st gear and synchro.

every time i have this problem and i do not know why. i have always run it in for 25 mins at 2000 rpm at start up.

origionaly i was using a kent 276 cam with mini spares followers
the second time i used a kent 286 scatter with mini spares followers
the last time i used a kent 276 cam with kent followers. (also new cam bearings and lots of lube)


why is it doing it? ive got 3 cams which arent much good now :0(

could it be double valve springs and roller rockers?
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[liirge]

Wowzers! what is the spring poundage and the rocker ratio?
also with something like a 286, are leaving it on idle? followers would hate this

[Cooperman]

Heavy valve springs, high-lift rockers and high revs will all contribute to followers getting 'sh*g**d out quite quickly.
If you are stripping and re-building once every 2 years on a high-output high revving engine that would seem reasonable. With that sort of spe a strip every 15000 to 20000 miles would seem about right.

[liirge]

what about the idle time? i think this could be an issue...honestly cams like this hate road idle time!

[Cooperman]

what about the idle time? i think this could be an issue...honestly cams like this hate road idle time!

Especially with heavy poundage springs.
What sort of revs do you use? The roller rockers will make things worse and won't actually gain you very much, if anything. I gained 2 bhp with roller rockers, but only at 5700 rpm and above with a 286 cam.

[liirge]

yup as cooperman says, High poundage, higher ratios are not good on the cam followers, especially when combined with a lot of idle time

[MRA]

And of course you are not running an oil cooler........ this looks like oil film breakdown caused more often by excess oil temperature..

And or too slack on the valve clearances.... are your rocker pads worn ? as this forms a bridge for the feeler gauge, which means that too much clearance is obtained

Edited by mra-minis.co.uk, 24 July 2010 - 09:23 PM.

[m1n1]

i never really abuse it to be honest. The drive to work takes 30-45 mins mostly on an a road and of an evening its usually crawling. So yes idling/slipping clutch so it doesnt stall to drive at 5mph.
the head is a med clubman head with double valve springs.. think they are 240lb's! im not racing it tho,, i dont even go near the red-line.

the last rebuild was in 2005.. so im getting better at putting it back together!

perhaps if i had weaker springs?? but what type?

[m1n1]

And of course you are not running an oil cooler........ this looks like oil film breakdown caused more often by excess oil temperature..

And or too slack on the valve clearances.... are your rocker pads worn ? as this forms a bridge for the feeler gauge, which means that too much clearance is obtained

i was using an oil cooler. only a ten row tho.
i was using roller-rockers for 4 of the 5 years at 15 tho .. then i got hold of new old stock std rockers and ran them at 12 thou - (bit better in traffic)

[MRA]

Well that type of damage looks like metal to metal contact, which is usually caused by the issues stated in my last post, however you are telling us that neither applies...... curious

[Ethel]

240lbs is a lot with high ratio rockers. You could run original springs with a 276. If you're in neeed of another cam you could look at the Swift ones that are developed with hi lift rockers in mind.

[MRA]

Yes they are excessive for a 276, and could also go a long way to explaining the excessive wear rate

Also the slower the speed the more the wear on valve train parts, hence why you bed them in at 2500 to 3500rpm for 30 minutes

[m1n1]

yes i think im giving kent cams a miss from now on. what can i do with my 3 x old ones? are they paper weights or can they be reconditioned.


i am going to try one of those sw5 things with different springs.. lets see what happends in another five years!

thank you all for your advice.

[mini13]

what oil and how often do you change it?

Edited by mini13, 24 July 2010 - 10:38 PM.

[Southy]

And of course you are not running an oil cooler........ this looks like oil film breakdown caused more often by excess oil temperature..

And or too slack on the valve clearances.... are your rocker pads worn ? as this forms a bridge for the feeler gauge, which means that too much clearance is obtained

i was using an oil cooler. only a ten row tho.
i was using roller-rockers for 4 of the 5 years at 15 tho .. then i got hold of new old stock std rockers and ran them at 12 thou - (bit better in traffic)

I know for a fact that that Kent state in there book that the 286 valve clearence should be set at 14 thou with standard rockers, I'd imagine that the 276 would be similar so this could be some of your issues.