Rocker Arms aftermarket vs original

Hi everyone...

I have a question for those with more experience. Are the £3 aftermarket rocker arms a disaster waiting to happen? Or are the £30 genuine ones a rip-off?


Having removed and dismantled my rocker assembly I've noticed there's a bit of play in the rocker arms. I thought about trying to change the bearings, but I'm not confident I'll line up the holes for the oil ways.

I noticed "quality aftermarket" ones are very cheap, where the genuine ones are 10 times the price. I've also noticed plenty of people with cracker rocker arms.

Not sure what to do, so looking for some advice and experience.

Thanks!!

Never used an aftermarket one so can't really comment on quality but bear in mind the old price / equality equation. Have you measured the rocker shaft itself to see if that is worn or are there grooves / steps you can see / feel on it? There will be a little bit of play anyway as there has to be a working clearance for the oil and thermal expansion, its just a matter of confirming if your actual play is within spec or not. Have you tried sliding the arm along the shaft to an unused section and checking again?

If it were me, and the play was in the arms then I'd probably go the re-bush route after checking that the rocker faces (where they touch the valve stem) are in good / pristine condition. However if you do actually have wear in the bush then the faces could be worn too. If you aren't confident in aligning the oil ways you could always take them to an engineering place, cant imagine they would charge too much to press 8 bushes.

Most rocker arm cracks that you have read about are generally a result of cambelt failure, but that is more a maintenance error caused by neglect or leaking oil seals degrading the belt prematurely.

Turn the rocker shaft through 180 degrees and see if the wear is still there.... it could be the shaft wear not the bushes. I had almost no wear on my bushes at 140k but there was some wear on the shaft.

So, I did actually check the shaft with a micrometer; less than 0.01mm difference across the length. The rocker bearings aren't down to the second layer of metal, but I'm not sure how much play is allowed. Basically, if I hold the tip on the valve end, I can feel it move slightly side to side. Not loads, but if it was a wheel bearing I'd be changing it. Interesting point about having space for oil though.

Might have a go at changing one of the shells at work (we have a press), then use to compare to the other.

In general; Britpart - good or bad? Or does it depend on what part?

Thanks!

That sounds like mine when I looked at them. A dial gauge on the arm showed a clearance of about 0.1mm on the arm - installed and they went to Romania and back with no problems.

If there is only a slight side to side movement on the end of the arm I think it's fine.

Britpart if the part number suffix ends in G then it's an OEM spec part. Otherwise I wouldn't trust them from the crud I've been supplied with myself...

Suffix G... Understood. Cheers for the tip!

Valve stem oil seals and caps ordered; and a few tools to get it done. I don't see any reason to change the springs, unless I'm missing something?

Considering trying to offer some of these guys at the hand car wash a few notes to blast the gunk off the head and the inside of the intake manifold with a pressure washer. Shiny engine is good engine!

If you are taking the head off then I'd probably do the springs myself since the heads off... (unless you are doing the springs with the head on? Is that even possible?)

The head is off... You can get a spring compressor which will work with the head in - it looks like a lever, where the pivot bolts down to an exposed thread in the head.

I've only got the engine, no vehicle as of yet. Plan being to build one up over time.

Then I'd be rebuilding the head - so measure valve stems, guide wear and swap as needed. Lap the valves in. New stem seals, springs, seats and collets as a matter of course for me regardless. For the cost of them compared to the aggro of swapping the head on and off it's a no brainer.

I'd also at the minimum have the mains and big ends off and check for wear and measure the journals, and the bores.

There is also a known issue on certain of the core plugs that weep/leak so whilst the block is easily accessible I'd check all them.

Engines are not meant to have water inside them though. I'd steer clear of a pressure blaster as it may start surface corrosion where you don't want it...