mk1-forum.net

The guy who posted this knows what he's doing.....

2. Minispares 1.5:1 forged rockers, C-AHT436
I was warned that the valve lift on currently sold ones (unlike those sold years ago) was all over the place, so after bolting a set on a fresh motor, I checked all the lifts. I used a fresh RE13 cam and checked each rocker in turn on the #1 exhaust valve position (easy to test and remove each time from there).
With .019" rocker clearance, they ranged from .416" to .438" lift and I wondered WHY...?
a. All the adjusters were .020" undersized on the threads and loose in the rockers.
b. 7 of the 8 adjusters were bent in heat treatment.
c. All 8 nuts were loose on the threads (est 50% thread engagement).
d. The nuts only touched the rockers at 1 point, because where they seated on the rocker was not machined square to the threads.

After replacing all 8 adjusters and nuts with A+ ones, and machining the top of the rockers square where the nut sits, the lift range improved to .419" - .433", with most in the range .424+ - .430".
Worth using now after this work, but not perfect.

Cheers, Ian

Why not just send them back for comment from the makers.

Pete

I've just noticed this was two and a half years ago!!

What all that about then, it was probably sorted then, why post now.

Pete

Interesting ! Especially if you've got or are buying old rockers !

36inter wrote:I've just noticed this was two and a half years ago!!

What all that about then, it was probably sorted then, why post now.

Pete

Sure you aren't looking at the joined date? The original message was posted on Ausmini on Friday.

http://www.ausmini.com/forums/viewtopic ... 427#894427

Tim

I'm pretty sure it's not the rockers at fault here.

Tim,

You are right of course, I must learn not to be a complete muppet and engage brain before posting, thanks for being so polite, you should have been completely ruthless and called me a TWAT.

Pete

Spider wrote:I'm pretty sure it's not the rockers at fault here.

I always feel that matters like this can be addresses more constructively with the manufacturer / supplier than on a public forum.

Its difficult to comment of the problems the original poster had with the c-aht436 rockers, as there is no indication in the post as to when they where bought, so its impossible to judge which batch they came from.

There are six different suppliers involved in the production of this part, and there have been (from memory) four seperate batches (of the actual rocker arm) made, each batch has improved as various ideas have been tried out. The problem with anything that is heat treated is that it will alter in dimension slighty, so as these have evolved as a product different methods of heat treatment and grinding of the pad area have been tried. The current batch is just about bang on really. The lift is just about perfect now.

Adjuster screws are a constant bug bear in these cast rockers, the top and bottom tolorance of the thread rolling can alter so much, plus how the threads alter in size from the heat. we scrap a vast quantity of the things off, i weighed nearly a full wheel barrow full in for scrap the other month!

We usually hand select them for use in the roller rockers (its possible to see by eye which ones are 'best') as they alloy rockers are very intolorant of poor adjuster screws (due to the grabby nature of the anodising), the remaining ones are then used in the cast rockers, but if they are too tight or slack they are discarded. I dont however assemble the cast rockers as they are a 'budget' part and there isnt enough money in them to pay me to sit and hand sort adjuster screws for them. We simply count the component parts and box them up for the warehouse lads in London to assemble and box them up.

ive just looked at a random selection of 20 rockers here and cannot even get a 2 thou feeler gauge between the nut and the top of the arm (even though the nut is not 100% flat), it only takes a few seconds to pass a file over the top of the rocker to sort this 'problem' out.

we are looking into getting a cnc machined super dooper adjuster screw made, but of course the price will go up as they will cost a bit to make, they could easily add 10-20 quid to a set of rockers.

i must say though, we have sold over a thousand sets of these rockers in three years, and people like swifty are happy to buy them in quantity and use them in his race engines (although, to be fair, he does use and expensive adjuster he sources himself).