Club 80-90 Forums

This has slid down the board a bit

My fixture needed a little re-work to improve the location and get consistent results, esp. around the little end (they now have wall thickness controlled to under 0.02mm which is a lot better than the Oettinger rods)

So... ConRods v2.5 are now machined and ready to go for re-sizing, new OEM bolts etc. I popped them on the scales, less than 3g total variation across the four, I reckon we can live with that (619.1 to 622.0g)

Pics shortly...

Better do a set for myself while the machine is set!

Still got a few clearance snags, rods and pistons ok upon the last dry build the camshaft/big end bolt clearance wasn't quite right (the old Oetti cam is now looking well carved about) and two of the big ends just clip the top of the case, so that needs a tiny bit more work.

Its no exaggeration to say that the 82mm stroke really pushes the 025 architecture to the limit.

At last! One set of lightened, rebushed & resized conrods arrived in the post, fitted with my LAST set of con-rod bolts.

Now I can get the last bit of clearance work done and get the bottom end assembled

Getting more and more excited Ian! Been away in Northumberland and Dales for last two weeks so just catching up as I've got wifi on my phone for the first time for ages. See you at AO I hope.

Pete

I have to be at AO, too many people to see already

Hot off the press: Final dry assembly with rods and pistons, roll the crank over and it all clears!!!!!!!!!!!!!!!!!

(insert shiny pic here when I get home)

A good way to end the week.

Slight aside: I have weighed some pistons.

DJ 593g
Oettinger 537g
Omega 516g

This is very good news because a lighter piston puts less strain on the big ends, so it increases bearing life

Bling!
Next job: dismantle again, time the cam, get it all torqued down.

PS with my case clearancing work, the big end bolt heads only needed a touch on a flap wheel, as opposed to the carving that Oettinger gave them...

Will take a pic later for that!

silverbullet wrote:Bling!
Next job: dismantle again, time the cam, get it all torqued down.

PS with my case clearancing work, the big end bolt heads only needed a touch on a flap wheel, as opposed to the carving that Oettinger gave them...

Will take a pic later for that!

Engine pron!!!! Love it

Its not easy to show the difference in my approach to rod/case clearance work compared to Oettinger, but this is the critical half-stroke point, looking through the gap and showing my mods:

Its all very tight in there!

Looking good Ian

Sweet !!

An afternoon hunched over the bench, ear defenders and specs on....
Yes, I have been doing some basic porting to get these AMC's more like the correct shape down the pipes. They all need this it would seem:
Before. Steps, ridges, snot.

After. Short side turns all sorted and even the exhausts got a bit of attention.

The camera doesnt really show the extent of the work, but they are now a lot closer to equalized than before. No shiney polish nonsense, its all about having good profiles and smooth port forms.

The valves will get a little attention too, the standard ones lack a shallow angle back-cut between seat and head/stem transition which really is a flow-killer. Only takes minutes to do the lot but makes a difference.

silverbullet wrote:The valves will get a little attention too, the standard ones lack a shallow angle back-cut between seat and head/stem transition which really is a flow-killer. Only takes minutes to do the lot but makes a difference.

How are you doing that, in the lathe?

Yep. Held in a collet (not a chuck!) and carbide tools for 21-4 stainless.