Club 80-90 Forums

silverbullet wrote:
A fiver a pop though...

One of those "it is, what it is" situations...

Better to buy new than reuse old ones

Ordering a dozen or so in the morning...

I found 4 dome nuts in superb condition so they went into the mix. Swapped the timing gear for a -1 because I wasn't happy with the clearances when it was stone cold (something funny about the eccentricity if the gear that I couldn't readily identify)
Double check the valve timing and got it closed:

Reworked the valves with a 30 degree back cut, ended up doing them on our Jones & Shipman universal grinder, these look more like the part:

Next job, get them lapped in...

Delays delays....

Waiting for a new piston ring gapping machine to arrive from the USA, waiting for some more carbide burrs to arrive so I can do the last awkward corners on the heads...
At least my double thrust Glyco cam bearings arrived from Florida for my own 2500

Looking great Ian. Good to see the green sealant between the case halves and the new end cap!

Those valves look the business as well.

I bought a small quantity of those end caps (seven) via BW, I think I may have the largest stock in Europe now

They are well and truly NLA which seems daft for what is a Type 1 part

The burrs arrived today so the last bit of port work can be sorted, I couldn't quite reach round into the exhaust ports to remove all the snots from either end...

Some further inlet valve mods.
Turned about 1mm off the head face to get a nice crisp corner (helps to reduce backflow and keep inlet charge in the cylinder) but with a tiny corner break (sharp corners go incandescent...)
Seats are now ~1.5mm inlet, 2.5 exhaust, not the dirty great things they start out with.

Still waiting for my ring gapper...

PS the valves from AMC seem to be very good quality: chrome stems and the heads were tough as **** to turn. The swarf glowed red even with carbide...

Love the attention to detail Ian. This is stuff most engine builders would never even think about.

Its all just detail work to well established principles, I posted this pdf download link in Tech/Modified a while ago, originally written by A.Graham Bell, the authority on all engine tuning:
http://nocoastmotorsports.net/Manuals/M ... Stroke.pdf

silverbullet wrote:Its all just detail work to well established principles, I posted this pdf download link in Tech/Modified a while ago, originally written by A.Graham Bell, the authority on all engine tuning:
http://nocoastmotorsports.net/Manuals/M ... Stroke.pdf

Linkynoworky!

You are right Paul, its gone

"Four stroke performance tuning" by A.Graham Bell

Now in its fourth edition.

It's available if you google it.

A little more detail work. The AMC heads seem prone to having a bit of a post-machining ridge around the valve seats, quite pronounced in the case of the exhausts.
Not great for exhaust flow!
A quick bit of work with a 15 degree hand valve seating tool and it's gone:

You know what this means:

Rings gapped (tedious) and the gaps oriented (agonizing, looked to the samba in the end) then got them fitted for the last time:

Pete you have an email for the last bits needed for me to finish up;)

Ian - you have an e mail in response. On it all!!