Thread: Just bought a 2A

Bit of advice needed on the internal engine parts.


I think I just need a hone, new rings and mains. Measurements as follows:


Mains - 63.22 64.24 64.22 63.22
Big ends - 58.46 58.47
Thrust washers - 2.33 2.34
Bore - 91.17 on all of them


Also on the 2a engine what colour should it be painted, its not going to be a show car but I'd like it as standard as possible.


Thanks in advance.

Here is what the book states:
However it is in imperial (inches) measurements so you can do the conversions.
They have the Bore Dia in Metric which is odd!
However in Imperial it would be 3 9/16" or 3.5625"


Bore: 90.47 (they have this figure in metric).
Main Journal Dia: 2.4995 to 2.5
Main Bearing Clearance: .0008 to 00285
Main Journal Minimum Regrind Dia: 2.460
End Float: .002 to .006
Crank Pin Dia: Early Model 2.126 (cannot be reground)
Crank Pin Dia: Late Model 2.312
Crank Pin Minimum Regrind Dia: 2.72
Piston:
Clearance top of the skirt: .003 to .004
Clearance bottom of skirt: Series 2, 2A: .0019 to .0023
Series 3: .0019 to .0024
Compression Rings:
Gap: .015 to .020
Clearance in the groove: .0018 t0 .0038


Oil Rings:
Gap: .015 to .020
Clearance in the groove: .0015 to .0035


Hope this helps.
Cheers, Mick.

Well just dropped the engine off to Mendham engineering, they are going to check the block, crank, pistons, rods ect. Acid dip it to clean the inside of the water jackets, I've also opted to have the head rebuilt and machined for unleaded fuel.


Once they have finished I will know what parts to order and I can start the rebuild, looking forward to this.

I'm really curious how the convert it to ULP can you please keep us posted as to how the process goes.

Thanks

Nathan.

I thought the head already suited unleaded petrol without any modification. What do they intend to change?

Aaron

They fit inserts to the head which are harder, I'll take pictures when I collected them. I also read that they don't need doing, but then read on one of the UK forums that they do, so decided that petrol wasn't getting any better and opted for them to be done! Another reason was I couldn't see my lad adding upper cylinder lube to the petrol every fill!

The 2.25 engine, because of its low compression and good valve seat cooling, is mostly unaffected by use of unleaded. However, if used extensively for high power operation for long periods, such as long distance freeway travel or some stationary operations, valve seat recession can occur.

The fix for this is to fit hardened steel valve seats, as is required for many engines that are designed for leaded fuel. (This engine was designed to tolerate a wide range of fuel) Many people, seeing the publicity about hardened valve seats on "leaded" engines in general, assume that they are necessary for this engine, and it is a not unreasonable thing to fit hardened exhaust valve seats if you are overhauling the head, although little is lost if you leave it until you actually encounter valve seat recession (I have been running mine for years without hardened seats, with no signs of valve seat recession - easily detected when you check tappet clearance at your regular services).

Note that the six already has hardened steel seats.

John

Good post John, I think while the engine is in bits it will be worth doing, I wouldn't bother taking the head off just to fit inserts.