Re: Motor rebuilding questions

[Glenn Merrell <gmerrel@domain.elided>]

Hello Thomas,
	When I needed pistons for my engine rebuild, the only ones I found were AE
pistons, which were the UK flat top style, so I bought them.  One note here: 
When I had the engine balanced, the balance shop had to take a bunch of meat off
the AE pistons, noting that some of them were +15 grams from the lightest one. 
He balances them (all parts) to all within 0.5 gram max across the lot.  I had
thought that the manufacturing tolerances would be less than a gram since the
pistons are all machined, surprise to me!

Just for background, here is the ROM and parts catalog info:

	From the ROM, there were four compression ratios as follows:
LF HE engines up to 20000: 8.80:1
LF HE engines, 20001 on: 9.25:1
LE UE engines, up to 20000: 8.00:1
LE UE engines, 20001 on: 7.75:1

The Parts Catalog also indicate that there were four types of pistons, but I
have only ever seen three types:  Flat top, full dome dished, and dished with a
middle dimple.  All four types are supposed to be available in two grades, "F"
and "G".  
	I also recall that there was a head gasket change in 1972 that increased the
head gasket thickness from 0.040 to 0.055 inch, reducing the compression a bit
(technical notice Volume 1, Issue 12, Issue 49), and never saw a recalculation
showing the new reduced compression ratios from the thicker gasket change.

As for sources for a new oil pump, call John at East Coast Jaguar in Delaware,
(800) 475-9257, ask if he has "new".  If you check with Rimmer Brothers, I am
sure you can request "new" vs "Remanufactured", and they will galdly exchange
your current remanufactured one. for a "new one" if they have it in stock. 
Remanufactured ones tend to have a sticky pressure relief piston if the
machining was not done right, or if the relief piston was not replaced.

Regards,
Glenn  Merrell
Triumph Stag Register USA VP

"Keep Your Stag Cool, Install a NEW Composite Cowl Today"
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Thomas Santee wrote:
> 
> My mechanic is rebuilding my '73 Stag motor. I've over $3,000 in parts
> from Rimmer Brothers and their service has been very good.
> 
> I do have two concerns. The oil pump I received is reconditioned. Does
> anyone have a source for a new oil pump?
> 
> The pistons I received are the U.K. low compression pistons with a
> compression ration of 8.8 to 1. The U.S. low compression pistons are 8.1
> to 1. Would it be better to install the U.K. pistons or try to find a
> source for lower-compression pistons? Is there another source for pistons?
> 
> Happy Thanksgiving to all you U.S. readers.
> 
> Thomas Santee