[Healeys] Healey 100 4 cyl (A90 actually but same) Engine Bore Q

Alan Seigrist healey.nut at gmail.com
Sat Dec 22 09:00:18 MST 2007

John -

Inspected it all.  The crank is fine and the cam/tappets are fine.  Nothing
is wrong with any of it, and the motor mostly looks to be like
new condition.  Best as we can tell one of the valves stuck for a brief
period causing the bent push rod so we are running the head for a valve job.


On Dec 22, 2007 6:48 AM, John Harper <ah at jharper.demon.co.uk> wrote:

> Alan
> I believe that you would be disappointed with the result if you did not
> make a proper job of this. If the engine were mine I would bite the
> bullet and get the engine out. You might unfortunately find more that is
> wrong such as a cracked crank but is better to discover the whole story
> now than wonder how your engine might stand up to continued use.
> There must have been a reason for a bent pushrod !
> Regards
> >
> >We pulled the pistons to check the bore and all looks pretty good except
> #4
> >had a broken compression ring (no scoring on the cylinder).  The cylinder
> >bores all look very good with no scratches or scoring.  The bore
> >measurements appear pretty much standard except for #4 which is about 15
> >thou over.  See the table below.  The Standard bore measurment for the
> motor
> >is 3.4375".   All the pistons weigh and measure well so I will reuse
> them.
> >
> >My question is with #4 a little over, can I just hone the cylinders and
> buy
> >a set of standard rings and put them on?  I also assume I want to hone
> the
> >bores?
> >
> >The compression on this engine is only 6.9:1 (standard for the A90) and I
> >really don't want to bother replacing a bunch of stuff.  The old lady
> just
> >toodles about town so a very soft rebuild is all that is necessary.
> >
> >I don't want to rebore the cylinders as it will be a huge pain for me to
> >pull the block, and even bigger pain for me to find someone in Hong Kong
> >that can bore the motor properly.
> --
> John Harper

More information about the Healeys mailing list