[Healeys] Sprite question for my neighbor

[Michael Salter]

In my experience Steven, that's not how it works with piston rings.
Rings are specific to a particular bore size. If the bore is say 0.010" oversize then 0.010" oversize rings are what must be fitted.
Installing an oversize of ring without accurately measuring the bore and checking that the pistons and rings are correct for  that bore just won't work.

M


________________________________
From: Steven Kingsbury <airtightproductions at me.com>
Sent: Sunday, November 16, 2025 2:24:30 PM
To: Harold Manifold <manifold at telus.net>
Cc: Michael Salter <michael.salter at gmail.com>; Healey Mail List <healeys at autox.team.net>
Subject: Re: [Healeys] Sprite question for my neighbor


The engine was a fresh rebuild when bought. The car was sold because of the excessive oil blowing out after the fresh rebuild. The head was taken off and examined at a local machine shop and passed with flying colors. The pistons and rings were also taken to the shop where the machinist remarked that the rings might have been too small and suggested 10 over rings. New rings went on, everything put back into the engine and again, it runs great, just blows the oil all over the place!
Michael, compression test today after a bit over 100 miles with the new rings: 160, 148, 120, 130. Saw some suggestions on an MG forum for fixing crankcase ventilation. Will see what my neighbor decides to do and will update later. Thanks all for the words.
And just now, after driving the car another forty miles or so, the compression now sits at: 165, 155, 130, 150. So that's getting better. Will definitely take a closer look at the rocker shaft and bushings. Again, thanks to all for the possible foibles facing this engine.
Steven

On Nov 16, 2025, at 8:52 AM, Harold Manifold <manifold at telus.net> wrote:


Hi Steve,

The issue you described with your neighbor's 1275 engine may be related to a similar problem I've encountered.

I know of a recently rebuilt engine that experienced comparable excessive oil blow-by. The cause, in that case, was a poorly refurbished and refitted rocker shaft and bushings. Without adequate restriction between the rocker shaft and the bushings to regulate the oil flow, it resulted in an excessive amount of oil being pumped to the top of the engine.

I hope this provides another avenue for investigation.

Regards,
Harold

On Sat, Nov 15, 2025 at 1:12 PM Michael Salter <michael.salter at gmail.com<mailto:michael.salter at gmail.com>> wrote:
Hi Steve, what you describe sounds to me like excessive blow-by.
I would recommend a compression test before going too much further.

M


________________________________

From: Healeys <healeys-bounces at autox.team.net<mailto:healeys-bounces at autox.team.net>> on behalf of Steven Kingsbury via Healeys <healeys at autox.team.net<mailto:healeys at autox.team.net>>
Sent: Saturday, November 15, 2025 3:33:19 PM
To: Healey Mail List <healeys at autox.team.net<mailto:healeys at autox.team.net>>
Subject: [Healeys] Sprite question for my neighbor

My neighbor bought a bugeye that had a 1275 engine put in it. It runs well, but blows oil like crazy out of the oil cap on the valve cover. It does not have a timing cover ventilation valve, but a fitting was made to fit onto where the old fuel pump fit on the side of the crankcase/block. When he hooked the hose from that fitting to the carbs, oil was no longer being blown out, but oil was then being sucked into the carbs and he was burning oil like crazy.

It seems the pressure in the crankcase is so great it is pushing oil up the push rods into the rocker assembly, out the filler cap and all over the engine. I'm not familiar with the 1275 and have no ideas on how to vent the pressure in the crankcase. Can anyone of you guys point me to a possible solution? Thanks in advance for the advice.
Steven Kingsbury
BN1
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