My rebuild - It's amazing how well it ran

[Randy Forbes]

My mechanic, Russ Thompson, says pistons in a shape like mine are common in LBCs, especially MGs.
I bought the car in 1999 so who knows if the pistons were like that then?

They're not so common that I'd ever seen one in the 115-120 LBC engines that I've rebuilt (mostly MGBs, but with a high concentration of Big Healey 6s, maybe a dozen or so Spridgets, and a handful of TR-250/TR6 & GT6).

I did see one (1) MGB piston that had shown the slightest bit of top-land degradation, but not even so much as to affect the ring groove itself.

Although I am not incline to rebuild my engine, having owned and driven my Healey for so long, I always wonder what triggers enough concern to rip into an engine rebuild...

I think that falls into only a few basic reasons; sometimes the owner of the car just wants it done. This may be part & parcel of other major work, like a restoration (or merely wanting to clean up & paint the engine compartment).

Necessity, either from obvious (or embarrassing) smoking to knocking noises would rank high on the list. Preemptive maintenance, which like in Steve's case, could be predicated on low/irregular compression (or leak down) testing, spark plug readings, or the inability to keep the engine in time (a worn/stretched timing chain comes to mind).

My money says that the Number One (#1) most likely reason people will elect to get an otherwise decent running engine rebuilt, is low oil pressure.

Remember that in the earliest days of the Healey, it wasn't too long after decoking (decarburising) an engine was still commonplace; engines were only expected to see sub-100,000 mile intervals of service. We've come a long way.

 

[RAC68]

Hi Randy,

I really appreciate your opinion as one with quite a background in the mechanics of British marques. Although these engines were not built with an eye toward a 200K+ mile longevity and some resurrected after being discarded for years, most Big Healeys have only gone less then half that distance in the more then 50 or 60 years of their existence. Our Healey 6 does have its issues and some owners, like Steve, have the knowledge to properly address and manage a proper engine rebuild, however, there seems to be quite a number of posts looking for help after an engine rebuild that seems to indicate an unaddressed issue or even something improper in the rebuild.

Just a thought
Randy, your comments are a very good start in evaluating when to consider an engine rebuild. Based upon this start, it could be very advantageous to have a check list for owners to review before entering into a full engine rebuild. This check list could include both operating indicators as well as things to consider and/or include or discard. There may even be this type of list available already that could be modified to focus specifically on our Big Healey engines (4 and 6).

Is there any interest? Should this be a separate thread?

Ray(64BJ8P1)

 

[Bob_Spidell]

Since it's--arguably--easier to remove engine and gearbox together; one might consider an overhaul--or at least a 'refreshening' (rings and valves)--when a new clutch is needed. This should be at around 100-120K miles depending on usage and technique.

 

[RAC68]

Hi Bob,

Your comment seems a reasonable consideration for preempting possible issues from developing rather then waiting till they do. Still, for those that have past that point, what signs would trigger, or have triggered, enough concern to realistically move on a full or partial engine rebuild? Additionally, what should be included in a partial rebuild and should all parts of a given function be replaced or only those parts that show problems i.e. if all other pistons after cleaning appear undamaged, should Steve only replace the 2 that appear damaged?

Ray(64BJ8P1)

 

[Bob_Spidell]

Hi Ray,

Good questions. As my BJ8 engine is undergoing a complete overhaul I've asked myself all those questions--and spent a few sleepless nights--pondering those things. At one extreme, you simply chuck all wear items--pistons, rings, valves, bearings, bolts, studs, nuts, etc.--and at the other you selectively replace or refurbish only the parts showing wear, and do you spring for top-of-the-line parts or just 'good enough?' It depends on your goals, the last time we rebuilt the engine we settled for a hone of the cylinders and reused the pistons, but the engine suffered from low compression right from the start, and I was determined to not suffer that fate again. In my recent teardown, my cylinders needed boring so I needed larger pistons. IIRC, most (all) pistons are sold as sets, so I think that decision was made for me and Steve (unless your cylinders were perfect and you get get ahold of identical pistons). And what about balancing? If you just replace a couple pistons, how do you balance against the remaining four? Can you settle for a (slightly) shakier engine? Will you even feel a difference? I'm having machining and assembly done by a reputable speed shop so I've gone with their recommendations across-the-board; if they said something needed replacement, I bought a new one. Surprisingly, they felt most of the fasteners were OK except for the rocker arm studs, main bearing nuts and flywheel bolts. I was glad they didn't insist on new conrod bolts--they run over $20 apiece! Since nothing I know of on a Healey is 'torque-to-yield' unless a bolt had bunged-up threads or shows excessive stretch they should be OK. My cam had suffered excessive wear and the rebuilder insisted on going through every moving part to check for metal, and I sprung for a DWR gun-drilled camshaft which, surprisingly, wasn't unreasonable considering they include lifters and the pound has tanked against the dollar (the support guys at DWR were terrific to work with). Since this engine has nearly 200K miles on it I decided new valve springs were in order, along with new valves, seats and guides. The head showed surprising exhaust valve recession even though the seats had been replaced with hardened and the exhaust valves with SS at the last rebuild. Go figure.

Another thing to consider is usage; if you only fire up the Healey occasionally on nice spring or summer days for a 50-100 mile tour why 'gild the lilly?' In my case, I drive up to 5K miles/year, often in deserted areas, so reliability is Job1. Yet another consideration is parts quality--you can give your rebuilder a blank check and say replace every wear part, but can they get quality parts? My rebuilder said he's seeing more and more parts from places like China and India, even for common engines like SBCs, and they may be fine, or they may not (and the 'Made in England' part may be repop crap, too).

Now I'm struggling with another decision: My rebuilder will do final assembly, mount the engine on a test stand and do initial startup, run-in and tuning. Probably the way to go, but it's at least another $500 and my wallet is getting pretty thin already, and I always enjoyed the suspense of the initial startup.

And do you go through the gearbox--new synchros, bearings, etc.--or do you leave well enough alone? I left well enough alone, except for replacing the shaft and bushes on the clutch fork.

Bob

 

[Randy Forbes]

Bob, with the trans out, I'd sure be inclined to__at a minimum__replace the layshaft bearings. And well, how much would three (3) synchro rings cost...?

 

[RAC68]

Hi Bob,

I believe you and Randy put this in proper perspective. It seems to me that, as you have stated, an engine rebuild is really a reasonable all-in commitment and the all is determined by the Experienced Rebuilder you choose to go with. Although a few of my friends have rebuilt their own engines (using a favored machine shop and other specialty services) their initial results were mixed and a few required additional efforts to restore adequate performance. When I hear owners talking about their engine rebuilds in a casual manor, I wondered if the job was that easy, were they just lucky, or were they actually involved. Randy make a good point in that most rebuilds are performed as part of an overall restoration or by individual desire and not the result of faulting performance.

Although some owners are open to depend on servicers and merely drive and polish, many who have selected the ownership of a Healey have had to, and wanted to, build a more in-depth experience with their mechanical monster. However, the experience curve of many, including myself, is far short of knowing and being able to make and judge good decisions in a somewhat complex and definitely expensive undertaking as an engine rebuild. To this end, understanding When to address this issue and How is highly dependent upon Who you select to be your guide. The When, for most, is the question I keep coming back to.

Thanks again, I really gained from your responses,
Ray(64BJ8P1)

 

[Michael Oritt]

Unless one has unlimited funds or does not care about whether or not he/she is upside down in a car the decision to rebuild or not, and if so how extensively, should ideally include some reality considerations. Bob makes the point that the car's intended usage be taken into account and I wholeheartedly agree. It is one thing if a car is to be driven 500-1500 miles per year with, perhaps, no road trips planned and one could get by with a lot less than if it is likely to be taken on extensive tours and used frequently. Other factors might be the age, health and activity level of the owner and how long the car will likely be owned and used.

I bought my car in 1999 with less than 20K miles on the odometer and within two or three years and an additional 10K miles some serious engine issues presented. At the time I was driving the car a lot and going to Conclave and/or a long road trip every year. Because I then had little experience with working on LBC mechanics I was forced to have the engine professionally and expensively rebuilt and I took the opportunity to replace all top and bottom-end parts with top-notch stuff, which translated to about everything except for the crank. Since then I have logged another 60K or so miles and though my usage of the Healey has decreased considerably since I got seriously involved in vintage racing (other cars) I think the decision to go big has served me and the car well.

If I were faced with the same situation today I would proceed from the perspective that I probably will not be traveling more than 100 miles from home very often. Saturday my wife and I drove the Healey over to Saint Michael's MD for the day and if something let go it would have resulted, at worst, in a trip home on a rollback which would have been covered by insurance. Unlike a race weekend where a breakdown becomes a waste of considerable time and money invested the Healey's potential failure would just not be that big a deal. Plus I have gained considerably more mechanical skill and knowledge and would be less likely to feel a complete top to bottom engine rebuild necessary or comforting.

Don't get me wrong--I like my car to run well and I leave the garage with every expectation of driving it back in under its own power. I just don't believe I will be likely to find myself in the middle of Kansas worrying about the inconvenience and effect of every cough, miss, tick or rattle.

 

[steveg]

They're not so common that I'd ever seen one in the 115-120 LBC engines that I've rebuilt (mostly MGBs, but with a high concentration of Big Healey 6s, maybe a dozen or so Spridgets, and a handful of TR-250/TR6 & GT6).

....

Maybe I misinterpreted how many he was talking about. Mine weren't the first he'd seen. In my case it's 100% of the AH rebuilds I've been a part of.

Wish I knew for sure what caused it - whether it was my tinkering with lean UL needles while at the same time using headers. I've run regular gas quite often - maybe that's the problem. Maybe California gas is part of the problem.

Wondering if too much advance causing detonation could have caused it only on #2 & 3 or if damage would have been more evenly distributed.

Wonder if I caused it at all - maybe it was that way in the 1990s before I bought the car.

When I get it back together, it'll be premium gas and 32 degrees approximately on the advance.

And planning on installing a knock sensor.

 

[Bob_Spidell]

Bob, with the trans out, I'd sure be inclined to__at a minimum__replace the layshaft bearings. And well, how much would three (3) synchro rings cost...?

You're right, of course Randy (as usual). But, we went through the gearbox at around 70K miles and the layshaft bearings were OK, but the shaft was warn (I think this manifests itself as a whine in 1st, 2nd and 3rd?). I'm putting a ton of dough into the engine and decided to roll the dice on the gearbox and OD; I'll probably only put another 20K or so miles on this car and I think the odds are OK. I did query the mailing list on an OD rebuild, and the consensus was 'let it be;' even with almost 200K miles they're apparently good for even more if not abused (and I always babied the gearbox).