Rex,
You and Berry may be right about the break-in oil weight, I certainly
don't claim to be a master, but barely competent engine builder. I chose
straight 30w oil on the advice of area racers/mechanics. I also cranked
the engine without plugs to get oil pressure prior to starting the
engine, used plenty of assembly lube on all wear surfaces except the
bores and added a pint of GM EOS in the crankcase.
Every book on high performance engine building I have read, as well as
local professional engine builders ALL recommend running the engine at
2000 to 2500 rpm for 20 to 30 minutes on initial start up to insure
enough oil is available to all reciprocating parts as they wear in.
Admittedly, these books and the local guys are all dealing with American
V-8s, but with the poor upper oiling characteristics of TR6 engines, it
makes sense to me.
My question that was never addressed was, "should I drain the oil now".
Well, I did, and replaced it with 10w40 and a new Wix oil filter because
of the likely presence of tiny metal particles from the initial
settling in of new parts. Cheap insurance and peace of mind.
Thanks for the response,
Jim
"Rex R. Townsend" wrote:
>
> I agree with "Btp44" that SAE30 is little heavy for the initial start-up
> of a newly rebuilt engine. The dozen or so rebuilds that I have done
> (including two TR6s) have all roared back to life with a light oil for the
> first start up on the theory that getting lubrication everywhere quickly is
> very important, and that clearances will never be as tight as they are on
> that initial run. I always preoil the engine before the first start and
> using 10w-30 or 10w-40 makes this easier and quicker.
> Running the engine at a constant speed such as 2,000 rpm when breaking
> it in usually is not recommended, as new pistons rings will not seat in
> properly under constant speed and load. On my newly overhauled engines, I
> employ a break-in technique that my father says was developed years ago by
> Buick's experimental engine department and was recommended later by Tom
> McCahill, the old automotive guru of Mechanix Illustrated magazine.
> Basically the technique is as follows:
>
> 1) Pre-oil the engine until oil pressure is showing on the gauge. Then
> start it up and double check ignition timing and make sure that the idle
> speed is fast enough. The new tight engine may want to idle too slowly
> until it loosens up.
> 2) Drive the car gently to a sparsely traveled road. Accelerate through
> the gears normally until the engine is turning about 2,000 rpm in high gear
> (not overdrive). Accelerate at full throttle until you reach 3,000 rpm and
> then take your foot completely off of the accelerator. Let the car coast
> until the engine slows back down to 2,000 rpm and then repeat the full
> throttle acceleration back to 3,000 rpm. Repeat this cycle about ten times
> and the new rings should be properly seated (assuming they were correctly
> gapped and the proper cross-hatch pattern was honed on the cylinder walls).
>
> The theory behind this unusual technique is that the full throttle
> bursts create maximum pressure in the combustion chambers to properly seat
> the rings and valves, and that the in-between coasting periods create high
> vacuum to suck oil up the cylinder walls to lubricate everything and prevent
> excessive wear or hot spots on the cylinders. In fact, if someone is
> following behind the car being broken in, they may see little puffs of blue
> smoke come out the tailpipes between each cycle of the
> deceleration/acceleration routine. This is normal and good, as it shows
> that the cylinders are actually getting an extra dose of oil with each
> cycle. The smoking will stop as the rings seat.
> My experience with this technique has been excellent. The only car
> which I didn't employ the technique was my Healey 3000 Mk3 which was fitted
> with 5-ring A&E pistons and chrome moly rings. I followed the instructions
> which came with the pistons which only suggested gentle driving at changing
> speeds. The car always burned a little oil the rest of the years that I
> owned it! I think that those chrome moly rings really needed that
> on/off/on/off treatment to correctly seat, and that the gentle driving I did
> never loaded them enough.
>
> Regards,
> Rex Townsend
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