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Advice after rebuild

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bcbennett

bcbennett

Senior Member
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Hi all,

Just got my '74 TR6 out of the shop...completely rebuilt engine and tranny by bona fide British shop. Since they had to bore a bit, the mechanic told me that I'd have more power, but my car doesn't feel as zippy as I'd like, nor does it seem to want to go over 55 mph easily.

Now: bear in mind that I am heeding the advice to "run in" the new engine (from the owner's manual when it was new), and I've put only 200 miles on the rebuild. Am I being impatient? Will this engine get its legs soon, or should it be blowing away the highway already?

I also rebuilt my suspension...what a nice ride.
 
The best way to wear in or seat the new rings is to drive in high gear and start at about 25mph or so and floor the gas up to about 70 then let off the gas and slow back to about 25mph again and then floor back up to 70mph. Do this procedure about 10 times. The will cause a rapid heating and cooling of the rings which makes them expand and contract and seat with the cylinder.
 
There are a lot of questions and variables here. First, if you had to bore, your engine must've had a lot of slap in the cylinders, ie, flat worn out. Since this sounds essentially like a complete new engine, aside from your rings seating (sometimes as much as 500 miles), nothing would make it run with less vigor than if some or more of your settings may well be off. Are you set to run completely stock? Are your valves set properly, might want to check after a few hundred miles. Timing set to spec.? Have you considered a hotter coil and perhaps centrifugal timing? I would put a few hundred miles and recheck all my valves, timing, gap, and so on. Unless you have had this baby awaile, you might know that these machines were never that hot, just exhilerating to drive and listen to. Patience is a virtue. I would think your mechanic would want to get her back in for a checkup.
Too, a mild overbore will show no appreciable increase in HP, by it's self.
Bill
 
Hi BC,

A fresh rebuild , assuming we're talking about new pistons, camshaft, big & small bearings as well as the normal renewable parts that go along, should be driven normaly for a few hundred miles with out any undo burdon or stress to the motor. This means no sustained redline runs, no lugging the engine (low rpm under load ) . Other than that drive & enjoy.
As far as performance goes , If the mechanic meant the car should be faster because the original engine was low on compression or just way out of spec that depends on the previous condition. Generaly a newly rebuilt motors tolerances are tight & require some run time to "seat" before things spin more freely. It will also require readjusting & tuning after the breakin period as well as retorqueing the head bolts & changing the oil.
Increasing the bore as stated , will not increase HP , in fact it lowers your compression slightly. Unless a performance cam or other parts were modified to increase compression, ignition, intake or exhaust the car should feel the same after the break-in.
 
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