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Discussion Starter #1
My 91 NA with 97k miles was smoking blue at start-up and acceleration. I figured bad valve stem seals. Then a coolant exhaust gas test came up positive and I figured BHG. At tear down, my mechanic said there was no warp in the head or block, I saw a few small breaks in the head gasket. Had the following work done: New Toyota gasket/seal set, including factory head gasket and valve stem seals. Cylinder head slightly machined to remove gasket impressions. New head bolts, torqued to 70 ft/lbs. Valves and seats lapped, intake cleaned, new NGK copper plugs cuz I wanted to check for rich/lean A/F mixture. Gas cap, fuel filter, thermostat, radiator cap and coolant flush and fill. The smoke at startup is gone, but it still smokes (blue) like a chimney under medium to hard acceleration. Smoke calms down when I level off at cruisin speed. SO... what could it be and can it be tested without a tear down ? If it's piston rings (the only thing my limited knowledge brings to mind), do you know if it's cheaper or better or advisable to repair mine or maybe buy a new or remanufactured short block. I've got this bad feeling that my paint job money is about to be re-allocated :(
Thanks for your time, michael ... [email protected]
 
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Sorry to hear this. That is relatively low milage for rings, unless you forgot to change the oil for the last 4 years; but with the burning from the valve guides, you must have had almost new oil in it all the time. You didn't let it run dry, did you?

Pull the plugs and do a compression test. To make it easy, start with #6; that one goes bad first in 95% of all Supra engines. If it's above 150 it's not rings. If it's below, at say 110, pour a couple spoonfulls of 30 weight oil into the cylinder and repeat the test. If the compression goes up, it's rings. If the compression is still low, it's the valves. There aren't many other choices. We'll take it as read that the cams got put back in correctly.

You can get a factory block from Toyota for $2400. That would be the base from which to work. You can check on a rebuild with a local shop, or drop a rebuilt or "used" Japanese spec engine in. Since you just had the head work done, I'd go with a short block replacement or rebuild my existing block. (Is it time for high-compresison pistons?) It won't be cheap in either case.
 
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Thanks Yonaga,
I bought it with 62k miles and since I've had it...
OIL - Never got below 3/4 qt short. Changed every 4-5k miles with Havoline 10W30.

CAMS - The car runs as strong as before the work. Is it possible to put the cams in wrong and it still run OK ? I got warranty on the work but suspect it would be difficult to prove. Any way to check without taking off the head ?

COMPRESSION - Checked it about 6 months ago. Don't have the numbers in front of me (I'll recheck my notes when I get home) but I think they all were around the 130 range and cyl-cyl difference was in spec (I think 15lbs ) except for one which was out on the low end by about 7lbs. Dropped a little oil in, rechecked, it came up to spec. Friend ( ex Toyota master tech ) didn't think it was enough to worry about.

HIGH COMP PISTONS - I don't think so. Why bother with a NA ? If I want real speed I jump on my motorcycle or borrow a friend's 'Vette or Z28.

SHORT BLOCK - Got any links to quality rebuilt short block sources ?
I'm bummed. Now I would rather have sold it and bought a nicely maintained Turbo. Oh well, you roll the dice...
 
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Discussion Starter #4 (Edited)
Test303: If it's running good and strong, obviously the cams are in correctly. The only reason I suggest doing the compression again is because the valves might not be seating properly, in spite of the $$$$ involved in the head work. You can get to #6 without taking the TB off, so you might check at least one.

130 is not too good anyway, you should be looking for 150 on an NA. On the other hand, with a new valve job and no leakage up top, you might now be down to 110 and blowing by the rings. There is a blow-down test kit you can purchase from a good auto supply store.

I don't have a source for short blocks, but there are a lot of remanufacturers such as Jasper or PowerPro, who apparently do a reasonable job.

I only suggest the pistons if you were going to rebuild anyway. At 11.5:1 you might find the NA is not too bad;)
 
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Discussion Starter #6
I decided to rebuild last year when #6 finally got down to 100PSI, after 15 years and 210K miles. It was more than past time to do the valves, so it was either that or a new car. Since I had replaced/rebuilt the starter, alternator, R&P, PS pump, AC, (and put in a new antenna,) I thought....why not. I'm now at 198-210 on all cylinders, measured after 3000 miles. I run 93 octane at 13 BTDC.
 
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