I finally got around to checking the compression in my motor, and it looks like despite the $3000 engine rebuild reciept that came with my car, it hasn't been rebuilt. I found low compression in 3 cylinders, and it came up considerably with oil...

Anyway, there is an '87 engine available locally, and I'm wondering if all of the accessories and intake with carbs will bolt up? The engine appears to be the same except for the fuel injection.

 

Pretty cheap rebuild. How many miles on the rebuild? Might not have rings seated yet!

 

It's very similar, and the ancillaries should bolt up the same. Injected motors had larger valves from what I recall.

FWIW, an engine rebuild used to get billed out at around $6000 plus about 10 years ago when we were doing them all the time. There are plenty of people out there who have no business touching a Jag motor!

 

YUK!

And, if the cylinders were not properly honed, it may never seat the rings and bring up decent compression.

I suspect a quicky, cheap ring,bearings and valve job improperly termed as a rebuild.
Can work, if carefully done.

Now, one last shot to seat the rings before tossing it on the apron at the regbuyild shop. 1. Drive it fast in accelerate, slow cycles. 2. Use a seat the ring snake oil.

I'd check the 87 engine out with a wet and dry before swapping.

Caveat: Many a decent overhaul and or rebuild has been ruined in the start up and or leaking carbs that wash the cylinder walls and create undue wear.

Carl

 

The "rebuild" was done 24000 miles and 15 years ago. I also have a trans rebuild reciept from the same previous owner... it doesn't work well either.

I'm actually torn between putting another Jag motor in... and doing a V8 conversion. My plans had always been to keep this car extremely original despite the seeming lack of rising value. A rebuild of the Jag motor will likely be much more expensive, and the threat of oil leaks will always be there. And then there's the transmission.

Before I give up completely on this motor and start spending piles of cash, I'm going to check the valve clearances... maybe there are a couple of tight ones preventing good compression. The best 2 cylinders were 125 psi, and the worst one was 105. I know these are low compression motors, but I was expecting closer to 140psi.

 

When my OHC wetn to 0 in all holes, I studied carefully. I chose the lump route. The trans in the car was OK.

Either way isn't cheap. Or easy. After a lot of travails in getting my car right, it is a very pleasing car to drive and ultra reliable. More CI, more HP, more torque and OD!!
But, I did like my car as it was when it ran nicely.

I wrote a paper, "Lump thoughts". I'll share it with you if you want. Contact me PM.

 

Up to 145 seems normal on a warmed-up engine, cold will be between 105 and 120. Of course, every compression gauge I've ever used reads differently when compared side to side. A leakdown test on the affected cylinders will tell you far more, especially on a warmed-up engine.

 

I posted a thread re a rebuilt 1975 4.2 l engine I have for sale. I have put more than a $1000.00 on this rebuild. Fortunately I have a brother living in England and was able to get all the parts for my rebuild at a very reasonable cost. The engine got new rings, bearings, timing chains and guides,exhaust valves, valves seals tappet shims etc. I did the rebuild myself and it runs great. I am selling the engine and transmission. the engine comes with all of the accessories. Plug and Play. Reason: Someone purchased my car, but wants me to install an LT1 engine and a 700R4 trans. He already paid me for the car and I will be pulling the engine and tranny as soon as the used LT1 gets here. I am rebuilding the LT1 before it goes into the car. If you are interested, I am willing to take a loss and sell the engine and tranny for $1400.00, rather than leaving it in my garage to gather dust.

 

here is a pic of the engine