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TR2/3/3A Surprise on compression.

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tinman58

tinman58

Jedi Knight
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I am going to have Jeff at advanced dist. build me a new dizzy. On his work sheet He asked for all the info on your engine. I know most of it in my head. But never did a compression check, Just did it this morning 190-190-193-190. I was surprised on the high numbers. On my TR 250 the reading are in the 145 range... The head must have been shaved a little more than stock. LOL.
 
Dan-

I'm not knowledgeable at all on superchargers, but don't you get a bump from that as well? 190 sounds pretty high as is.

Randy
 
That does make sense. I hope that somebody will respond with a better understanding.
 
I dug through the service manual, and indeed, 190 psi is high. The general section says 120 psi average. That's not a bad thing, though, unless you are having detonation issues...
 
I use premium gas. No detionition issues. Just wanted to get as much info to Jeff as possible. Now off for a quick drive to burn off some fuel so I can put more fuel in. OK it is just an excuse to go for a drive.
 
:wink-new: It's a wonder the spark plugs haven't blown out their holes.
 
I have a Healey head that is severly ported by someone that was racing. The compression was 245 psi, and it went very fast. But you needed about 100 octane to keep from pinging so I replaced with with a standard head. I want the power back but don't want to buy racing fuel! Boy what torque!

I bet the compression and the supercharger on the TR3 gets the results also.
Jerry
 
We just did my friends TR4A and got 175 to 170, runs great, just takes forever to warm up and normal for this car is a little above center. Lets face it. could be the gauge or sending unit, maybe replace the thermostat with a 196 degrees and see if it runs better as it never (KNOCK ON WOOD) overheats.

Wayne
 
Hey

FWIW, my TR4A runs 180psi/ 175psi/ 180psi/ 175psi dry compression test and 208psi/ 200psi/ 208psi/ 200psi wet compression test. Took readings with both my brother's gauge and my best friend's. Reading b/t the two gauges were within 5psi of each other. Otherwise, car runs perfect. No pinging and instant throttle response. I do use the highest octane gas I can find.

The reason I was checking was because I suspected excessive blow by which was overwhelming the stock PCV valve. It is the "pancake" PCV valve which is a closed loop feeding gasses back into the intake manifold. I will say, I run the car without the PCV now and it does run/idle much better.

Bob
 
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