Autoshrine

1971 Spitfire MKIV - An Adventure

Problem Solving

John Gallagher   USA — Posted on The Triumph Experience
Wednesday August 19, 2009 3:48 PM



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Member Comments on Journal Entry: Problem Solving   ↵
2009-08-20 10:17:58 # 1553
Comment by Loren Welch
I've read that compression from one cylinder to the next should be 10-15 lbs. Within that range wear from cylinder to cylinder is normal. Your average is 162.5. With 185 being the best and 145 the worst, forty pounds is probably indicating a broken ring or a bad valve seat. Allot of variables here.
As long as it's running good and sounds ok I'd drive it. Like mine, I'm going to do a compression test soon. I take it easy, keeping the rpm's below 3k. I hope to get the rest of the drive train rebuilt and enjoy the car for a couple years before pulling the motor and then ultimately taking the car apart and repainting.
2009-08-21 22:36:19 # 1554
Comment by John Gallagher
Since I bought the car I've been using a lead additive and the highest octane gas I can buy, but I expect previous owners weren't as conscientious. Especially when premium gas came close to $5/gallon last year. I suspect you're on track and that some of the lack of power has to do with the valves. I'm not going to address it until the fine weather is over. Nice and handy until then.
2009-08-22 20:46:29 # 1556
Comment by Greg Deyo
I don't want to dispute what Loren is saying, but those are perfectly acceptable compression readings. A broken ring would cause a huge drop off to possibly no compression, or dead hole. The car probably has 185 to 200 brand new. If you are in the mood to try again, test the compression in the cylinder and log it, then squirt some oil in the cylinder and do it again. If the compression goes up, you have some ring wear. With your numbers I would stress MINOR ring wear. If they stay the same, then you have minor valve leakage. As Loren says, if it runs well, drive it. You are worrying about something that needs no worrying over. These cars don't have lots of power and are geared poorly. It is usual to have to downshift to 3rd to get power.
2009-08-22 20:55:58 # 1557
Comment by Greg Deyo
I forgot! If you have lower compression in to companion or side by side cylinders it can sometimes be due to cylinder head gasket failure between the cylinders. I only mention this because of cylinders 2 and 3. Run the wet test. I would be very interested to see what comes of that. You only need to pour in the equivalent of a capful of oil from an oil bottle. A couple of squirts from a tin man can works well as well.
2009-08-22 22:15:48 # 1558
Comment by John Gallagher
Thanks Greg and Loren. I want to learn more about what I can do to get some more umph out of the engine. I'm in 4th at 3000 rpm and am only doing 40 mph or so. I've maxed at 55mph, but I think it might hit 60 if really pushed. Is that normal? I think some of the horses that originally came with the car have since died and moved onto greener pastures. Spitfire MKIVs certainly seem to be geared low. I've found myself on more than one occasion trying to put the car in 5th....I haven't found it yet
2009-08-22 22:58:33 # 1559
Comment by John Gallagher
Greg - Your point about cylinders 2 and 3 is a good one, and a head gasket might well be on the calendar. My wife tells me we're going broke $60 at a time, but it's a great education However, waiting a week for the gear shift bushing to arrive has been excruciating, so I think any more projects that render the car un-driveable will have to wait until the weather dictates that the car is un-driveable....January maybe.
2009-08-23 17:47:18 # 1562
Comment by John Gallagher
Loren - I see what you're referring to with the 10-15psi max variance....it's mentioned in the Haynes Manual. Something to bear in mind down the road. Thanks for the advice. John

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By Degrees....

John Gallagher   USA — Posted on The Triumph Experience
Friday August 14, 2009 10:31 PM



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Creating The To-Do List

John Gallagher   USA — Posted on The Triumph Experience
Friday August 14, 2009 8:38 PM



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The Plan

John Gallagher   USA — Posted on The Triumph Experience
Friday August 14, 2009 8:04 PM



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In The Beginning....

John Gallagher   USA — Posted on The Triumph Experience
Friday August 14, 2009 7:53 PM



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2009-08-15 18:39:38 # 1546
Comment by Greg Deyo
It is exciting. You will have a great time, and they are easier than you think to figure out. Good luck!

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