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74 Spider
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Discussion Starter #1
I know this has been discussed before and I searched on the forum but can’t really find an answer as to compression #’s . I did a compression test this past weekend & the results are as follows :

dry wet
4 - 155 160
3 - 160 170
2 - 160 170
1 - 155 160

I know the numbers seem pretty good in the sense that they are within approx <5% of each other across the cylinders, butis the actual compression number low? Also is the variance from the dry to wet test Acceptable ? Thanks
 

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those numbers are fine. Drive your car, enjoy it!
 

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‘73 Spider
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Those numbers don’t look too bad. Is it the original engine? If not, when was the last rebuild?
 

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74 Spider
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Discussion Starter #5
The dealer told me the motor was rebuilt approx. 10yrs ago ( I have no way of confirming this though )
Those numbers don’t look too bad. Is it the original engine? If not, when was the last rebuild?
 

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‘73 Spider
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I’ve seen a few times where an “R” was stamped beside the serial number on an engine to identify it as having been rebuilt. Not necessarily a common practice. If present, you know it’s been rebuilt, but wouldn’t tell you when. If you aren’t blowing a lot of smoke, just drive it and enjoy.
 

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74 Spider
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Discussion Starter #7
Ok , it’s leaking oil from the head gasket on the exhaust manifold side & runs pretty rough under 3k. I was planning to replace head gasket and update ignition system ... would you happen to know the location of the engine serial numbers ?
 

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Ok , it’s leaking oil from the head gasket on the exhaust manifold side & runs pretty rough under 3k. I was planning to replace head gasket and update ignition system ... would you happen to know the location of the engine serial numbers ?
Before you go changing the head gasket try re-torquing the head. On a cold engine you remove each head nut in turn, clean the thread inside the acorn nut and the stud, make sure the washer is free of any build up, the surface of the top of the head too, then oil them, replace and re-torque, one by one. Do a search, there are more detailed instructions around.
Oh! I should have said, I had an oil leak just like you describe and once re-torqued it was gone.
 

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74 Spider
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Discussion Starter #9
Before you go changing the head gasket try re-torquing the head. On a cold engine you remove each head nut in turn, clean the thread inside the acorn nut and the stud, make sure the washer is free of any build up, the surface of the top of the head too, then oil them, replace and re-torque, one by one. Do a search, there are more detailed instructions around.
Oh! I should have said, I had an oil leak just like you describe and once re-torqued it was gone.
I actually tried to re-torque them and they didn’t budge , I assumed that meant they all are in spec. Do you think I should still remove the whole nut and re-torque down? Should I go a few pounds past the original spec ? Thanks
 

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You have to remove each one and go through the process as described to get the result you want, only tighten to specification.
 

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Are you sure it is the head and not the valve cover that is leaking?
BTW, none of my 3 spiders have compression numbers that good and they all run great. Just 100,000 mile engines that are showing their age.
 

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74 Spider
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Discussion Starter #14 (Edited)
Yeah, it’s definitely coming from the head . The valve cover has some kind of white caulking that seams to have sealed it up pretty good . The head looks like it’s leaking on both sides from pretty much the middle . . Kinda strange that it’s leaking in the same spot on both sides
 

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74 Spider
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Discussion Starter #16
Hey, it was worth a shot & honestly I don’t mind wrenching on this thing to much . Lol .... I just have to get more familiar with the platform to build some confidence
 

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Not that difficult to do a had gasket. If you have any water in your oil, be sure to get it ALL out.
Also, don't forget to do a retorque after about 1000 miles on the new gasket.
I am sure you will have the head checked by a machine shop while it is out but though I would mention it.
In take valve guide seals could also be done while it is out of the car.
Just my two cents.
 

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Discussion Starter #18
Thanks . I keep going back and fourth on tackling it myself ... my biggest concern / fear is the timing chain and lining up the cams
 

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If you follow the correct procedure timing up the cams is easy, what is strange with yours is the two cyliners showing the best compression is where there may be a head issue. Rather than just replace a gasket I think you need the head check and/or skimmed. I could be warped.
 

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Discussion Starter #20
Yeah it is strange how it’s leaking in the same spot (middle of head) on both sides . If I pull it I’ll get it checked out and maybe even do a valve job
 
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