1973 Mustang – Project SportsRoof – Compression, Rods and Heads

Thanks for check in on #ProjectSportsRoof.

If you remember a of couple months back, shortly after bringing the ’73 Mustang home, I conducted a compression test on all the cylinders.  The 351C was running rough (to put it mildly) and smoked like a pile of tires on fire (only the smoke was blue).  Clearly there were some issues.

Here are the links to the posts were you can view the compression tests – RIGHT BANKLEFT BANK.

To summarize, the cylinders topped out like this:

Cylinder 1 (Left Bank) – 130

Cylinder 2 – 25, 35, 60, 90 (Fail!!!)

Cylinder 3 – 140

Cylinder 4 – 135

Cylinder 5 (Right Bank) – 160

Cylinder 6 – 155

Cylinder 7 – 160

Cylinder 8 – 140

Clearly cylinder 2 has a serious problem and it could a host of things.  Since it was so bad, I didn’t feel it necessary to conduct a wet test and just planned out pulling the heads.

Well the time came to get take care of that and it wasn’t long to disassembling that it was clear what was wrong with cylinder 2.

What the....?

What the….?

At first we thought…”Hey Cool!!! Extra parts!!” But of course that’s just not the case!!


 No extra parts.

It couldn’t be that the tappet just rolled there. Something else has to be an issue.

Oh…maybe…one of these was the problem?


Ya Think???!!!

Close inspection of the piston in cylinder 2 showed no signs of impact. As it appears thus far, that the bottom end of the engine is in good shape and the compression numbers for all the other cylinders and we bolstered that assumption with a visual inspection.

Think the heads need to be rebuilt and machined?

That’s coming up.

Thanks for reading.





1973 Mustang – Project SportsRoof – Compression Test Part I

Thanks for reading. Tim. #ProjectSportsRoof. projectsportsroof. 1973 Mustang Project Sportsroof – Engine Walk-Through. There is a quick walk-through of the 351C tucked between the fenders of the 1973 Mustang Sportsroof.
1973 Mustang – Project SportsRoof – Compression Test Part II

#ProjectSportsRoof. projectsportsroof. 1973 Mustang – Project SportsRoof – Compression Test Part I. I’ve done all the clean up and all the adjustments necessary to get a good reading on the health of the ’72 351C engine in …


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5 Responses to 1973 Mustang – Project SportsRoof – Compression, Rods and Heads

  1. Tim Sweet says:

    from klousGT via /r/s550mustangs/ sent 2 days ago

    Cool car, I bet /r/mustang would be interested.

  2. Tim Sweet says:

    from kylerw0617 via /r/Mustang/ sent 2 hours ago

    Do you have some pictures of the dismantled head? I would imagine the rocker, spring, valve is the issue, and I would be interested in seeing it.

    Just my guess: The valve/rocker assembly bound up on closing, causing the the lifter to bend the push rod when the cam came back around, the push rod had nowhere to go so it bent, the lifter went back down, the push rod fell out or to the side, and the cam launched the lifter out of the guide.

  3. Anonymous says:

    I have seen this before when water was in a cylinder on startup and fortunately the push rod was the weak link. No other damage.

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