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Discussion Starter · #1 · (Edited)
This morning I fired up my '71, backed it out of my garage, then let it fast idle to warm up. After several minutes of fast idling I heard a BANG followed by black smoke belching out of my air filter (???). I removed the air cleaner assembly and when I cranked it over I got another BANG followed by more black smoke. I walked around to the passenger side and was shocked over what I saw.

My HEI was sitting 3/4" up and out of the intake manifold. Huh? When I recently stuffed a bunch of foam rubber between the underside of the transmission tunnel and the transmission I had put my HEI back in but didn't put the clamp on the top of the HEI's flange. I had pushed the clamp up against the flange then tightened it. That was on June 16th!

I have driven about 250 miles since June 16th and I'm wondering how in hell it managed to run perfectly for the last three weeks when my HEI wasn't even clamped down. The tachometer cable and stiffness of the spark plug wires prevented it from rotating very far (it would have rotated into a slightly retarded position). but not far enough to noticeably affect its running.

This is what can happen when you work in dim lighting conditions. I'm just VERY lucky it decided to let go when it was sitting on my garage's apron and not on a freeway in heavy traffic during rush hour.

One other thing: When I pulled out the #1 spark plug to verify TDC I also pulled out the #3, #5, and #7 plugs just to see what they looked like after about 60,000 miles. The DENSO 5305 (aka IW16) iridium spark plugs had .037" gaps or only .002" larger than they had been when I installed them 8 years a ago. When it comes to spark plugs NOTHING beats the iridium plugs. Yes, they're 5 to 6 times more expensive but as they'll go 100,000 miles they're worth it.
 

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