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Discussion Starter #1
I did a camshaft and head swap on my 350 about a month ago. I've been out on business and vacation, so I'm just getting back to it now. At first I thought I had a wiped cam, broken pushrod, pushrod geometry issue or I installed the timing chain off a tooth. The engine was running like it was on 7 cylinders. No power, and wouldn't idle below 1300 rpm or so.

I tore the motor back down again the other night. Timing chain is dead on. The camshaft appears to be fine. Lifters have a nice break in pattern on them, nothing obviously destroyed. I installed my stamped rockers and stock length pushrods. All of them are adjusted to about the same spot and are holding steady, so I don't think the cam is going away. I pulled the plug wire on cylinder #8 and the rattling went away and motor smoothed out a bit. So now I'm thinking - valves must be hanging open. Do a compression test. My crappy harbor freight tester reads consistently about 40 psi below a good Snap on gauge (I don't think the o-ring or connections are sealing right), so don't get too worried. This is a stock small dish short block with ported 67 cc heads on it. All cylinders, including cylinder #8 were between 90-110 psi, including the rattling cylinder #8.

Sooooo....... any thoughts? Heads were visually inspected and seemed okay to me. Valve springs looked okay. What's wrong? Spark plug looks like the electrode melted just a touch, so that's the first thing I'm going to change.

Kev
 

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I don't have an answer for the noise in number 8 but from reading your engine build problems over the years maybe you should give up building your own engines and have someone else build them.:D:D:D
 

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Discussion Starter #4
I don't have an answer for the noise in number 8 but from reading your engine build problems over the years maybe you should give up building your own engines and have someone else build them.:D:D:D
You're probably right. But I'm broke until my wife finishes pharmacy school. I had a fine running pretty much stock 350, obviously I should have left well enough alone.

Kev
 

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Hello Kevin.


This is just a guess on my part, but if it started melting the plugs Im guess the cyl temp was pretty high and possibly caused some detonation issues.

If it did, I would be surprised to find a cracked piston od a colapsed skirt.

To me if the knock goes away with the wire off there is probaly no valve train issue.


Knocks are funny could be a brg issue as well, but it dosent sound like it.

Maybe lean on a cyl or 2? Possibly the whole engine?


You should be getting pretty good at this by now?


Is it worse when its cold?
 

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Discussion Starter #7
It's not a knock. It's a rattle, but not like detonation. Sounds like a really loose rocker or a pushrod rubbing or a rocker hitting the valve cover. It's kind of hard to describe....

Kev
 

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Broke bank and car broke, not a good combination. Tell Westinghouse you want a raise. I have entertained the thought of sending a resume over. When Gretchen is done with school she'll make enough to buy a 10.5 car.

I'm using my backup motor now or I'd say throw it in an use it for the summer. I'm busy through this weekend but if you need a hand wrenching afterward give me a shout.
 

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Why would the piston start slapping now when it was fine before? Piston to valve has plenty of clearance.

Kev
Piston slap is the skirt slapping the cyl walls due to excessive wear or something broken causing the piston to be able to move in the bore.
 

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Discussion Starter #10
Geezzz..... sometimes it's the stupid things. I left the back bolt out of the passenger side header tube. Must have "left that one for later" and later never came. The bottom of the header gasket was completely blown out (physically torn). Left that cylinder sucking air. Time to go tune the thing and get it all sorted out:). It's funny how something like a header gasket can effect running so much and make so much noise!

Kev
 

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Geezzz..... sometimes it's the stupid things. I left the back bolt out of the passenger side header tube. Must have "left that one for later" and later never came. The bottom of the header gasket was completely blown out (physically torn). Left that cylinder sucking air. Time to go tune the thing and get it all sorted out:). It's funny how something like a header gasket can effect running so much and make so much noise!

Kev
Haha, yeah. Things like this will drive you crazy and make you worry a little. Im glad it was easy to take care of.

-Dan
 
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