Well this sucks TBI down

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Gramps

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The TBI motor I built a few years ago has some severe health issues. The piston married the exhaust valve. Match made in heaven but the pushrod was bent out of shape. Cam gagged on the lifter and puked it out.

Fun puns aside it’s a can of bees being kicked around. Head is junk, cracked around the valve guide area, cam is garbage. Good thing it was a cheap comp roller…. Piston is junk. Valve and pushrod and dog bone and spider retainer all trashed. Just lucky the block is ok..

I’m being told it’s fuel related - low engine use and these modern “pump gas” we are being sold. The garbage fuel contaminated the valve and caused it to stick. The rest was mechanical hemorrhaging as a result.
I wouldn’t normally buy that but this this literally has less than 2 miles on it since it came off the dyno 4 years ago. And has just been fired up and run in and out of the garage occasionally whenever I needed that stall….

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Gramps

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DeCaff2007

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That totally sucks. Sorry for your misfortune there. If you choose to rebuild, parts shouldn't be too bad to find, except for a single piston. Believe me I know, I just went through it myself.

As for modern pump gas causing that... Uhm... I find that hard to believe. Looks more like unforseen mechanical failure to me.
 

Gramps

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Did the engine builder tell you its fuel related?

That looks more like a money shift than ethanol.


It was something he mentioned having seen on very low usage engines that the fuel breaks down so quickly and gums up the valves.
However that was a thought while on the phone, without actually seeing/inspecting the parts. I’ll be bringing them to him in the next day or so and will figure out what actually happened.
 

GoToGuy

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If a valve spring lock failed, and dropped the valve, piston crammed it into the head , cam came around... Catastrophe.
 

Gramps

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just got home from the machine shop. He stayed late to check it out for me. Definitely not a fuel issue. 6 of the retainers have been contacted by the rocker arms. Looking at pictures from when I put it together it appears that I may have gotten a mixed set of self aligning/non aligning comp magnum roller top rocker arms. Some have the shoulders that keep them aligned and some don’t. I never noticed… so some of them were dancing around until it got sideways and knocked the keeper and retainer out.
Had this thing been run down the road I’m sure it would have happened years ago although I’m surprised it made it through the thrashing on the dyno.
 

tayto

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hard to see what heads you have, but i have seen self-aligning and non-self aligning rockers on TBI era heads. the push rod slot is fairly narrow and doesn't allow the push rod to wander much. I would still run self aligning myself unless going to guide plates. this is why we check rocker geometry especially when being no longer stock. the roller tip rockers are a sales gimmick. either run stock rockers or go full roller rockers.
 
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