Runs on high octane 100+ octane. Or should I say it did run.


89' Eliminator
Stroked BBC Berkley Jet

To the OP. What was your exhaust water system set up. Did you have a valve for this. Also did you test it to make sure it was working properly. Too much water is not a good thing.

What's the stuff on the intake valve (next to the missing exhaust valve)?

What's the stuff on the intake valve (next to the missing exhaust valve)?

Gotta think that's aluminum,, look at the rest of the chamber, and don't forget how many pieces the piston was in.

Also checked your original post,,,  if you we're doing about 40 mph you had to be revving that engine at least between 3500-4000 rpm's and you probably  didn't hear anything wrong due to the exhaust being pretty loud

I do faluire analysis for a living and  By looking at the pics you have....valve keeper was not installed correctly.... You had to be revving that engine above 3000 rpm, valve dropped, impacting the top of the piston crown their cast aluminum pistons they will shatter if hit hard enough.........

The valve stem is still in the guide, no photo of the top of the head to say whether the retainer is still intact, but I bet a nickel that it is. 

I will stand by my initial guess, have PMed the original poster for the rest of the engine specs, thinking it may have had some detonation or pre-ignition problems.  It's very common for a marine engine to lose an exhaust valve under those circumstances, then the head of the valve can do similar damage to what the photo shows, and parts then bouncing in the crankcase can get up and jamb up the camshaft.  He stated it lost power (hmm,, missing exhaust valve head, and broken piston would definitely kill power,, then when the cam broke it would stop running, unless the rod happened to jamb itself into the block first, which apparently it did not.

As to 40 mph and RPMs I was turning 3600, yes the exhaust tends to dilute the motor but my son was seated with back against the bench seating directly in front of block. For what it's worth he said nothing out of ordinary, just the audible clunk and sudden quietness 😁
As for my previous Cam loss, the push rod/lifter chewed up a lobe, made it nearly flat. It still ran but made a popping sound and you could hear the marble sound in the motor as the lifter swam about.
 Obnoxious gave me some info on KB pistons losing the top of piston. I read the rings are higher in these pistons, so have to account for that. Could be the issue, im not sure. My brother is on the same idea as its a detonation problem as one of the members here mentioned. The saga continues!


89' Eliminator
Stroked BBC Berkley Jet

You stated that your previous lifter and push rod ate up a cam lobe......If you we're running a flat tappet cam......improper break in,  using oil with out an zinc additive, high coil spring rate pressures will run a cam flat not the push rods and lifters them selfs.......the wear you see is premature wear that a result not a cause....what caused these part to wear is what you need to find out the why...........and if running a flat tappet get it hardened/ nitrited it it will make that cam live..........

Personally I think that .090 over is a tired block, unless it was a Dart or Bowtie block. And I agree that your 2 events are related...it might be cheaper to replace the block. Perhaps a lifter bore is worn badly, or is oversize? That would explain eating the lifter and pushrod, along with the cam lobe.

.090" over is not a size that KB makes in hypereutectic, as far as I know.  I had asked him to get more particulars on the pistons.  I also have some personal doubts about 4.5" stroke, since it would require lots of grinding for clearance in a stock GM block, maybe not even possible without hitting water jackets, and from what I can see in the photo, there is no grinding, so I have to guess it's a much more common 4.250" crank, with .060" pistons (he did state that it was originally .030")

That being said, I personally have run a .100" over block stroker motor, 505 cubic inches, with first an 8-71 blower, and later a Gentry turbo setup making 15 lbs of boost.  I raced the block for 6 years once the turbo kit was on it, took it apart after the boat was sold (less engine), then rebuilt it again for the guy that bought it from me. 

While I have to rely only on photos of the broken parts, I am still waiting on more information about the piston part number and/or dome volume to see if the static compression is what he was told.  I still think the cam was broken due to pieces of piston, valve and block (look at the bottom of the cylinders) bouncing around inside the crankcase, being batted around by a lose connecting rod. 

Until there are more facts and evidence, I continue to stand by my previous statements, I have seen too many engines come to me with the head of the valve broken off like that.

I wouldn't reuse a block that ate 2 cams so quickly either. I'm not saying that a naturally aspirated BBC can't make 700hp - but I'm pretty sure that this random collection of parts didn't, and it sounds like your builder doesn't have a clue either.

I will bet another 5c that the cam didn't break until the debris from the other destruction got into it and jammed it up.  The photo of the cam and lifters is not quite good enough for me to see any other damage than the breaks, which are common when pieces of iron and aluminum and exhaust valve are bouncing around in the crankcase, being batted around by connecting rods.  He stated it lost power(that would be when the valve let go, taking out the piston and cylinder wall) , then after that quit running (when the cam snapped)

The block appears to have a big hole in the cylinder wall, not to mention damage at the bottom of the two cylinders.  It may not be a candidate for the rebuild, but I think it's pretty hasty to say that it "ate 2 cams"

I'm sorry I was indeed hasty, remind me to wait a week before I mention the holes in the block... You're right, hasty...that camshaft looks totally reusable...custom even. Did you invent it??

Don't want feedback?  Don't post your sob story whilst asking for feedback.

You don't know engines... You hired someone to put yours together with parts you got a deal on from someone who wanted to get rid of some junk parts...and this is what happened.  The only to to blame for this is you...for your
Ignorance. 

We all had to start somewhere... because we were all ignorant once...but we all got fed up with others screwing stuff up, and made the investment in research, mistakes, experience, tooling, etc to be able to build engines that stay together. 

The people offering you advice here demand big dollars for their work, and it's worth every penny, because they're builders, not assemblers.  It's only because of communities like this that they offer the advise for free. 

I build better engines than 90% of the engine shops out there...only because I've spent hundreds of thousands of dollars over the years paying them to teach me how not to do it.  Listen up, don't be a dick, and you'll accomplish
two things...you'll learn something and earn the respect and knowledge of people who have been down your road 100 times.

Barry is a great engine builder.

We're here to help...seriously...that's the whole point of this website....just don't show up without a slice of humble pie when you admittedly know very little about the subject matter.  We'll help you fix it, we'll help you make it fast.

  WTF? I'm not the guy that blew his engine??? I'm just a guy that said it appeared to have EATEN that cam. I didn't ask for anything especially some pompous blowhards resume in the mail. My engines don't come apart EITHER...so what?

I say it might have been cheaper for him to have replaced the block when it ate the (FIRST) cam and lifter and that it also ate a bunch of MONEY - I stand by both of those statements! Hardly flameworthy..but hey I guess everyone misses their meds once and a while! :-)