OK, most of you don't know that I've been having issues with the Hondo pushing oil out of the dipstick on longer, near WOT runs.  It has happened twice so bad that it pushed nearly a quart of oil out each time.  Other times it pushes the dipstick up and I'll find a couple spots around the area.

I've been checking out my options and decided that without knowing what's inside my engine I can't make an educated decision.  I ran a leak down test the other day and found it at nearly 60% (might explain why it would only do low 50's WFO).

So, I pulled the engine and disassembled it today (now the fun begins).  I was pleasently suprised to find that the engine was still stock bore and std crank.  It looks like someone had done rings/bearings at some point, and the cam looks near new (from what I can tell it is a Comp 280H). 

Now, I want to get this thing going again PDQ.  I'm not looking at building a "Ford killer"    just a good "pump gas" mild hot rod.  But I would like to get some performance out of it.

I'M looking at the KB Hyper pistons and have a choice of about 8.9-1 or 9.9-1 compression, and want to know what the forum thinks.

8.9-1 with a little more timing or 9.9 and a little less timing (with pump gas)?

(for the technical guys, I have a set of 049, oval port heads with 122cc open chambers)

I'd go 7.75-8:1....but that just me 

I didn't read this as being a blown engine?

Thats whatthe winky guy was for. Terrys blown!

never never never put hypers in a marine applicatiion....they are too brittle when kept at high rpms for a long time.

i am no expert engine builder, but this is from experience and research i have done.

Lots of marine engines, or I should say engines running in boats, have cast or hypereutectic pistons, but probably not the best bet unless someone is on a super tight budget, and not planning to run the boat real hard.  Consider all the guys that stuff car or truck engines into a boat.

So, wouldn't say "never", but certainly a better idea to find the extra cash for forged as I suggested above.  Pretty sure they are available under $500, if not, check with me to see what I can do for you.

Consider maybe going to the KB forged pistons, not only will they be more durable, there is one with an 18.3 cc dome, would be more like 9.3-1.  They have two series of forged pistons, one slightly cheaper than the other.

Also, you could have the heads surfaced down a bit to give a little bump to compression also, regardless of which pistons you choose.

  I agree I just took .030 off my 049's done it before really helps acceleration and throttle response for a few bucks. Also you know your gasket surface is square.

Got everything cleaned up and received most of my parts.  Dropped everything off at a local machine shop and confirmed what he is going to do. 

One thing he brought up that I haven't heard discussed around here is wrist pin to piston clearances...

He understands that it is going into a jet boat (has some boat racing history from what I'm told) and noted that besides the extra clearance for the cylinder walls he has had some people ask to have added clearance for the wrist pins 

Has anyone heard of this?

I went with the Speed Pro/TRW forged pistons and don't really want this thing to rattle worse than it already is.

Hey Crew,

Not to sound like an idiot here, but could he be referring to floating pins?

I have never heard it said the way you said it, "had some people ask to have added clearance for the wrist pins", but IMO it actually does not sound like too bad an idea to be honest. I would be talking in the .0002" range, but not sure it will pay dividends at the end...I have had a wrist pin sieze in the piston before, to this day don't know why  Had a piston slap you would have sworn was a rod when cold...And no the piston was not collapsed, just a little skirt scuff (cleaned up and ran killer).

The cylinder wall clearance is necissary due to the extreme temp difference between the piston and the block (effected less by high quality forged slugs), there really should not be any issue with the wrist pin and the piston.

Now floaters on the other hand, as long as they float, I would call it adequate...

I was lazy and I apologize in advanced, but are you running coated pistons?. If so, less clearance when the block is done.  I think the number was .0005 for every inch of bore, but I would check that before i called it fact...


Sounds like a sweetheart.

Wow! There is more information in there than you can buy!

Glenn's the man! lol

Still concerned about the rattle though, lol And the wrist pins. Something new to me.

Floaters I get, but that is a ford/mopar thing, not a chebbie thing.

Ray

"Floaters" is a piston thing, Chevys work so good, they can take something from everyone and still run good...LOL 

The JE pistons in my other 468 are full floating pinned coated and clipped badboys that used long rods for a modified piston speed, there was a lot of top secret experimental crap in that build that I have yet to wrap my head around.

My uncle built it and his words were "don't ever sell it, just give it back to me when you're done with it and I'll build you another one".

Was not really sure what that meant until we tried to rebuild it, we're talking several mistakes when ordering parts, there were no numbers stamped in the pistons, funky rods, cam bearings were upside down and had orifices in the oil holes, knife edged forged crankshaft, tiny hole drilled in the front galley plug, thrust bearing for the cam...

GT

Got a call from the machine shop today, he should have everything ready tomorrow. 

So if I get it picked up Saturday and start on the reassembly, I don't see any reason why I can't make the Big River trip on Fathers Day