A buffalo’s first bowtie

skim the heads=surfacing? I don't think he needed to but will ask.

open up the heads=port and polish? No, they're rebuilt with new components but otherwise they're stock. I suppose that could still be done; the guy I met yesterday does that, but I didn't ask how much and he didn't bring it up.
And yes, I'm doing the assembling. The machinist matched up the important parts. I still need a few things like a ring spreader and a ring compressor, but I think I'm ready.

My mouth is watering too. I'm having the new strainer welded to my new oil pump and pick that up today, and then the fun starts!

Don't forget that when using hypereutectic pistons, the top ring gap needs to be wider than that of just plain cast pistons. The reason for this is that hypereutectic pistons hold more heat in the head of the piston and make the rings expand to the point of closing a stock gap setting. Check with your piston manufacturer for the spec. A Keith Black HU piston in the 350 Chevy requires a ring gap of approx. .028 as apposed to the stock .014. This is very very important. Tight ring gaps can break the heads off your pistons.

Greg, as far as piston clearance goes, stick with what the piston manufacturer recommends. If your clearance is within the range of what Sped Pro recommends, you are good. My guess is the reason for the larger clearance for the 4-bolt is that it probably came with forged pistons. Forged pistons normally require a larger clearance because they expand more. Hypereutectic pistons typically use clearances (piston to bore) that are near stock. Also, remember that piston clearance is measured at the piston skirt.

Joe, the Keith Black pistons may require more ring gap clearance because of the top ring being closer to the top of the piston (more heat there). I agree that the piston clearance does sound a little tight though for a marine engine.

Greg, did you specify to Speed Pro that you are using this engine for marine use when you got your piston clearance?

nuttyskier2002 wrote: Joe, the Keith Black pistons may require more ring gap clearance because of the top ring being closer to the top of the piston (more heat there). I agree that the piston clearance does sound a little tight though for a marine engine. Greg, did you specify to Speed Pro that you are using this engine for marine use when you got your piston clearance?

I agree the speed pro piston may require less end gap than the keith black due to ring location, as well the piston to wall clearance may be different as well (although less so because the material is basically the same) however I was making the point that the clearances provided by those manufacturers that publish specs for both marine and auto are typically different. If you can only find auto specs for speed pro you need to call and ask for marine and they should be different. If they tell you they are the same as automotive I would be leary of the information.

In addition to the cooling differences mentioned above marine engines are typically loaded higher and at longer durations than automotive engines as well, which also generates greater piston temperatures.

You guys are great!
Here's where we stand. I talked to my machinist(Sherman) and I'll try to put this together where it makes sense. The question about piston clearance opened him up a little. It turns out that he is a modest man and has years of marine experience. He did the machine work for a pro marine rebuilder who just retired. They were selling my repower for $7500 per for years until recently. Anyway, he said that cast pistons would swell a good bit more than my hypereutectic ones and that the older pistons were made 'sloppier' and thus the larger measurements in the older manuals.

My take on the whole thing is that he meant it to be as close to idiot proof as he could get for me. I told him up front that I wanted to learn, and I asked him if he'd have the patience for questions. He really is a nice guy.

The actual clearance hasn't been measured. He said he did the machine work to achieve .0025 The minimum for these pistons is .0015   I do agree that a call to speed pro is in order, but it looks like my parts guy has to call monday.

My feel is that he halfway likes me and he wants to come by for dinner and to check my progress. He also offered to let me fire it on his stand because of the lake level...and I didn't ask. My gut feel is that I'm in good shape.

More thoughts?

Brian, I will make the call to speed pro, and I do appreciate your concern about me screwing up. I haven't started anything yet and won't till we're all happy. Right now, the block is on the stand and the rest is still bagged from the shop or on order.

I'm not sure if Sherman will ever want to go skiing, though he does want to see my boat. It's been an all business relationship for what it's worth. That changed a little on new year's eve when I had a check and my bank was closed, but that's another story in itself. Long and short of it...he vouched for my check. As with dealing with anyone(unless they just rub the wrong way), I've gotten to know him over my visits, and if he wants anything less than the best for me I'll have to relearn some things about life at almost 40?!!?   

I hope you're right Brian and I really appreciate your thoughts...Joe, Eric, Tim, Chris, Eddie, Jim, and everyone else. And Keith just for having this site here! We shall see...

At the very worst, this'll be a good say on what not to do?!!?   LMAO

I'm curious and have a related question on clearances. I have done several flat head rebuilds but have always relied on the shop doing the machining to handle the bore clearance. I have fitted rings but with the old marine engines there is only one spec on ring gaps. Living in the Midwest closed cooling systems are rare. Are marine engines with the closed cooling built with automotive clearance specs?

Here's a side note for 87 and others. I had some difficulty finding the oil pump pickup strainer. It had to come from GM and they don't have pictures. The oil pan set-up...and maybe the whole engine is from the GM P30 chassis.
Thanks Woody(secc)!

2 and a half

are you sure the spec isnt 15 to 25 thousandths? on piston to wall clearance?

eric lavine wrote: are you sure the spec isnt 15 to 25 thousandths? on piston to wall clearance?

I must be losing something in translation on the 2 and a half vs. 25 thing. Eric, call me if you want-770-536-2328. Sherman checked the rods and said they were a little nicer than standard and had harder bolts than normal...said to torque to 50 instead of 45lbs. I paid to have it balanced; the crank is on my receipt, and I'll check the rods.

BuffaloBFN wrote: eric lavine wrote: are you sure the spec isnt 15 to 25 thousandths? on piston to wall clearance? I must be losing something in translation on the 2 and a half vs. 25 thing. Eric, call me if you want-770-536-2328. Sherman checked the rods and said they were a little nicer than standard and had harder bolts than normal...said to torque to 50 instead of 45lbs. I paid to have it balanced; the crank is on my receipt, and I'll check the rods.

The piston clearance would indeed be .0025" or 25 ten-thousandths. .025" (25 thousandths) is way way way too lose for piston clearance in just about any engine. An engine that is worn completely out to the point of needing oil squirted into the spark plug holes in order to build compression would have something like ~.010. Maybe a likely more or a little less. Now I'm not saying that .0025" is the clearance he need to run, He still needs to check with Speed Pro. But if his clearance should be more, it's not more than .001" to .002" more. Hope this helps to clarify, Brian

Math isn't my weakest suit, but there does seem to be a machinist's lingo. However a body wants to say it, my clearance is .0025.