Pricing a rebuild

[MickLovin]

Ok, I have just been phoning around and I have sourced 4 x pistons for my Chrysler 100hp, but they are 4 thow so the people who do the reboring said they would rebore to the new pistons. Sorry if it sounds like I don't know what I am talking about as I don't . He had no 2 thow left ? So what I am asking is, will this motor handle the extra bored and honed?
I got the wiseco pistons for $136 aus each and the boring and honing for $220. I will need new gaskets? so would a set be the best way to go? And could I do this myself???
Anyone in Australia living near Tweed Heads PLZZZ help LOL

 

[Frank Acampora]

Re: Pricing a rebuild

Mick--am I missing something? It is late here and I may be a bit out of it. WHY are you considering rebuilding an engine that runs well?

Although Wiseco makes .040 oversized pistons, Chrysler Recommended never boring more than .030. Any more makes the cylinder liners too thin. I can not comment on what a .040 overbore would do in your engine--I simply don't know. I am just spouting what I read in a manual.

If you do go for a rebuild, your engine is 3.3125 standard bore. The machine shop does NOT bore to piston size because the piston is cam ground (oval) and sized for correct clearance. The machine shop overbores and hones to a finished size of 3.3125 plus .040 or 3.3525 (plus or minus a couple of .0001 tolerance)

Now, you may ask: What about the four cylinder engines with the 3.375 bore? 3.375 is more than .040 larger than 3.3125. Answer: Although they LOOK the same, the cylinder liners are larger and are made to accept the larger bore diameter.

 

[pnwboat]

Re: Pricing a rebuild

Seems a tad high price on the boring and honing. Yes you'll need a gasket set. I vote for you do it yourself!

I always get a set of the crankshaft seals ( get a least one extra....very easy to break ) too. Your motor has three of them. They are metal and look like piston rings. #11 in the diagram below.

Mercury, Mercruiser, Force, etc. - CRANKSHAFT AND PISTON GROUP - 100 H.P.

 

[MickLovin]

Re: Pricing a rebuild

Mick--am I missing something? It is late here and I may be a bit out of it. WHY are you considering rebuilding an engine that runs well?

Although Wiseco makes .040 oversized pistons, Chrysler Recommended never boring more than .030. Any more makes the cylinder liners too thin. I can not comment on what a .040 overbore would do in your engine--I simply don't know. I am just spouting what I read in a manual.

If you do go for a rebuild, your engine is 3.3125 standard bore. The machine shop does NOT bore to piston size because the piston is cam ground (oval) and sized for correct clearance. The machine shop overbores and hones to a finished size of 3.3125 plus .040 or 3.3525 (plus or minus a couple of .0001 tolerance)

Now, you may ask: What about the four cylinder engines with the 3.375 bore? 3.375 is more than .040 larger than 3.3125. Answer: Although they LOOK the same, the cylinder liners are larger and are made to accept the larger bore diameter.

Thanks Frank for your honest advice, I told the machinery workshop what I had and they said they could do it, but after reading what you are saying looks like I better find the .020, as he only had one of these. I am just doing a price comparison, with no real means or consideration of doing the job now. I haven't even re-done the compression yet. As soon as I complete a compression test, I will post my correct readings and then ask for a bit more advice. Mine is a 4 cylinder with my manual quoting what you have said 3.3125. The machine shop didn't have 4 .020 pistons only .040, but in saying all that I may only need to do 2. I WON'T be doing anything for ages, so it was just an excercise to see how available everything was, and to be honest, the machine shop is getting rid of the last wiseco pistons, and these were the last 4 he had.

 

[MickLovin]

Re: Pricing a rebuild

Yea pnwboat, it probably is but the pistons from them are cheap as they are the last 4 they will carry, I only have the one price for honing and boring so far, but it should be easy to get more costings from others. It's just for the future rebuild, not one I am doing now. Hopefully I can get a few more seasons with what I have now.

 

[jerryjerry05]

Re: Pricing a rebuild

When you get to .040 over you'll need to rejet the carbs too.
At 20 they can stay the same.

 

[MickLovin]

Re: Pricing a rebuild

My carbs are for a 140hp not my 100hp Jerryjerry, and so they are jetted at .096 already. I changed from my WB to a TC5D carb from a 140

 

[oldboat1]

Re: Pricing a rebuild

Maybe you need a motor to go with the one you describe -- maybe a little older, good mechanicals, decent purchase price (maybe a bargain) -- something you can always tweak to run a little better. I sure wouldn't get into the weeds with rebuilding unless I really enjoyed it. Lot's of different hobby approaches, all of them good.

think I'll call it the theory of redundant outboards -- man needs two or three to interchange, at a minimum. Never the end of the season if one craps out.

 

[MickLovin]

Re: Pricing a rebuild

Thanks ildboat1, they are rare as hens teeth over here in Oz at the moment, I will find one though proably a 105hp with a one piece lu would be good. I troll Gumtree and ebay every day.

 

[oldboat1]

Re: Pricing a rebuild

Good luck with the search Mick. Had a 105 in the late '80s (think it was a '74, but not sure now). All good.