What are my options? 44 mod pistons

[blueskyracer]

All last year I tried to run a 44 with Vertex pistons.. The motor kept sticking and it was always a different cylinder.. Well with some help and playing around I found out that the rings were sticking in the ring groves right at the locator pins even during assembly before being run.. I have done some minor chamfering but the problem still exists I just found out.. So I am wondering does anyone else make rings for these pistons.. The bores is at .015 over.. I figure if no one has rings I need to find used first over Mercury pistons or I will buy a set of .015 Sierra pistons.. Weisco are out since they are .020 over and I don't have time to get .005 more taken out with testing on the 26-27 of April.. Advice is welcome since I don't want another year like last year..

[Steve Dunn Racing]

Mile give me a call 843 455 1393 Steve

[ZUL8TR]

All last year I tried to run a 44 with Vertex pistons.. The motor kept sticking and it was always a different cylinder.. Well with some help and playing around I found out that the rings were sticking in the ring groves right at the locator pins even during assembly before being run.. I have done some minor chamfering but the problem still exists I just found out.. So I am wondering does anyone else make rings for these pistons.. The bores is at .015 over.. I figure if no one has rings I need to find used first over Mercury pistons or I will buy a set of .015 Sierra pistons.. Weisco are out since they are .020 over and I don't have time to get .005 more taken out with testing on the 26-27 of April.. Advice is welcome since I don't want another year like last year..

If you can get them the Mercury 0.015 over piston kit 2 ring design is what you need. When I rebuilt my 22 ci Merc 25ss stock engine back in late 2012 I conferred with Jerry Wienandt on pistons and lots of other items, he was very helpful. I needed to go 0.015" over and Jerry recommended only the Merc 44 ci 2 ring piston kit p# 780- 9229A10 kit for stock or mod engines. Pistons come with matched pins, rings and retainers. Bought them from Marine Parts Plus for best price at the time, NLA now. Jerry says that these pistons are well made, accurate and weigh very close. The piston kits I used weighed within 0.3 grams of each other and all measured the same which attests to the accuracy of these piston kits. BTW made in Japan. Been running them at 7200 rpm with 16:1 oil and non E fuel and skirt clearenced at 0.0062", no stick issues. Mod would have greater clearance, per Harry Brinkman's build manual.

Did a quick INET search for these Merc pistons and they seem to have disappeared, the Sierra units are available but I do not know about them.

What are your present bore dimensions and trueness?

[blueskyracer]

Does anyone have a part number for the .015 oversize two ring Mercury pistons.. I will do a interweb search and then if I cant find them I will get the Sierras since they are readily available and I have them in my other engine I have won with.. Right now almost all the stores on the web have them for $98.. Steve when is a good time to call?

[dndsam]

You will need large wrist pin connecting rods with these +.015 2 ring keystone style pistons. I have a set of standard bore in this style, if you happen to start over at some point with a fresh block. I will keep my eyes peeled for a set of +.015.

[ZUL8TR]

Does anyone have a part number for the .015 oversize two ring Mercury pistons.. I will do a interweb search and then if I cant find them I will get the Sierras since they are readily available and I have them in my other engine I have won with.. Right now almost all the stores on the web have them for $98.. Steve when is a good time to call?

See my post above, p# included

[blueskyracer]

My bad.. I should of ready more carefully.. Just trying to hurry I don't have much time till we test..

[blueskyracer]

well just did a search and everything comes back to Sierra so to get Mercury stuff it would have to be used.. Or a select bit of some ones stash

[dndsam]

I believe I may have +.015 Mercury rings for the 3 ring piston design. I would need to check later this afternoon/evening, but not sure if this would help or work on your Vertex Pistons.

[ZUL8TR]

well just did a search and everything comes back to Sierra so to get Mercury stuff it would have to be used.. Or a select bit of some ones stash

I just found the Merc 780-9229A10 15 over at 116 each

http://cmmarinedistributing.com/inde...productId=4921

Call them to make sure they are the OEM merc kit.

Just a reminder the merc keystone rings have an 'O' marked on them that must face the piston crown when installing.

[blueskyracer]

Thank you.. They are OEM pistons and I just bent over and ordered a set.. I am also going to rework the Vertex pistons for a back up.. They use the large rods so I have them in the motor already and I also have a set of reworked small rods also.. All my machine work was done by Jim Ruck

[ZUL8TR]

Ha! Got ya on the bend over, so did I and all I needed was 2 kits. I am sure Jim did the best wall clearance based on your mod engine with pipes but did he do it for the Vertex pistons dims? You can always check the piston diameter at the skirt 90 degrees from the pin 1/2" up and compare to the new Merc piston for a relative measurement to compare difference in wall clearance if any?

Does inspection of the Vertex pistons you pull show any signs of wall scuffing? Same Q for the cylinder walls?

Good luck.

[blueskyracer]

Yes it was a big bend over.. Just made the payment of almost $500 with shipping.. I will compare everything when it gets here.. I guess its time to take the pistons apart and clean up for the new stuff AGAIN.. I must say I am getting lots of practice on tear down..

[ZUL8TR]

Racing costs $$$.

[blueskyracer]

Racing costs $$$.

When did that start!!

[blueskyracer]

Well after all of this time I just got notified that Merc pistons are no longer available.. What crap.. So back to after market

[ZUL8TR]

Sorry to here that I thought you were set. I will look some more. Were you planning to be at USTS Winter haven the end of April?

[blueskyracer]

I was planning to test the motor next weekend but that's not happening.. Hope I can have it ready for our first race on Memorial day.. I hate testing new stuff under race conditions but that's all I have.. Winter haven is just a wee bit far from Western Montana and you guys run D mod?

[blueskyracer]

I just ordered another set of pistons and they will be here the 7th of may.. And I am not holding my breath.. I am beginning to think way back when I should of just ordered a Tohatsu