MK58 Sport Port 44

Show & Tell time! Photos, comments, stories, etc

MK58 Sport Port 44

Postby ctpdsr » Fri Jul 19, 2019 9:15 pm

It's time for another Sport Port "Giant Killer" build I think.

Donor powerheads include the MK58 #1142983 and a Merc400. Here are a couple of "before" shots to belie the impression that all is shinny and pristine in this shop. Time to get this block in the soak tank and bead cabinet! Question - why do so many feel the need to paint everything black?...

Chuck

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Re: MK58 Sport Port 44

Postby dave bernard » Fri Jul 19, 2019 9:25 pm

Quick easy clean looking. so they think.
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Re: MK58 Sport Port 44

Postby ctpdsr » Mon Jul 22, 2019 5:56 pm

Now that looks better!

Time to start building the "Parts Pile".

Chuck

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Re: MK58 Sport Port 44

Postby Locomotion » Mon Jul 22, 2019 10:10 pm

Chuck,

Thanks again for sharing.
Is that finish on the block from glass beading or?
I always bead blast Harley heads but I am really reluctant when it comes to the engine cases it's so hard to get it all back out.

Thanks
Ray
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Re: MK58 Sport Port 44

Postby ctpdsr » Mon Jul 22, 2019 10:28 pm

Hi Ray,

Yes - medium glass bead. After a serious wash, I then apply a thin spray of hi-temp ceramic clear to the outside surfaces. Duplicolor Caliper/Engine Block.

Chuck
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Re: MK58 Sport Port 44

Postby ctpdsr » Tue Jul 23, 2019 6:17 pm

I thought this photo might be of interest. The first 44 Sport Port Stage One built in Jerry's Fox Point shop about 15 years ago. Still runs like a champ and the block finish has held up quite well. In the shop today for a mag refresh and general maintenance.


Chuck

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Re: MK58 Sport Port 44

Postby mercaholic » Wed Jul 24, 2019 1:22 am

What exactly was it about the Mk58 powerheads that made them such strong runners?

Racers seem to like them but I never knew why.
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Re: MK58 Sport Port 44

Postby 194268 » Wed Jul 24, 2019 2:03 pm

44 cu/in and bigger carbs.
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Re: MK58 Sport Port 44

Postby ctpdsr » Wed Jul 24, 2019 4:23 pm

Unlike the 40 Mercs, the port design remained constant throughout 44 production - round 5/8" single cut. Please see the attached article by Jerry with regard to the issues involving the 40 Service block racers.

As is the case with any long term production run, the early blocks, in this case 1958, tended to be more consistent. A couple of additional features with regard to the early powerheads that I like include lighter weight pistons, additional cooling passages and pressure oil feed to the top bearing cap where it belongs. We retrofit newer blocks & bearing caps.

The problem inherent to ALL 44 blocks has to do with the round exhaust ports that create flow issues. The "Sport Port" design solves this and adds significant performance without sacrificing start/idle behavior.

40 and 44 Porting, Urban Myths.doc
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Chuck
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Re: MK58 Sport Port 44

Postby ctpdsr » Thu Jul 25, 2019 9:56 pm

Selected and prepped a nice crank today. This happens to be an early large-taper crank, perhaps from a MK58 or 58A. Early cranks had the coper plate vs. the dark tinted treatment. Nothing magic about that except the later dark cranks went to a single center-main bearing race. Nothing wrong with that for a service powerhead. I prefer a double race for a 44 Mod. With regard to overall condition, any pitting on the rod journals sends any crank to my recycling bin. And I do mean any...With regard to wear or "out of round" on the ends, I prefer within .0005" +/- for a racer and within .0015" otherwise. The bottom end is almost always the subject here, although both ends should be checked. Need to mic these, a caliper is not accurate enough.


Chuck

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Re: MK58 Sport Port 44

Postby zul8tr » Fri Jul 26, 2019 10:45 am

ctpdsr wrote:Unlike the 40 Mercs, the port design remained constant throughout 44 production - round 5/8" single cut. Please see the attached article by Jerry with regard to the issues involving the 40 Service block racers.

As is the case with any long term production run, the early blocks, in this case 1958, tended to be more consistent. A couple of additional features with regard to the early powerheads that I like include lighter weight pistons, additional cooling passages and pressure oil feed to the top bearing cap where it belongs. We retrofit newer blocks & bearing caps.

The problem inherent to ALL 44 blocks has to do with the round exhaust ports that create flow issues. The "Sport Port" design solves this and adds significant performance without sacrificing start/idle behavior.

40 and 44 Porting, Urban Myths.doc



Chuck


Chuck

You do very nice neat meticulous work, great shop.

When you select these 4x blocks do you check the port timing and what do you like?
In the 2019 APBA Stock Outboard Inspection Manual they give the ports specs for the 44 and their +/- on them:

Intake     A1 dim  3.382" + 0.015 - 0.025"
             A   dim  4.007" +/- 0.015"
Exhaust  C1 dim  3.596" + 0.015" - 0.025"
             C   dim  4.221" +/- 0.015"

The manual lists intake and exhaust port height as 0.625" +/- 0.010"

With 5/8"(0.625") holes they allow a lot of variation on placement

On the 25ss 22 c.i blocks I raced in the 70's the APBA Inspection manual A1 and C1 tolerance on intake and exhaust was +/- 0.025" for the 5/8" holes thus there were great, good and not so good blocks related to this tolerance.

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Re: MK58 Sport Port 44

Postby ctpdsr » Fri Jul 26, 2019 3:44 pm

Hi Pete,

Short answer is no. The overall condition of the bores, heads, etc. are the primary concern. We like to see the port timing consistent from cylinder to cylinder. The Sport Port design does not significantly alter port timing. Higher is not always better.....

Chuck
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Re: MK58 Sport Port 44

Postby zul8tr » Fri Jul 26, 2019 5:57 pm

ctpdsr wrote:Hi Pete,

Short answer is no. The overall condition of the bores, heads, etc. are the primary concern. We like to see the port timing consistent from cylinder to cylinder. The Sport Port design does not significantly alter port timing. Higher is not always better.....

Chuck


Chuck

I agree higher is not always better depends on what the power head is going to do. In the 70's I raced a lot of 5 mile 3 lappers and the high port exhaust on the 25ss was a benefit with the right prop and set up. For the shorter courses the high port exhaust was matched with less pitch/diameter prop to make it work for acceleration. Harry Pinner made me experimental very thin SS props that would flex just enough under load during acceleration and tighten up as engine approached max rpms, like shifting gears it worked well.

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Re: MK58 Sport Port 44

Postby ctpdsr » Sat Jul 27, 2019 7:29 pm

That's right Pete - you had to use those specific blocks correct?? If so, that would make sense. I remember a certain local 25SSR guy got tossed for running a Merc200 block. I was a rookie at the time trying to get my first CSR 30H rig together and dont't remember the details. Were certian years/serial#s OK or no Merc 200 blocks period?


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Re: MK58 Sport Port 44

Postby zul8tr » Sat Jul 27, 2019 8:11 pm

Chuck

To answer your question:

Looking back at my the APBA  the  SO Inspection Manuals for 1974, 1977 and 1978 the Merc 200 power head was allowed. The 25ss  class started in 1973 and I do not have that SO Insp Manual.

In 1974 the 25ss + Merc 200 + OMC 25 were allowed
In 1977 the 25ss + Merc 200 they dropped the OMC  not sure what year 75 or 76.
In 1978 the 25ss + the Merc 200

I left racing in late 1979 and the Merc 200 was still allowed don't know what happened after that.

BTW the Merc 200 had same spec as the 25ss on the intake ports but was ported lower for the exhaust: 4.235 (25ss) vs 4.221 (Merc 200 and the same as the 44xs in my post above). Both had +/- 0.025 on the intake and exhaust ports location.

I believe some used the Merc 200 power head on short courses but never really heard of it but it was legal. I know I didn't use the Merc 200 head, I played with props and set ups for different courses. I bought my 25ss new from Dick O'Dea in early 1973 and has matching numbers and same gear case to this day but I use the 2 ring + 15 over 44xs pistons. But it has different recoil covers that were always breaking  icon_thumbdown.gif

Hope this didn't hi jack your build thread.

Pete
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Re: MK58 Sport Port 44

Postby ctpdsr » Sat Jul 27, 2019 9:18 pm

Thanks for that info. Pete. I always enjoy learning stuff, particularly of the Mercury Racing variety. Maybe the issue was an older 200 block ie: late 1960's?? I digress.

While visiting the smart tall guy last week, I asked him to prep a top bearing cap for this build. Here is the issue. We have a 1958 powerhead with top cap oiler and old-style slotted cap. I have zero problem using these older caps for service builds, but a 44 Mod should get an upgrade to a solid cap. Problem is there is no oiler hole on these newer caps. They were plumbed from the Center Main to the lower cap. No worries, we can fix. Key trick here is to work a "channel" for the oil to feed around the body of the bearing itself. You just drill a hole without this additional step and the top of the bearing will block off the flow. This essentially mirrors the design of the older caps.


Chuck

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Re: MK58 Sport Port 44

Postby zul8tr » Sun Jul 28, 2019 1:50 pm

Chuck

What is the issue with the slotted cap in the 44 mod ? Is it a problem with bearing looseness with the interference fit when at operating  temp or some other issue?

That drilled oilier hole just feeds the ball bearing. The oilier hole in my 25ss goes to the top roller bearing's outside case perimeter groove to get to the rollers then oil runs down to the ball bearing.

I see, the 44xs does not have a top roller like the 25ss and other 2 cylinder Mercs  20H, etc.

https://www.crowleymarine.com/mercury-o ... 1504_9.cfm

Pete
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Re: MK58 Sport Port 44

Postby zul8tr » Sun Jul 28, 2019 3:53 pm

ctpdsr wrote:Thanks for that info. Pete. I always enjoy learning stuff, particularly of the Mercury Racing variety. Maybe the issue was an older 200 block ie: late 1960's?? I digress.

Chuck

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Chuck
Yes to possibly older 200, the approved 22 ci Merc 200 blocks were 1970 and newer and 25ss carb etc. were allowed to be added.
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Re: MK58 Sport Port 44

Postby ctpdsr » Sun Jul 28, 2019 5:38 pm

I have actually seen bearings slide south over time in D-Stock racers. The solid cap just does a better job of retaining the bearing. Mercury changed the design in 1959 (white motor era). A telltale symptom is loss of endplay.

Chuck
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Re: MK58 Sport Port 44

Postby Tom Brockmeyer » Sun Jul 28, 2019 8:08 pm

zul8tr wrote:I see, the 44xs does not have a top roller like the 25ss and other 2 cylinder Mercs  20H, etc.

https://www.crowleymarine.com/mercury-o ... 1504_9.cfm

-Pete


44XS has an upper bearing...  Key #5, Ball Bearing, Upper End Cap,  Part No. 67342T
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Re: MK58 Sport Port 44

Postby zul8tr » Mon Jul 29, 2019 11:04 am

Tom Brockmeyer wrote:
zul8tr wrote:I see, the 44xs does not have a top roller like the 25ss and other 2 cylinder Mercs  20H, etc.

https://www.crowleymarine.com/mercury-o ... 1504_9.cfm

-Pete


44XS has an upper bearing...  Key #5, Ball Bearing, Upper End Cap,  Part No. 67342T



Tom
Never said 44xs does not have a ball bearing? Said it does not have a top roller bearing that sits above the ball bearing like in the 20H, 25ss, etc 2 cylinder jobs.
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Re: MK58 Sport Port 44

Postby ctpdsr » Mon Jul 29, 2019 8:57 pm

Slowly getting the pile-o-parts together. Time to ship the block & rods to the machine shop.

Chuck

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Re: MK58 Sport Port 44

Postby Locomotion » Tue Jul 30, 2019 2:00 am

Do the rods get honed or other work?
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Re: MK58 Sport Port 44

Postby zul8tr » Tue Jul 30, 2019 12:53 pm

ctpdsr wrote:Slowly getting the pile-o-parts together. Time to ship the block & rods to the machine shop.

Chuck

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Chuck

What are your specs for out of round and taper to machine shop to determine if a bore is required and oversize pistons?

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Re: MK58 Sport Port 44

Postby ctpdsr » Tue Jul 30, 2019 4:04 pm

Good question Ray.

The rods get honed via Sunnen machine to a specific size depending on the crankshaft we are working with. The center main bearing gets a similar treatment. The flat sides of the rod are also dressed on a surface plate and carefully measured. Easy way to get them all the same is to lightly dress all 4, pick the skinny 1 in the bunch and match the other 3. Same goes for the spacers.


Chuck

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Re: MK58 Sport Port 44

Postby ctpdsr » Tue Jul 30, 2019 10:23 pm

A couple of thoughts on bore specs. My goal with these 30, 40 & 44 builds is to produce a quality performance result at a reasonable cost with consideration to available parts. The decision to bore these vintage 44 blocks involves significant costs including machine work, pistons, rings & rods(large pin size). The good news is as long as there is no structural damage, it is very rare to find a vintage 44 Service block that is "worn out". I would call the example we are working with in this build to be on the low side of average in terms of mileage. By my inexpensive dial bore gauge, I calculate we need to remove .0005" to get DOWN to optimal spec. I am comfortable with +.003" beyond that spec. The general idea here is that these early 44's have a lot of meat on the bone. On occasion, as was the case last fall with a real 55H block we looked at that had been bored twice (+0.015" / +.030") and measured in at +.006" over that. That in addition to a bunch of cracked port webs steered us in the direction of finding an alternate block. The Master Service Manual tolerance for out of round is +/- .006". That's a lot. Keep in mind, when a skilled machinist with a Sunnen machine & proper setup hones this block, it will come back with straighter bores that when it left...


Chuck

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Re: MK58 Sport Port 44

Postby zul8tr » Wed Jul 31, 2019 2:00 pm

Chuck

You said - "My goal with these 30, 40 & 44 builds is to produce a quality performance result at a reasonable cost with consideration to available parts"

Very appropriate target to have.

Also - " By my inexpensive dial bore gauge, I calculate we need to remove .0005" to get DOWN to optimal spec. I am comfortable with +.003" beyond that spec. "

With each + 0.001" over on bore diameter is + 0.0031" more ring end gap. Your comfort + 0.003" spec would be + 0.0.0094" more ring end gap. What would you do with the rings for that case?

Brinkman suggests +0.015" oversize rings and trim gap to a spec.  I have heard others against that since the over size ring becomes to oval (from original perfect circle of ring machine process) when put in a smaller bore not sized for that ring :?: Where is Jerry W. on this?

Nice neat work
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Re: MK58 Sport Port 44

Postby ctpdsr » Wed Jul 31, 2019 4:27 pm

I have heard of stuck pistons resulting from guys trying to get the ring gap super tight. I am quite happy to run OEM rings in my slightly loose bores.

Chuck
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Re: MK58 Sport Port 44

Postby zul8tr » Wed Jul 31, 2019 4:31 pm

Me too, seen it many times with other racers back in the day.
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Re: MK58 Sport Port 44

Postby Michael » Wed Jul 31, 2019 6:05 pm

ctpdsr wrote:I have heard of stuck pistons resulting from guys trying to get the ring gap super tight. I am quite happy to run OEM rings in my slightly loose bores.

Chuck

[yeahthat.gif] we have watched a member try to stuff oversize rings  in tapered cylinders several times, results are always the same
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Re: MK58 Sport Port 44

Postby ctpdsr » Fri Aug 02, 2019 6:10 pm

Couple of notes with regard to reed cages. Always use the MK58 style or later solid brass cages with the labyrinth oil seal. MK58 typically had 1" reed ports vs. the later white Mercs with 1 5/8" ports. Both work fine. Keep in mind the larger port openings are partially covered by the back end of the reed. Any reed from the brass cage era will work fine. Inspect carefully and clean up with scotch-brite pad. I bead blast the stops. If the tops of the cages are worn, they should be resurfaced.
I also do a very light hand chamfer on the port openings.

Setup is critical. Reeds should be perfectly centered as well as the stops. Stop height should be uniform. Not too low OR too high. The photo shows a 3/16" drill for refference. Not uncommon to find a stop or two that got slightly squished down during assembly. I wick in a drop of green Loctite after final assembly.


Chuck

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Re: MK58 Sport Port 44

Postby ctpdsr » Wed Aug 14, 2019 5:34 pm

Shipment arrived from Machine Shop yesterday. Yay! Sport Ports and rods honed. Time to get busy!

Chuck

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Re: MK58 Sport Port 44

Postby ctpdsr » Sun Aug 18, 2019 11:50 pm

After a fun day as "pit crew" for the kid yesterday, I got back to work in the shop with an intense hand chamfer of this sweet 44 block. Now we can ship back to MN for a final hone to spec. This build has the potential to be a silly fast racer.

Chuck

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Re: MK58 Sport Port 44

Postby ctpdsr » Fri Aug 23, 2019 6:31 pm

While the block is in transit, time to get the bearing caps and rod/piston assemblies together.

A word about the bottom end caps. Early style 400-2 cranks were partially finished on the bottom end and require a single-seal cap. We are using a later style 413-1125 cranks machined 100% and fitted with double seal caps. Trick with these is to get the seals perfectly aligned at the proper heights within the cap housing. I have a custom set of aluminum "pusher" tools and a decent Arbor Press. Can't do this job properly without both in my opinion.


Chuck

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Re: MK58 Sport Port 44

Postby ctpdsr » Tue Sep 10, 2019 9:23 pm

Block arrived yesterday. The finish hone looks awesome! I can now approach final assembly knowing that the bores are consistent. Prior to the finish hone, they varied by as much as -.003". For some reason, the lower the cylinder, the higher the wear(larger bore). What we essentially found was #4 was very close to spec and we removed material from the rest to match. Cylinder #1 was the tightest. This is going to be a solid performer. Time to stage the final "Pile O' Parts" photo!


Chuck

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Re: MK58 Sport Port 44

Postby ctpdsr » Wed Sep 11, 2019 10:33 pm

Forgot to note the bearing caps are now complete. New seals and trick bearings. Note the orientation of the bearings. Anything of interest?

Chuck

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Re: MK58 Sport Port 44

Postby zul8tr » Fri Sep 13, 2019 11:17 am

ctpdsr wrote:Block arrived yesterday. The finish hone looks awesome! I can now approach final assembly knowing that the bores are consistent. Prior to the finish hone, they varied by as much as -.003". For some reason, the lower the cylinder, the higher the wear(larger bore). What we essentially found was #4 was very close to spec and we removed material from the rest to match. Cylinder #1 was the tightest. This is going to be a solid performer. Time to stage the final "Pile O' Parts" photo!


Chuck

IMG_3488.jpg


Chuck

With material removed from bores to match #4 what is the final piston to bore clearance in the cylinders and what is the final ring end gap?  

Thanks
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Re: MK58 Sport Port 44

Postby Michael » Fri Sep 13, 2019 11:24 am

zul8tr wrote:
ctpdsr wrote:Block arrived yesterday. The finish hone looks awesome! I can now approach final assembly knowing that the bores are consistent. Prior to the finish hone, they varied by as much as -.003". For some reason, the lower the cylinder, the higher the wear(larger bore). What we essentially found was #4 was very close to spec and we removed material from the rest to match. Cylinder #1 was the tightest. This is going to be a solid performer. Time to stage the final "Pile O' Parts" photo!


Chuck

IMG_3488.jpg


Chuck

With material removed from bores to match #4 what is the final piston to bore clearance in the cylinders and what is the final ring end gap?  

Thanks


I was just going to post the same question
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Re: MK58 Sport Port 44

Postby ctpdsr » Fri Sep 13, 2019 4:29 pm

Nobody curious about the bearings?  Note the polymer retainers for sort of a "cup" that will hold a little oil.  I orient these to face northward.  When it gets to some of the specific numbers, porting specs, etc... they are not mine to share.  My goal is to build every powerhead as if it will be raced.  Some may appreciate the journey, some may not.  I have seen way too many of these motors sold with real fancy paint jobs and polished everything that are basically junk inside.  My first client years ago pulled into my driveway with his prize "MK55H" all pretty with a nice gearcase.  Powerhead was a MK58 with a factory seal and KA9A carbs...


Chuck

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Re: MK58 Sport Port 44

Postby Tom Brockmeyer » Fri Sep 13, 2019 5:54 pm

ctpdsr wrote:Nobody curious about the bearings?  -Chuck


Well, I was curious but your pictures are quite small.  Can't seem to click on them to enlarge.
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Re: MK58 Sport Port 44

Postby ctpdsr » Sat Sep 14, 2019 12:19 am

Thanks Tom. I used to insert the photos directly from my iPhone. As a test, I went back to a prior build and was able to click to enlarge photos.

Is this better?


Chuck
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Re: MK58 Sport Port 44

Postby Tom Brockmeyer » Sun Sep 15, 2019 10:39 pm

Way, WAY better pic.  Now the bearing caps again with the plastic cage..?
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Re: MK58 Sport Port 44

Postby 208rooster » Mon Sep 16, 2019 1:01 am

Chuck I agree way better.. [drinkingcheers.gif]
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Re: MK58 Sport Port 44

Postby ctpdsr » Mon Sep 16, 2019 3:52 pm

E895A657-1C04-4546-8F0B-00E13476DCF5.jpeg


This one?
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Re: MK58 Sport Port 44

Postby zul8tr » Mon Sep 16, 2019 4:47 pm

Chuck

Nice to see the details of the retainers. Did you press the bearing in or heat the alum cap to about 250 F and drop them in then put the seal in?  

Pete
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Re: MK58 Sport Port 44

Postby ctpdsr » Mon Sep 16, 2019 6:42 pm

I use my arbor press and round “pusher” tools specific to each seal and bearing. It is critical to get the double seals lined up right or you will bind the bearing. A drop of green Loctite wicked in after assembly along the outer edge for good measure.

Chuck
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Re: MK58 Sport Port 44

Postby ctpdsr » Mon Sep 23, 2019 6:18 pm

After a break last week for fishing in Northern Wisconsin, it's back to the shop. The rod/piston assemblies went together nicely. Note BOTH ends of these rods have been dressed. The big ends were done professionally to a specific dimension. The small ends I do by hand. The spacers are finished on a surface plate. All the 44 pistons have thin washer looking spacers vs. the fatter versions on a 40.

Chuck
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Re: MK58 Sport Port 44

Postby Tom Brockmeyer » Mon Sep 23, 2019 11:40 pm

Machinist Question:  How do you keep both sides of the small ends parallel..?
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Re: MK58 Sport Port 44

Postby ctpdsr » Tue Sep 24, 2019 11:46 pm

Not sure if this answers the question - the flat sides (small and large) are dressed on a surface plate. I measure with a mic both side-to-side and end-to-end. It takes a little bit of work just to get the faces uniform. After I get a uniform finish on both sides, I find the skinny rod and match the hatch. I also use the surface plate to check for straightness. The rods and spacers as a set are all within .0005" total thickness. Takes about 4 hours work to dress a set of rods. Hope this helps.

Chuck
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Re: MK58 Sport Port 44

Postby ctpdsr » Wed Sep 25, 2019 9:29 pm

Fun part getting close now! After a serious bath, the 44 Sport is ready for pistons. Brass oilers have also been installed.

Gents - I spoke with my client in VA today. This project has now expanded to into a full engine build including tower, gearcase and professionally painted cowls. I typically stick to powerheads only, but this will be a special deal. Speaking of powerheads, I have a 2nd Pile O' Parts under way for a 44 Sport Port Stage 1 very similar to this build. AVAILABLE FOR OWNERSHIP.  Feel free to send me a PM or call. The 2020 order board is starting to fill...


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