Author Topic: Fatso Q  (Read 3639 times)

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Offline 88fxstc

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Fatso Q
« on: Thursday, July 12, 2012. 07:08:40 AM. »
I have a 100" Fatso motor in my 88 softail. Cracked my stock cases bout 10ish years ago and had a line on the Fatso so in it went. No down time for rebuild and added cubes and the price was right, if I remember right it was $5800 installed at a buddy's indy shop.
This motor came from a company called Milwaukee Performance and has been a strong running reliable mill for years.
The lower end is Merch, I was told it is a lower end from a Merch 120 which I believe was 4.25 x 4.25 cause I seem to remember those 120's by Merch being all bore.
Here's my question:
Would that mean that the spigot holes in my cases are already big enough to go bigger bore without needing to be split and opened up??? Or, did these cases come special from Merch with holes for the 3.875 (I think) 95" TC jugs.
Delkron makes 114" Fatso jugs and I'm wondering if those or any other TC style big bore jugs up to the 4.25 that the Merch 120's I'm pretty sure came with ,  would drop in without case splitting.
I'm also curious what I have in there for a crank, I know it's 4.25 stroke but did Merch make their own cranks and if so, whats the word, were they decent cranks?? or did they use S+S or Jims, HD ,or someone else???

Thanks for any info
88 FXSTC 100" Fatso    07 FLHX R&R 131
68 Bonneville 650

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Re: Fatso Q
« Reply #1 on: Thursday, July 12, 2012. 05:03:11 PM. »
When it comes to Merch motors the only way to know for sure is to open it up & check.
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Offline badcooky

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Re: Fatso Q
« Reply #2 on: Friday, July 13, 2012. 02:56:02 AM. »
From memory the Fatso/Fatvo is the Evo stroke on Twinkie barrells, and jugs, the pistons are 3-7/8 with an Evo wrist pin.The pushrods are a special size too I think.Sputhe or Delkron cases from memory with Evo crank ,rods and timing gear, basically an Evo bottom end in the cases after market (Sputhe,Delkron,or ?) with the twinkie top end..
Man I don't know if I've helped at all.
Cheers.

Offline 88fxstc

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Re: Fatso Q
« Reply #3 on: Friday, July 13, 2012. 05:25:20 AM. »
From memory the Fatso/Fatvo is the Evo stroke on Twinkie barrells, and jugs, the pistons are 3-7/8 with an Evo wrist pin.The pushrods are a special size too I think.Sputhe or Delkron cases from memory with Evo crank ,rods and timing gear, basically an Evo bottom end in the cases after market (Sputhe,Delkron,or ?) with the twinkie top end..
Man I don't know if I've helped at all.
Cheers.

Yup, thats the idea pretty much and I've been running mine for years and it really is a strong runner. Never dyno'd but the a$$ dyno says it's a runner. I'd guess at least 100/100 hp/tq, if not more.  Like I said , mines based with a merch single cam bottum. I'm just looking for more power and I'm thinking of my options. I might just get the heads worked b, it's currently running the early style Twinj cam heads that are stock except for the pushrod hole mods.
88 FXSTC 100" Fatso    07 FLHX R&R 131
68 Bonneville 650

Offline 88fxstc

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Re: Fatso Q
« Reply #4 on: Friday, July 13, 2012. 05:41:16 AM. »
When it comes to Merch motors the only way to know for sure is to open it up & check.

Hey Larry, curious, what gains would I see if I threw a set of 07 TC heads on there, I realize the pushrod holes would have to be dealt with. Are the newer heads that much better than the original early TC heads to do this and be worth it???. It would probably be cheaper than getting the heads that are on there ported, but I'm sure the gains would be less than a good port job on the heads I have on there as well. . I'm thinking maybe just get the heads flowing better (port the existing ones or throw on the set of brand new 96"ers I have) and a different cam. It syupposedly has a SE57 evo cam in it now.  How bout you, If I sent my 96"ers to ya for headwork I'm guessing you could easily fix the pushrod holes for me as well as do the headwork, correct???
I know you have Fatso experience thats why I'm picking your brain.  Sorry if I'm being a pain in da ass.
88 FXSTC 100" Fatso    07 FLHX R&R 131
68 Bonneville 650

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Re: Fatso Q
« Reply #5 on: Friday, July 13, 2012. 06:19:15 AM. »
If you want you can update the heads you have to flow a LOT better. CNC porting eliminates any advantage between the two.

If the money's tight having those heads ported [Stage 1] would still be better than swapping them out.
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Offline 88fxstc

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Re: Fatso Q
« Reply #6 on: Friday, July 13, 2012. 06:36:32 AM. »
ThAnks dude, I just gotta weigh my option$$. The reason I even mention the 07 heads is I have a brand spanky new set collecting dust in my garage Along with a set of 07 jugs. So working the 07's would keep the down time down. I'm thinking now maybe taking the 07 jugs up to the 107" bore size guys are doing now which should put me at bout 103" on the fatso if I'm mathing it right. So, if I had you cnc machine my 07 heads could you address the pushrod hole issue as well to make them Fatso friendly??
88 FXSTC 100" Fatso    07 FLHX R&R 131
68 Bonneville 650

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Re: Fatso Q
« Reply #7 on: Friday, July 13, 2012. 07:31:45 AM. »
Yes
I have the pushrod cutter tool that I can let you use to make a perfect cut in the heads after you bolt them on.
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Offline 88fxstc

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Re: Fatso Q
« Reply #8 on: Friday, July 13, 2012. 02:11:32 PM. »
I appreciate the response and the offer Larry. I think I'll just wait till winter and have the heads that are on there done.
If so, I'll probably be talkin to you about it.
I was supplied with contact info for Gerry Merchant by a member here so hopefully I'll get some Merch answers from him.

Thanks
88 FXSTC 100" Fatso    07 FLHX R&R 131
68 Bonneville 650

Offline eke166

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Re: Fatso Q
« Reply #9 on: Monday, August 13, 2012. 05:38:24 PM. »
Question about the Fatso.  I am building one (tring toooo)  I have read that I need to relocate the pushrode hole.  Any help with that?  Any thing else or any knows anybody that can do that? Thanks Eric

Offline eke166

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Re: Fatso Q
« Reply #10 on: Monday, August 13, 2012. 05:47:26 PM. »
Looking to see if anyone knows anybody that can relocate my pushrods for a fatvo / fatso

Offline 88fxstc

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Re: Fatso Q
« Reply #11 on: Tuesday, August 14, 2012. 05:05:34 AM. »
Delkron's site says they do the pushrod geometry mods. If you go to their site, read the Fasto cases page and it says there that they do this. Maybe some of the head guys on this site might  be able to straighten you out, though it might be such a small job they might not want to deal with it less yer getting yer heads worked over as well. Just a guess though dude, I don't speak for anyone here.
Also, there's a shop up in Canada that has the dude from Merch motors building fatsos,.do a search for kent county customs.
88 FXSTC 100" Fatso    07 FLHX R&R 131
68 Bonneville 650

Online e-glide90

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Re: Fatso Q
« Reply #12 on: Tuesday, August 14, 2012. 06:36:28 AM. »
That motor you have is one good motor. Just sold mine about two months ago (still sorry).  Got mine in 99 from same place.  Had it apart once because of flood, the bore measured 4.055, and flywheels were Merch.  Thought about going bigger, mechanic advised against it.  For cylinders to fit bottom of bolt holes were reamed out some, mechanic thought going bigger would make cylinder walls little on the thin side. Had head work done, really made difference. For awhile ran a Dave Mackie 580 cam, was noisy, but really made power. Hope this helps,and good luck, they are one great motor.  e-glide90

Offline 88fxstc

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Re: Fatso Q
« Reply #13 on: Tuesday, August 14, 2012. 09:36:03 AM. »
Eglide90, appreciate the info, my knowledge of the guts of the motor has always been a little hazy.
I think I'm leaning toward just a jug cleanup this winter and some headwork and a cam, i'll leave cam choice up to the porter. The thing runs really strong as is, with nearly stock early style TC heads, so I should be able to get it breathing a good bit more. If I remember right, it's running a Screaming Eagle 57 cam in it, and it runs strong but it's always been slightly pingy if you didn't ride it they it liked to be ridden. Had to keep those rpm's up there.
88 FXSTC 100" Fatso    07 FLHX R&R 131
68 Bonneville 650

Offline eke166

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Re: Fatso Q
« Reply #14 on: Tuesday, August 14, 2012. 04:48:46 PM. »
once you move the pushrode holes which tappet blocks do you use.  (Evo or Twin cam)

Online wfolarry

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Re: Fatso Q
« Reply #15 on: Tuesday, August 14, 2012. 05:18:58 PM. »
once you move the pushrode holes which tappet blocks do you use.  (Evo or Twin cam)

Evo. Twin Cam's are in the cases. They just use covers. The only thing you have to watch for is which cases you're using. There are some [Sputhe] that use stock flywheels so you can use stock lifter blocks but there are others that use the longer pinion shaft. With these you would be better off using lifter blocks like S&S's for their bigger motors with the longer pinion shaft. Ultima has some nice cases out now & I'm sure they would have the lifter blocks as well.
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Offline badcooky

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Re: Fatso Q
« Reply #16 on: Tuesday, August 14, 2012. 05:49:20 PM. »
.....
« Last Edit: Thursday, August 16, 2012. 08:30:37 PM. by badcooky »

Offline eke166

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Re: Fatso Q
« Reply #17 on: Wednesday, August 15, 2012. 04:51:23 PM. »
Larry  thanks you been a big help I will prob get some Ultima tappet blocks.  My case is a Ultima Fatso  they should work.  Just to let some other folks know I found a shop in PA to move my pushrode holes and port and polish my heads.  I will let yall know how it turns out.  Very reasonable prices

Offline CaptMike

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Re: Fatso Q
« Reply #18 on: Thursday, August 16, 2012. 05:57:15 AM. »
Keep us Posted.  I've found this thread very interesting...  Hummmm.   I'd like a 100" in my Evo "bob/rat".   
1957 Pan, 1997 Black Betty Bobber, 1998 RoadGlide
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Offline eke166

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Re: Fatso Q
« Reply #19 on: Monday, August 20, 2012. 12:21:11 PM. »
What type of tappet blocks do i need to run

Offline catmcaw

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Re: Fatso Q
« Reply #20 on: Monday, August 20, 2012. 03:33:57 PM. »
  I think you need Ultima part #91-697

Offline 88fxstc

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Re: Fatso Q
« Reply #21 on: Monday, August 20, 2012. 04:22:45 PM. »
What type of tappet blocks do i need to run

Larry answered that one for ya a few posts back
88 FXSTC 100" Fatso    07 FLHX R&R 131
68 Bonneville 650

Offline eke166

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Re: Fatso Q
« Reply #22 on: Thursday, August 23, 2012. 05:53:26 PM. »
OK thanks.  Are the Ultima tappet blocks offset?

Offline catmcaw

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Re: Fatso Q
« Reply #23 on: Saturday, August 25, 2012. 12:40:56 PM. »
   I know some of you have built a Fatso. Can someone tell me the reason for relocating the pushrod tubes in the head? Do the pushrods rub the tube or do the tubes leak? What exactly is the problem?

Offline 88fxstc

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Re: Fatso Q
« Reply #24 on: Sunday, August 26, 2012. 05:37:37 AM. »
I didn't build mine, It's a crate mmotor, one of the experts can probably answer this better than me  but I think it's just that TC heads don't have the exact same pushrod locations/angles as an EVO so you gotta move the holes to make em work.
88 FXSTC 100" Fatso    07 FLHX R&R 131
68 Bonneville 650