looking for some advice

[ozzy]

Hi fellow FJ owners
I'm looking for some advice on a rebuild I'm about to undertake
I have a 89 that has a broken crankcase due to improperly installed ape studs 3BC
I have a 3XW case, does anyone know if there is any issue with using this case? and also I have a question about the head studs, the ape ones were obviously installed in the wrong locations as I believe there are different lengths depending on where they are installed
I cant find any definitive information about the lengths or locations so I can make sure my new case is correct.
any help would be appreciated.

Cheers

[fj1289]

When I started on the nitrous engine, Randy advises AGAINST the APE studs.  I guess they put a lot more stress on the case threads and it is common for them to pull the threads out of the case.   I've sprayed up to 150 HP shot of nitrous in the engine for a LONG pull (running a full mile) and never had an issues with the stock studs doing their job. 

The APE studs don't allow for the amount of "growth" these air cooled engines experience - especially when run hard.  The stock studs "grow" with the engine better while still maintaining a good seal between the cylinder and head. 

Chris

[fj1289]

I "THINK" the 3XW case will swap right in — I think the differences are in the frame and motor mounts for the rubber mounts. 

[Old Rider]

I'm not a expert so about the studs I'm blank that is for Randy and the other gurus to answer.One thing i do know is that you will have to use both upper and lower cases from the
3xw because the cases are mated together .I also think you will have to use the crankshaft and bearingsshell  from the 3xw to get the bearing colors and clearances right.
if you use another crankshaft you will have to calculate the bearing colorcodes size  by the numbers stamped on the back of the upper case and the crankshaft.
Also as fj1289 say the differences are in the frame and motor mounts for the rubber mounts. You can maybe compare the enginemounts of pictures of FJ engines on ebay with
the one you got.

[Troyskie]

G'day Ozzy,

Both 1289 & Old rider are correct, however...My brother successfully mated a 3XW lower case with 50K upper. Straight fit for the cases, different frame mounts front. You should be fine, but I've not done your particular swap.

I have no idea about studs that are not original & can't help there.

Troyskie

[ribbert]

The APE studs don't allow for the amount of "growth" these air cooled engines experience - especially when run hard.  The stock studs "grow" with the engine better while still maintaining a good seal between the cylinder and head. 

Chris

That's interesting Chris, are you saying they don't expand as much longitudinally with heat? If that's the case, how does this manifest itself or become apparent?

Noel

[ozzy]

Hi thanks for the feedback, I figured a few pics will make the situation clearer as they speak louder than words.

The replacement case I have is missing two studs, the ones in the case are pictured, I have some spare studs from the damaged case that are 220mm long and 210mm long
not sure what I should use to replace the missing studs.

The rear studs all seem to be the same height

the front centre two studs are different.

I also added the images of the damaged unit perhaps someone can tell me if this can be repaired.


Cheers

[ozzy]

I think I have it

Cheers

[fj1289]

The APE studs don't allow for the amount of "growth" these air cooled engines experience - especially when run hard.  The stock studs "grow" with the engine better while still maintaining a good seal between the cylinder and head. 

Chris

That's interesting Chris, are you saying they don't expand as much longitudinally with heat? If that's the case, how does this manifest itself or become apparent?

Noel

Noel,

That is how I understand it.  Randy says he sees the studs pulling the threads out of the engine cases.  If you have a fairly mild street engine in a normal application, you probably won't have any issues with the heavy duty studs (but also probably don't need them!).  The engines used in cars see an extremely hard life and see very high temperatures.  These elevated temperatures bring more issues that 95+% of the bikes will never see.  With the heat we expected to see on the long pulls with a lot of nitrous, we actually DECREASED the torque on the stock studs slightly to allow for the expected expansion.  BUT, you have to make sure you fully warm up the engine before running it hard at elevated temps and pressures. 

This seems to be fairly unique to the FJ engine - maybe the case threads are a weak point?  I know other engines - like water cooled Hayabusas - definitely benefit from heavy duty studs.  I looked over a set of cases hoping to find a way to use a thru stud.  I didn't see a good way to accomplish this.  I've got a broken case half on the bench so I may try looking at it again. 

Chris

[racerrad8]

...how does this manifest itself or become apparent?

Noel

Ozzy posted a photo of the failed repair to his case.

Here is one I have sitting on the shelf. This car was brought in due to an oil leak the engine builder could not fix....

The engine builder tried to epoxy it in the car and the result were a big fat fail. This car got a new engine after this find.

Randy - RPM

[ribbert]

Thanks for the feedback Chris and Randy, I did a bit or research as well, interesting. As you say, it seems to only be a problem in the cars and motors with substantially increased power.

Are the car engines susceptible because of heat and WOT alone or are they modified?

Noel

[ozzy]

Hi All
Unfortunately my replacement block also is cracked "bugger" my next questions is if the FJ 1100 crankcase is interchangeable with a FJ 1200, this motor is intended for a motorcycle as the missus is begging me to revive the old FJ as she's not a fan of the FJR.

Or any advice on possible repairs or where to source a new crankcase.

Cheers

[racerrad8]

All FJ cases are the same.

There were upgrades over the years to larger bolts, longer studs and portions of the casting were beefed up, but the 1100 case will work just fine.

Randy - RPM