1989 J225TLCED: retrofit 1996-2001 90 deg looper Al carbs?

Forgive me if this has been discussed, I searched the forum for a similar thread but I did not find a match.

Is it feasible to use Aluminum carburetor bodies from a 1996-2001 90 deg V6 looper (PN 0437323) to replace the plastic carbs on a 1989 90 deg looper (0432513)? If this is possible, I would re-use my existing jets.

Both 1989 and 2001 have the same P/N for the carb-body to throttle-body gasket, as well as the throttle body to intake manifold gasket. This gives me some hope that they may be compatible, but that's hardly conclusive metric. I'll have access the 2001 throttle bodies as well, so I'll swap these if that's necessary.

thanks for any input,

Paul

I think OMC switched to the Plastic, partially for costs, but also the Plastic reduced Heat Transfer to the Carb, and didn't corrode when exposed to those nasty additives(like Ethanol) added to Gasoline to chemically burn Leaner.

There is more to a Carbs Fuel Delivery Curve than just the Jets. Air Bleeds for example may be different, as may be the Off Idle Transfer Slot. Do they have the same size Venturi? Appearing similar, even looking the same at a glance may not really be be.
Are both sets off of the same HP? Were there any differences between the Yrs with regards to Exhaust Tuning, Port Timing?

jimmbo said:

I think OMC switched to the Plastic, partially for costs, but also the Plastic reduced Heat Transfer to the Carb, and didn't corrode when exposed to those nasty additives(like Ethanol) added to Gasoline to chemically burn Leaner.

There is more to a Carbs Fuel Delivery Curve than just the Jets. Air Bleeds for example may be different, as may be the Off Idle Transfer Slot. Do they have the same size Venturi? Appearing similar, even looking the same at a glance may not really be be.
Are both sets off of the same HP? Were there any differences between the Yrs with regards to Exhaust Tuning, Port Timing?

Click to expand...

Or ......
Chuck em on , jets an all , and see what happens .

What is wrong with the plastic carbs? Other than replacing the carb bowls once, I have had no issue with the ones on my '98 Johnny 150HPV6.

Jimmbo: Existing engine is also 225. My concern is exactly along the lines you point out: I'm not sure how the internal plumbing differs. Venturi wise, I don't have the later model aluminum carbs on hand to compare. There can be other differences, min passive area when the plates are fully closed, etc... I was somewhat hopeful that metering would be largely set by idle/intermediate/high speed orifices, but as they say, hope is not a plan.

I was looking into the forum to see if this was a tried and true retrofit, perhaps requiring some modification (e.g. need to down size idle air 0.00X" to compensate for YYY). I'm reluctant to go down this path without evidence that it actually works.

Regarding my motivation for "upgrading" to aluminum:

My existing carbs are getting a little leaky. On last rebuild (reman OBParts powerhead 3 seasons ago) both sides of the bowl contact surfaces were carefully sanded using 400 then 600 grit on flat glass. I'm using the recommended brown gaskets. I don't think the problem is the contact surface per-se, but the bowl attachment screws: when I hand-tighten, the screws want to slightly "back-out" after I release the screwdriver (maybe 10-20 deg), it seems the threads are compromised. A few solutions I've been thinking of:
- Using incrementally larger screws. Be careful not to do more damage!
- take my chances on a used set of carbs and rebuild
- as I was looking online for carbs, I came across the subject aluminum set. This motivated me to check whether these might be adapted to 1989...
... Actually I just checked ebay for those Aluminum carbs, it looks like they sold!

I'm going to go ahead and purchase a used plastic set I found at a reasonable price. At that point I'll have some backups and I may entertain putting oversized screws in the existing carbs.

The service manual is very careful to explain how to install the bowl and other screws into the plastic carb bodies, so they do not strip. The procedure is to put the screw into the hole and then turn it CCW until the screw thread matches the existing plastic thread. This avoids stripping them.

It sounds like you need new carb bowls. They obviously should not leak.