Can I use an Rfi head on carb engine?

[azsxr]

Like it says can I use a 787Rfi head on an 787 carb engine?

 

[SabrToothSqrl]

check the parts site - are the part number the same?

 

[Brad_GSX]

They are not the same. At least one difference is the hole on the port side where the injectors go in on an RFI head.

 

[mikidymac]

They are not the same. At least one difference is the hole on the port side where the injectors go in on an RFI head.

Injectors are in the cylinders not the head.
The RFI and carb 787 both use the same head part number.

 

[azsxr]

That’s what I thought. The part number only changes with different color.
Thanks

 

[Brad_GSX]

Injectors are in the cylinders not the head.
The RFI and carb 787 both use the same head part number.

I'm an idiot. I'll try reading next time.

 

[etemplet]

The head cover is different on some 787's as the water temp hole size and location may not be the same. I remember drilling one. Good Luck.

 

[Gritzlor]

Also,be careful the head covers are different plus bolt lengths are too. Have to match bolts and head covers basically. I failed to notice this, put too long bolts and broke through into the exhaust port when torqueing them. No good.
The temp sensor threads are different too.
It seems like the heads themselves are identical, same cast#. I have a carb head and cover on an RFI and it is working good.

 

[azsxr]

I’m going to use the old cover Ill check the bolt lengths.

 

[Gritzlor]

Good call. Unless the cover is corroded as heck, just reuse it with the bolts you have. But. Yes. It is a good call to check the lengths. They should start compressing the lid before any resistance from the threads. Dry fit it all to make sure then lube and loctite as the manual says(dont remember exactly what it states) but I believe there is a good reason for all that stuff.

 

[azsxr]

I may be crazy but I’ve used grease on the head o rings for 20 years and never had a leak.

 

[Gritzlor]

Yeah, I'm not a fan of the 518 on these rings myself either. Would have bet on Molykote 111 instead actually, haven't understood why sealant is called for on rubber seals/O-Rings. Don't have 20 years experience but followed the manual and used 518 in the called for places so far and no leaks. Doesn't mean it's 100% needed.

I was mostly referring to the bolts and such anyways. I guess threads can seize or leak if the right stuff isn't there, and there sure is some rhyme and reason to some of the recommended complexity Rotax has for these things. Maybe some not, or even a theoretical approach from an Austrian engineer.
Being an engineer myself I like to understand the why's and how's of these engines, things are taken so close to the limit and many detailed smart solutions to be found just about everywhere. Decades of trial and error and experience (as above) add to the mix to further understand what works and what's really needed.