RV-4 engine mount question

[n144sh]

Originally Posted by Russ McCutcheon

I talked to AX-O today about this and could not give him an answer, however the gear legs have no impact on the position of the crank flange regardless the engine type the mount is made to fit or the length of the legs so anyone who changed from conical to dynafocal or vice versa regardless the gear legs, how did the crank flange match up, did the spinner end up in the same place, if not then how much did it change?

I did this exact swap last year on my RV-4. Conical to Dynofocal. (both long gear legs)

The prop flange and spinner are in the same place within what I consider normal manufacturing tolerances. With the new dynofocal setup the prop flange was maybe 3/32" closer to the firewall. I did not change the cowling, although the new clearance to the spinner is less than what I would have liked. I am watching it closely, no rubbing so have not made a change.

It was a bigger job than I thought it would be. New baffling - not sure if that had to be done but mine was pretty beat up and ready for new.

[AX-O]

Originally Posted by n144sh

I did this exact swap last year on my RV-4. Conical to Dynofocal. (both long gear legs)

The prop flange and spinner are in the same place within what I consider normal manufacturing tolerances. With the new dynofocal setup the prop flange was maybe 3/32" closer to the firewall. I did not change the cowling, although the new clearance to the spinner is less than what I would have liked. I am watching it closely, no rubbing so have not made a change.

It was a bigger job than I thought it would be. New baffling - not sure if that had to be done but mine was pretty beat up and ready for new.

Thank you.

[131RB]

Originally Posted by Russ McCutcheon

If they were both type one Dyna mounts and they both came off my fixture then the engine position would not have changed at all, that fixture has been a constant since the early 80s, probably about 1982. All we did for the long gear was re position the "Z" frame in the base of the mount fixture and the center two attach points moved almost one hole but the dyna ring never moved in relation to the fire wall. How old is your -4, there are a few very early ones out there that have home made mounts and a few that have mounts from a different vendor, the ones i've seen where very rough.

Russ,
Was not trying to indicate that anyone was making sub standard parts.
The RV4 was not mine, it was one that I had taken on as a side job to help a friend. It was older and the build quality not top notch. I cant say why the cowl and baffle fit were so much different but they were. Even with no baffles the engine just did not want to line up right. Like I said a job like this may be easy and It may not.
Ryan