thsorens

Well at least it was a 260, its been bored and stroked since then. Anyway, I got some Corsa 4" diverters off Ebay and need to know whether they will fit, and need some info on wiring them. The boat is in storage, or I would just look at it. Ayway, I have the factory square center risers with 4" outlets, but a 3" wishbone. Currently there is a 4" elbow after the riser that connects to the wishbone with a 4" to 3" rubber coupler. Corsa doesn't think the diverter will fit because of the angle and/or the 3" wishbone. Any experience on this one? Also, these did not come with the wiring harness, and Corsa wants $179 for it! I guess they are 2 stage solonoids. Pull takes 10 amps, and Hold takes >1Amp. I was thinking of making my own harness, but they use relays and/or an electronic switch that goes from "Pull" to "hold" to get the job done. Any experienc on this?
Thanks in advance!
Tom

SmallPP

You can change the wye "Y" pipe for cheap. I bought my 4" for $25 off eBay and it is perfect. This should solve your fit. How many terminals are sticking out of the solenoids? If only two, then the switch over is built inside the solenoid like on a car starter and it is easy from there. If 3-4 each, then it is a little more complex but can still be done with timer relays. Let me know if you need help. I live for these projects. I made a box to switch my diverters open at any RPM automatically. My switch is off/on/auto. Very slick.

thsorens

Thanks for the info! I have seen the Y pipes cheap also. What does it take to change that? Do I just need to pull the outdrive or does the gimble housing need to come off also. I need to change the trim sensors anyway, and I just checked on EBAY, and there are still 4" Y pipes out there for $25. The solonoids have 4 wires each. I was thinking about a switch that has on/off/momentary. Then I could switch to momentary to get them open, and back to on to keep them open. As long as I used a switch and wire that was capable of 10Amps, and fused it properly, do you think I would need relays? Not that a relay would be that tough to hook up either........................I'll take any ideas you have though. Thanks again.
Tom

SmallPP

Your idea sounds perfect. You can measure the resistance to figure out which circuit is pull and which one is hold open. The lower resistance will be the pull, as it draws more power (Ohm's law: Voltage=Amperage*Resistance).

SmallPP

I'm not sure if you can weasel the pipe in there or not. You actually should be able to. If not, you'll have to pull the outdrive and move the engine forward a few inches or out. It's not that bad actually. I have not switched mine yet, but will when I switch engines (4.3L to 5.7L swap) so all my stuff will be out of the way already. It attaches with 4 bolts at the base of the inner outdrive transom plate. Has an odd shaped O ring.

88Fount33

I had 3" thru hull on an (18') '83 Formula with 260, built a 406CI killer, upsized to 4" thru hull but still used the 3" Y-pipe and the Merc rubber reducer (4" to 3") all worked out OK. Nice and quite for slow crusing and Idling, always "opened the pipes" for anything above slow cruise. Using Stainless Marine SBC manifold and SS riser, never had problem with reversion (Old Ultradyne big lift long duration solid lifter marine cam).

IMO, you could keep what you got unless you intend to go more than 3000 rpms with the pipes closed.

thsorens

Good info. I'm not as much worried about the performance as the fit. Like you said, open it up when you are running hard. Are the 4" Y pipes any different shaped or different length? If not, I should just be able to use the reducers like you did. I need to just get the damn thing out of storage and do some measuring, but I'm paid through the end of March, and it really isn't very warm here yet (Nebraska). Sounds like changing the Y pipes require the engine to be pulled, which although not a huge deal (done it twice already), its something thats nice to avoid!