Pumpkin Update

Greg, is this the same Lunati that you sent me the specs for last winter? The spreadsheet I have is showing ~390hp at 4500rpm, though Im not sure if that was the Lunati plugged into my setup (rectangle heads) or yours (large ovals). Is that about what youre expecting for hp?

Ive had several good conversations with Bob from Marine Kinetics- the man knows his stuff. He had concerns with too small of a cam on our engine because of the high (~10.4:1) compression. He said that if the duration is on the short side, it can lead to very high cylinder pressures. If propped too close to max pressure (same RPM as max torque) it can lead to detonation. Pretty sure this is what Joe saw when he ran the big prop on his 408w. For that reason, we went with a wilder cam than he normally would have recommended. Spinning it higher is apparently safer. Not sure if that info is at all applicable or helpful- just throwing it out there!

Keep a real close eye on that cam, it doesnt take much to wipe a lobe, apparently. Im sure youre feeding it a healthy diet of ZDDP.

Cant wait to hear how it performs when you get some numbers back. Remind me, which prop are you running? Same intake (Eddy RPM?)? Which carb did you put on it?

Im curious how many RPM's you'll turn that 1598. Im guessing close to 5k?

Holley 4160? I assume so.

Stock intake?! I thought you upgraded to a decent dual plane like the RPM (or at least a Performer) on your original Pumpkin build. Do you have 2 complete motors now? Id put that on the list for the new one- I would think that to be a major choke point.

Yup, 781/049's are very similar. I forget which one has smaller chambers, but I know those 2 are the sought after big ovals. Thats the route we would have gone if we didnt already have the rectangles.

Lifter preload... like you, I read a lot of different info, but everything fell into the 1/2 to 1 turn range. Pretty sure we went with 3/4. I assume you checked to make sure your pushrod length was ok?

Im surprised that the stock 781 springs werent enough... I didnt think the Lunati cam you had picked out was all that wild (.515/.530, 213/219 @ .050). I guess you live and learn though!

Yes, Bob confirmed that the last of the roller cores have been spoken for. LSM Engineering said they could do a custom core as well though, and the ground price was right in line with Bob.

I hear you on wanting to move past the powerplant... I cant wait to get ours back onto the water and running reliably!!! Talk about a long road.

If doing carpet (again already?) and vinyl this winter, I would take the opportunity to raise the motorbox a bit so you could clear a larger intake!

You have more restraint than I do if you havent checked to see what the thing is capable of! Once that cam is broken in, I would imagine you'd be wanting to seat those rings. Maybe Joe will remind us of the proper break in procedure, but Im pretty sure babying it wasnt on the agenda.

(I think you mean 118.5 cc.)

We've got the same 750cfm 4160 on ours. We converted the secondaries to a block from a plate. I want to add the adjustable vac secondary housing... which one did you go with?

Eagerly awaiting your performance results!

Greg - When you get it dialed in, maybe you can record a sound byte for us.

I bet it growls big time.

Just FYi got curious so looked it up; correction its 374 miles of shoreline.

74Wind wrote: Greg you sound like a guy who knows his stuff. I've got a 74 Southwind on Oconee thats needs an expert for a bit of troubleshooting, if you'd be interested in helping out a fellow GA CCFan let me know!

You give me too much credit...I fit better in the category of 'I've learned much more about my boat than I ever expected to'. I am happy to help though. What's up?

74Wind wrote: If you've never been on Oconee, it's great. 285 miles of shoreline and on a busy day you might see 30 boats.......

The thing is, my tools are up here.

If you could get them to set it on the trailer, Tim and I don't need much encouraging to have a w/e up here?

We won't get toothpick surprise, but Tim knows how to cook while we ski; it's a great deal.

PS-look for chattahoochee run/way down yonder... threads in the reunion section.

LOL   Well, I tried to get you to come this way, but you seem pretty set. I'd like to spend a day on Oconee sometime. It's a bit of a drive though for a 1 day turn around after food, fun, and tinkering are worked in. Not sure what you mean by a lake like Lanier? There is a ramp that's only a 5 minute walk from here and a 2 minute drive back to my dock, and I have a collection of stuff from a 79 SN and my BFN.

We'll let Tim get his .02 in when they get back from TN.

Buffalo comes from a band my wife and I like to hang out with: Donna the Buffalo(DTB).

BuffaloBFN wrote: LOL   Well, I tried to get you to come this way, but you seem pretty set. I'd like to spend a day on Oconee sometime. It's a bit of a drive though for a 1 day turn around after food, fun, and tinkering are worked in. Not sure what you mean by a lake like Lanier? There is a ramp that's only a 5 minute walk from here and a 2 minute drive back to my dock, and I have a collection of stuff from a 79 SN and my BFN. We'll let Tim get his .02 in when they get back from TN. Buffalo comes from a band my wife and I like to hang out with: Donna the Buffalo(DTB).

I live in Peachtree City so, ironically, I think you are closer to Oconee than me....

No offense was intended, Lanier has a reputation for being kinda busy, although maybe thats a good thing, easier to get a tow
Only been out once testing a Resorter. Sounds like you've got a great setup. Be great to check out your boats sometime.   

I've also got another boat there I think you'd like, although currently
out-of-service; a steady stream & stuffing box nuts won't budge and can't see 'em anyway, probably needs repacked. V-drive..what a pain in the ass.

I've heard of DTB, I've spent my life boating in the Finger Lakes, aren't they from NY?

jimsport93 wrote: Did somebody say weekend at Lanier? Count me in. Morfoot commented to me that we need a Lanier get together soon. Stay tuned.

oldcuda wrote: Hey BuffaloBFN glad to see you got it sorted out.Hopefully when I get home I can get mine going I am waiting for delivery on one of those roller cams. Hope it gets here soon I am tired of looking at this pile of parts want to get this thing going!

I'm looking forward to seeing what you put together. Maybe you'll do a write-up?

Sounds pretty stout! That should be in the 53mph range, I would think.

TRBenj wrote: Sounds pretty stout! That should be in the 53mph range, I would think.

It has a lot more kick than it did before. It's still a bit up in the air though. I tried my 650 and lost 150 rpms. It also didn't reproduce WOT every time and the idle adjustment screws have little effect.

The 750 idle screws are puzzling too. They will kill the engine, but they aren't very sensitive beyond that. And I don't have a steady vacuum reading anymore. I don't think I have a lopey enough cam to cause the needle to jump, so I still have valve issues? I wonder if the lifters pumped up? I know they did when I had 3/4 of a turn on them; what to do?

And how can I get full alt voltage without going through the dash? I saw this, but I don't understand it. It does look a bit like the other relay back there...does it have a post I can use?

Hows the holeshot? Thats one thing thats still not overly impressive with our rectangle port motor... though it improved greatly with the weight loss.

Interesting on the vacuum readings... I would think that you'd have some clatter if you had insufficient preload. I wouldnt think it would be holding valves open when they werent supposed to be. Did you put a vacuum gauge to it prior to adjusting the preload? I would not expect that cam to be causing any idle issues either... we didnt have a terrible idle with our Comp bumpstick last year (.564/.566).

You dont want full alt voltage (+14.4v), and that "full battery voltage" is actually misleading, as you want full ignition voltage. So you cant steal power from anywhere but the dash. Unless youre ok with your ignition key not being real effective.    You'd want to add another basic relay that stole power from the breaker and was controlled by the ignition switch. Though, I have to say that I doubt that the DUI is suffering from low voltage. We havent noticed any issues with our original OMC wiring.

Morfoot wrote: I think I need a day after I get back from a 5 day trip to anywhere just to play catch up here on the site with all the posts going. Yes, I'm back in the water after the Chainsaw Massacre and after talking with Natiquehunter & Skicat this past weekend in Nashville we want to get a Hoochie Run going of some sort. I said I'd like to try and get the ATL crew together soon so that maybe we could do it again in late September. I'm thinking maybe the June 30 or July 6th? What do you guys think? Greg it's your call as we may wanna use your place for Gnd Zero. Jeff up at Gregs place the water isn't bad as the big yacht's and house boats can't get to his playground because he is between two bridges that they can't get under. Water is pretty calm for a Lanier and plenty of places in calm water to dock or float the boat. Fireing up the smoker isn't a problem. Just plug it in a go play. I might be able to talk the girls into going down to Oconee this Sat but I doubt it as they are in camp this week and we won't be home til late Friday night and they'll sleep forever. Jeff I'll call you soon so we can try to work this out. Sorry for the thread jack.

Glad to hear you all had fun in TN. In the perfect world maybe we work out my bugs first, then drag it up there & join in on Gregs 21st idea, sounds fun. Like I'd discussed w/ him, wanna get (both?) your help with a stem-to-stern multi-test & inspection; I'm sure with a little talent & teamwork can figure out the root cause; component, wire, connection..whatever. Then maybe diagnose the tranny noise, if not too bad maybe put that fix off till fall.

Once it's starting consistently & running properly I'm not as concerned about lake-mania (a Southwind takes the chop like a battleship) as I am about inexperience & ramp-mania. Been inboarding since I was an infant but never once used a trailer (or had to)till I moved here, and even here, since I keep it in a rack, I've only launched/loaded maybe twice. It's also roller-style and not particularly user-friendly...

You, on the other hand, are "Mr. Trailer" apparently, so if you can be so kind to work out a little Oconee time, perhaps you can drag along Miss Scarlett.....