!!!Project 80 Ski!!!

Intake duration of 291 and an exhaust duration of 311, intake lift of .541 and exhaust at .526 and a lobe seperation of 107 deg. which means I am safely clear of the 115 deg no no zone. I do however understand that my (VE) is at about 134% at 5500 rpms with the 750 carb...BUT I will be spinning faster than that. More to the tune of 6000. The (VE) of 134 is with the carb spraying static. So with the carb bridled a bit I will have no problem getting pretty close to 100% (VE). No I dont mind adjusting valves and with the limited time the boat will be in the water the adjustments will be minimal. Besides it will grab RPMs alot faster than a Hyd-Lifter motor.

have you been building motors for long?...Because if you know what you are doing....6000 rpm is not a death certificate.....like I posted earlier I built a 383 that would spin to 8 grand if need be....and its still going strong with many trips to the strip

Doc He will never get 68mph out of a nautique. He will have to prop it down if he wants 6000 rpm . He may need a 13 x 13 or maybe even a 13x 12 1/2 . Is that the acme 541? He will have one hell of a hole shot .

Eric

I don't agree with you on your post implying a gear to gear timing assembly will not hold up to high rpms. Please correct me if you ment something else. But every engine builder I know, goes gear to gear on timing when you really want to spin a motor at high rpms. Plus the rotating assembly should be balanced also.

P/allen
I agree 68mph he wont see, the 351 just not capable of pruducing enough torque to spin a prop at 6k with out backing off some of the bite.

Which is why I have this question why spin the motor any faster then you need to if there is not going to be a gain of some sort whether it be out of the hole or top end speed?

Ive heard that for some reason on the RH rotation that the pistons need to be installed backwards with the notch that is in the piston pointing towards the back . Look at thepistons again and check it out .


I dont know why . Its just what Ive heard .

I just noticed in your 5th pic that the notches are going to the front .

Wow.....I love this place.


Where is 79 when you need him?

john

MarineSRT8 / Nate,

Before you get too carried away with the motor work, please go inspect the prop on your boat. You have a reverse rotation, RH motor in the boat. This was STANDARD in the 80 SN. By reverse rotation, we mean OPPOSITE of a car. Not wanting to add to the argument, but go look at your prop, it will tell the tale!

I should know, I used to own the boat you are working on, I sold it to the man you bought it from.....and I have plenty of photos of it, one showing the prop and the fact that it spins RIGHT to propel the boat forward. As stated earlier, this will make a difference in the parts you have purchased.

pc       

boat dr wrote: Better yet,see if the cam shaft you bought will mesh with the distr. drive gear............boat dr

M8, Pleeease read and heed. When a body has put everything else together with patience and care, and then he goes to drop the distributer in...?!!? At that particular moment in the space-time continuum, LH and RH become VERY clear! LOL

Guess how I know! ...and I'll tell that story later   

Glad to know you are on top of it. I will tell you though, it seems you are going a long way and spending plenty to NOT rebuild the bottom end. A fresh set of slugs (hypers that MM has for sale), ARP rod bolts, polish crank, and hone the block wouldn't be more than a few hundy. Then you could balance the crank, rods, and pistons as well.

I saw that CCF links Barts Watersports....reminds me of home. The lake I go to is in the town where Barts is based.

And how many quarters?!!?   LOL

boat dr wrote: MarineSRT8 wrote: WOW....Ok so the prop post knowledgeable, yes. But come on doc gimme somethin to work with your proving to be an easy target    Yes I may be an easy target for the sharpshooter you are.Just fire away,I know very little about motors and boats.I just post on this site because of my illness.I get caught ,and the real me comes to light for all to see. As i write this I am in solitary lock-down.It gives me a way to pass the time till my next parole hearing. Sorry to have suggested that you were less than knowledgeable about building a 6 grand tow boat motor.Sometimes the MEDS,heavy doses by the way,don't seem to work. Sorry to cut this short,but it is time for a shake down,A knife is missing from the kitchen, and i have not hidden it well...........boat dr

And here all this time I was thinking that the Doc had slept in a Holliday Inn last night ... LOL!!

Marine, I just thought of something that hasn't been mentioned in this post, and I don't know if you are familiar with. Make sure you tell the machine shop that you need piston to cylinder wall clearance to be double of a street motor. There are threads on here that talk about this, and many bad experiences of motors that were built by reputable street builders. Motor always under load (pistons heat and expand), block constantly cooled by lake water (stays cool, less expansion) = more clearance needed. Good luck, just thought I would try to help.

Marine, Wawasee? Dewart? Syracuse?

I just hope that thing isn't coming to Green Lake next summer. Looks like 400 HP to me.

But Nathan, if I could I'd like to throw out several issues for more discussion if it's not too late: The 1.23 trans and stretching her legs I feel are not hand in hand. The 123 will allow her to squat, grunt and sprint a short distance quickly with lots of authority, while a 1:1 with a smaller dia/higher pitch prop will typically make the most of a higher rpm engine, i.e., most speed in a lighter boat. If your cam is the only direction-specific part you've bought, then RR is still your best direction in this hull. At least CC thought so, and I know you've probably heard or been told that it will list to starboard with a LH engine. It will.

As for RPM, it'll turn what it can with a 13x13 or 13x14 depending on prop design/brand. By that I mean you won't prop it with the intentions of making it get to 6K, but more so prop it as you would with a typical 350-351 ci engine. Then let the cam, heads, and other mods take it from there, and see just what it will turn, 6K or whatever with a max of around a 13x14 prop. THEN step up the prop (more pitch) and see if you can lower r's and gain speed, and thus find out what your combo's sweet spot is for making the most speed. Even though this pkg would want to turn 6500-7000 thru the gears in a car to get the max in terms of 1/4 mile acceleration, in a boat for max top speed the ideal rpm is typically somewhat reduced down towards that HP/torque intersection racintj mentioned. In the meantime thanks for volunteering your efforts and funds as our newest guinee pig. It'll be fun for all of us...............until next year's reunion.