Monkey Spanker

Never meant to upset anybody (RLW), all I wanted for everyones info on here,was someone to back up their opinion with proof that every boat motor has or needs inconnel valves. They have been putting 455 olds motors in boats since the 60's but I don't think they had those valves back then, what have they used for the past 30 years?

PatriYacht

The Olds engines realisticly put out about 350 hp. My ski boat has a 350-260 hp Mercruiser with stainless valves. I guess it depends on what hp level you plan to build to. Spanker, you never said what you are building.

bobl

The inconel valve gives you an added margin of safety at the very least. I've seen several engines drop exhaust valves from being too lean at cruise speeds. Had they been using inconel they most likely would not have failed, even though the root cause was fuel mixture. I will not build a modified engine without inconel(or super alloy) exhaust valves. Not worth the risk.

articfriends

iTrader: (1)

You can't really compare a 1970's passenger car olds 455 that was marinized in a jet boat to a modern bbc. The old jet boats didn't really run much past 4800-5200 rpm's and they NEVER lasted 400-600 hours unless babied. My first boat was a 79 cobrajet with a olds 455,I blew the motor up so bad after a couple of rides that the only parts left that were still good was the valve covers and intake manifold. Them old motors didn't use oil coolers, electronic ignition or performance exhaust manifolds either,technology and hp levels have advanced forward in 35 years,Smitty

Monkey Spanker

The beginning of this question started because I had a 1050 Dominator with a set of square port heads off of my Chevelle that I didn't need anymore. I don't race it anymore, so I figured I would put them on the boat motor. You can still use the extra power on the water. The boat motor made 521 hp with ported peanut heads and a Performer rpm manifold. The heads already have severe duty valves in them. With the heads, intake and carb, it will make "around" 625 hp. I was trying to decide if it was worth the extra money for the valves and valve job for the inconnel's.....Now.....Let's say there are only "two" types of performance boaters on here. The high dollar 27'-42' offshore boats that "can" hold it wide open for many miles on big water, and the 19'-25' inland lakes and river boats that may only be able to hold it wide open for a few miles. I think you would have to agree there is a difference in the way these two types of motors would be built and driven. Obviously there is or nobody would hold Merc blue motors in such high regard. (nor would they be able to get the money they do for them). I think the common sense answer is how and where you intend to really use the boat and motor dictates what parts you need or should put in it.

formula31

Its a valid question you ask. Let me tell you my experience. I build my own stuff, on a rediculous budget. I use a lot of take out or used parts and can tell you you this, the only major failures I have had were valve or valve train related. As cheap and broke as I am, I have inconnel and severe duty intakes in both my engines now. I also have the most expensive one piece pushrods I could find. Do what you will, but I have learned the hard way over many years of experimenting where the money needs to go. Skip the fancy flame arrestor and ignition system and pretty hoses and put that money in the valve train. Thats my $.02.

ratman

exactly, BTW it would be foolish to not do a fresh valve job before putting a set of heads on any engine. the inconel valves are cheap compared to dropping a valve. im 100% sure about that!

Monkey Spanker

Does doing a quick hand lap count? At least the next guy with this question can avoid the pounding I took on this one Lets take this one step further, should you add extra clearance in the valve guide for the extra heat?

formula31

I do. and I take the springs out of the exhaust valve seals.

PatriYacht

Btw, all of my Crane 3 piece pusrods have cracks in the ends where the tips push in. Using reccomended springs for Crane 651 cam. Probably going to switch them out for Trend 1 piece pushrods.