blue thunder

I have a tough choice to make. I have two 454s (all cast) on the engine stand now, and have found they have the small oval port heads. I was hoping to find the large ovals, but have been disappointed. Was planning to port the large oval port heads, install better cam(s) and hopefully find something better than the existing stock exhaust. If no (used and cheap) exhaust is found, I will have to stay with the stock for this year, then buy new Stainless Marine of something next year.

The tough decision comes with the heads. Most (but not all) people say to use the large ovals instead of rect. port heads for 5000 and under rpm. I understand the concept of mixture velocity and torque and the negative affects of rect port heads. I though have $4,000 in edelbrock aluminum rect port heads and now have found I do not have the large ovals, but the small. I believe the small ovals will limit my hp at WOT and am not comfortable dumping money into them.
The edelbrocks have non magnetic valves (ss?), hardened seats and only need some minor repair due to dropping a valve. I had these heads on at the beginning of last season and had a lot of trouble with blown head gaskets, and in the last instance, what appears to be a valve that stuck open, hit the piston and resulted in a destroyed engine. Ran the small oval port heads the remainder of last season with no problems other than my boat was a slug (65-67 mph).
I could maybe go to a junk yard and find some of the good large oval port heads, but not sure about that. My boat came original with the 365hp magnums that had rect port heads and ran well. I think at the moment I am inclined to go the edelbrock head route but am afraid I will start having trouble again and wreck my season next year. My priorities go like this... able to go boating is #1 and performance is #2. The highest level of both is what I work towards. What do you guys think?

BT

Vinny P

BT;

I am sure that you asked yourself the obvious questions. How much power am I looking to make? How much money am I willing to spend? How much reliabilty am I willing to sacrifice?

It sounds like you are looking to step up a bit, maybe at least crack into the 70 m.p.h. range. Personally, I would not dump money into the small heads, they are just too restrictive when it comes to making any kind of power. Aluminum heads can make good power even with low compression motors. If you can find a good reputable machine shop who can repair those Edelbrock heads properly, I say go with them. They may not be the optimum head for you, but unless you are looking to get every last bit of horsepower from these motors, I think that you will be happy. You already have $4k into them, it's too late to dump them now. If a valve hung open and smacked the piston, I would make sure those valve guides are O.K. ( they must have bronze guides??) There must be a reason the valve hung. Maybe water got dripped onto the valve? Blown head gaskets, that should not be either. Are the head and block surfaces flat?? What gasket are you running?

Good luck in your decisions....

formula31

Theres a few on ebay. search oval heads. These even have the large valves. 781 casting is what I use. They are very close to the 049's. http://cgi.ebay.com/ebaymotors/ws/eB...tem=1872549563

tripps

you can usually find those heads at a car showswapmeet,those guys need big ports. if you cant get them fixed by you try Mcbetts racing engines they know bbc bigtime and if they cant fixem they wont jerk u. i did heads there 4 10 years. sometimes its better to buy 1 new casting than fix them .call richie 631 8429638 tell him tripps sent u

blue thunder

Yes Chechmate, the guides are bronze. Had the heads gone over just before this happened, so I am at a loss to understand why. You mentioned water dripping on valve. Could you elaborate. I did replace the riser on that side after the engine blew because I thought it looked suspect. As far as the heads gaskets blowing... I blew them several times with the original engines. Maybe the decks were not flat... I had the heads milled each time. New engines should be flat now. I am on the same thought path as you with the $4,000 investment in heads.

I'll look into ebay Formula31. Maybe I can come up with something. Otherwise, I'm with checkmate... small ports are a waste to invest into.

Where is richie located Tripps? Edelbrock won't sell single heads and a set is $2,200!! Finding a single for a reasonalbe price would be nice.

BT

Vinny P

I have no first hand experience on this one but I have beed told that is possible for the exhaust valves to bend a little if cold water dripps onto them, from a leaky exhaust system, when the valves are hot. I would suppose this could be enough for the valve to get stuck in its' guide.

blue thunder

I think that may have been what happen checkmate. Looking into the valve pocket, the remaining stem has been bent to be pointing directly at (parellell to) the cylinder. Clearly stuck open and the riser showed signs of leaking, I originally thought water infiltrating the cylinder caused detonation which melted the exhaust valve causing it (the head) to drop, then smashed a hole into the piston, but what you said adds up better. Thanks for the insight.

BT

Tinkerer

The exhaust water leak ran down on the valve and that caused the head of the valve to break off - it then wedged itself into the port and when the valve went to open again it bent the valve stem over. Fix the heads and have JIM V. put wedges in them and YOU WILL BE HAPPY.

Vinny P

That sounds like the most likely scenario. Good luck with the repairs. If you need a really good place to do those repairs, we have a great place here on Long Island, New York. He does tons of marine work.

tripps

Hey blue,he is on LI ups them to him and he will check them out,and as far as the large oval port heads being good for power,my buddy hasem on a 540 with 2.19 intakes,1.88 ex,minor porting,hyd cam,850 carb in a 30 footer,alightone goes 85 at 6000 rpm,I have used them before and work good,by the way,my friend has merlins on the 540 tripps