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"Floatin' Motor"
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Discussion Starter #1
Looking to get aluminum heads, what i'm not sure about is if i need rectangular ports or oval. On the top of the stock heads i have it says "PASS", so from what little i know about engines i know this means oval ports. What i need to know is, do i need to buy oval port heads or can i buy rectangular port heads and be okay??
 

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Looking to get aluminum heads, what i'm not sure about is if i need rectangular ports or oval. On the top of the stock heads i have it says "PASS", so from what little i know about engines i know this means oval ports. What i need to know is, do i need to buy oval port heads or can i buy rectangular port heads and be okay??
Is your intake oval or rect? Are you planning to change the intake?
 

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What are they going on? If you are planning on a bigger engine later on, you may want to take that into consideration.
 

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"Floatin' Motor"
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Discussion Starter #4
Is your intake oval or rect? Are you planning to change the intake?
That i'm not positive about yet, from the casting numbers on my iron heads they say "PASS", which when i looked up online it means they're oval. Was kinda looking for clarification from you guys on here.

What are they going on? If you are planning on a bigger engine later on, you may want to take that into consideration.
Not looking to go bigger on the motor, just wanna free up the one i've got.
 

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That i'm not positive about yet, from the casting numbers on my iron heads they say "PASS", which when i looked up online it means they're oval. Was kinda looking for clarification from you guys on here. Not looking to go bigger on the motor, just wanna free up the one i've got.
Rectangular ports flow way better. No need for aluminum heads though...a good set of 990's or 088's (casting #'s) will do the trick and last for years. The rects have bigger valves too...2.19 intake and 1.88 exhaust
 

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"Floatin' Motor"
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Discussion Starter #6
Rectangular ports flow way better. No need for aluminum heads though...a good set of 990's or 088's (casting #'s) will do the trick and last for years. The rects have bigger valves too...2.19 intake and 1.88 exhaust
Does this mean i can use rectangular ported heads if i want then, even though the stock ones are oval (assuming)??
 

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The thing to remember is what mates with what. If you go with retangular but your intake was
made for oval that's not good. If you have high dome pistons and a low dome heads that's not good. If your plan is to rebuild the motor for HP then go domed pistons oval ports matching intake and verify that it will all work with your head MFG or motor builder. If you just want aluminum heads and not change anything else match what you have and again check with the head MFG.
 

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Purple headed member
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Looking to get aluminum heads, what i'm not sure about is if i need rectangular ports or oval. On the top of the stock heads i have it says "PASS", so from what little i know about engines i know this means oval ports. What i need to know is, do i need to buy oval port heads or can i buy rectangular port heads and be okay??
You are leaving out alot of information. In order for someone to give you a proper head reccomendation, info on the shortblock, boat size, desired RPM range etc are required. I would personally stay away from factory casting such as 990's and 088s though. Old technology and they weigh a ton. Also, you can run your oval port intake on your new aluminum square ports. Many people have done it. Like I said though, a bit more info would be nice.
 

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"Floatin' Motor"
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Discussion Starter #10
You are leaving out alot of information. In order for someone to give you a proper head reccomendation, info on the shortblock, boat size, desired RPM range etc are required. I would personally stay away from factory casting such as 990's and 088s though. Old technology and they weigh a ton. Also, you can run your oval port intake on your new aluminum square ports. Many people have done it. Like I said though, a bit more info would be nice.
Well first off i've only owned the boat for a year so i'm still a little unfamiliar with it. Here's what i do know about it.... 19ft Eliminator Sprint, It has a Mark IV block cast #3999289, Edelbrock Torker 2-0 intake mani, Schneider Racing Cam. I can't remember what the #'s were on the heads themselves, i do know they said "PASS" on them and that means that they're oval ported heads. I'll have to get back to you on what the #'s are, i just know they're GM stock iron heads. The boat does 72mph at 4800rpm, like to get it closer to to 80mph or more eventually, some people on here on another thread have recommended getting aluminum heads to let the motor breath better and make it a bit lighter, they may not make it do 80mph but 1mph or 2 would be a significant difference to me. I was looking at some ProComp heads and am waiting to hear back from them to see if they are compatible with my intake mani, whether they are rectangular or oval ported.
 

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Well first off i've only owned the boat for a year so i'm still a little unfamiliar with it. Here's what i do know about it.... 19ft Eliminator Sprint, It has a Mark IV block cast #3999289, Edelbrock Torker 2-0 intake mani, Schneider Racing Cam. I can't remember what the #'s were on the heads themselves, i do know they said "PASS" on them and that means that they're oval ported heads. I'll have to get back to you on what the #'s are, i just know they're GM stock iron heads. The boat does 72mph at 4800rpm, like to get it closer to to 80mph or more eventually, some people on here on another thread have recommended getting aluminum heads to let the motor breath better and make it a bit lighter, they may not make it do 80mph but 1mph or 2 would be a significant difference to me. I was looking at some ProComp heads and am waiting to hear back from them to see if they are compatible with my intake mani, whether they are rectangular or oval ported.
If you use the ProComp 320cc intake runner heads you should be ok with your manifold and your pistons. These are open chamber heads and are 115cc's. I used them with an oval port manifold to keep port velocities up and they worked very well, but it was a drag racing application. I am new to boating but engine performance should be basically the same.
What rpm are you shooting for? Getting a BBC above 4800 should be no problem, even with oval port heads.

How's that for my first post? lol
 

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The Man
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What impellar are you running? My Eliminator Sprint would turn an A to 5000rpm at 70mph. I sold it and the guy switched to a B and hit 80mph at close to 6000rpm I think.
 

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"Floatin' Motor"
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114 Posts
Discussion Starter #13
If you use the ProComp 320cc intake runner heads you should be ok with your manifold and your pistons. These are open chamber heads and are 115cc's. I used them with an oval port manifold to keep port velocities up and they worked very well, but it was a drag racing application. I am new to boating but engine performance should be basically the same.
What rpm are you shooting for? Getting a BBC above 4800 should be no problem, even with oval port heads.

How's that for my first post? lol
Nice post, lol. The heads are the 320cc/115's.

What impellar are you running? My Eliminator Sprint would turn an A to 5000rpm at 70mph. I sold it and the guy switched to a B and hit 80mph at close to 6000rpm I think.
I'm running the "A" impeller, did you know if he did anything else other than change to a "B"??
 

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Nice post, lol. The heads are the 320cc/115's.

I'm running the "A" impeller, did you know if he did anything else other than change to a "B"??
The 320 cc's are the runners...115 cc are the chambers. Personally I think the 320 cc runner is a little large for what you have...but I am far from a guru there.
 

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"Floatin' Motor"
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Discussion Starter #16
From what he told me, all he did was change the impeller and replaced some leaking gaskets in one of the carbs.
Hmmm, well it's worth checking into.

Anyone have an opinion about just swapping the impeller??
 

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Whatever you do, don't buy pro comp heads. Try googling them. Made in china with crap parts.

I would also try researching & reading some old posts to educate yourself on jetboats in general. Lots of information on this forum but you have to try and read, comprehend, and then act. Otherwise you are going to buy parts twice or end up with a boat that doesn't perform. We've all been where you are now...Be patient and absorb some info before you do anything.
 

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Whatever you do, don't buy pro comp heads. Try googling them. Made in china with crap parts.

I would also try researching & reading some old posts to educate yourself on jetboats in general. Lots of information on this forum but you have to try and read, comprehend, and then act. Otherwise you are going to buy parts twice or end up with a boat that doesn't perform. We've all been where you are now...Be patient and absorb some info before you do anything.
I used the Procomp heads without any problems, but I did order them without springs since I used a roller cam and needed roller springs. I built a 454 and ran it in a Camaro about 3 years ago when they first came out. The castings looked great for a supposed "cheap" head.
The car had 3.91 gears and a powerglide, it ran a 10.67 at 125 mph and was only 11:1 compression.
I sold it to a friend and he still runs it today.
There are lots of great choices when it comes to cylinder heads, but none as affordable as the ProComps.
 

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Hmmm, well it's worth checking into.

Anyone have an opinion about just swapping the impeller??
cutting it down to a b/c will add plenty of rpm's and you'll probably be happy with it. you could find a bronze or ss imp's every now and then. i had some worked over 781 heads with a b/c imp and my rpm's were 5800 and my distributer locked at 36 degrees. im sure i couldve got more rpm's if i worked at it.

Whatever you do, don't buy pro comp heads. Try googling them. Made in china with crap parts.

I would also try researching & reading some old posts to educate yourself on jetboats in general. Lots of information on this forum but you have to try and read, comprehend, and then act. Otherwise you are going to buy parts twice or end up with a boat that doesn't perform. We've all been where you are now...Be patient and absorb some info before you do anything.
buy them bare and you'll be fine.

I used the Procomp heads without any problems, but I did order them without springs since I used a roller cam and needed roller springs. I built a 454 and ran it in a Camaro about 3 years ago when they first came out. The castings looked great for a supposed "cheap" head.
The car had 3.91 gears and a powerglide, it ran a 10.67 at 125 mph and was only 11:1 compression.
I sold it to a friend and he still runs it today.
There are lots of great choices when it comes to cylinder heads, but none as affordable as the ProComps.
right on! the castings are good out of the box and once the springs are changed, they will be fine. theres a few bbc alum. heads on ebay for about a grand. the guy buys them bare and changes out the springs, seats, guideplates, ect.
 
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