Rectangular or oval heads???? Is this a deal??

[396_WAYS_TO_SPIT]

Ok guys heres the deal. I am working on my "other" boat now. I got tired of the damn olds thing so now I am ready to finish my chevy. I have a set of 781 oval port heads that i was going to run but i talked to guy today at a machine shop and heres what he said. He has a set of rectangular port heads with 2.19/1.88 stainless valves,ported,polished,new studs,guide plates and springs that will handle up to .650 lift. he wants $750 w/ exchange. he said he set them up for a boat and the guy never came to get them. is this a good deal or what? will they work well on my jetboat? I plan on spinning 5500 rpm's. could someone let me know some info?
thx 396

[wideopen545]

what kind of rpm are you trying to pull
that is a good price i just paid 500.00 for bare cast
and how is the weather out their we miss not being their

[Hotcrusader76]

To answer your question, yes that sounds like a good deal to me. Are they assembled or bare?
If you're going to spin 5500 RPM you might be better off sticking with the large oval ports. The ovals out-fitted with 2.19/1.88 and a mild port job will keep you strong till 6000RPM and if sourced right could keep you under a good set of rect.ports. Just have to check around.
What are the specifics of the engine?

[Hotcrusader76]

wait a minute....."with an exchange" ??? Hell no!
Offer him $750 cash and keep your oval ports. For an exchange they better be FULLY assembled.
Seariously re-consider is offer and counter offer.
~Ty

[396_WAYS_TO_SPIT]

The heads are fully assembled and ready to bolt on. i was thinking about giving him a different set of heads for the exchange not my 781's.
right now I have a set of 781's and a half set of stainless steel vlaves. i was thinking about replacing the studs and guide plates so that everything is new. If I was to complete my 781's these would be the cost.
studs-$40
guide plates-$30
rocker arms-$300
valves(8)-$100
machining-about $250
springs would come with my custom ground cam kit
plus time porting
=$720
What should I do?someone told me that i cant fit 2.19/1.88 in my 781's! So I decided to only open up the exhaust side to 1.88 and leave the 2.09 stock.
396

[GofastRacer]

Did I miss something??, you didn't mention what heads these are?, are they 049's or equivilant??, you don't want the peanut heads!..:eek:

[396_Z]

I'd open up my intakes way before I'd touch the exhaust. I'm a firm beliver that BBC's flow enough on the exhaust side already when you run an open header style exhaust so go after the intake side first.
Second point is that if you plan on staying below 6k rpm rec port heads will probably hurt your performance vs. a good oval. While rec ports will spank oval castings above 6500 if you look at the flow #'s ovals do just as good and have a better velocity below 6k.
Third is the last set of BBC heads I had done for $400. That included tank, mag, surface, ream guides .030, 16 new valves (+ .030 stems) new springs, locks, retainers, cutting the guides for the lift and assembly. For $750+exchange I'd want some KY too.

[77charger]

IMO the oval ports will be better to 6k rpm with mild porting then the square ports take over.Another thing is that the square ports wil need a manifold that is for a square port to get the most out of them.(an oval port type will work but will be restrictive)and vice versa

[gnarley]

Don't forget the exhaust valves. What type of exhaust valves would you plan on installing?
I should have asked what type of boat is this going in & how do you plan on using it?

[H2OT PURSUIT]

You said 5500 RPM. That being the case you need rect. port heads like, you guessed it, a hole in the head. IMO.
Scuba, Sky or Muff, No Dive Too Tuff.

[396_WAYS_TO_SPIT]

the boat is a 18ft jet w/ an a inpeller.

[AZKC]

Stay with ovals. 049's are the way to go it seems
KC

[gnarley]

Originally posted by 396_WAYS_TO_SPIT
the boat is a 18ft jet w/ an a inpeller.
Not knowing much about jets or how you plan to use it or drive it I would still wonder IF std stainless exhaust valves are adequate for your needs? Due to extended run times the heat generated in std stainless exhaust valves may cause a failure. You may consider for safety or longevity an inconnel valve or special heat treated valves, they can take the heat and save you from building it again.
You can spend it now or spend it later, the fact is YOU will spend it!
An old saying I learned in racing was "do it right the first time, you don't have time to do it a second time!

[Cas]

396,
The 781 heads have 256/114 cc port size runners, with 118cc combustion chambers.
The 049 heads have 255/119 cc port size runners, with 122cc combustion chambers.
So, it's a toss up. The 049's flow just a little more, the 781's give you just a little more compression.
I just got through having Manley S/S 2.19 intakes and 1.88 exhausts put in my 781's, they do fit. Since you said you're going to run around 5500, stick with the oval ports.
I went round and round with the same dilemma, recs or ovals. The machine shop I used had a real good deal on some rec ports but he strongly suggested I stick with the ovals on a jet boat. He said throughout the 35 years of building engines, the ovals worked best for a good strong lake boat. According to most, you won't get the hp out of the rec ports until the engine is at 6000 or above.
just my $.02

[DansBlown73Nordic]

I have also been wondering the same thing. Ovals or square port. I have four sets of 781s. I think im just going to use a set of them. Looks like they will be great for my 427.

[396_WAYS_TO_SPIT]

Originally posted by Cas
396,
The 781 heads have 256/114 cc port size runners, with 118cc combustion chambers.
The 049 heads have 255/119 cc port size runners, with 122cc combustion chambers.
So, it's a toss up. The 049's flow just a little more, the 781's give you just a little more compression.
I just got through having Manley S/S 2.19 intakes and 1.88 exhausts put in my 781's, they do fit. Since you said you're going to run around 5500, stick with the oval ports.
I went round and round with the same dilemma, recs or ovals. The machine shop I used had a real good deal on some rec ports but he strongly suggested I stick with the ovals on a jet boat. He said throughout the 35 years of building engines, the ovals worked best for a good strong lake boat. According to most, you won't get the hp out of the rec ports until the engine is at 6000 or above.
just my $.02
Ok I am sticking with the 781's. But I have another problem! The book I looked in yesterday told me that the 781's and 049's are 110 cc! Whats the deal with that?

[Cas]

Originally posted by 396_WAYS_TO_SPIT
Ok I am sticking with the 781's. But I have another problem! The book I looked in yesterday told me that the 781's and 049's are 110 cc! Whats the deal with that?
Here's where I got my info http://www.mortec.com/bbc.htm
It's a real good site for lots of info.
Oh yea, along with having the larger valves installed, I also had the heads ported to the 049 runner size. The machinist said it should add about 75 hp to the engine, on the conservative side.
Since I haven't run the engine yet, I can't give you any running knowledge. The cost to have everything done to the heads was $830.00 here in CA. That included valves, guides, springs, locks, retainers and all the machine work necessary.
The one thing you "HAVE" to do if you get the heads done like that is to definitely clay the piston to valve clearance when you put the heads on. You need to make sure you have the clearance or you WILL grenade the engine.
In claying mine, the depth of the valve relief in the piston had plenty of clearance. The situation I ran into was the relief wasn't quite big enough on the radius. A little machining to the pistons cured that.

[Cas]

if you haven't seen it yet, here's a pic of the completed project
http://www.***boat.com/image_center/data/500/210motor1-med.jpg
this is what I started with
http://www.***boat.com/image_center/data/504/210engine-med.jpg
Was torn whether or not to run the little blower but certain circumstances (motor in other boat took a dump) forced me to sell it.

[gnarley]

Originally posted by 396_WAYS_TO_SPIT
Ok I am sticking with the 781's. But I have another problem! The book I looked in yesterday told me that the 781's and 049's are 110 cc! Whats the deal with that?
You should CC them just to make sure where they are anyway & to determine what your real compression is. If you don't mesure it & calculate it yourself it will never be known for sure.

[blowngas]

for most lake boats that are gonna hold the rpm's down to 6000 or less, the oval ports will out perform the rectangle ports all day----do not try and increase the valve size on the small chamber heads at all------what will happen is by increasing the valve size, you shroud the flow and it will perform below what the stock size valve would----go with a good 1 piece stainless exhaust valve----for your conditions, you don't need a severe duty valve----you should be able go get by with a good $10 to $12 valve----if you want to do something, get you a grinder and some sand paper rolls and polish out the exhaust ports----you can gasket match them but don't change anything else, just smooth out the surface-----you can likewise gasket match the intake ports but do not try and do any polishing on them---the casting imperfections help mix the air/fuel by causing the mixture to tumble----gasket match the intake manifold also----and go with a manifold that works within the rpm range---don't expect good performance at lower rpm's with a high rpm intake----be safe and keep the shiny side up

[gnarley]

Originally posted by blowngas
go with a good 1 piece stainless exhaust valve----for your conditions, you don't need a severe duty valve----you should be able go get by with a good $10 to $12 valve
I spoke to the MANLEY rep at the SEMA show on Tuesday who strongly advises severe duty valves in a boat if it is going to be used in longer runs, as in the 30 to 60 minutes or longer range at sustained RPM's in the 4000 range. If it is a 1/4 mile race boat or something that you just take out for short bursts & don't develop much sustained temperature in the engine he said std SS valves will do fine. Otherwise severe duty is the recommendation.

[HammerDown]

My 049's fully set up, larger valves,new guides, springs, bowl blend port matched etc with Fria(sp) inconnel exhaust valves were just over $900.00
For some reason the #'s 300+260 ring a bell for flow numbers...I'd have to dig out the flow chart.
They cc'd out at 118 if I recall...and for sure with a marine use head the Inconnel exhause valves are a must...how do I know...because I busted the head off a standard Manly HD exhaust valve that cost me $$$$$$.
With OT Wet Headers the exhaust valves will sometimes get damp at idle...and the Hot/Cold cycle is what breaks them. Inconnels been in there for years and years.
My cylinder Head shop (Brandewine Cylinders) said that the 049's were the Best oval head GM ever made...and they are the head to have for my application.
Now if they were as light as Aluminum I'd be real happy:rolleyes:

[Infomaniac]

Edelbrock makes an oval alum head. A lot of the HTM n/a engines used them.

[HammerDown]

Originally posted by Infomaniac
Edelbrock makes an oval alum head. A lot of the HTM n/a engines used them.
I here ya, I found that out to late in the game, and I've got to much $$$$ in these iron heads.
Unless I sell...but whats the top dollar they could be worth?

[Infomaniac]

Look around on e-bay to see what they are going for.
Not sure myself. Sorry.

[Dr. Eagle]

Originally posted by 396_WAYS_TO_SPIT
He has a set of rectangular port heads with 2.19/1.88 stainless valves,ported,polished,new studs,guide plates and springs that will handle up to .650 lift. he wants $750 w/ exchange. he said he set them up for a boat and the guy never came to get them. thx 396
You need the rectangular port heads from all i have read, the other thing that I have read is that you want Inconel exhaust valves, not Stainless. Just my .02

[powerplay230]

Look around on some of the boards for Hot Rods or the Super Chevy's or resto' or something of the sort. From what I have heard and seen some of the automotive market will pay big bucks for the 049 heads. I had someone offer me $1500 when I took mine to shop to have them cut for bigger valves etc... They are a hot head on the street, not sure why when for just a little more jing you could buy aftermarket aluminum... Go figure but then again I have a hard enough time trying to figure out my boat..:p
Rich

[HammerDown]

"automotive market will pay big bucks for the 049 heads. I had someone offer me $1500 when I took mine to shop to have them cut for bigger valves etc... "
:eek: :eek: :eek: Maybe I should advertise mine;)