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Old 03-03-2006, 09:21 PM
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250 Integrated head

I have a 250 with an integrated head in my truck at the moment and was wondering about the horse power it made. Well i did a search at Inliners International and found out that because they were trying to make the engine more efficient they gave it a different cam that gave it 15 more horse power over a regular headed stock cammed engine. So my question is how much horse power would this engine make with the higher horse power cam and a regular head. I would think it would make more because the regular head is less restricted and has more potential to be ported and put on headers and intake. Can anybody validate this information? The engine is a 76 truck engine by the way.

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Old 03-03-2006, 10:31 PM
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250 heads

Im not sure what brand engine you are talking about, but as far as the intigrated head producing more power than the old head, its highly possible and feasable.
You mentioned that they use a larger cam with the newer head design. That may well explain the increase in HP.
As for restriction, Im not sure I follow you on that. Are the port runners smaller? Have more or less bends in them? Smaller valves?

Some points to consider:
1. Just because an engine has smaller valves and or runners, doesnt necessarily mean its more restricted. For instance, if the runner design has less of a bend to it, than the stock runners, IE where the runner makes a drastic turn to go to the port, the flow is far more restricted than it would be with far less curvature. A rule of thumb is that if a tube has a bend in it with smaller than a 12" radius, then that bend will cut the flow in half, compared to a straight tube. Most heads have a turn radius of less than 3 inches on a conventional head, so if the intigrated head has any kind of a larger radius than does the conventional head, all else being equal, it will flow better.
Smaller runners are a big boon to low RPM engines as they inhance the velocity of the fuel/air mixture, thereby assuring a better vaporization maintainance of the fuel. This also will insure better filling of the cylinder at low RPM. Even if it has nominally smaller valves, if you have the better port design, then the valve size is negated, in comparison to the valves in the early head.

2. If the intigrated intake has smoother bends in the runners than does the bolt on older style, then if all else is equal, the intigrated intake will flow better than the old intake design.

3. In referance to the bends in a tube, an 1 1/2" straight tube will flow as much as a 3" tube, if the 3" inch tube has a 90 degree bend with a radius under 6". At least thats what I was told in science class, when we were discussing such issues.

While its not as simple to do, porting out or working out the runners on an intigrated intake isnt impossible. I refer back to the old Ford 144/170/200/250 I-6 used in Falcons, Comets, Mustangs, and Mavericks. Those heads could be made to flow extremely well, especially when modified for mulitple carbs.
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Old 03-03-2006, 11:33 PM
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Thats some good info, the engine im talking about is a Chevy 250, the not so good picture of the painted one is the one that i am running now.Here the exhaust manifold(which is the bottom of the intake manifold) is removed and you can see the rest of the intake is part of the head. The other picture is my other 250 with a non integrated head. The reasoning i have for saying that the engine is restricted on the integrated one is the the exhaust has to leave the combustion chamber go up through the valve,make a 90 degree turn,go straight for an inch,turn another 90 degrees down ward,then another 90 to the exhaust manifold itself the finally out to the exhaust. Where as on the non integrated head it goes up through the valve makes a 90 out to the manifold, followed by another and to the pipe . Not to mention the since the exhaust manifold is the bottom of the intake,carbon builds up from where fuel hits the hot exhaust before it even goes into the combustion chamber. I know the intake and exhaust on the non itegrated head are pretty close to but not on the way they are on the integrated. Im not to concerned with the horse power the engine is making now because I dont care. Im just wondering if there would be any advantage to running the regular head over the nonintegrated that i would really notice.
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Old 03-04-2006, 08:20 AM
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The biggest disadvantage with the integrated head is that they are almost all cracked by now. They had a terrible scrap rate and I don't recall the last time I saw one that wasn't cracked.

The other disadvantage is they are so dang HEAVY.

There are also issues with the exhaust manifold.

They are not a good choice for a performance build cause almost nobody (or maybe nobody by now) makes headers for them.

tom
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Old 03-04-2006, 02:05 PM
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intigrated head redux

Based on what both Rust Trucker and Tom wrote, I would opt for the early head myself, since the old style head will fit.
I would surmise that given the later model upgraded cam, you may well see some extra gains by doing nothing more than going to the older head, intake, and exhaust, over what you have now. Maybe even as much as 5-10 HP at peak RPM,
There are some good aftermarket goodies out there available for your 250, as well, and if you did nothing else to the engine, a good set of headers and free flowing exhaust would definately be a big plus.
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Old 03-04-2006, 09:02 PM
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Maybe I had the last uncracked integrated head -horrible looking design, and gutless, but reasonable fuel economy and even better dieseling (the super high-tech 1 barrel carb wasn't quite right) -the thing would run-on for more than half a minute a lot of the time.

Because the prospect of a 1-barrel carb feeding 6 cylinders was so horrible (all the fuel going down one or two cylinders and the air going down the rest), I figured it would be neat to try and build a sheet-metal two-carb intake for a non integrated head. 'Sold the truck for $700 Cdn to fix my other truck instead...
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Old 03-04-2006, 10:07 PM
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heads

Maybe i have your uncracked head now! Anyway if I were to put tha non inegrated head on my engine and assuming that its true that the integrated headed engines have 15 morehorse power. I could expect 20-25 horsepower from an afternoon and 30 dollars worth of sparkplugs and gaskets????? If thats true then thats pretty sweet.
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Old 03-05-2006, 09:03 AM
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I can't give any exact numbers on chevy heads,but on the ford sixes the combustion chambers varied from year to year,as well as different style heads,some of the integral head/intakes had smaller chambers and higher compression.

You might want to check the cc's of the heads before making a decision,if you put on a head with bigger chambers and change nothing else,you may lose compression and power.

Some ford guys I know cut into the "log" and welded flanges to accept 2 more carbs and run 3 singles,some of those intakes were capable of delivering all the air that those heads could flow anyway.

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Old 03-05-2006, 02:52 PM
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Ive already checked the head numbers and they are the same cc
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Old 03-05-2006, 06:51 PM
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Well I was at the junkyard today helping my brother get parts for his 68 and i found a 81-84 Chevy with a 250 that had the integrated head BUT it had a dual outlet factory exhaust manifold and a progressive 2 barrel carbureator. The head is uncracked and i can have it for free so i think ill try it out when i get the truck on the road. any thoughts or experiences with this setup???
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Old 03-02-2014, 07:52 PM
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I have a great running intigrated head engine. I was in a 79 c20 that I scrapped out. It has the 2 exhaust outlets and a 2 barrel carb on it. It had been setting for some time, but the engine was very clean and looked as tho it had a new distributor put in it. I bought it for the utility bed on the truck. We hooked it to a gas can, it fired right up and ran great. Cruzed it around out on the road. I have since put the 3/4 ton running gear into my 1965 c10. Front bolts right in with like 2 holes to drill. The rear end with in with only new axle mounts. I did have trouble locating the motor mounts in even with the 79 mounts and brackets. I have never owned a 6 cylinder in anything including any of my old c10 trucks. So I have no idea if the old 6 mounting brackets are diffy. It is very hard to find info on this integrated head engine. But my runs like a top. I did put a turbo 400 behind it. But I was also, like others i see, wondering what upgrades can be done to it. Just any old Chevy head with the same valve size and chamber area will fit on it?
I'll be reading more posts thru out here as I saw a lot more info on this one of a kind motor.
Thanks guys
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