was just wandering using the same cam intake carb headers which would produce the most amount of power out of a 6inch rod 350 /383 /5inch rod 350 all using the flat top piston i prefer the comp cams remeber all have to use the same size camshaft.this question is for mainly the experts.  

A larger engine should make more torque and should make it at a lower RPM, but with street carbs and camshafts associated with frequently driven street machines it will really choke off a larger displacement engine at the top end. I'd say it depends a lot on the vehicle setup and cylinder head budget.

SO WHAT YOUR SAYING IS THAT BUILDING A STREET STROKER MOTOR AS FAR AS AN 383 WOULD BE A WAIST OF MONEY AND TIME? SEEMS LIKE THE 350 IS THE PERFECT ALL AROUND MOTOR NO MATTER WHAT U WANT TO DO WITH IT STREET/STRIP/OVAL TRACK/DAILY DRIVER WHATEVER.HEY THANKS.SO WHAT KIND OF DIFFERENCE WERE LOOKING AT AS FAR AS THE 6INCH ROD 350 AND THE 5.7 INCH ROD 350?PROBALLY NOT 2 MUCH HUH'?  

A 350 or a 383 with a 6 inch rod would make a happy engine. It's just that this isn't easy to do in stock block without compromising piston pin position to keep its crown no higher than the deck at TDC. The solution is the Rocket block. Taller from crank center to cam center and head deck makes space for stroker cranks and long rods without so many other dimensional compromises in other places.

A friend of mine in Houston was making a stretched block before the Rocket block came out by afixing an aluminum spacer, boring the block to the max, then putting a thin wall sleeve in the bores. This sandwhich was held together with the heads by their bolts. This actually worked pretty well. But keep in mind when I first met this guy he was milling a Datsun head with a Craftsman belt sander using a rafter square and set of feelers to check flatness.

The 5 inch or did you mean 5.7 inch rod is stock to the 350. By the time you get to a 383's 3 and three quarter inch stroke you've got to shorten the rod or run the pin way up on the piston. The factory decided on a short rod. These tended to jam the piston into the wall as the crank came off BDC resulting in rather heavy wear in the bottom of the bores with some power loss. After all you can't wear out the engine without putting some force into the effort. It's currently popular to raise the pin in 383 stroker motors allowing for a longer rod but this leads to a couple other problems. One, the pin gets up into the ring pack, so you can only go so high. Two as the pin migrates to far up or down the piston, you get cocking moments that result in one end or the other wanting to dig into the cylinder wall. Getting to high also results in having to deal with skirt slap, so you have to tighten up the side clearance which increases the possibility of galling between the skirt and bore which increases wear which increases clearance which causes piston slap which results in cracked skirts and or bores.

As for power, if you constrain the ability to pump air to say that best for the 350. The 383 will develop nearly the same horsepower as the 350 it will just occur at an RPM that is proportionally lower where the two engines are pumping the same amount of air. The torque charateristics will look different with the 383 delivering more torque at lower RPMs by virtue of its greater lever arm (stroke) but the torque will drop off faster as RPMs go up due to breathing limitations. "Work" is the physics measure of how much (well OK) "work" an engine can perform. Simplistically, this can be calculated with some Integral Calculus as the area under the dyno generated horsepower power curve. If you can call that simple? Anyway, theory says that if you you had a 350 and a 383 and you constrained them both to the same ability to move air through them with heads, induction, exhaust, and cam timing and lets say these selctions were made to optimize the 350, the area under the power curve of each engine would be the same. Curves would look different with power against RPM happening at different rates.

Now this answer is different if we choose constraints that benefit the 383. Here if the heads, induction, exhaust and cam timing were optimized for the 383, it would show greater power peaks and more "Work" area under the curve because the common cam and components would limit the rev potential of the 350. For the 350 to move as much air through itself as the 383, at this point it needs more cam and related parts to achive higher RPMs that would then allow it to move an equitable amount of air through itself when compared to the 383.

Confused yet? This all boils down the ability to move amounts of air/mixtrue through the engine. Theoretically, a 283 turning 7000 RPM is pumping as much air as a 400 turning about 4950 RPM and therefore the two would be capable of the same amount of work. The power curves would look different, but the areas under the curves would be the same. In the real world it's not quite that simple since power looses go up to the square of RPMs and induction effort goes up to the square of the air velocity and bunches of engineering stuff like that. Not to mention that the 283 needs a cam and components that can keep a valve under contol at 7000 RPM and strength in the bottom end to keep things connected together under the structural loads of those speeds. But the scenario I described is not outside the realm of current technology to actually go and do. That's where practicality comes in; the average person driving a 4000 pound car doesn't want to listen to a 283 revving its guts out to move you down the freeway at 70mph with the airconditioning running. A more humane solution is a 400 inch engine turning slower, thus quieter. If you're going racing the answer might be different. However, state-of-the-art engineering being what it is, you can use cam designs and have component strengths that are available to turn a 400 at 7000 RPM so the 283 looses on the track since the technology is not available to run it that much higher than a 400 to make it competitive. Assuming both engines have to move identical vehicles.

Assumptions, it's all in the assumptions. What you constrain and what you don't leads you in different directions. Materials and their strengths, shapes of lobes and ports, the speed of burn in the combustion chamber; things like that place limits and constraints on whats reasonable to achieve.

Bogie

so what youre saying is that it takes a special block only if u want add the 6 inch rods?  

Not necessarily, I'm kinda over talking myself here. A 6 inch rod into a standard production block can be done for a 350 or even a 383 with its 3 and 3/4 stroke in a 9.025 inch tall block. But by the time you're stuffing a 3 and three quarters stroke into a small block you're working up on the upper limit of what can be fit without comprimising cam to rod clearance and piston pin position to points where either you just can't go an further physically or ar starting to place operational loads in ways that reduce efficiency and durability.

An example of a physical limitation is pin placement, you can't get higher than the ring pack. There are stroker pistons that push the pin into the area of the oil control ring and in fact use a small insert to support the ring over the pin hole. But this is competition only stuff to be used on an engine that sees regular teardowns. These designs are not intended for long mileage street engines where teardown is a function of rebuilding for excessive wear in a decade or so. Serious competitive racers out there on the leading edge have regular tear down schedules which may be as frequent as between races. The reason is that their design is right on the edge of component life and many parts need to be inspected and replaced between races to prevent failure during races.

There are several GM and aftermarket companies that make short or tall blocks for competition. The short block is intended for displacement constrained classes that don't need a block as tall as standard because of exceptionally short strokes used so there are some 8.2 inch tall blocks made for these classes. The intent is to reduce un-needed weight and size.

There are tall blocks for use in building larger displacement stroker engines that postpone the problems of rod clearance and pin position by raising the cam and head deck further from the crank. These come in an assortment of heigths but most common are 9.325 or 9.5 inches.  These allow the small block to be built out to 455 inches or more. Or can be used to build smaller engines with exceptionally long rods of 6.25 inches or more.

These blocks can get pretty pricey so their use is pretty much by high buck race teams. The average guy can build a pretty successful 377 to 406/8 street engine using a 400 crank and either a 350 or 400 block. But 400 junk yard blocks are getting pretty rare as none have been built for 25 years.

A 6 inch rod on a 3 and 3/4 crank in a standard 9.025 height block is the upper end of what's doable with in practical limits of reliability, durability and cost.

Bogie

so whats the difference between the 400 block 377 and the 350 block 377.i know the difference as far as puttin the 2 together but what im askin is as far as power.would they put uot the same power? let me get this str8 with the 350 i can use the 400 crank and keep the standard bore of the 350 but as far as the 400 block i would have to use the 350 crank?would the 350/377 be worth buildin or waste of time.it sounds good as far as being rare on the streets because i dont hear of many people daily driving 350/377.whats your opinion on these 2 motors old bogie anybody???? thanks