DOES a 383 use a 350 block and 400 crank , or is it the other way around ??

which rods are used ???

is it hard to clearence a block, something that can be done at home with a die grinder ???

thanks!

Will

DOES a 383 use a 350 block and 400 crank , or is it the other way around ??

which rods are used ???

is it hard to clearence a block, something that can be done at home with a die grinder ???

thanks!

Will

A 350 block is used with a 3.750 stroke and a crank with 350 mains and we use the 6 inch rods so we can internally balance the crank as its a much better deal all the way around.

And the block can be clearanced at home with a die grinder and we use a small base circle cam as well.

Just to elaborate a bit more.....Carl likes the 6 inch rods as he mentioned(and I agree that its the way to go mainly for weight and balance purposes).....but that doesnt mean you cannot use anything else than a 6 inch rod. Many are using stock length 5.7 inch rods...and some even use the shorter stock 400 rods(5.565). You just have to buy the correct piston based on the rod length used. But even though there are these other options, longer rods are often more beneficial for a few different reasons. And again...Carl mentioned one benefit. Balancing. Im not a machinist, but more than a few have said that an internal balance job often(surely not every time) but often goes easier with longer rods. Less heavy metal needed and less money for you to spend(on expensive heavy metal). Plus, your working with a lighter piston if your usin longer rods. This is a good thing. Its always good to be swingin around less weight. Cylinder wall loading is less as well......dont know if its enough to honstly matter...but it is a little less...so I guess you can say it matters a little.

Dont let anybody tell you that X length rod makes more or less power. In some intense applicatons, experimenting with rod lengths can show some kind of gain somewhere over the power curve....but especially in a street car, youd never know. So dont base a connecting rod choice on what kind of power a different length rod is said to make, cause you wont get much of a reward. Use the lenght that fits your application the best and forget about any talk about power(and longer ones again are often better for many applications for some of the reasons mentioned above). But you have options if you dont want the longer 6 inch rods for one reason or another. And many do just fine with the shorter 5.7 inch rods. So dont be afraid of that length cause there aint nothin really wrong with it when done right.

And to add to what Greg said ;) A 5.7" rod can often be balanced when using an aftermarket crank to build a 383 -- just no guarantees.

Hehe....I would imagine the same thing could be said for some 6 inch rods combo as well(meaning.....no positive guarantee) but the odds are often in yer favor a lil more with the longer pieces.

I built the engine Carl described this winter.

I had the machine shop clearance the block. They took a LOT of material off, I wouldn't do it myself.

On the balancing, with 6 inch rods and 404 gram srp pistons (a stock 350 piston is 550 grams or so!) they took nearly 2 POUNDS of metal OUT of the crank to balance it. Many run external balance with no problems, and many run shorter rods. 5.7" 350 rods are nearly free, where mine cost almost $300.

We balance a lot of 383 assemblies for our shop and quite a few other smaller shops in the area and on the 5.565 and the 5.7 rod cranks require external balancing. And if you ever had to change a flex plate or flywheel or have it resurfaced there would be a good chance of throwing off the balance in the engine, And a least on the internal jobs we always balance the flywheels neutral and then do the pressure plate neutral.

And so far the 6 inch rod cranks we have done ALL of them internally and no heavy metal.

so if I buy one of those 383 kits from summit will it need balanceing.

also is the 383 with 350 +.030 bore.

this is just a street motor with a little hot rodding a track time.

(this is going to be bottom end to the vortech headed 2 x 4's set up from the other thread.)

That's interesting Carl. I just did a 5.7" rod 383 with Scat 5.7" H Beams, SRP dish piston, and a Scat 4340 3.75" crank.

We had planned on balancing externally and even had the ext balance flexplate and dampener. When we got it on the ZE machine we found that we would have had to drill 4 good size holes in the rear counterweight alone. Instead we decided to balance it internally and got an internal balance flexplate and dampener. We wound up with one hole on the front counterweight and 2 on the rear counterweight. I forgot what bob weight was on this job exactly, but it wasn't exactly light.

I personally think that some of these aftermarket forged cranks have as much weight in the counterweights as they can get.

Yeah, if you buy a complete kit you will need to send it for balancing. Even if you buy something deemed "pre balanced"...it could still use a trip to the machine shop for a good balance job. Yes, even the pre balanced ones! Youd be lucky to find a pre balanced kit that shows up done as well as a good machinist could do. As around and you will find lots of machinists that arent particularly thrilled with the quality of any pre balanced store bought setup.

And to add to what Eric said - my 383 uses an Eagle 4340 crank, Manley 5.7 sportsmaster rods and Wiseco pistons and it easily balanced internally, with a bobweight of 1650 ish as I recall.

so what could be the consequences of an unbalanced engine? i mean something you bought off the shelf out of balance.......my 327 was unbalanced but i was using stuff that was close to the originall specs,besides the cast pistons......

just curious is all,definately not doubting anything said here....

so what could be the consequences of an unbalanced engine? i mean something you bought off the shelf out of balance.......my 327 was unbalanced but i was using stuff that was close to the originall specs,besides the cast pistons......

just curious is all,definately not doubting anything said here....

Balancing reduces internal loads and vibrations that stress metal and may eventually lead to component failure. The better the engine is balanced the better your chances are of the engine living a longer life. A common misconception is that you are guaranteed more power. That being said it is possible to have power loss due to a poorly balanced engine.