I want to change my 350 over to a 383 and keep hearing the term small circle cam. I plan on using a ZZ4 cam. Is this a problem?

 

I don't know if it will be a problem, but I know its not a small circle cam. The term refers to the base diameter of the cam core. THe bearing journals are the same as the factory ones are, but the rest is based on a smaller diameter. This helps in stroker motors b/c it gives more clearance for the rods. I have never used one, but on a stout big inch SBC stroker, I would question the reliability of the cam. For a 383, you could use the ZZ4 cam, just make sure you check all clearances.

 

The "corner" of the rods on the side that points upwards, and the top of the rod bolt, comes quite close to the cam even in a normal engine. The clearance there is sufficiently small that in a 400, you can't pull the cam out sometimes because a rod is within the volume the cam occupies, so you have to turn the motor a little bit. 400 rods are shorter in their shoulders and use different bolts to clear the cam in a stock 400. When you build a stroker motor with non-400 rods they don't have the special treatment, and so they may hit the cam. Sometimes you can grind enough off the rod and bolt to fix this, sometimes not, depending on what rods and hardwre you have. The cam mfrs make cams with small lobes to get them out of the way of the rods. Since lift is simply the difference between the top of the lobe and the bottom of the lobe, you can still make a "big" cam just by reducing both dimensions equally. This makes a weaker cam (smaller shaft) so usually they use a special core if it has to be more than .100" or so smaller than stock.

 

I have read posts which refer to grinding the rod bolts off. I also see some manufactures offer rods ready to install. I had one guy tell me to see if I have a High casting or normal casting block where the cam sets. Whats that ?????????

 

i very seriously doubt you have one of those. those are expensive Bow Tie blocks available from gm. also the Oldsmobile Rocket block. it is basically a tall deck small block chevy. there is a greater distance between the crank and cam centerlines. they use stock style chevy cams and cranks but require longer timing chains, and either longer rods or taller pistons. good thing about these tall deck blocks is that you can build up 468 cubic inches of nasty small block chevy! but like i said....i doubt you have one of those. if you are serious about building a stroker and don't want to have to worry about clearances....i'd go with Eagle ESP rods. they are stroker clearanced and cheaper than other rods like lunati and crower. mine clear my non small base circle GM Performance Parts solid lifter can with .512" of lift. cleared by a mile. either way you go...you will have to do lots of grinding in about 16 places on the block itself. hope you're good with a die grinder. gets aweful expensive when ya have a machine shop do it. costs lots of labor because they actually have to partially assemble the engine to see where and how much to grind off. took me about 2 hours to grind my own block.

Rich

 

I knew you had to grind by the oil pan gasket lips.Where else is there any problems? I have grinders and would do it myself. The Eagel rods sound good.What part number did you use? Overall was it worth building the 383 over the 350?

 

you also must grind 1 spot at the bottom of every cylinder wall...don't worry, it won't hurt anything. just make sure you debur all the edges so not to scuff the piston skirt. i used a CRS6000B3D connecting rod. it is a 6" rod. i like to turn high revs so i built a long rod motor. it helps relieve stress on the pistons and cylinder walls and increases the upper rpm potential. but a 5.7 rod will suffice in a street engine. the part number would be CRS5700B3D. i advise you to do lots of looking and price checking, as these are expensive rods. (abaout $500 for a set which really isn't bad compared to crower sportsman rods) i bought mine brand new still in the vacuum packaging for $175 at a swap meet. a vender from Noble Racing in Ky. was there dumping overstock fast and cheap. got my eagle steel crank and those rods for a total of $525!!!!! and that crank sells for $659 from jegs. they have really good prices. you can check em out on the web at www.nobleracing.com they specialize in circle track motors and the 383 is one of the most popular roundy round motors you can get. they got an 800 number on the web site and you can call and talk to Mr. Noble himself. he's a real nice guy. gave me a really good hook-up when i met him at that swap meet. if you have any other questions i'd be more than happy to help you along the way with you build up. i just finished mine not long ago and i can tell you that i guarentee you won't be sorry building a nice healthy 383. i promise.

Rich

 

Do I have to grind the cylinder off even with 5.7 rods? If so you mean on the inner wall of the block right? Using those rods you listed do you have to grind rod bolts? Thanks for input.

 

absolutely no mods to the rods (hey that rhymes! haha) they clear the cam by a mile. man i wantefd to take pics while i was building my motor and i got so into it i completely forgot about taking any.