What is my next step to get the pre-86 350 I have now to the base of the Dec. 06 build-up? It stated that it started with a 388ci small block before bolting these top end parts to it. What parts and part numbers would you recommend I go with to bring my current 350ci up to the short block used on the tech. build in this particular article? I read the specs on page 23, but with my limited knowledge and hestitation because of it, I don't want to start a build going down the wrong path with incorrect or inferior parts. Thanks- Stan Sexton.  

Am I posting this question in the wrong portion of the site?

 I have stripped my engine down to the bare block and have had it sonic cleaned and ready to begin contacting machine shops for align boring and anything needed to start down this path. I would like some guidance from the ones who'd just performed this build, seeings how you guys have achieved my goal I'm striving for. Please help with these answers.  

No you landed in the right place.

I take it you want to build a 383 as a 30 over 350 with a 3.75 inch crank or a 388 as on a 60 over 350 block.

The block sounds like you're looking for a pre 86 with the two piece crank seal.

I'm not as crazy about a 60 overbore as I am a 30 overbore only because I like more meat in the cylinder wall and the extra 5 cubes just doesn't buy enough power to justify pushing wall integrity to the limit. But that's a personal thing, kinda like prefering Coke over Pepsi.

These days building a big inch, small block is pretty easy as there are manufacturers that supply complete balanced kits consisting of crank, rods, pistons, rings, bearings, damper, and flex plate from about 900 dollars for a street engine to around 4 grand for a full out race motor. So you plunks down your money and takes your chances. See Summit at http://store.summitracing.com/egnsearch.asp?Ntt=383+crank&N=700+115&Nao=10&Ntk=KeywordSearch#rstop  for 6 pages of kits. There's also Jegs, Competition and others that catalog these things, pick up a copy of CHP and cruise the advertisers.

Up front, before you buy a kit, or any other parts for that matter, you need to decide what this big, small block is about as that will drive you into the decision of forged versus cast crank, "I" beam versus "H" beam and 5.7 versus 6 inch rods, cast versus forged pistons and flat top versus domed or dished. The piston decision also hangs on the heads selected as combustion chamber volume of the head will drive the piston crown shape that will establish the final mechanical compression ratio.

The final horsepower goal has probably less to do with your selections than how you use it. The more often you take it to 400 horses and the longer you keep it there, the better the parts have to be. If the engine can make 400 horses but you putt along a crowded free way seldom using the ponies, the parts can be of a lesser quality and still get the job done. So you need to come back with those kind of answers before we talk part numbers. It's the old question "speed costs money, how fast can you afford to go?" It's pretty easy to dream bigger than your bank account, so choose parts wisely.

Bogie 

DAMMIT! I knew it wasn't gonna be as cut and dry as I'd hoped for.lol

I agree with the more meat on the walls theory and is the direction I'd like to go. Less expensive is also where I'd like to go, since it won't ever see a strip. I know it's a waste having the ponies to sit in traffic, but it would be nice to have on tap for a little play time and the dependability, seeings how it will be for taking the family to cruises too. What I'd like to get to, would be the base 388 motor (or 383), found in the article I'd mentioned, using the AFR heads etc. as written in that particular top end build. 

If you're not going to race this then a cast crank, decent "I" beam rods, and hypereutectic cast pistons will serve you well.

Before we get to piston selection you do need to decide on a head, even if you don't have it yet. The reason is static or mechanical compression ratio. For the street a modern fast burn type cast iron head running 91 octane should stay between 9 and 9.5 to 1. A similar design aluminum head can run 9.5 to 10 to 1. With a large displacement 383/388, a major proportion of the combustion chamber volume will be in the piston dish in order to control compression. So if you go with an open chamber head of 74-76 ccs you will need a smaller piston dish volume than if you run a tight chamber head of 58-64 ccs. The arithmetic for this calculation is swept cylinder volume (bore area times stroke) plus the volumes of deck height above the piston plus gasket thickness plus combustion chamber volume plus piston dish volume. All this is divided by the volumes of deck height above the piston plus gasket thickness plus combustion chamber volume plus piston dish volume. The tricky part is that any change to the volumes affects both sides of the equation, so you have to do a lot of recalculation when playing with this.

Large, open combustion chambers are preferable when running very high RPM engines on fuels like alcohol or nitro-methane. On the street they tend to be lazy, inefficient power producers on the bottom to mid power range. Closed chambers work better on the street offering improved swirl which benefits low to mid range torque and reduces emissions with improved fuel mileage. They start to crap out above 6000 RPM compared to open chambers, so select on where you intend to spend most of your time.

Pistons that require a dish to hold overall compression ratios at livable levels should use a "D" shaped dish rather than the more typical circular dish. The "D" dish located under the valve pocket with a step under the head's squish pad opposite the sparkplug and valve pocket, provide the best flame propagation and minimize detonation tendencies.

Getting to the bottom end, for strokers I prefer to buy individual pieces rather than kits. The reason is that many prebalanced kits still require the engine builder to grind material from the rods to gain clearance around some of the cam lobes. If you have a prebalanced kit, this destroys that balance, then you have to pay to rebalance the crank. Another way out of this problem is to purchase a small diameter cam to achieve the clearance in which case you don't need to mess with the rods. The down side of a small base circle cam on the street is that the loading between the lobe and lifter goes up and their life span goes down. The best rods for stroker engines are those that retain the cap with a cap screw rather than the traditional bolt and nut. That way is grinding is required, it's usually a little off the threaded end of the rod's big end rather than in the case of a bolt/nut design where material is removed from the bolt's head and the rod's head land area. In my opinion this removes a great deal of strength from a highly loaded area of the rod.

If you decide to run a small base circle can, than you've absolutely have to run a button cam spacer to prevent fore and aft cam movement. This will help the cam to live a lot longer. Actually it's a good idea with any non roller Chevy engine.

Bogie

As for the heads I plan on using AFR's195 Street Eliminator heads. I also plan to be using an Edelbrock Victor Jr. single-plain intake, topped by a 850 Mighty Demon carb. As for cam selection, I was going to stick with the prescribed Comp Cams Xtreme Energy 284 w/ 1.6:1roller rockers.

In the Dec. 06 article it said they used KB forged pistons(PN UEM-KB-704) with a dish of 6cc's. It also stated that the motor had a bore of 4.060in. and was using a stroke of 3.750. The deck height was milled to 9.005 in., keeping the piston deck height to between 0.000-0.003. The heads have 65cc chambers but are specified in the article as to being milled to 64cc. All of this brings it to an approx. compression ratio of 10.6:1.

Having the piston PN's in hand, I am guessing that I am only needing guidance in the PN selection for a recommended crank and rods.

Thanks to your earlier advice I now understand why and how this makes it a 388 versus a 383. If you could help give me the guidance to get back to our agreed upon and comfortable 383 I'd appreciate that as well. I'm really new to this and is my first engine build. With this limited knowledge, I'm merely following a written plan I've found in my CHP magazine that has, in my opinion, potentialy great HP/TQ numbers and is within my budget.

I didn't realize what a Pandora's Box I was opening by asking the first question that started this thread but I'm grateful for your patience in helping me build a motor that I can hopefully be proud of for years to come.

Please Bogie or anyone from the magazine, inform me of which parts or specs to get me to my beginning point. Thanks- Stan  

Hang on I'll be getting back to you. It's just my boss expects me to take time out of my busy days to design him airplane parts on occasion and that gets in the way of funner things.

Bogie

Woops! Yeah, those pesky boss'. Expecting you to go doing stuff they pay you to do.  Huh!  

One more question, how do you intend to use this engine? The part selection answer for a hot street engine, a towing rig, or a competitive racer will be different based upon usage. This difference has a big effect on cost. These parts can get pretty pricey, so you don't want to by race parts where they're not needed.

Bogie

Hot Street. Wanting to have the HP on tap for a good stab at the go pedal every once in awhile.

I was also wanting to keep the plan as to building it as a 383 instead of the 388. So what would the measurements be changing to, from the previously posted 388 measurements?  

Jeeze, where to begin; you’ve done a lot of part selection already which is driving in the direction of a very powerful engine. With your cam, rocker, head, intake and carb choices you’re easily building a 500 hp motor here. I forgot to ask what type transmission you’re using. If an automatic, this will require a 3000 RPM stall converter, converters with that much stall are miserable partners on the street, at stop light to stoplight speeds, like twiddling Tweedy in Van Nuys makes for a lot of heat. In this circumstance you’ve got to provide a lot of cooling for the transmission which means a separate cooler with an electric fan, or expect roasted transmission to be on the dinner table. You can use the brown ATF for gravy.

Some will think the AFR 195s would limit the top end to more like 470 hp but I think the 1.6 rocker ratio recovers the port limited flow with faster and greater opening of the valves, so I’d expect flow in and out of the cylinder to be equivalent to AFR 210s with a 1.5 rocker.

Let’s talk compression ratio, zero decking the block with a flat top piston and a composite gasket of .050 inch crushed thickness and a 65 cc chamber gets a compression ratio into the 11.5 to 1 range by my arithmetic, which is about a ratio higher than what you stated. Even with this cam and rocker combination, 11 and a half even with aluminum heads could be a problem on the best available premium unleaded. You can with a carb, however, easily throw more fuel in it for some rich side cooling effects in the chamber; certainly a cold air source to the carb as well as a cool say 160 degree thermostat may let you get away with that much compression. If worst comes to worst, you’re better off to open the chambers a little to get the ratio down than you are to stack head gaskets. Raising the head increased the distance between the piston and the head’s quench deck (flat side opposite the valve pocket) which makes the chamber more detonation sensitive.

Given what you’ve spent so far, it appears that financial limits are pretty liberal for this project and given the power this engine should make, I’m recommending a forged crank over a cast version, this is a lot more expensive, but if the bottom end blows, now matter how much you spent on the upper end, it’s all junk. So you just can’t cheap it out where all that spinning mass is at. This kinda leads us to the block; the power levels you’re looking at are rather hefty for a 2 bolt 350 bottom end. Hopefully this is a 4 bolt block, or you can step up to some 4 bolt center caps on a 2 bolt block.  

There’s a number of choices for cranks and rods, first off let me say I prefer to select a crank, rods, and pistons as separate pieces rather than a kit and bring them together for a trial fit. For a stroker 383 or more, where any grinding needs to be done to the rods, piston skirts or crank counter weights, I can do this prior to balancing. Some prebalanced kits have run into clearance problems when brought together in certain blocks requiring additional clearance grinding, then rebalancing. Given that balancing is a rather expensive art form, I don’t like to buy it twice on the same crank assembly. I also prefer an internally balanced engine. Externally balanced engines require that each set of crank throws run slightly off balance. This causes the crank to bend and flex as well as wanting to find a center of rotation that isn’t necessarily in line with the bearing bore. These events cause the crank to wind and unwind resulting in vibrations that need to be resolved by the damper on top of all the other forces found on the shaft. Second, the desire of the crank to run somewhere beside the bearing centers causes forces that must be resolved by the main bearing bulkheads of the block, all this is un-necessary stress and strain that goes away if you just balance the motor internally.

For crankshafts you can get a SCAT 4340 twisted forging (4-350-3750-6000) for about 500 bucks, it weighs in around 53 pounds, a lightweight version at 49 pounds is available for about a thousand bucks. These are imported forgings. See SCAT at http://www.scatcrankshafts.com/http://www.scatcrankshafts.com/ .  Callies makes both imported and domestic cranks, you should be able to score an imported forging “Compstar” for about $700. See them at http://www.callies.com/crankshafts/compstar.htm . I haven’t used anything from Wheeler, but from what I read they’re not good enough for a high power engine. Trick Flow had screwed around with cranks and there might be some still out there check out Competition Products at http://www.competitionproducts.com/ to see if they have any left. These guys tend to buy up odd lots of things and run specials, sometimes you can find extraordinary deals. They ran about 800 dollars. Howard’s makes a nice non-twist forged shaft 353769TS2 I think is the part numbers these can be found for 1100 dollars or so, they are real nice. See at http://www.howardscams.com/ . Lunati makes some cranks as well, their web site always screws my computer up, the P/N on this thing is AJ117DN.

Rods can be found at the same sites. I prefer cap screw rods, where the upper part is threaded and the cap is held on by a machine screw (bolt) from the bottom that screws into the long end. That, rather than a bolt and nut type is easier and safer from a strength standpoint to grind for cam lobe clearance should that event become necessary. For an engine running gasoline, the I beam rod is plenty good. H beam rods offer more buckling strength but this is needed for engines running either high energy fuel like nitro-methane or high volume fuels like methanol where either the rod gets hit really hard or the engine is running with so much fuel it’s on the edge of hydraulic lock. At your power level you should select a bushed rod rather than a press fit pin. The bushing provides an additional point of rotation for the rod relative to the piston. The insurance this buys is that if you cook the piston and it expands to seize the pin, the pin can still hinge inside the rod if it’s riding on a bushing. If the pin is pressed on the rod there’s no hinge point in this situation, but believe me the rotating crank will make one where the pin is seized in the piston, it ain’t pretty. So a bushed pin buys you a little piece of mind. It also allows the piston and rod to kind of jiggle around and adjust themselves to the variable loads of the different cycles of the engine. The SCAT 4340 I-Beam P/N 2-IRC6000 can be had for about 250 dollars a set a little tougher is the H-Beam 2-350-6000-2100 for about 100 dollars more. Howard’s makes a Sprint Lite 6 inch rod that only weights 550 grams, these run about 550 bucks a set; they’re a race rod and are good for a continuous 550 horsepower which is about what you’re making but I doubt you’ll do that all the time every time on the street. These are easier to balance as with a forged piston they could keep you away from the expense of having to add heavy metal to the counterweights. But if you’re squeamish Howard’s also makes the I Beam Ultimate which weighs in at 670 grams and is rated 750 horsepower continuous. This could be a bit tougher, read more expensive, to balance requiring tungsten or spent uranium be used in the crank to counter balance the rod and piston combination. You’ll find that Lunati and others also make rods. If the piston and rod is too heavy for the available counter weights, if the crank you selected isn't already relieved in the rod journal cheeks adjacent to the lightening hole of the throw, you can get in there with a die grinder and take a little metal out. You'd come with a vertical line drawn about 1/8th inch to either side of the lightening hole start to grind a relief that runs from the rim thickness at the top of the cheek go down to the unmachined thickness above the main journal and remove all that metal out toward both edges of the cheek. Make sure all cuts have generous radiuses on the inside as you don't want to create stress concentrations. If this is a forged shaft, it must be shot peened in the machined area after this is reworked.

The difference between a 388 and a 383 is .030 inch of bore. The 388 is bored to 4.060 inch, the 383 is 4.030 inch.

Bogie

Thank you Bogie, these answers are just what I was looking for. Seeing how I now have a few more pennies to start saving, I now have my complete shopping list to go from. Thanks once again- Stan  

Best of luck.

Bogie