I have a delima and need some opinions. I just got done doing a Hot Cam and porting my heads and took it out and spun a bearing. Now I need a bottom end. I have stock ported LT1 heads that flow 255 CFM . I have lt4 Hot Cam 218/228 525 Max lift. I have the SLp shorties (California thing)I can have my engine rebuilt to a 355 for about a 1000.00 That would be regrinding the crank, Using old rods, new Pistons,Bearings, Machine work and assembly from a reputive builder with a warranty. Speed-o-motive will build me a 383 for about 1500.00. Cast everything,machine work assembly. No warranty. I can also buy a used 40,000 mile Lt1 out of a f body for 300.00. What would you all do and why ?

 

383. More torque is a good thing. It wouldn't have a warranty but you know it's an all new rotating assembly. If you build the 355 then you'll have used parts that could fail soon. They may never fail, but for the price I would say go with new. If you make it a 355 and it fails 13 months later you're up a creek. If you make a 383 it probably won't fail 13 months later, but if it does you're no worse off than you would be otherwise.

Any freshly built motor should easily last a year, so the warranty isn't an issue. Now if it was a 3 or 4 year warranty then it might be worth considering.

 

383

 

383 gets my vote, it's not much more money to have everything done right. insist on bearing clearances and ring end gap sheets. this is the most common screw up on a rebuild. sloppy clearances will end a new engines life rather quickly when you spin it up. also ARP main studs are a great idea, espessially with the extra stroke. another thing to consider is a scat 9000 crank for $200, eagle SIR rods for $200, $80 to resize them for tight main clearances. $250 for pistons, speed pros are probably the best forged cheapies, wiseco also would be a heavy contender as they have a 6" rod 383 piston with rings for $400ish. as long as the parts are assembled correctly and attention is paid to doing it you'll be loving life. the ONLY reason i don't have a 383 is becuase i thought i was doing a TPI motor & would have more torque than i needed anyway. then this dang miniram came up really cheap in the newspaper...oh wel :lol:

 

383 :cheers:

 

406. :yesnod:

 

Pretty good advice from gtsyellow........ :seeya

 

383

 

Either way you go, I'd pop for forged pistons. :yesnod:

I've got a 355, I think its more than enough for a great price. I wouldn't go 383(actually I'd go 406) unless I had $8K to put down to make EVERYTHING work right.

 

i would have said 406 too but it wasnt an option to pick from :D :cheers:

 

I have a spare 4-bolt main short block lying around and I'm starting to look into my options for rebuilding it as well. I figure a 383 would be the best route to take since AFAIK there are no necessary mods require for the block itself. I can throw in the updated rotating assembly and basically swap the short block in under my top end.

I'm curious though. What exactly is required to move up to a 406? a 427? Are we talking major $urgery or just a couple of small clearance mods for the rods?

 

your talking a 400 block and retro fit lifters, drilling steam holes, it's not too bad but it's a little more money. 383's on the other hand are only a couple hundred more than a 355 & you can use your existing block.

 

Well, the question of the day is....how fast you wanna spin it? You can get away with a 383 that will live at 7k for a while....and I don't mean a long while. At 7k rpm on a 383, you're pushing the engine criteria that endurance racing teams use when designing engine strokes vs. rpms (mean piston speed...critical measure of how long an engine should last). You also MIGHT be able to get away with a 6" rod on a 383 for a long-lasting motor, but you first need to ask if the wrist pin is encroaching on the oil ring land. If it is, the oil ring will wear out faster, i.e. less time to an engine rebuild. Also, the killer on the 383 is the 1.6:1 rod/stroke ratio. You had better have friggin STRONG rods if you want to run that 383 to 7k a fair bit, otherwise, with an R/S ratio like that, you'll tear your rods up.

In other words, if you're looking for a low-end and midrange motor (and with heads that flow that low, that what you're stuck with), I'd go 383. If you find some high-flowing heads and want a high-revving V8, go with the 355.

 

yep...on a hyd. roller motor you redline at 6500 your fine but if you want a solid rpm happy engine the 355 would live longer. one of the worst things about stock blocks and high rpms is in the mains..they can walk & there go your bearings.

 

Thanks for all the replys. One quick question is a well built 383 any less reliable than a 350/355.

 

With my heads and cam setup I think that 6300-6500 is tops. I am also leaving in the hydraulic lifters so I think that 7000 is not gonna be an option now.

 

So my basic impression here is that utilizing hydraulic lifters puts a natural limit on the top speed of the rotating assembly, by design keeping it within the safe operating limits of a suitably built 383. I wouldn't think that 6500 rpm would be so much as to really put a bind on a properly built stroker motor. Is the safety margin really that super critical for building a motor you'd expect to last at least 50K miles under 'proper' driving conditions? :D

 

your completely right, a 6500rpm 383 will last a long time. hyd. roller lifters just start showing there weight between 6500 and 7000rpm. how much oil psi you have & even things like spring pressure help determine where your engine floats. with good quality assembly and quality components a 383 will live for many years provided you don't detonate it. here's a shopping list of things that are a must for a budget minded 383 builder

1. make sure your engine builder knows how to measure main bearing clearance down to the thousandth and also ring end gap. john lingenfelter has a book on small block chevys that lists where the numbers should fall, most high end engine builders agree with what he says. you can let your top end ring gap go a little looser than he suggests if your a real RPM happy kind of guy, have a habbit of detonating motors or plan on using nitrous oxide. {has anyone guessed my top ring gap is slightly loose? :lol: }

2. don't break the bank on parts, just buy good stuff from good places. scat has a 9000 series 383 crank that can be had on the net for $200, eagle has a SIR rod for $200 and i think i mentioned the speed pro and wiseco forged pistons, both good units & the wisecos come with plasma moly rings which brings up another point. buy moly rings !! they seat nice and are stronger. wiseco has a off the shelf piston made for a 6" rod and a floating pin {i think} this would create a nice light setup & mantain a great rod ratio.

3. use ARP studs on the mains and there bolts on the heads, seriously, these spendy bolts are worth the money. melling makes a nice oil pump that's real easy to change pressure on. the springs pop in and out to change pressure settings. i used a pink spring and have 70psi at full temp by 2000rpm. the guage pegs when i redline the motor.


[Modified by gtsyellow, 3:36 AM 12/12/2002]

 

The impression I got was that a 383 will require alot more additional expenses though- like different injectors, computer reprogramming, etc. while the 355 would not. Anyone know?...

 

383, no question. :yesnod: :cheers: