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What is your 383?
Mine.....
Block is factory 1976 2 bolt L-48. 010 casting. I would like to build my first 383. Just a little power. Wont be pounding on it.
I'm looking for someone who has built a 383 that can vouch for
A) Good flat tops that with 64cc heads will achieve 10.1
or
B) Complete rotating kit with same requirements
Will be using aluminum heads
Personally I prefer a complete rotating assembly. Expecting 350 hp
I ask because I want to avoid others mistakes.....cam next. TIA..
Flat tops with 4 valve reliefs, zero decked block, 64cc heads is 10.1:1 on a stock stroke 350. Back to square one, that's not possible with longer stroke/more cubes.
My old guru told me that a small chamber with reverse dome is a better combo than flat tops with larger chamber, it breathes better.
While some have had good luck with buying complete kits, I always have all my machine work, including balance, handled locally. If an online kit is off - and most of the time you don't find that out until the engine is together and/or running - it'll cost more time and cash than it's worth.
383's have a dished piston on the street. You need to make sure the rods are cam clearanced, sometimes the oil pan rail/side web needs to be relieved depending on the rod you use. If using a roller cam, it will need to be a small base circle....(.990)......this is just three things.....
You need to do a TON of research if you building your first one.
Contact Eagle for a rotating assembly and take it over to a competent machine shop to double check everything and block prep. Pick a dual pattern street cam pattern and a good set of heads and you'll be at the 350 horse range easily and be reliable for the long haul .
Mine has a SCAT crank, so no machining reliefs on the block webbing. Forged rods and pistons, dished for pump gas. It is a bit clattery at startup due to the forged pistons but you get used to it. Vortech steel heads air gap intake manifolf, Fitech fuel injection. Cam specs are 224 / 234, about .532 lift. Very choppy idle, but smooths out with rpm. Make sure you get the right damper and flexplate / flywheel for the crank. GM had a nasty habit of changing things around a lot which can make timing near impossible. Mild really, around 400HP, 440LBF.
If you purchase I beam rods you may need to do less block and pan relieving/clearance work than if you go with H beam rods.
For what you are building I beams will work fine.
You can certainly save money staying with a cast crank.
Again for what you are building you don’t need to spend the money on a forged crank.
Your 2 bolt block will also work fine.
For about $300.00 you can get your pistons coated which will eliminate all the cold start piston clatter.
I built a couple big blocks years ago, but after seeing what it takes to build a good stroker, I’m glad I let a professional build this one for me.
Things have really changed over the years.
Scat cast crank and some of their ProComp rods, you shouldn't need to touch the block. My experience has been that Scat is closer to spot-on with journal dimensions, I've had to have a couple of Eagle cranks tweaked at the shop to get 'em right-on.
Good hyper pistons will be quieter than forged and unless you're planning to spray it hard, they'll be fine.
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YOu can build up your 350 and get your power pretty easily, its the torque at low RPM that makes the 383 so popular. Building a HIPO 350 will be a lot cheaper as there is less machining involved. You can reuse your crank and connecting rods if they are good quality. If you have the block cleaned and honed then have the shop supply the pistons and rods, cam and lifters and a good intake and aluminum heads, maybe at a discount, you can have them balance them. Then its just measuring and reassembly. No messing with clearancing and having to buy specific 383 stroker parts. If you want the torque off idle, then you may need the 383. It will be at least $2000 cheaper if you are not having to clearance the block and buy a new crank
My 2 cents:
Scat crank with 6" Scat stroker rods - 6" rods required so you can have it "internally balanced" without the use of heavy metal slugs. Improves reliability and cheaper to balance this way. External balance means extra cost special damper and special flywheel required along with somewhat less reliability. I prefer to go the other way.
Pistons will need to have a dish of some kind to work with 64cc heads OR you can use larger combustion chambers in the heads with flat top pistons. Be sure to get pistons that are set up for 6" rods if you go that direction. Forged pistons are expensive so you can either spend a lot of cash or save a lot of cash and be extra careful with sizing your ring gaps. Need to be conservative on the dynamic compression ratio especially with the hypereutectic cast pistons if you go that way. Hypers are not very tolerant of detonation.
Add an ARP 2 bolt main cap stud kit and have your machinist align hone the saddles. Gives you a stronger bottom end.
Your machine shop may be able to do the block clearancing for you. It is not expensive. My guy actually has a template for it.
I have a 383 at the machine shop right now being internally balanced and block clearanced. Scored some great deals so I deviated from the above advice a little bit....Forged Mahle flat tops with 72cc Dart heads, Scat 5.7" stroker rods, Howards solid flat tappet with EDM lifters. Should be a great street stroker motor.
Only buy internally balanced rotating kits. That way in the future you can use any damper , flex plate, or flywheel. I had bad luck with Keith Black Hypereutectic pistons. I had a beautiful engine build and the first time I went out and really tested it the pistons failed. I was pissed so I called Keith Black because they were locally manufactured. I was informed that NO WARRANTY because I had exceeded the piston feet per minute. They knew that they fail because of the high silicon properties. They just don't tell you that when you buy them. That motor has sat in the corner of my garage ever since. Totally forged rods and crank and smeared pistons in the bore.
As your stroke length goes up the piston speed in feet per minute limits go down in RPM
Only buy internally balanced rotating kits. That way in the future you can use any damper , flex plate, or flywheel. I had bad luck with Keith Black Hypereutectic pistons. I had a beautiful engine build and the first time I went out and really tested it the pistons failed. I was pissed so I called Keith Black because they were locally manufactured. I was informed that NO WARRANTY because I had exceeded the piston feet per minute. They knew that they fail because of the high silicon properties. They just don't tell you that when you buy them. That motor has sat in the corner of my garage ever since. Totally forged rods and crank and smeared pistons in the bore.
As your stroke length goes up the piston speed in feet per minute limits go down in RPM
That is terrible, I have had mixed reviews on Hypereutectic pistons. Now i go forged only.
Forged pistons are the safe bet.
Research all the brand names of any parts included in any kit and the materials they are made from.
If you have questions, ask your builder what they recommend, use and trust.
Overall the additional cost of using better parts is cheap insurance compared to rebuilding it right with quality parts the second time.
That is terrible, I have had mixed reviews on Hypereutectic pistons. Now i go forged only.
Hypereutectic pistons have a place in the engine world. Because of lower expansion you can make a stock rebuild have closer piston to cylinder wall tolerances, higher efficiency, and less ring blow by as the engine ages. So they are better than cast pressed pin pistons if you have a sub 5500-6000 rpm motor.
Hypereutectic pistons have a place in the engine world. Because of lower expansion you can make a stock rebuild have closer piston to cylinder wall tolerances, higher efficiency, and less ring blow by as the engine ages. So they are better than cast pressed pin pistons if you have a sub 5500-6000 rpm motor.
They have a place in mass produced factory engines to meet warranty and emission requirements. No place in a mild to wild performance build.
Every ZZ crate engine ever built has hypers in it........I have hypers in my own 406......thousands of circle track racers use hypers with zero issue. The rings must be gapped accordingly and the piston to wall must be adjusted to accommodate. 4.030 bore uses about .0025 piston to wall as opposed to .004-.005 for forged. Excessive piston to wall on a hyper will make noise and beat up and/or crack skirts.
I have never had a problem with KB pistons.......although I am very careful about what application gets them....N/A only and under 6000 rpm, for a max power level of 500.
I lean on my 406 pretty good......max RPM is 6000 and I shift at 5700......it will be getting some Wiseco Pro-Tru pistons here soon as my direction is changing......I may want to put a 150 shot on it.
The C5 and C6 Z06 Corvette's have hypers in them FYI.
383 pistons are dished and are available in a "D" dish for proper quench......I do not recommend anything but these "D" dish style pieces.
This KB Hyper was in my last 383 motor. As you can clearly see it is broke. Also, the pin hole is much too high up on the piston for my liking and IMO contributed to the piston slap you could hear at cold start which annoyed me to no end. The piston has little stability in the cylinder with the pin so high up going into the ring groove using a 6" rod.
Anyway, this is not what broke the piston I don't believe. The real reason is more from a detonation issue I had at the track that night when I got a little too jiggy with the timing on the laptop and not enough octane to help with that. OK, that was my fault, but because of this, I would never consider using a hyper piston again in any of my motors. In retrospect,, I have never used a hyper on any other build and took a chance. I shouldn't have done that on both accounts, that piston and more timing. That's OK, this current 383 is solid, all forged and runs like the wind...for a CF motor.
Also, I didn't even know the piston was broken until I tore the engine down a few days later. It was still intact and no damage to my Dart heads which was amazing, but didn't help the block much since I had to get a new one because it was already .040 over and didn't want to take a chance at .060 and have it a heater. SBC power. LOL
Wow! That looks like the old design where the rod pin is in the ring lands making for an unstable design at higher rpm. I believe they have redesigned those pistons. Still, that is ridiculous!
This KB Hyper was in my last 383 motor. As you can clearly see it is broke. Also, the pin hole is much too high up on the piston for my liking and IMO contributed to the piston slap you could hear at cold start which annoyed me to no end. The piston has little stability in the cylinder with the pin so high up going into the ring groove using a 6" rod.
Anyway, this is not what broke the piston I don't believe. The real reason is more from a detonation issue I had at the track that night when I got a little too jiggy with the timing on the laptop and not enough octane to help with that. OK, that was my fault, but because of this, I would never consider using a hyper piston again in any of my motors. In retrospect,, I have never used a hyper on any other build and took a chance. I shouldn't have done that on both accounts, that piston and more timing. That's OK, this current 383 is solid, all forged and runs like the wind...for a CF motor.
Also, I didn't even know the piston was broken until I tore the engine down a few days later. It was still intact and no damage to my Dart heads which was amazing, but didn't help the block much since I had to get a new one because it was already .040 over and didn't want to take a chance at .060 and have it a heater. SBC power. LOL
That looks like a 1.0” C/D piston.....how long were the damn rods?
No matter what you do to this piston, the pin is in the ring land.....
Did it have an oil rail support?
That looks like a 1.0” C/D piston.....how long were the damn rods?
No matter what you do to this piston, the pin is in the ring land.....
Did it have an oil rail support?
Jebby
Yeah, short skirt piston, don't remember what the dimensions are anymore. The rods where 6" in a .040 over block. Yep, I was hoping for the best back then and learned a valuable lesson. No other support than just the oil ring normal config. I should have NEVER went with that piston set for sure. I actually had two pistons come apart that night and drove it home. This was the worst one and now sits on my desk as a reminder.
The pistons in my current motor are forged Wiseco Pro-Tru pistons and I love em so far and they are taking a beatin' at times. 6" rods on the Wiseco's as well and rated to 750. That broke piston is around 12 years old, maybe a little more.
Wow! That looks like the old design where the rod pin is in the ring lands making for an unstable design at higher rpm. I believe they have redesigned those pistons. Still, that is ridiculous!
All stroker 6, 6.125 and 6.250 rod length have the piston pin way up in the behind the oil ring area. Especially in the 3.875, 4.00 4.125 SBC strokes. I have a 396 ci in my vette and my racing 434 SBC. I don't think any of them are unstable. They used to use pin buttons behind the rings.
In retrospect I was dumb to spend $4000 many years ago on a super crank 4 inch when I could have the 4.125 and built what most circle trackers use. instead of a wimpy 434 CI I would have had a 447. Lots more TQ I just already had a set of 10 custom pistons from Wisco for 6 inch rod 4.155 bore
04-07-2021, 04:08 AM
383 Build question
This was the worst one and now sits on my desk as a reminder. 
I just already had a set of 10 custom pistons from Wisco for 6 inch rod 4.155 bore