I'm about to build a 383, and I need to know what do I need to do about a flywheel or harmonic balancer?

Is there a way that I could keep my stock componets?

This is the setup........

383 crank, around a 230/236XE cam(small circle base), stock flat top pistons, home ported & polished heads, long tube headers, and about a 2000rpm stall converter.

Any suggestions?

D Moss

 

Is the crank externally or internally balanced?

 

What do you mean by "stock flat top pistons"? The stock '350' pistons have too much compression height to work with the longer stroke unless you use shorter '400' rods. So while you're getting a new crank and rods, you may as well pony up for new pistons sized for the job - less comp. ht. for a longer rod and sized for the larger (by 0.030") cylinder.

You don't mention what compression you are aiming for or how much power you expect to make. You will need to figure that out to determine if cast or forged parts are appropriate.

 

Well if you ask me then I will tell you that stock 400 rods which are 5.5 are a waste of time and if you plan to use them then you'de better crank that rev limiter down to about 5k. Also the hb depends on whether you are going to use just a stock 400 crank with beaRING spacers or are you going to get a good 383 crank from lunati or some place like that. This is because the 400 crank is externally balanced however the aftermarket crank could be internally balanced. If it is a internally balanced crank and you plan to not turn too many rpms then I would say yes you could use your stock hb but if you are using a 400 crank then no because as I said it is externally balanced. I could be totally blowing smoke up your a** but I am very sure that I am right.

 

Also it is dido on the flywheel question because it to is balanced on the 400 crank.

 

Lunati is way overkill for the average sub-600 hp 383. No question they have a high quality product, but for the cost of one of their "cheap" cranks you could get forged pistons, rods and crank from someone like SCAT. Heck, if you plan on staying below 450 hp and you don't see boost or juice in your future, you don't even really need forged pieces. For what you save on cast over forged you could spend on a good quality balancer or some professional headwork. That would be money well spent.

 

Were going to be around 400 hp, so we figured cast pieces will work.

We're going to be looking for around 10:1 or 11:1 compression on this engine.

We haven't purchased a crank yet, so I can get either externaly or internaly balanced, which ever one I need. I was wanting to use the stock balancer and flywheel if possible, to save $.

All info is appreciated!

Thanks yall,

David Moss

 

scat = trash...... do you know what scat is short for? scatter. thats why they are so cheap.(no offense zwild) You are way better off going with a stock 400 crank. + the money you save buy not goin with an aftermarket crank you can buy a good externally balanced flywheel and harmonic balancer.

 

Young'un,

You say "SCAT = Trash" and their product is cheap. It's called inexpensive and it's what happens when economies of scale come into play. SCAT has been around for 35 years (probably older than you) and sells to a lot of respected engine builders and race teams. With that kind of longivity (sp?) (which is about as long as Lunati has been selling cranks btw) and that kind of clientelle, I'd say they must be doing something right. Don't mean to sound like an ad for SCAT, but I hate when reps are trashed over misinformation.

Not withstanding the trouble of finding a stock 400 crank (most 400 motors have had their cranks scavenged long ago), if I was going to use a 20 year old crank (i.e., a stock 400 crank), I'd want to have it thoroughly checked and tested. Then you've still got to get the mains trimmed and buy a new externally-balanced balancer and flywheel. For the same money or less, you could get a new internally-balanced cast crank. The internally-balanced crank will rev easier and make more horsepower, than using the heavy externally-balanced balancer and flywheel.

BTW, several years ago, CHP built a 406 using a cast SCAT crank. If I remember correctly, that puppy made 450 hp and 500 lbs/ft. Sounds like their stuff is plenty tough,... especially for David's planned 400 hp.

David,

Are you really planning on only 400 hp? If so, I'd question why you'd even want to build a 383, you could get there quite easily with your 355. But, I couldn't help noticing in your sig that you're planning on juicing the 355. Will the 383 be normally-aspirated or will it be a bottle-fed baby? A 150-shot on top of 400 hp should have you seriously considering leaving stock parts behind and looking at the forged pieces.

 

I agree with ZWILD1, Young'un. If you have had specific problems yourself with Scat stuff, please expound. Our experience has been just the opposite. I was very impressed with the design, machinework, overall quality, and reasonable price of their 9000 cast stroker cranks. Sure they are made in China, but the quality is there. FWIW, some US machined forged cranks (and rods too, I believe) are made from forgings produced outside the US, including China.

FWIW, Scat has a new program for building custom forged cranks to your dimensions for a couple of hundred over their standard stroke/bearing size, etc. Now you can run an odd stroke to make a class and smaller (or larger) bearing sizes without having to modify a new crank and maybe screw up the heat treating, etc.

dmoss, 96Z's 383, which made 433 rwhp and 420 rwtq(oops, originally typed 320) used the 9000, and was basically an internally balanced budget engine with good breathing. You might ask him about it.

 

I have heard nothing but good about scat, I planned on using a scat for my 383 build-up until I came accross this used eagle cast steel crank. I used 5.7 rods from eagle (I beam) and a 18cc dish piston. I took the whole shebang to the machine shop since I didnt really know the history of the crank and had them balnce the stuff to where I oculd use my stock flexplate and balancer. They had to add only 1 peice of malory to balance it so cost was very minimal.
About 10 years ago me and a friend built a 383 using a GM 400 crank, we wanted it internally balanced and had to shop around for a while to find someone that was willing to do it, after having the crank tested for cracks, resized journals and hardened they moved on to lightening and balancing, the total for the balancing and other crank machine work using 5.7 inch pink rods and a lightwieght TRW forged piston was 1200$. not including parts costs!!!!
We could have bought a forged crank and been better off.

 

ZWILD

I'm shooting for a for sure 400 hp. You're right about the 355, I just got back from the DYNO, and I'm all over 400hp with my 355. MAX 339rwhp/@5400rpms, and 352rwtq@4200rpms-4800rpms (tq line was flat from 4200rpms to 4800rpms). Torque curve never went under 310 ft lbs of torque from 2000rpms all the way up to 5500.
HP line was steady all the way up to 5400 rpms where they quit, it was climbing.

I was going to shoot this engine, but I don't have a forged crank, only forged pistons, so I decided not to.
383 is a friends engine I have in the shop that we're getting ready to build, and I want his faster than mine with the 383.(that sounded terrible didn't it?) His will be N/A motor.

I just needed to know what crank to buy to keep our stock balancer and flywheel, or his he going to have to buy these items either way?

Oh yeah, I was going to purchase an Eagle crank, but looks like the scat crank has the popularity here.

Thanks yall,

David Moss

 

you can shot a 150 shot easily on a stock crank and forged pistons.. I sprayed 150 on my stock interal engine all last season with no signs of dammaged what so ever. I would agree to go with the scat 9000 as i have only heard good thigs about them and i will be running one of there cranks next year i hope.

 

I don't think it matters if you choose Eagle or Scat, both have solid reps. You might even check out GMPP, their parts are generally reasonably priced. If you use an internally-balanced crank and, your balancer and flywheel are made for an internally-balanced crank, I can't see a problem reusing them. If they were made for an externally-balanced crank, it would probably be cheaper getting a new crank, balancer and flywheel than to get a new crank adapted for the old parts. Adding 3 or 4 pieces of mallory to a crank would buy you a new balancer and flywheel. Given the choice, I'd rather have all-new parts than a mix of old and new.

Scat is on my short-list for some of the pieces I'll need for a motor I plan to start on this spring,... how does a 3.927" stroke in a 4.160" bore sound (I plan on using Dart's raised-deck 'Little M' block)?

 

lt1camaroman93

I think you can spray 150 on stock internal parts, but I don't think that it is a good idea to spray 150 on stock internal parts that is already seeing 400 hp.

I think that it is too much, but if it isn't, I'll spray soon!

ZWILD

If I'm correct, we have externaly balanced cranks now, so if I purchase an externaly balanced 383 crankshaft, I can use my stock parts. Is that correct?

Thanks yall

David Moss