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383 build kits?

7K views 38 replies 11 participants last post by  Camaro R/S LT 
#1 ·
I'm seriously looking into stroking my 350 to a 383 when I get around to redoing my engine. This is a ways off, but I wanted to start my research now.

Can anyone who's familiar with 383 stroker kits recommend one. I'm looking for something mild/occasional strip. A few things I want: 6in rods, 1.6 rollers, internal balance and I want to keep my compression below 11.5:1. A kit seems like the best way to go for me and I'd rather not have to mix and match parts. I like the idea of a kit that's already done that for me.

Also, I'm going to run a tko500 with a posi rear end, any suggestions on gear ratios? i'm leaning towards 3.73 for now.
 
#2 ·
Scat has good quality Stroker kits. A kit with a Cast Series 9000 Crank, Forged I-Beam Rods & Forged Pistons would be a reliable start.
If you use 5.7" Rods you'll have a much larger Piston selection to choose fromand also keep the Piston Pin out of the Ring area.
For a Pump gas Engine you should stay around 9.5:1 Cr w/Iron Heads and 10.5:1Cr w/Aluminum Heads.

What year Block do you have?
What size Combustion Chambers do your Heads have?
You can narrow the choices down more here.
CHEVROLET SCAT Engine Components Engine Kits & Rotating Assemblies - 383 Actual Engine CID - 5.700 in. Rod Length - Forged aluminum Piston Material - Cast iron Crankshaft Material - SummitRacing.com

Rear Gear etc.. calculators:
Gear Calculator
 
#4 ·
Scat has good quality Stroker kits. A kit with a Cast Series 9000 Crank, Forged I-Beam Rods & Forged Pistons would be a reliable start.
If you use 5.7" Rods you'll have a much larger Piston selection to choose fromand also keep the Piston Pin out of the Ring area.
For a Pump gas Engine you should stay around 9.5:1 Cr w/Iron Heads and 10.5:1Cr w/Aluminum Heads.

What year Block do you have?
What size Combustion Chambers do your Heads have?
You can narrow the choices down more here.
CHEVROLET SCAT Engine Components Engine Kits & Rotating Assemblies - 383 Actual Engine CID - 5.700 in. Rod Length - Forged aluminum Piston Material - Cast iron Crankshaft Material - SummitRacing.com

Rear Gear etc.. calculators:
Gear Calculator

Thats the kind of info I'm looking for...awesome thanks!...

It's a 1976 with 75cc heads...all the internals are original.
I'm also wondering about the rework on the 5.7 rods I know i'd have to grind them down, but what kind of work is involved exactly or would it be better to just buy new 5.7 rods? money is tight :(
 
#3 ·
I agree with SS, you don't need 6" rods or 1.6 rockers, you can build a screamer with standard parts, Scat make very good stuff. I would use the Scorpion 1.5 roller rockers and a good cam "kit" (hate that word) roller or flat tappet. All depends on how fat your wallet is. You are starting out the right way though by doing lots of research prior to buying anything.
 
#7 ·
I dont think 11.5 CR is what you want.If you are getting a T.K.O. consider the 600 and make sure it has the updated insides to make the 2-3 shift faster. The 2.8 first gear and 3.7 gears will make it jump pretty good. Spend some time putting that beast on a diet ,they are heavy. If you drag race maybe get a little more rear gear and get the optional .68 O/drive instead of .82
 
#9 ·
of course check balance,and send in related parts. If you drag race,plan your gears and et before you start. The O/drive makes it "streetable". Ive run gear ratios from 2.7 -5.57,,,what are your intentions?When I was young it was fun street driving with 5.13s and a 4speed,now I use 3.50s and a 5 spd,you decide?
Steeper gears are most notice able when you launch the car.
How quick is this car going to be?
 
#10 ·
Most "kits" that you buy from say SCAT or Eagle have "stroker" rods that are already made to clear the cam, cylider wall bottoms and the pan rails. It is still a really good idea to mock the engine up and turn it over slowly to see if there are any problem areas which you can just take a die-grider to those areas of the block.

If you aren't trying to make tons of power, just say in the 430-470hp and 440-480tq range then you would do fine in buying an externally balanced rotating kit with "hyper" pistons instead of forged. I would assume that you are planning on changing the heads as well. Look for a set in the 195-200cc intake runner range: AFR, DART, Brodix are who I would recomend. If you are on a budget then the DART platinum iron heads are the greatest deal for the money IMHO. To run easily run pump gas with a pair of 64cc combustion chamber iron heads you will want to look for a piston with a 15-18cc dish. This will put the compression right in the range of 9.5-9.8:1.

IMHO your rocker ratio choice should depend on whether you going to run a flat tappet cam or a roller cam. If you plan to go cheaper with a flat tappet cam then I would suggest just going with a 1.5 rocker ratio, but if you plan to spend a bit more money (which is WELL worth it) and go with a roller cam then I would go with the 1.6 rocker ratio.

Your gear ratio really be a well thought out choice. The size of your tire, cam you plan to use, use of the vehicle, weight of the vehicle, the last gear in the transmission, and the desired cruising speed are all factors in selecting your rear gears.

The 3.73:1 gears you mentioned would work great in the TKO 600. When you calculate out the 2.87/1.89/1.28/1.00/0.64 gears of the TKO 600 with 3.73, the final drive ratio is almost identical to using a th350 with a set of 4.10:1 gears. When you calculate out the TKO 500 which has 3.27/1.98/1.34/1.00/0.68 with the 3.73 rear gears it comes out to be really close to what a th350 would be with a set of 4.56:1 gears (all done 1-3rd).

but again it all depends on what kind of use this car is going to get and what kind of cam this car is going to get. putting it all together with a set of 28" tall tires the TKO 600 and 3.73's would do great with a cam in the 220-240° @ .050 duration area, which would make for a pretty decent street car with some track use. The TKO 500 and 3.73's would do better with a cam in the 235-250° @ .050 duration area, which this motor would want a bit more compression (Iron= 10:1+ and alm 10.5:1+, which could still be tuned to run fine on pump gas) this would make for more of street/strip car with a bit less street manors. Both are still very do able for the street, you just have to decied how far you want to go with it.
 
#12 ·
I will be running this on the street as well, cruising speed at 65(to and from the strip) about 20 min one way so I do need that O/drive gear.

Right I don't want tons of power, my87Z had it right; 430-470hp and 440-480tq range and I very much want a roller cam.

I talked to a friend and he immediately recommended gears in the 5+:1 range with a 5 speed.

As for weight I'll be gutting the car, engine bay and interior trying to drop as much weight as possible; thinking about getting rid of the power steering (racing seats if budget allows.) I'm not too sure about what weighs the most that you can get rid of really, so suggestions are welcome. Power to weight is something very important for sure.

Suspension is a whole other ball field, I'm not really to that yet but I'll be looking into it.

As for tires I'm gona go with a pair of slicks at the track(not sure on the overall size yet) and then just some cheap street tires.
 
#13 · (Edited)
The problem in choosing a transmission and a rear gear is getting both ends of the equation to where they will be effective for every day use.

I might use a first gear final drive of 10:1 (also called starting line ratio) and a top gear final drive of 2.90 or numerically lower with a ~28" tire. Multiply the rear gear ratio times the first gear ratio to find the first gear number. For instance, a 3.55 rear gear times a 2.87 first gear would yield a 10.18:1 first gear final drive ratio, assuming a ~28" tire. A taller tire might require a numerically lower rear gear. A shorter tire might require a numerically higher rear gear. The same 3.55 rear gear with a 5th gear of
0.82:1 will yield a top gear final drive ratio of 2.91:1, making all gears useable in everyday driving or for drag strip use. You don't want the cruise ratio too low, numerically, if you plan to use any kind of decent cam timing. For instance, if the cam begins making power at 1600, then you might want to cruise at ~2500 to be "up on the cam" at highway cruise speed. A 2.91 final drive ratio with a ~28" tire will cruise at 72 mph at 2500. The Tremec TCET4618 5-speed fits the bill here, with a torque capacity of 600 ft/lbs and the right gear ratios.
TTC: TREMEC Transmissions
I know what you're thinking and the answer is no. You will never get out of 4th gear on a 1/4 mile drag strip unless you're building a 1,000 hp motor and mounting it in a 2,000 lb car. The average "hot" street driver will post a trap speed of ~115-120 mph in the quarter. With the above combination, you'd be at 120 mph at 4,200 rpm's in 4th gear, so like I said, you'd never get to 5th gear in the quarter mile.
 
#15 ·
If you used a 4.56 gear and built an engine that makes power to 6400 rpm and used a 28.5 tall tire...That car could go 120 mph at redline and at 2700 rpm(using .68 O/drive) would be cruising over 70 mph. That an extreme scenario in my opinion. like tech says thats an 11 second car that can cruise to the track.If it spends a lot of time on the track,then buy a trailer for race days,long walk home if something breaks
 
#36 ·
I know all about this, at first I used a well built 700r4 with it's 3.06 first gear and a set of 4.10 gears which comes out to a drive ratio of 12.55, if you compair this to a th350 and it's 2.52 first gear it would be the same as running a 4.95-5.00 rear gear with a th350, then the 700r4 has a 1.63 second gear which is about the equivilent of running a th350 (1.52 2nd) with a 4.56 rear gear.

this was all in a high 11 sec car, I enjoyed the o/d if I was driving on the highway (which was rare) but I didnt enjoy trying to make it hook. My 60ft times were too inconsistant because I had the hardest time finding that happy medium on take off. Not to mention that 1st gear felt like a "granny" gear. I have since swaped out to a th350 and now have 4.56 rear gears.
 
#16 ·
my87Z is right on the money with his suggestion of 9.5:1 to 9.8:1 static compression ratio. Here's the roller cam I might use with that SCR
Amazon.com: Crane Cams 119671 Hr-216/339-2s-12-90: Automotive

9.5:1 with this cam will produce a dynamic compression ratio of 8.399:1
9.8:1 with this cam will produce a dynamic compression ratio of 8.660:1
Either of these DCR's are easily compatible with pump gas if you build the motor with a tight squish (0.035"-0.045").

You see, what you have to understand is that you will be BRACKET RACING, so your E.T. and TRAP SPEED are unimportant. Build the car so that it's a pleasure to drive on the street and then just live with what times you post at the strip. You'll be bracketed against faster and slower cars, so it won't matter what speed and e.t. you go. The only thing that will matter is your reaction time and running consistently on your dial.
 
#17 ·
A few things I want: 6in rods, 1.6 rollers, internal balance and I want to keep my compression below 11.5:1.
Agree on keeping the CR a lot lower if this will be fed pump swill. If you're building an engine to run on race gas or E85, that's another thing altogether.

But at the target you have for power, there's no need to use race gas gas. Better to go w/around 9.5:1 CR like mentioned above that matches the cam you need to make the power you want. It's all interrelated.

By not pushing the limit on compression, you have a cushion against detonation caused by a bad tank of fuel or something causing the engine to run hotter than normal.
 
#18 ·
Thanks a lot for the info everyone. Think I'll be going with a setup that runs the 10:1 "starting line ratio" for gears/trans. I definitely want a mild/slight performance roller cam(I'm looking for power in the 1600-6000 rpm range) with 1.6 rockers on intake at least; probably 6" rods. 9.5 CR with a typical 0.035-.045 squish seems to be my ticket for what I want.

I'm not too keen on heads and I will be changing them, a suggestion for 195-200 cc intake runner range was made and I'm not sure what valve size to go with either...I'm looking into a 750 cfm carb and I know this depends on the combustion chamber/piston size too.

I have a better idea what to get with the other components in terms of a kit, but I am a little concerned about piston weight/balancing, etc. when it comes to forged and "hyper" pistons...just trying to find the right balance
 
#19 ·
Its a start. Please explain why you want 1.6:1 rockers? They have a place,just not sure where on a mild engine.I use 1.6 rockers on my engine and a fairly big(for the street) solid roller cam. before you get those rockers,the first thing you need is a good set of heads. Take flow measurements to choose camshaft and figure what CR you need to make it all work
 
#20 ·
After reading up on it and seeing that they dont make a difference unless you're REALLY racing, I see your point since I'm going for a mild setup. I guess I initially thought that with the roller cam and more pressure from the .1 increase, it would create a little extra top end power with the 1.6s.
 
#21 ·
as seen as this is a build you'll be doing down the road..
I'd see if you can come across a 1987 up block as they are roller cam ready.. and the 100.oo you'll pay for it is cheap compaired to the 800.oo+ retro fit roller cam kit to go roller cam in that 1976 block..
if moneys tight. this might be the best 100.oo you spend before you start machining the block..
If not going roller.. then forget this post..
 
#22 ·
This is a general statement.Torque is = to E.T.,the first 60' to 330' and MPH is = to HP. If you want to bracket race you should for both a street vehicle and a bracket racer a engine that is more slanted towards torque. Have I ever been beat by being MPH'ed??. Yes I surely have,but those times are rare. My averages early on racing where won in the first 60' to 330'.
 
#24 ·
Vinnie-A Honda with turbo and a small c.i. engine in a relative light wt car doesn't have a power curve the same way a bigger heavier BBC does.But both cars are relying on the torque curve.The Honda has to buzz high because the smaller engine doesn't develop any power until the later in the RPM range.And then it transitions to HP faster to create the MPH it ends up getting.

My suggestion is two fold.He dials on a E.T. for the car to bracket race and the torque is surely going to help him get to the dial or goal he has in mind for that and the torque curve that is low enough in the RPM range he'll get to use and enjoy more often driving the car on the street.Would be more effective in some street light to street light racing with the right cam/head/T/C,gear combo/tire size.
 
#25 ·
383 build

Check out this 383 Scat rotating assembly. This rotating assembly is used in a 2pc rear main seal block. It is external balanced and comes with a balancer and flexplate. Scat Engine Rotating Assemblies 1-90355BE - SummitRacing.com. This assembly is for using 64cc chambered heads for a compression ratio of 9.7. Here is a 383 Scat rotating assembly for a 2pc rear main seal block. It is also external balanced and comes with a balancer and flexplate. SB Chevy 383 Scat Rotating Assembly Kit, 3.750 Stroke 5.700 Rods 9.8:1 Hypereutectic Keith Black Dish Pistons - 383 Kits with 5.7' Rods - 9000 Series Kits - Small Block Chevy - Scat Rotating Assembly kits - Rotating Assemblies | CNC Motorsports | Car. This kit also uses 64cc chambered heads for 9.8 compression ratio. Since you are going to have a stick shift transmission I also looked at this 383 Scat rotating assembly. It has 6" rods and Keith Black Hypereutectic 18cc Dish Pistons. This is an internal balanced assembly by CNC Motorsports. The balancer and flexplate (which is not needed) does not come with an internal balanced kit. It also uses 64cc chambered heads for a 9.8 compression ratio. SB Chevy 383 Scat Rotating Assembly Kit, 3.750 Stroke 6.000 Rods 9.8:1 Hypereutectic Keith Black Dish Pistons - 383 Kits with 6.0' Rods - 9000 Series Kits - Small Block Chevy - Scat Rotating Assembly kits - Rotating Assemblies | CNC Motorsports | Car.
 
#27 ·
if heads are already sourced then use what gives you the compression you need/want..
if heads are not already on hand and need to be bought..
flat top 99% of the time is the better choice.. and use the heads chamber size to get the compression you want... no always possable ..but mosttimes you're not reinventing the wheel.. and the parts needed are out there..

of cource I'm talking n/a, boosted is a totally different animal
 
#30 · (Edited)
Yeah this must be at the flywheel, but they don't mention the rods, rockers, pistons, or crank. It got me thinking about 5.7 rods with 1.5 rockers.
So 2 question:

What kind of difference is there between 1.5 roller rockers and flat-tappet?

AND

I'm leaning towards Comp Cams XR288HR. One thing I don't like about this cam is that the RPM Range starts at 2500.
I want something closer to 1600-2000. Is there a better cam?
 
#32 ·
With newer flat tappet cams they already have aggressive ramp rates for the material and the design of the lobe to lifter geometry. Using a 1.6 rocker increases this ramp rate, meaning that it will cause the valve to open farther and then close in the same amount of time. This increases stress on the cam lobes and lifters. If you are just talking about using a roller rocker on a flat tappet set up, you can do it. In this case since you didn't spend a bunch of money on the rest of the valvetrain I don't see a big need to spend a bunch of money on the rockers.

As for the cam you are talking about, if the cam card says 2500-whatever, this is just a broad-generalized guesstimate made by the manufacturer. You also have to understand that these guesstimations are made based on an engine of 350 cubic inches. You are planning on a 383, those extra 33 cubes eat up some of the range on the cam (the larger the displacement, the more duration is needed to produce the same effect). So as a general rule of thumb you can take about 500rpm off the guesstimated ranges. If the cam card says 2500-6000 then it will be closer to 2000-5500.

I didn't look into the cam specs of the cam you are looking at but I have built and driven a good few 383s, and for different uses. What I have figured out with the experience is that street 383s like around 222-232 degrees of duration at .050 (keeping in mind 9.5:1CR, mild heads, dual plane intake)
 
#33 ·
So its been a while but I'm still searching...looking for some 190cc heads with 76cc combustion chamber bc i want to run flat top pistons...however I can only find 76cc combustion chambers on heads that are maybe 170cc or lower?? Do heads exist that are 190cc with 76cc comb. chamb.? and where are they?
 
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