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                      Small Block Chevy 
                   Stroker 383 Cu. In. Motor

 

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All photos of the car painted white were taken when the car had a SBC motor.  From 1993 until 1999, the motor was a 383 Cu. In., having a .030" overbore, 350 Block with the 400 Crank. This 13.5:1 CR motor, built by me, produced 560 horsepower and propelled the 2960 lbs car (with driver) to a best time of 10.13 sec @133 MPH on racing gas, VP-C12 or Sunoco 108.  I know there are quicker SBC out there, but I am happy with what I did with this one!

This motor had KB Hyperutetic Pistons (see Lesson #7) with a .100" dome, and Chevy cast crank.  The heads were Dart II, that I ported in my back yard, by hand (never again, I'll pay for it next time).  The porting job came out very good, and picked up the car significantly.  I did not use a flow bench and had no templates to make sure everything was the same.  The Exhaust side was polished to a fine shine, and every thing was very smooth.  The Intake side was port matched to the intake manifold.  I only polished about 1" down on the intake side of the head .  The heads were sent back to Dart for new seats and guides, and new springs were installed.  A mild .600/.600 lift with 304 duration @ .050" Roller Cam and Kit from Erson was installed to make it go.  The fuel system was a BG 280 pump with Holley Regulator turned around backwards to act as a by-pass regulator in the return system.  This fed a BG 825 CFM carb, or a Stage IV Divenchi reworked Holley 750 (they claimed 925 CFM) double-pumper.  Both carbs. turned in the same times (10.13 sec. ET's).  The fuel system will pump one gallon of gas to an open container in 12-13 seconds. 

The key ingredient to a good 383 Stroker is the block preparation.  This is the part that people do not tell before you start.  Especially if you decide to go with other than the stock 400 rods.  The best setup, according to the engineers, is to use 6" stroker rods.  I used 5.7" normal length 350 rods (made by Crower with good ARP bolts).  This turned out to be the most labor intensive method to arrive at 383.   Using the stock length rods is not so much of a problem as not using any length stroker rods.  The stroker rods do not require any trimming to make them clear the CAM and the pan rails of the block because the rod bolts enter from the bottom and nothing comes out of the top.  (Lesson #1:)  Always use stroker rods to make a 383.  If the stock type (5.7") rods are used, you must trim the top of the rod bolt and some of the rod shoulder to make it clear the CAM on rods #2 and #6.  To balance the engine, I did all of mine the same.  You must provide at least 0.040" clearance between the cam and the rod bolt top, at the top of the rod travel on # 2 and #6.  If this is not done correct, the motor will not turn over when the cam is installed.  You are also limited to the amount of lift in a stock configuration cam, about 0.645" lift is all you can get.  To solve this problem, (Lesson #2:)  use a Reduced Base Circle Cam.  While we are talking cams, (Lesson #3:) use the best push rods you can afford, with a Roller Cam of course, and make sure the length of those pushrods is correct for the required valve train geometry.  You are giving away a horsepower, valve train stability and RPM, if you do not have the correct length pushrods.  (Lesson #4:) Lash Caps can help here, sometimes.  I purchased sets of +.100"; +.150"; +.200" and +.250" pushrods in order to run three different cams.  Lash Caps are much cheaper, and will work, in some cases, for correcting the geometry.   Try running different Rocker Ratios.  Try stock 1.5:1 ratio rockers and 1.6:1 ratio rockers to see which "Your Motor" prefers.  Try running 1.5 on the intake and 1.6 on the exhaust.  Only your motor will tell you what is best.  I did better with 1.5 all around, but all motors don't respond the same.  Be very careful when purchasing the 1.6 ratio roller rockers.  Make sure they will clear the spring retainers.  I had to cut clearance in my 1.6 Crane Roller Rockers.  They never broke in over 200 runs and now another racer is using them, with no trouble.  I am told that the Harland Sharp Roller Rockers will clear almost any retainer.  I am partial to Crane valve train components, made in Daytona Beach, Florida, my hometown.  See the October 2002 issue of CHEVY HIGH PERFORMANCE Mag. for a very good article on Push Rod selection and push rod length checking tools.  There is another great article on a new Melling Oil Pump, for SBC and BBC, that solves the loss of pickup tube and screen problem that we have all experienced (unless you weld the pickup tube to the oil pump as most of us have learned to do). 

Back to Block preps.  (Lesson #5:)  The block must be given sufficient clearance at the bottom of each cylinder bore to clear the counterweights of the 400 crank and the bottom of the rods must clear the pan rails.  The pan rails must be ground down.  This is the type information that people don't tell you when you start a project like this.  This is even more critical with 6.0" rods.  Don't worry, there is enough meat in the cylinder bores and the block to handle it.  (Lesson #6:)  Make sure you leave everything very smooth.  These are ideal spots for cracks to start if the block is not properly prepared. 

When you assemble your engine, measure everything and write it down.  Be prepared to assemble and disassemble the motor more than once.  Use a good torque wrench that has been checked for accuracy.  Stay on the tight side of  tolerances that are known to work for racing engines.  There are a lot of books that will tell you what is correct for your motor.  I will not give what I used, except this one tip:  Use the recommended ring gap for the KB Hyperutetic Pistons.  (Lesson #7:) Don't listen to the old people that say your gap is too big.  The top ring on these pistons (Hyperutetic only) must be large to allow for extra expansion.  This top ring rides above the water jacket on a SBC and does not get the cooling that the 2nd ring gets.  Therefore it must be able to expand more (more gap).  There are warnings all over the box that the pistons arrive in, and in the paperwork.  Read and follow the instructions!   Get the clearances correct.  This is the way you get them to last for more than 250-300 runs, and make max. power. 

(Last Lesson, #8:)  Use good sealants on the head bolts (I recommend Loctite PST, comes in small, expensive, tubes).  Just a little on the threads of each head bolt will stop any water that may want to leak up those threads.  The same is true for the screw-in rocker arm studs.  Use PST on all of the screw-in rocker studs.  Then you won't have to find the source of that "milky looking stuff" inside the valve covers.

I could go on, but I will stop here.  I could write about my adventures with Alky on my SBC 383.  The initial investment is high and you need help at the track.  When you come home there is maintenance to do before putting the car away for a week  Think twice about an Alky setup.  I think the people that improve a lot when switching to Alky have not extracted the max. from their gas setups.  I did not go any quicker with Alky, but I must admit, the car was super consistent and I had some engine problems that probably would have let the car gain a few tenths.  It is an expensive initial investment, and it is maintenance intensive with a steep learning curve.  I accumulated a lot of fuel injection information during the 9 months I played around with Alky.  The correct information for your particular combination may be very hard to come by.  You must keep very good records and be able to go back to some combination that worked (Baseline).  Always work from this baseline to make changes.  Only make one change at a time!  Call and talk to your vendor or other fuel injection experts when you can. 

I am thinking about a similar page on my 540 CID Big Block that has been running in the car for the past six years.  The first overhaul was completed in March 2002, and the rings and bearings were replaced after 270 runs.  They looked almost as good as the day they went in.   That may be the subject of my next story.  In August 2004, the 2nd overhaul was completed.  The engine is still doing well and has over 80 passes on the most recent overhaul.  Best to date is 5.21 @ 143 MPH, before the first overhaul.  The best since 2nd overhaul, 9.26 @ 145.MPH.  Weight with BBC, 2940 lbs. with driver.  
The engine is now a 555 BBC, and is in the process of being rebuilt.  We are trying to get into the 8 second range. (6/6/06)

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