here is the answers to your questions taken from the 2016 rulebook
Carb or injection (2bbl to 4 bbl, increase TB size)
CARBURETOR
Must be correct year, make, and model specified for car’s engine;
fuel or air bleed passages may be resized. Drilling idle holes in
primary throttle blades permitted. Other modifications prohibited.
Sandblasting, grinding, flash removal, dry film coating, or any
other modification to carburetors prohibited. Replacement
carburetors permitted provided they are same model, type,
throttle bore, and venturi size. Computer carburetors use latest
model non-computer carb for engine application.
FUEL INJECTION
Fuel injection must retain OEM throttle body(s), plenum, and
manifold. If OEM throttle body(s) was equipped with electronic
throttle control (i.e., drive by wire), the throttle body(s) may be
adapted to mechanical throttle linkage if an aftermarket OEMtype
electronic-fuel-injection system is used. Larger fuel injectors
permitted, provided no modification or redrilling of manifolds is
performed. Electronic fuel injection must be closed, OEM-type
system; i.e., may monitor only engine functions. Monitoring of
vehicle performance criteria, wheel speed, driveshaft speed,
vehicle acceleration, etc. by fuel-injection system prohibited. All
aftermarket OEM-type electronic fuel injection must be NHRAaccepted.
A current list of NHRA-accepted electronic-fuelinjection
systems is available on NHRARacer.com. Open-loop
systems permitted on production vehicles as equipped with OEM
electronic fuel injection.
Intake
INTAKE MANIFOLD
Must retain the unaltered stock manifold, consistent with year
and engine horsepower claimed. Grinding, sandblasting, or any
other modification to manifold prohibited. Any film coating inside
manifold prohibited. Runners and plenum must retain OEM
appearance.
Heads
CYLINDER HEADS
Must be correct casting number for year and horsepower claimed,
per NHRA Technical Bulletins or NHRA accepted. Porting,
polishing, welding, epoxying and acid-porting prohibited.
Combustion-chamber modifications prohibited. Cylinder heads are
additionally restricted in that they must retain original-size valves at
original angles +/- 1 degree and must be able to hold original
cylinder-head volume per NHRA Specifications
. Runner volumes
may not exceed the current Super Stock cylinder-head volumes as
listed on
www.NHRARacer. com. Regardless of the poured volume
measurement, any modifications to intake or exhaust runners
prohibited. Any evidence of modifications from the original castings
will be grounds for disqualificati
ons as determined by NHRA in
NHRA’s sole and absolute discretion. Any aftermarket steel valve
permitted, must retain stock head and stem diameters. Only
engines OEM-equipped with sodium-filled valves may use sodiumfilled
replacement valves. Titanium prohibited. Hardened keepers
permitted. Lash caps prohibited. Valve-diameter tolerance: +.005-
inch or -.015-inch from NHRA Specs. The following are prohibited:
spark-plug adapters; any grinding in ports or combustion
chambers; removal of any flashings; sandblasting or any other
modification to cylinder head; any film coating of intake and
exhaust runners; any film coating of combustion chamber. Runners
and combustion chamber must retain OEM appearance. Final
acceptance as determined by NHRA in NHRA’s sole and absolute
discretion. External modifications prohibited. Intake side of head
may not be cut into any part of valve cover bolt holes. Valve-cover
bolt holes must remain unaltered and in their original location.
Heat riser passage may be blocked from intake manifold side of
cylinder head. Blocking passage down in valve pocket prohibited.
The following are permitted: polylocks, jam nuts, screw-in largerdiameter
rocker studs or pinned studs, bronze-wall valve guides,
cylinder head studs. Valve spring umbrellas optional. Cylinder
head may have all of the seats replaced. Any valve job
permitted,O-ringing prohibited. Exhaust plates prohibited.
Valves
Cam (deviation from Stock)
CAMSHAFT/LIFTERS
Camshaft must retain stock lift for horsepower claimed per NHRA
Technical Bulletins. Front-wheel-drive vehicles and stock trucks,
maximum lift is limited to .430-inch or OEM, whichever is greater.
Aftermarket OEM-type replacement lifters permitted. Lift checked at
valve retainer, with zero lash. Hydraulic lifter cam will be checked
with pushrod and rocker as run, plus solid lifter, at zero lash. Plunger
height of checking lifter will match extended height (no preload) of
hydraulic lifter. Hydraulic lifter may not be plugged or bottomed.
Aftermarket gear drives/belts prohibited. Aftermarket timing covers
permitted as long as OEM-type timing gears are used. Adjustable
pushrods or adjustable OEM rocker arms (not both) permitted; must
be same or greater weight as stock. Pushrod guide plates permitted.
Cylinder head may be clearanced for larger-diameter pushrods.
A late change to the rulebook while the 2017 season was going on, is
now every car can run a solid lifter cam and solid lifters
Block, crank, rods, pistons
CONNECTING RODS
Stock OEM or NHRA-accepted aftermarket rods permitted. NHRAaccepted
aftermarket rods must meet specifications as found on
the then-current NHRA Stock & Super Stock Replacement Rod
Acceptance List. The combined weight of the piston, pin, rings,
and connecting rod must be equal to or greater than the Minimum
Assembly Weight as found on the then-current Stock Replacement
Piston Acceptance List. Accepted replacements are published on
NHRARacer.com. Grinding and polishing permitted on beams only.
Shot-peening of connecting rods permitted. Length must be stock
+/- .025-inch center to center. The use of rod and crank spacer
bearings prohibited. Cylinder block housing bore size and rod bore
housing size must maintain sizes as designated per NHRA’s thencurrent
approved rod listing.
ENGINE
Must be same year and make as car used, aftermarket NHRAaccepted
cylinder blocks permitted. Equipment other than
original factory-installed prohibited. Any special equipment export
kit (superchargers, dealer-installed options, etc.) automatically
disqualifies car. Engine must remain in stock location — height,
setback, etc. Cylinder bores must not exceed .080-inch over
stock. Bores are measured at top of cylinder where ring wear is
not evident. Crossbreeding parts prohibited. Normal balance job
(i.e., one piston/rod assembly untouched) permitted. Otherwise
lightening of component parts prohibited. All carburetors,
manifolds, heads, etc. must be tightened to prevent any air or fuel
leaks. Vacuum lines must be securely connected or blocked off.
Stroke tolerance is +/- .015-inch. Stock OEM or NHRA-accepted
aftermarket crankshaft mandatory. Aftermarket crank must retain
OEM configuration (i.e., billets, knife edging, etc. prohibited).
Lightening of crankshaft other than normal balance job
prohibited. Cylinder blocks may be sleeved. Aftermarket SFI
Spec 18.1 harmonic balancer mandatory in AAA/S through G/S
and AAA/SA through G/SA.
PISTONS
OEM or NHRA-accepted aftermarket replacements permitted
provided such items comply with all requirements set forth in this
section. Aftermarket pistons may be forged or cast and must
retain the as-cast or as-forged head configuration. The
manufacturer or ID number must remain unaltered and fully
visible to determine correct application. Piston may not be
remachined for special rings, deck height adjustment, valve relief
size, depth, location, or to modify dome or dish. Piston must be
of the same overall design with the same dome/dish
configuration as OEM piston with the correct number, location,
depth, and width of ring grooves. Valve relief and head land
modifications to aftermarket or OEM pistons prohibited.
Assembly weight must be equal to or greater than the minimum
assembly weight as found on the then-current Stock
Replacement Piston Acceptance List. Any steel pin of OEM
diameter permitted. Any lightening of pistons beyond that
necessary for normal balancing is strictly prohibited. Gas porting
of pistons prohibited. Piston may be installed with arrow in either
direction. NHRA-accepted aftermarket pistons and weights are
published on NHRARacer.com.
I hope this helps you understand today's "stock".
I am still searching for the right year pinto in my area. And I may go down to a local junk yard to see if i can find a 2.3 short block to start the engine build.