Inliners International Forums General Discussion Engines Stock to Strip (Building tips) 250 CID Inline 6

Level 0 - Stock

Bottom end - Stock (No Changes - Factory)
Cylinder head - Stock (No Changes - Factory)
Cam - Stock 250 Cubic Inch Cam (No Changes - Factory)
Ignition - Stock Points (No Changes - Factory)
Exhuast - Stock manifold, exhaust pipe and muffler. (No Changes - Factory)
Carb - Stock 1bbl (rebuild if needed)


Level I - Tame (Almost Stock) Street use, Manual or Auto trans w/stock torque converter and stock rear gears

* Ignition - Upgrade to Pertronix HEI Conversion Kit along with a 40,000 , 45,000 or 60,000 Volt Coil (ensure that vacuum advance is operating properly on early pre-1968 distributors)
** Cam - Stock 250 ci cam or 245-254 hydraulic aftermarket cam

Advantages:

Improved ignition and timing curve with both centrifugal and vacuum advance
HP will peak around the 4000 rpm range and torque will peak between 1600-2000 rpm.
This is a good, near stock rebuild which retains good driveability and off-idle low end torque.


Level II - Mild (Close To Stock) Street use, Manual or Auto trans w/stock torque converter and stock rear gears

* Ignition - Upgrade to Pertronix HEI Conversion Kit along with a 40,000 , 45,000 or 60,000 Volt Coil (ensure that vacuum advance is operating properly on early pre-1968 distributors)
** Cam - 245-254 hydraulic aftermarket cam
*** Bottom end - Stock, balanced rotating assembly. Moly rings, cast pistons.
**** Cylinder head - Three angle valve job, stock compression ratio.
***** Exhaust - 2" dual exhaust system or 2 1/4" single exhaust system with a low-restriction style muffler.
****** Carb - 350 Holley 2bbl on adapter to stock intake manifold

Advantages:

Improved ignition and timing curve with both centrifugal and vacuum advance
HP will peak around the 4200 rpm range.
Torque will peak around the 2200 rpm range.
Improved breathing due to carb and exhaust upgrade.


Level III - Street - Manual or Auto trans w/stock converter, 3.20 - 3.50 rear gears

* Ignition - Duraspark w/MSD, Crane or similar module
** Cam - 260-272 degree hydraulic aftermarket cam
*** Bottom end - ARP rod bolts, balanced rotating assembly. Moly rings, cast pistons.
**** Cylinder head - 1.75" intake valves, three angle valve job, pocket ported, exhaust port divider installed. Aftermarket valve springs. Compression ratio ~9.0:1, adjustable rockers.
***** Exhaust - 2" dual exhaust system or 2 1/4" single exhaust system with a low-restriction style muffler.
****** Carb - 350 Holley 2bbl on adapter to stock intake manifold or Triple 1bbl
******* Oiling system - Baffled oil pan. Optional windage tray.

Advantages:

HP will peak around the 4500 - 5500 rpm range.
Torque will peak around the 3000 rpm range.
Good idle with 260 cam, slight lope with stronger cams.

Dis-Advantage:

Slow takeoff at the start line when used with auto transmission and stock gearing but comes on strong above 2500.


Level IV - Street/Strip, Manual trans, Auto trans w/higher stall converter, 3.50 or higher gears

* Ignition - Duraspark w/MSD, Crane or similar module
** Cam - 272-300 degree hydraulic or solid lifter cam.
*** Bottom end - ARP rod bolts, balanced rotating assembly. Optional ARP main studs. Optional gapless rings. Optional forged pistons.
**** Cylinder head - Fully ported head, aftermarket 1.84 Intake and 1.5 exhaust valves, combustion chambers relieved, polished chambers, aftermarket springs, head milled to produce 9.5-10:1 Compression ratio. Exhaust port divider. High test only (octane booster may be required). Optional ARP head studs.
***** Exhaust - 2" dual exhaust system or 2 1/4" single exhaust system with a low-restriction style muffler.
****** Carb - Triple 1bbl, manifold milled for direct fit of 350-500 cfm Holley 2bbl, Weber DGES, IDF, or IDA
******* Oiling system - Windage tray, baffled pan (not comercially available - must be fabricated), Optional oil cooler.

Advantage:

A 250 L6 in this configuration could potentially make 170-200+ hp @ 5000 rpm complete the 1/4 mile in the mid 14 second range in a light car like the Nova.


Level V - Drag and Beyond

Nitras oxide
There's a great deal of room for exploring untested waters with this engine.
Unlike the Small Block Chevy very little development has been done.
Custom machine work and intake manifolds, EFI, reshaped chambers are all untested possibilities.
Very few custom cam grinds have ever been tested.
Comp Cams XE series may hold possibilities, as do other profiles from other manufacturers.
DIS ignition systems, custom forged connecting rods, and lightweight forged pistons may extend the rpm range higher than currently possible.

I allready did level v with a 292 and it ran purdy good

Steven

What kind of times did you get in the 1/4 mile

10.10 @ 128 mph in a 2800 lb truck with 150 hp of giggle gas

Steven

Steven,

On your site where you're doing the daytime drag in the quarter mile. Did that other vehicle "spank" the mighty6 that day?

-magic mike-

Magic-The race aginst the Mustang was for 1/8 mile. I put a hole shot on him and shut off at the 1/8 mile mark. The win light did not come on because the track personal forgot to switch it from a 1/4 mile test& tune to a 1/8 mile race. We won the round after the other driver and I showed our time slips. This is a new kind of street racing in Houston Tx. It's all heads up, 1/8 mile racing for saftey. No ET's are shown on the score boards. The racing fans get to walk really close to the starting line. They are bringing street racing to the track. NHRA wouldnt allow fans like this around the starting line but the track owners are seeing big profits in these races. They are having a race this Saturday 7.

Here is a link to the site www.hotrodgossip.com but be carefull the words are bad and the B.S. is deep.

Steven

BTW- I'm not racing because I'm building a new motor.

this is off another forum and the info is really good.