Having learned from so many of you here (and on .org), I felt obligated to share how things worked out with my long-rod build. The original writeup can be found
HERE.
This long-rod 225 slant-6 rebuild (now @ 231 CID & 3.8L) uses the 198 engine connecting rods to facilitate the use of better sealing and lighter weight pistons & valvetrain components as well as mods to create a performance street cruiser (not a red-light racer). Emphasis was on producing high air velocity through the intake tract, reducing parasitic power loss throughout, and lightening the reciprocating mass where budget allows - with all these stealthy mods hidden behind an otherwise plain-wrapper engine.
In all, it worked out great! Pulls strong from about 1,500 and rides in the powerband nearly forever. With cable throttle control - and an AVS2 carb - the tip-in is instantaneous, almost feels like it's injected. That said, the build was designed for deeper gears - which are planned in the springtime with an 8.25 differential swap (have it - from '74 Dart Sport) with 3:07 ratio (Jeep) gears. This will pick up the slack from off-idle and balance powerband range.
All said, I'm stoked with the results. Very drivable, quite a lumpy cam at idle (while pulling 10.5 Hg of vacuum) and pulls strong - with a balanced chassis. It's not a package for everyone - but works for me...
Comments are welcome :)
Induction
- Spectre Perf. #98881 14" 180-degree dual-inlet, aluminum air cleaner assembly. To make this work, you need to use the base from Edelbrock 1221.
- Edelbrock carburetor #1901 Thunder AVS-2 @ 500CFM w/electric choke. Running mostly on the primaries.
- Offenhauser #5270 four-barrel manifold - modified for water-heating under the carb baseplate. Saves several pounds from OE. [vintage part]
- Remflex #6008 carbon intake/exhaust gasket
- Attaching studs have been replaced with same-size parts from McMaster-Carr, but with an allen-head recess, which makes removing/installing the header quicker and easier
- Lokar throttle & kickdown cables replace mechanical linkage
Cylinder Head
- Street pocket-ported bowls and short-turn radiused - with the goal of increasing air velocity but not volume. Otherwise just cleaned things up
- Elgin supplied Ford 289 intake (I-1670 @ 1.78") & exhaust (E-1669 @ 1.45") valves. Oversized in slant-6 terms - and with a smaller diameter stem (5/16 vs 3/8), with positive seals and further modified with a back-cut.
- Street performance valve/seat angles
- K-motion #K-800 valve springs. Used only the outer spring resulting in 110/280 pressure - to match the cam specs.
- Comp-Cams valve spring locks & retainers
- Hand-fitted rockers & spacers
- Rockers are OE and only required cleaning to ensure oil-flow
- Endurotec BigBore cylinder head gasket
Block
- Line honed + new cam & crank bearings
- Deck was just kissed for gasket seating without much material removal
- Bored to 3.445" to match pistons, bringing the displacement from 225-CID/3.7L to 231/3.8L
- Wiseco #PTS536A45 forged pistons. Installed using press-pin option for endurance. Static compression = 9.6:1
- Wiseco piston rings #8750XX [1/16, 1/16, 3/16]
- Chrysler connecting rods from 198-CID slant-6 - which are longer than 225 rods. The essence of a long-rod rebuild!
- ARP connecting rod bolts from a Pontiac SD-455 engine [yeah, they fit!]
- NOS oil pump - standard pressure & volume
- Chamfer on the #1 crank bearing for proper timing chain oiling
- Chamfer on the lifter bores to increase oil pooling at the top of the lifter
- Crankshaft oil holes chamfered & journals polished
- Oregon Cam Regrinders #346 camshaft was further customized being profiled to use Ferrea's lightweight .904" lifters which require a custom ramp angle.
- Cam Specs: duration @ .050 234/228, Lobe Separation 106, Valve Lift .476/.479
- Ferrea lightweight mechanical lifters [66-grams each]
- CompCams pushrods
- True-roller timing chain - custom set through Elgin using the chain & crank sprocket from 440/426 Hemi mated to their HP cam sprocket for the slant-6
- Specta Premium #SP1051MP fuel pump delivering 4-6PSI @ 30-GPH [ample supply]
- Felpro and Mahle gaskets
- Driven GP-1 15W-40 Synthetic Blend High Performance Oil with Baldwin BT216 filter (integral standpipe). The oil has a lot of ZDDP for use with flat tappet engines and runs super clean.
Ignition
- OE alternator - rebuilt to factory specs @ 50-AMP
- HiRev-7500 electronic ignition module [from Rick Ehrenberg]
- NGK Iridium spark plugs - which draw fewer AMPs to fire than other plug types
- NGK spark plug wires
- Rebuilt and custom-curved (Sun) distributor from @halifaxhops
- Pertronix #40011 Flame-Thrower coil, selected for its quick saturation which helps deliver more torque at lower RPMs.
- Mini-starter [from R Ehrenberg] which draws significantly less amperage and startup than the OE. It also saves several pounds.
- New ignition/engine wiring harness was installed to ensure continuity and full-system reliability
Cooling
- Unbelievably - still running the stock radiator! Although, I doubt I'll be that lucky in the summer - so I'm on the hunt for an upgrade.
- 195F SuperStat Thermostat
- 16-LB cap
- Recovery Tank (soon)
Transmission
- Torqueflite 904 has been rebuilt & upfitted with HD internals including steels & frictions
- Edge Racing Converters, 2,800 RPM stall, high-efficiency torque converter with (9.5") impeller & turbine, Torrington bearings, with 4130 chrome moly steel drive hub & spline insert
- Flexplate is from a 440 w/ARP #240-7302 bolts (must be used, standard bolts make noise!)
- AFT+4 fluid
Performance estimations are 235-HP & 280-Ft/Lbs. torque [conservatively] I wanted to dyno it on a stand at the shop - but with more custom parts and labor than expected (which is always expected), I ran out of budget. I'll chassis-dyno it someday...
Special mentions are due to
@my68barracuda @halifaxhops @slantsixdan,
@RustyRatRod Doug Dutra, Duster Idiot, Slantzilla, Dart270, Charlie_S, Greg Ondayko, Joshie225, Dart270, Rick Covalt, CNC-Dude, and many more for directly or indirectly educating me on the ways of the Slant (my apologies for any omissions).
