What's the valve lift for the combo you're planning? Solid lifters I assume.
I would do all the seat R&D on some scrap 318 head to figure out what works. While the 920's are a little better than the later stuff, the port layout is very similar, so whatever you find works on the later head should also work on the 920 head.
Some Specs from NHRA I put together.
1966 Dodge Dart K/SA-L/SA
Dodge Dart 270, 2 Door Sedan, 111” wheelbase
13.47 pounds/HP
Minimum Weight = 13.47 #/HP*210 HP + 170 # =2999#
Engine Specifications from NHRA
235HP 273 CP 10.50:1 CR 1-4BBL Cart AFB-4119S/SM, 4120S/AUTO 2536770 2536563 Carb sizes – 1437x1563/1063x1250
NOTES: B,6,14
6 - Alt carbs - 4121S/SM 4122S/AUTO
14 – Alt intake manifold 2535583, 2536536, 2533771, 2531915, 2836139
B = 2465315,2658920,2843675,3671585,3769973,4323302 Head Casting Nos.
235HP 273 Dodge Plymouth Deck Height .011 Dome .140”, 16.1 cc Valve Sizes 1780/1500 Valve Lift .420”/.430” Head Gasket Thick..020” Valve Spring Outer Only, Mechanical Solid Lifter, Rocker Ratio 1.5:1 Chamber Volume 57.3cc
Cylinder Head Volumes
Head # Intake CC's Max Exhaust CC's Max Manufacturer
302 162 70 Mopar
315 130 59 Mopar
Pistons NHRA Legal
273 65-67 235HP Min. Compression Ht. 1.745”, Pin Diameter 0.984”, Ring Thickness 5/64, 5/64, 3/16, Top Ring to Quench Dist. 0.280”, Min. Piston Wt. 547G, Min. Rod Wt. 655G, Min. Pin Wt. 90G, Min. Ring Wt. 43g, Min. Rotating Assy Wt. 1335g
ROSS 57989
CP PISTONS M14-CP
I have a pair of 675 318 heads I can experiment with. My friend with the Chargers gave me a pair of them. I didn't see any port volumes listed for the 675 and 920 heads. I would think they should be close to the early 315 heads.
Cab, I plan on running a legal car even if it's slower. Cheating to run fast doesn't prove anything. Having to pull the whole engine at Indy and have no engine stand doesn't thrill me at all. There was a post on Classracer about that happening. The guy had to pull the pan off with the engine on a pallet or something. You'd think they could afford some cheap engine stands.
