The Dodge Challenger Message Board

Hi
I am now working on my 318 emgine. I want to keep it but make it much better

Here is a combo i was thinking about :

360 j heads casting 402 75 96
cam from Hughes HUGHE2328AL duration 223° 228°
Intake manifold - Edelbrock performer RPM
Carb -street demon 725 cfm
Valves 2,02 intake and 1,625 exhaust

The job is to mill the heads, porting, fit new valves, springs, lifters,locks and retainers

I am still unsure how much i should mill the heads to achive 10:1 compression ratio.

Please write me what you think about it and is there sth elso i should do. Mention everything what you know is importan as i do not want to miss anything, I do not have mechanical knowledge so i can miss sth important.

Looking forward to receiving your feedback.

I've done what you're contemplating many times in the past. Don't get too hung up on the compression @ 10:1, or rather milling the heads to get there, you'll just end up requiring adjustable rockers, $ $, etc., or were you getting them anyways ? It'll make it's own "wind" anyway once the rpm's come up, even @ 8:1. or slightly better.
NOT saying 10:1 ain't better, just not worth the cost with a "stock piston" and bottom end ?, as it sounds like you're using.

If you're rebuilding with a KB or better piston then forget the above.

Anyway, the wee-18 works surprisingly good with the head and cam mods, albeit the low end grunt suffers to get the mid, and top end "POP". Best use sufficient convertor to get a "run" at the cam powerband. Cover it, (the cam bottom number), by 500 rpm outa the hole-PERIOD ! and add some gear to the ass end. If you don't want that much stall speed, get a smaller cam !

Some thoughts; bowl blend only after the 2.02" installation, don't get too much volume above the valve, the wee-18 can't use it, it'll like a liitle more velocity at the seat. Step down 1 or more sizes in camshaft, something Low teens on the intake side is PLENTY. DO NOT OVER-CAM this engine ! Get 3.55 gears !

What we did; "STOCK" 1975 318 bottom end, re-ring only with better rod bolts and sized rods, used pistons swapped bank to bank (reversed), "J" heads with the big valves bowl blended, 340 "P" camshaft, the "P" designated the '68-70 standard trans tightened lobe sep. but still a 268/276. Stock 340 Intake and "tricked" thermobog carb. Stock distributor and ignition.
Little bastard ran mid 13's for years with subsequent owners using 3.91 gears and a 3000 stall convertor in a 3200 lb A body Duster. Nobody, mostly chev owners who just got spanked, believed it was a 318. Strange part was, we cc'd at a final C.R. around 7.8:1 with those heads ! We could throw initial timing at it forever ! Still went like a raped ape once it spooled up ! Bit of a terd until it got spinning though, hence the caution NOT to overcam at the low CR, and still give it some kind of looser convertor.

Don't reccomend you do the piston swap side to side, they get noisy, we didn't care back then, we'd swap "crap" around more often than most people do underwear in those days, you don't need to.

You may be surprised how well these "little motors" rev. they can be Lotsa fun on a budget if you're careful, providing an adequate environment for them to work, ie; gears and convertor with a more "tame" cam and heads. Remember, it's the "whole combination", not JUST the engine.

Special Note; the best valve head size we found for this combo, was to cut down a used up 2.02 valve to around 1.95 then 30/45/60/75 throat cut, on a J head, for the 318. We usually had lots of used and "wore out" 2.02 valves kicking around on the floor, so it was a good way to ressurrect them for use as cutting 'em down replenished the valve margins to serviceable, regrind the 45, then backcut the ski-jump to 30.

Ahhh, the budget days when it was fun ! Me bad, I'll quit reminiscing now, such an "almanac" of useless information !

Good luck with it.

Nothing useles about that lot matey.