440 engine build help, comp ratio/heads?

[68gtx]

hello everyone,

new to the dodge world i have have some question, eneded pulling a valve cover which eneded up being a teardown, lol, here's what i have found . lots of silicone plugging oil pumppassages from previous owner, since it's apart now is the time to maybe upgrade, but i am on a tight budget,but would like a healty street motor that will never see the track, maybe a few stoplight to stoplights. heres what i got, stock 72 440, flatops with no valve reliefs.346 heads, now if i end up putting pistons in this thing, is there a head and piston combo thaty i can end up with a streetable comp ratio, i think the heads i have now, are liek an 88cc? if i bought a set of 915's would this help. i was told that if i got stock six pack pistons with 906 heads i would end up with like 10.5 to 1, has anyone got a setup close to what i am looking for?that could tell me ge tthis piston with this head etc?don't wanna spend a ton, and does it make sense to go out and spend $1000.00 rebuilding stock heads when you can get some 440source stealth heads complete for that price?

 

[wedge5]

440source or ProComp heads would be fine for street/mild hotrodding. If you look around you will find someone that is selling good iron heads for cheap because they went to a fancy set of aluminum heads. I just read in an article in Mopar Muscle that your 346's are basically the same as the 906/452. The 915's are closed chamber heads so they won't work on your open chamber pistons in the motor now. I think I saw that there was a completely redone set of 915's on this forum for sale(cheap). As far a pump gas(93 octane) friendly a good rule of thump is IRON: 10 to 1 and ALUMINUM: 11 to 1 (safe numbers).
For a mild street 440 in the range of 450hp. I would do a basic rebuild. No need for forged unless you wanted to spend the money. Not sure but if your 440 has the LY rods get them checked over and if good use them; same with the stock crank and put on a new balancer. I would put a hi 400 lift cam with a LSA of 110. Hughes Engines make some good cams for Mopars. Good dual plane intake and a 700/750 carb. 1 3/4" headers with dual 2 1/2 exhaust out the back. 3000-3500 convertor. 8 3/4 rear w/3:73 gears with a 28" tire

This is just some ideas for you. Others will chime in also.

 

[moparstuart]

welcome

 

[Meep-Meep]

It sounds like I built the engine you are looking for. Very streetable if you have around 93 octane and runs low 13's on street tires and cheap to build. The low buck approach would be to run the KB pistons as high in the hole as possible and a closed chamber head like the 915. I have KB237's that are nearly zero deck and a steel shim gasket. My CR with that combo is 10.1:1 and 190 PSI but don't go on that alone. The best you can do is CC everything to know exactly what compression you will end up with. I'd keep it at 9.5:1 and about 170-180 PSI of cylinder pressure. The intake is not your limiting factor but compression is. You can run the stock intake and AVS and a mild cam but if you end up with 8:1 and low cyl pressure you will be pretty unhappy. I am running the MoPar .455" / 272 cam on a 112 lobe separation installed straight up. It doesn't need a lot of spring so it should live for a long time and no valve clearance issues. Cast cranks are fine too but with the KB pistons you really should balance the assembly as I don't think they are weight matched to the factory pistons. Oh yeah, spend the money on the iron adjustable rockers such as Crane or Isky and 3/8" push rods. Swap meet price is usually $100-125.00 for the rockers.