Thread: recomended rebuild, i have 225 heads

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I am goin to pull the motor back out of my pickup in a couple months and was wondering what you recomend.

I have a 350 bored .030, big motha thumpr cam, patriot 225cc heads 64cc chambers, port matched edlebrock air gap intake (recomended by patriot for those heads), edlebrock 750cfm carb (also have a 650 holley), headman 1 5/8 headers, msd distributor, current pistons 9:1 (although it will prolly be 10.5:1 after reuild)

I currently have no stall and a locked rearend with 3.08 gears, although i'm looking to get rid of both

The motor is very choppy sounding which i want to keep. I drive it on the street but don't really care about driveabillity. The motor has no bottom end which is the reason for the rebuild. I was debating a 383, but i'm now thinking just a high rpm motor

Any advice on a bottom end???

Originally Posted by jrod9989

The motor has no bottom end

Yeah, I'll bet. Heads with 225cc intake runners and a Thumpr cam on a 350 with 3.08:1 gears? No surprise here.

If you start windin' that 350 to try to take advantage of those huge heads, you're just gonna start breakin' a lot of stuff. You not only need a tough bottom end, you need a tough valvetrain as well. More revs equals more Shekels.

Admit to yourself that you made a mistake and start over.
383, 9.5:1, 230-240 degree cam ground on 110 degree LSA, 1 3/4" long tube headers, RPM or Stealth manifold, 195/200/205cc heads, 3.73-4.11 rear gears, 2500/3000 stall converter, 750 vacuum secondaries carb.

One of the fellows on another forum came up with what I think is a realistic match for heads to cubic inches. He said that if you multiply cubic inches by 0.5, you'll have the correct runner size for a street/strip driver, multiply by 0.55 for a comp motor. Now, these are not hard and fast scientific laws, but they will give the average rodder a pretty good idea of where he needs to be with head choice. Also realize the the higher you go in static compression ratio, the more head you will need.

I have a 406, 10.6 to 1 compression, hyd roller 236/242, dart 215 cc platinum heads, zero decked, flat tops. It's in a 3900lb car with 2500 converter and 3:42 rear. The car pulls very hard but needs more gear and I can't help but think of torque that i am probably missing out on with those 215 runners. A friend swore that those were the one's I needed as a more aggressive solid roller may be in the future. Currently, i like the cam and am kinda making the best of the heads. Wish they were a bit smaller though...say 200cc

Originally Posted by flanker1970

I have a 406, 10.6 to 1 compression, hyd roller 236/242, dart 215 cc platinum heads, zero decked, flat tops. It's in a 3900lb car with 2500 converter and 3:42 rear. The car pulls very hard but needs more gear and I can't help but think of torque that i am probably missing out on with those 215 runners. A friend swore that those were the one's I needed as a more aggressive solid roller may be in the future. Currently, i like the cam and am kinda making the best of the heads. Wish they were a bit smaller though...say 200cc

Different ball of wax. You have a larger bore, which will flow more cfm than a smaller bore like a 350 block. Plus, you have another 50 cubic inches. Looks to me like a very close to optimum combo, with the exception of like you said, needs more gear. I have to believe that you engineered the motor with a very tight squish to operate on pump gas, because running your stats through the KB Dynamic Compression Ratio calculator yields an 8.864:1 DCR.
RPM HP TQ
2000 151 396
2500 191 400
3000 242 423
3500 308 462
4000 372 488
4500 426 500
5000 465 488
5500 490 468
6000 491 429
6500 458 370
Peak volumetric efficiency 98.9% @5000
Peak BMEP 184.5 @4500
If you can make 400 ft/lbs at 2000, you have an excellent street combination. You're only off 4 ft/lbs from that. Good job! I used a 750 carb, RPM intake and 1 3/4" headers to run this Sim.

Those hydro rollers don't like much over 5,500 with the stock spider retainers.

ya i was told to get the 225 heads so thats what i bought. The top end is very strong it's all comp cams. The bottom end is the part im changing, i was thinking 406, 383, or just balance the 350 (to hit the 8500 range), and yes i will prolly swap cams in the process.

Any takes on a very agressive cam? my heads will clear .575 lift