I have a brand new eddy small port single 4 barrel manifold# 7158 I am not going to use and a good set of 379 heads cheap.
Best way to build a 350 hp 348
- Thread starter jim_ss409
- Start date
How would a 409 crank into a 348 block, 333 heads with 2.06 1.72 valves 9.5-1 pistons compare to a
348 crank, 333 heads with 2.06 1.72 valves with 11.25-1 pistons? HP, torque, drivability, pump gas?
As buildit mentioned internal balancing could be an challenge when mixing crank, rods and pistons.
What makes the 333 heads better than 379? don't they both have the same size valves?
348 crank, 333 heads with 2.06 1.72 valves with 11.25-1 pistons? HP, torque, drivability, pump gas?
As buildit mentioned internal balancing could be an challenge when mixing crank, rods and pistons.
What makes the 333 heads better than 379? don't they both have the same size valves?
The bowl volume is much greater on the 333 head, like it is on more modern heads. The port walls of a 379 head are not thick enough to be ported to the size of the 333, 817, or 1147. I had tested this with a Stress-Tel sonic tester a few years ago. 817 is the best bet if you have some as they will require less work, and are still cheaper than the rare 1147. Also, 333 heads have the trough in the chamber that reduces the available quench area and compression.
Found a set of rebuilt 333 heads with 2.06 and 1.72 valves, stainless steel intakes and stock gm exh. Isky 8005a springs for hyd roller 150 on the seats closed not sure what that means, heads have been surfaced, PEP press in guides and stock ports, so I will need to check into porting. $667.26 seemed like a good price?
Talked with Show cars and they recommend using their new409 rods (4340 moly, 7/16 ARP bolts, floating pins, 750 grams) part number 7225S $299 and Ross 348 pistons 11.25 to 1 #3337Ap with the 409 crank. With the 250hp 348 block with cylinder notches compression should be around 10-10.5 to 1.
So if the 348 stroke is 3.25 the rods are 6.135 = 9.385"
and the 409 stroke is 3.50 and the rods are 6.0 =9.500"
With a difference in length of plus 0.115" the Ross piston must make move the piston pin up in the piston body? Wouldn't that have an effect on balance?
All your support is VERY much appreciated!!!
Talked with Show cars and they recommend using their new409 rods (4340 moly, 7/16 ARP bolts, floating pins, 750 grams) part number 7225S $299 and Ross 348 pistons 11.25 to 1 #3337Ap with the 409 crank. With the 250hp 348 block with cylinder notches compression should be around 10-10.5 to 1.
So if the 348 stroke is 3.25 the rods are 6.135 = 9.385"
and the 409 stroke is 3.50 and the rods are 6.0 =9.500"
With a difference in length of plus 0.115" the Ross piston must make move the piston pin up in the piston body? Wouldn't that have an effect on balance?
All your support is VERY much appreciated!!!
The stock length for a 409 rod is 6.09.and it's an old trick to use that length rod on a 409 crank[3.5]and a 348 piston,however I'd suggest having a piston built for the application,or you can save considerable money by using the K-B piston for the 4 inch stroke,a 6.385 rod[same money as the 6.135 rod],and a 3.5 inch stroke[409 crank].Y our math should be 9.600[blueprint spec] minus the piston pin heigth,1/2 the stroke length,and the rod length that you intend to use.A 409 crank,an I beam 6.385 bushed rod,and the K-B piston[642 grams plus 142 pin weight] will need very little work[no mallory metal] to bring it into balance.I agree on the price on those 333's.I'd suggest a little bowl work such as opening up the throat under the valves to 85-90 percent of seat diameter,blend the machining marks from the machine work into the bowl area,and a port match for your needs and goals.The K-B piston,6.385 rod,333 head will put you at around 10-1,and depending on how you cam it,will make plenty of power on pump gas.
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Show Cars has the piston,and there's only one compression listed,so don't worry about that.Show cars,Competition products,Jegs,Summit,Lunati and others such as Eagle and Scat have the 6.385 rod listed.I got mine from Competion products for less than 300 a set.
Scat rods are very nice. And thats a great price on those heads! Especially all done
poison ivy
Well Known Member
consider,just minor mods, GEAR, exhaust, carb work, cam, in that order.1 hp per ci very easy,less exp, and more reliable, most of the time. then what rear end. power breaks parts..
I'd suggest the new Demon 625 for from 300 up to a little over 400 horse power.I think that you mentioned that you're planning on running an overdrive automatic transmission be hind this engine.One thing to consider when looking at carbs is the type of hook up for the trans.All Edelbrock,most Holleys,Quick-fuel's require you to spend extra money for a throttle arm bracket in order to properly adjust the T.V. cable.The Demon,as well as the Holley "Street Avenger" series carbs allow you to simply hook it up,adjust ,and go,since the proper geometry is built into the throttle arm to begin with.As to 2 4bbls,use the Edelbrock 500 cfm AVS carbs.
I will take a look a the Demon 625; is there something about them that make them better? I picked up a muncie m-22 4 speed instead of the auto trans and a winters 10" champ 4:10 ratio. It's going it to a 31 Ford roadster. I thinking it should be fun to drive.