Visit The Dirt Forum for More Information

Author Topic:   small block chevy engine
eaton89
Member
posted October 09, 2003 11:00 PM
Whats you guys opinion on what chevy engine to run(350,383,400) what are the benifits and down falls. I,m on a tight budget. I am running a 350 now and want to build a new motor for next year. I'm running a 78 olds metric at a big 3/8 mile track. I have a small block 400 short block. Dont know much about them. Can you turn them at 6400 rpm night after night.


Raz_900
Member
posted October 10, 2003 01:55 PM
A stock 400 short block won't live long at 6400rpm. Actually, it wouldn't live long at 5500 either. 400's used we short (5.565") little rods that put alot of side load on the pistons, rings and cylinder walls. Putting in stock 350 rods (5.7") will help, or using 6.0" aftermarket rods is really the way to keep them alive. With a decent oil pump and performance bearings it should work. Assuming you can use a 750 carb, headers and intake, the 400 would probably be the best power. Although it will be the most fragile of the 3 choices.

A 383 with 5.7" or 6.0" rods is the best compromise between power and reliability.

eaton89
Member
posted October 10, 2003 10:00 PM
what is a 355 ,377 or 406. And are these good race motors.


MEANGENE83
Member
posted October 10, 2003 10:26 PM
355 is a 350 bored .030 377 is a 400 block with a 350 crank and a 406 is a 400 bored .030. I agree with raz the 383 with long rods is probably your best choice.


jay116
Member
posted October 10, 2003 10:31 PM
these are motors that have been bored over or stroked/destroked. meaning different crankshafts.
355 is 350 bored 30 thousanths over
377 is 350 with 400 crank or
377 is 400 with 350 crank
383 is 350 bored 30 over and 400 crank
and 406 is 400 bored 30 over.
the basic rule for over bore is 5 cubic inches for every 30 thousanths over.

------------------
Jason Boivin
http://www.rcracing-team.com


eaton89
Member
posted October 10, 2003 10:39 PM
Hay thanks for clearing that up for me.383 has always sounded good but wanted to see what others think.


ssaamm
Member
posted October 13, 2003 08:37 PM
I can't remember how we did it, I know we had a 400 block, but we made a 434 with a small block... WOW it is fast. but it isn't a race motor, just a street car.
lots of potential though, if cubes is HP, 434 out of a small block is a lot.


Driver#4
Member
posted October 13, 2003 10:43 PM
Need more info #4. Why? A 377 is a 400 with a 350 crank but arent 350s main journals smaller than a 400. So do they make a specail 377 stroker crank or am I all messed up. Happens alot LoL


racer17j
Member
posted October 14, 2003 10:37 PM
your right they are smaller but they make bearing spacers for them but i would go with a 383 personally


dirtrace54
Member
posted October 15, 2003 01:15 AM
I would rather go with a 377 (destroke 400). The are very tight turnin motors, good horsepower, and very durable. We have seen others have probs with controling the torque of a 383, especially on a dry slick (jet black) track. Seen a guy out at our home track turn 7700 most of the year on a 377 with i-beam rods and a turned cast crank till he dropped something in the valve train. If you want raw horsepower and torque go with the 406, and if its built well, you can turn.


Dixon
Member
posted October 15, 2003 03:49 PM
A true 377 is a 350 block (4.00" bore) with a 400 crank (3.75" stroke). A 400 block (4.125" bore) with a 350 crank (3.48") yields 372.1 cubic inches. To really get 377 cubic inches you have to bore the 400 .030" over.

Stroker cranks are widely available for 350 journals, and while I'm sure there are short stroke cranks with the large journals, I'd bet they are a lot more expensive. I'm not a big fan of bearing spacers, but that's just my personal opinion.

A shorter stroke motor should be able to turn higher rpm (everything else being equal) but won't make as much low-mid range torque. It all depends on what you're after, and what the rules "allow".

bigcitycowboy
Member
posted October 15, 2003 06:09 PM
any of you guys ever ran a 400 block with a 327 crank?? comes to around 350 summin depending on the bore size.. but this motor will turn the RPM's all nite long. have a guy that runs one on a 1/2 mile track, i swear it sounds like hes turning over 8000 and hes very FAST!!!! just my 2 cents


eaton89
Member
posted October 15, 2003 10:35 PM
Thanks for the info. Rules at my track are a joke. They dont inforce the rules. But I dont have a lot of money to spend. Can you use power pack heads port matched and 1.94 in valves on a 406 or is that under valving the motor. Does this depend on RPM's turned. Besides the cost of putting bigger valves and seats in these heads how much port work needs to be done. I've done some port matching but not any valve unshrouding and not sure I want to take a chance on srewing up these heads.


kip77
Member
posted October 17, 2003 06:46 AM
We are building a 400 w/ a 327 crank for next year. We will be running a 3/8 mile (on the inside) on friday and a 1/4 mile on saturday. The engine guys I have talked to say this motor better for these type of tracks because you can really put the gear to them. And with the short stroke and long rod you aren't hurting the motor by turning it up there.

------------------
FASTEST WHITE BOY ON FOUR WHEELS...and sometimes none...


eaton89
Member
posted October 19, 2003 06:03 PM
Need some opinons with my last question. Please help. Thanks. ^^^
^^^


Raz_900
Member
posted October 22, 2003 09:22 AM
1.94" & 1.5" valves on a 400 would limit rpm somewhat. Depending on came selection, around 5500-6000 it'll start to really hurt breathing. Putting in 2.02" intakes is pretty simple, just cut the 45 degree seat bigger then blend in the bowl with a 75 degree cutter or grinder. Finish the valve job and it's done. The exhaust really should have hardened seats put in. Cutting them from 1.5" to 1.6" could expose soft iron that will wear against the valve faster. although putting hard seats in isn't that big a deal for a decent shop. Same thing, grind or 75 degree cut afterward to blend everything in. Putting big valve in and not opening up the bowl is a total waste. The rest of the port doesn't NEED to be done, but the bowls are very important.

[This message has been edited by Raz_900 (edited October 22, 2003).]

Speedway65
Member
posted October 22, 2003 10:02 AM
how come a 350 bored .060 over is a 358
and 350 bored .030 over is a 355?


Raz_900
Member
posted October 22, 2003 03:43 PM
A .040" over 350 is actually 357 CID and a .060" is 360 CID.


66jj
Member
posted October 22, 2003 06:16 PM
Eaton

power pack heads are junk. they are 72cc and have 1.72 1.5 valves.

you need to find some better heads.


eaton89
Member
posted October 22, 2003 07:43 PM
Thanks Raz 900 for the info. Thats a bummer. Had hardened seat put in last year.66jj I'm not sure if the heads are called powerpack or fuelie heads but they are a 186 casting(small humps)they have accessory holes 1.94 in and 1.50 ex and seem to do very well. Had them cut for bigger springs, put srew in studs and guide plates. I'm pretty happy with them but figured they may not have enough valve for a 406.


Raz_900
Member
posted October 23, 2003 04:05 PM
It wouldn't be all that much $$$ to put in 1.6" exhaust seats and valves. If I had to choose between 2.02" intakes or 1.6" exhausts, I'd do the exhaust and leave the intakes at 1.94s. You can always have the intakes opened up next year.


Mikey14
Member
posted October 24, 2003 04:10 PM
Cubic Inches can be figured this way:

BORE X BORE X .7854 X STROKE X 8 (cylinders).

For a 350 .030 over its: 4.03 X 4.03 X .7854 X 3.48 X 8= 355.1159

For a 350 .060 over its: 4.06 X 4.06 X .7854 X 3.48 X 8= 360.42273

To get a 434 from a 400 it would have to have a 3.94 stroke crank and be .060 over. OR 4.00 crank and .030 over.

Block Bore Stroke
327 4.0 3.25
350 4.0 3.48
400 4.125 3.75

I think this is correct information. ;-)

oluck96
Member
posted October 26, 2003 09:58 PM
IMO on a budget the 350 crank and stock rods will handle 6400 rpm all season and then some. the 400 block is fantastic if you can afford to put longer rods in it.but the long stroke dosent like the r's and all that torque can get ya in trouble on a slick track. best bet is to stick with the 350 and spend the money on valve train and exhaust.


Donnie Ross
Member
posted October 27, 2003 07:15 PM
if the 186's are the heads I'm thinking of put in the 2.02 1.60 bowl blend they are good castings along the line of the 461 and 462 double humps.


PEDDLER
Member
posted October 27, 2003 08:07 PM
6200 to 6500??? We normally turn 7200. 355 with a 2 bbl.


Back to the Archives