Visit The Dirt Forum for More Information

Author Topic:   motors
WPP
Dirt Full Roller

Total posts: 46
posted December 31, 2000 08:40 AM

I was thinking about building a back up motor for my mod and was leaning to a 377 what budget parts will last I hare heard scat cast steel crank and what pistons and rods will work i will be turning around 7500 rpm with a good set of heads.

'01HARRIS
Dirt Newbie

Total posts: 1
posted January 04, 2001 06:13 PM
A 377 is a good choice. Small stroke-winds up real quick. I don't think a cast crank is a good idea for the # of R's you're turning. I ran a 383 with the cast Scat and on average turned about 6600, didn't have any problems. My animal brother had a 406, a 377 and a 355 all with the cast Scat, and he broke every one of them in three pieces. On average, he twists his motors at about 7300. The cast Scat is a good crank for street use and a low budget street stock. Get a 4130 or a 4340 for reliability.
We've used Power Detroit rods from Competition Products with great success. Also, the Lunati street race rod is a light rod with good strength and a reasonable price. Usually, anything that weighs between 600g and 650g is good for between 500 and 700 horsepower.
Hypereutectic pistons have also been real good. I have used a cheap set of Speed Pro's the last two years with no complaints. We've used SRP's in the past with good luck. Only ones we've had problems with were a set of Keith Blacks. Had one that cracked in half in hot laps on first night.
Hope this helps, good luck.

WPP
Dirt Full Roller

Total posts: 46
posted January 05, 2001 07:23 AM
Thanks for your reply i was alittle bit worried about the cast steel crank and i am running the power detriot rods now in my 406 will it make a differts if the rod is a 6in with the scat crank.There are some other racers that claim they are tha scat cast steel and some claim a gm steel and claim 7500rpms.Just trying to build a cheaper motor to race when the tracks get slick.

fury
Dirt Full Roller

Total posts: 52
posted January 06, 2001 06:47 PM
I would not reccomend anything that uses a 400 block unless you are are going to concrete the block. That is the only way it will last. We have also heard the horror stories about the cast cranks eagle, scat etc. I would use a steel crank, from eagle for example for what they cost its a better deal and much more reliable.

MOD RACER#93
Dirt Freak

Total posts: 251
posted January 06, 2001 07:59 PM
You can beleive it or not, but I run "used" GM factory cast cranks in both my mod, and stock car, and I turn both the cars around 7500 to 8000 rpm on 3/8 mile dirt. I check the bearings at mid season. Both are 355ci. I have ultralight J&E flat top pistons in my stock car, and Hypertectic pistons in the mod. Both use a stock "apearing" aftermarket rod, nothing hight dollar though. Its all in the balance job. If its not balanced perfect anything will fly apart...Oh yea, most of the mods racing at our track use 377 wich uses 400 block. Like I say good preparation, balancing, and assembly techniques are the key to a strong dependable motor no matter what kind of motor it is...When I build again I will most likely use a scat steel crank, and H-beam rods, with hypertectic or speed pro 13.1 dome pistons and zero-gap rings. Hope this helps out some.....

WPP
Dirt Full Roller

Total posts: 46
posted January 07, 2001 08:18 AM
I am trying trying to see if i can get away running a cheaper motor i have heard of some of them running parts like some of you have mention.I know i am going to use a better rod and piston i have just figured out which crank.I am leaning toward a gm steel crank and there will be block hardner in the block. Thanks for the information

Roadhzrd
Dirt Maniac

Total posts: 101
posted January 07, 2001 02:47 PM UIN: 28276986
When you use block hardener do you just pull the water plug in the bottom and fill to that level?

MOD RACER#93
Dirt Freak

Total posts: 251
posted January 10, 2001 07:10 PM
WPP you may have already checked out this place but go to http://www.speedomotive.com/ they have 377 kits from mild to wild...

Limited5
Dirt Maniac

Total posts: 141
posted January 11, 2001 07:22 PM
I've heard you better know what your doin' when using block hardener. I'd rather use splayed caps.

MOD RACER#93
Dirt Freak

Total posts: 251
posted January 11, 2001 10:44 PM
Im not an engine expert or nothing, but I always thought block hardner was just for drag racing...Thats what I like about this forum, im always learning something...

Limited5
Dirt Maniac

Total posts: 141
posted January 13, 2001 11:03 PM
Block hardner is put into the water passages. And i think your right, its intention was for drag racers making short runs. Seems to me if you reduce water volume and its path your ask'n for trouble.

jammin
Dirt Administrator

Total posts: 3279
posted January 13, 2001 11:39 PM UIN: 16262997
I have talked to several engine builders and they have said this also...They use the hardener in the water passages below piston bdc from the top of the piston. They told me it was for cylinder wall support for high compression/high cylinder pressure motors that they would do this on. It would help support the cylinder wall in these situations. I thought the same thing you did limited...but I personally saw one of these motors run in a street stock....ran very good...no heating problems.
????

Go figure.

awkwardjeff
Dirt Freak

Total posts: 219
posted January 14, 2001 08:23 AM
Jammin, You mean to tell us that this street stock car had the whole block filled???
or just to the bottom of the soft/frost plugs?
We use this block fill in almost all our motors, we take out the frost plugs and fill to level............this needs to be done before the block gets bored.........otherwise if you do it after the bores don't stay round...........we fill our's so we can run a stroker crank and make clearance for the rods in the pan rail....sure you can do this with out hitting water, but if you miss and hit water it's not good................we have a aluminum rod 406, I had to grind the oil pan rail past the bolt holes to get those clubs to swing through the block. Three people owned this crank kit and every one ruined a block trying to grind the pain rail then weld up the hole they created. I bought the thing for $500 brand new crank kit.....ross pistons, Z-gap rings, Manley aluminum rods, scat cast crank, damper, and flywheel all balanced and set to go..............It took me a long time to get the thing to clear inside the block and I needed to mill the top of the big end on the rod to clear the cam...........then I called Dave Crower to build me a pencil thick small base cam......
I put this thing together and took it apart 9 times before I was happy every thing would clear...........It didn't cost much cash, but if I paid myself minimum wage I would be rich.......It was a nice winter project....
I just thought I would let people out there know not to try to add this block fill to a block that has the machine work done already.
And for those people that hit the water...DON'T WELD THE BLOCK.....IT WILL SPIDER WEB AND YOU WILL TRASH THE BLOCK....
get core fill and do this right..........Jeff

[This message has been edited by awkwardjeff (edited January 14, 2001).]

jammin
Dirt Administrator

Total posts: 3279
posted January 14, 2001 10:34 AM UIN: 16262997
No, just like your talking about, it was filled to the freeze plug holes on the bottom. So, your saying if you use this stuff, you do not have to worry about grinding clearance in the bottom end and it will not leak when you go thru to it on the bottom? Hmmmm.

awkwardjeff
Dirt Freak

Total posts: 219
posted January 14, 2001 09:28 PM
Jammin, That's correct no water in the pan.
I told you about our Aluminum rod 406, this has a home built pan to let the rods swing through,and only 3 bolts on each side of the pan, plus the 4 corner bolts.........the other bolt holes in the pain rail were gone to make clearance...........the pain rail is only 1/8 inch thick where the rod cap *****s swing close to the rail.......the rods miss the inside of the pan rail by .040.......
3 rod throw's are way deep into the water jacket at pain rail..........NONE leak.
Jeff

Back to the Archives