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Author Topic:   couple questions for chevy 400
johder
Dirt Forum Racer

Total posts: 100
posted September 18, 2005 07:00 AM  
what is maximum rpm for chevy 400??? with stock crank and rods???

do they come with a steel crank in the old "509" 400 blocks???


Eljojo
Dirt Forum Champ
Total posts: 968
posted September 18, 2005 10:45 AM  
Put the 350 rods in it and turn it about 6800 and you will be fine. Use a stock cast crank or an aftermarket. The steel ones are too heavy.

johder
Dirt Forum Racer

Total posts: 100
posted September 18, 2005 12:58 PM  
what do you mean by 350 rods??? 5.7" or 6.0" rods....what size rods are in the 400???

also which cam is better for this 400 stock bore setup???

will run an aftermarket aluminum intake..dont know which one yet...have to run rochester 2barrel

Lunati Circe Track Cam 30123...3000-6500 234/244 duration and .488/.510" lift

or

Lunati Circle Track Cam 30106...3000-6200
234/234 duration and .488/.488" lift

also how much power will a 400 make with double hump heads this cam. flat tops..intake and headers, with a 2bbl????


eenfield
Dirt Maniac

Total posts: 116
posted September 19, 2005 07:52 PM  
The 350 came with 5.7" rods... 400's came with 5.65" rods.

Your cam choice is going to dictated by the track size, banking and other conditions. Typically a 400 will tolerate more cam than a smaller engine like a 350.

None of us on here are dyno's, so no one can give you an exact figure, but with some port work to your heads and the right cam, I would expect 425ish hp. Hopefully someone else can back that up for me.

As for your rpm question jojo is probably pretty close, but you should definately go with an upgrade in rod bolts and main bolts or better yet, main studs.

johder
Dirt Forum Racer

Total posts: 100
posted September 19, 2005 08:03 PM  
if i put 5.7" rods in place of my 5.65" rods...will i have to get special pistons for the 5.7" rods??? i know if i put a 6" rod in there i have to get 6" rod pistons???

im going to get one of the summit rebuild kits...comes with rings, bearings, and pistons..like 400 something dollars...

basically my question is will stock 5.7" rods work with my stock 400 pistons???


johder
Dirt Forum Racer

Total posts: 100
posted September 19, 2005 08:05 PM  
also track is 1/3 mile paperclip "D" shaped with medium banking 1/2 and medium/high in 3/4

Eljojo
Dirt Forum Champ
Total posts: 968
posted September 20, 2005 04:15 AM  
Before you spend at Summit, shop http://www.dirttrackthunder.com/

johder
Dirt Forum Racer

Total posts: 100
posted September 20, 2005 06:07 PM  
ok now back to the question
<h1>http://www.thedirtforum.com/ubb/icons/icon10.gif http://www.thedirtforum.com/ubb/icons/icon10.gif</H1>

chrysler300le
Dirt Roller

Total posts: 10
posted September 20, 2005 06:21 PM  
Chevy 400 rods are 5.565" NOT 5.65". There is pistons available for both 6" and 5.7" rods for the 400. The 6" rod pistons are high compression only though.

johder
Dirt Forum Racer

Total posts: 100
posted September 20, 2005 06:56 PM  
how much difference will the 5.7" compared to 5.565" be???


eenfield
Dirt Maniac

Total posts: 116
posted September 21, 2005 06:51 PM  
Hey, thanks for straightening me out on the rod length... I dont know why I said that, because I knew the correct length.

Donnie Ross
Dirt Freak

Total posts: 264
posted September 24, 2005 07:02 AM  
the biggest difference is a stock 5.7 rod is stronger than the 5.565, the longer rod means less side load on the cylinder walls, gennerally will add some tourque.

racer17j
Dirt Forum Champ
Total posts: 5390
posted September 24, 2005 09:08 AM  
you have website addresses for them?

johder
Dirt Forum Racer

Total posts: 100
posted September 25, 2005 03:53 PM  
also if i put the 5.7" rods in it, will i have to have it re balanced????

my main concern here is if i turn it to about 6000 with factory crank/rods will it come apart???

eenfield
Dirt Maniac

Total posts: 116
posted September 25, 2005 05:22 PM  
YES, YOU WILL HAVE TO BALANCE IT.

It shouldnt come apart at 6000, with balancing and good quality fasteners. (rods & mains)

This is all assuming that the machine work and assembly are correct.

johder
Dirt Forum Racer

Total posts: 100
posted September 25, 2005 08:54 PM  
Ok so if i just reuse the crank/rods in it, put in new pistons, change the bearings it will have to be balanced?

Miller Racing Engines is doing all the machine work

mfcracing
Dirt Full Roller

Total posts: 30
posted September 29, 2005 12:31 PM  
If you change any part (weight) in the rotating assembly it will need to be re-balanced.... ie - rods, crank or pistons....

And to answer one of your first qestions, no there are no stock 3.75" forged cranks... Aftermarket - YES.

[This message has been edited by mfcracing (edited September 29, 2005).]

johder
Dirt Forum Racer

Total posts: 100
posted September 29, 2005 05:20 PM  
so if i only change bearings and pistons it will have to be rebalanced???? even with external harmonic dampner/balancer on it?

Koolaid
Dirt Forum Racer

Total posts: 82
posted September 29, 2005 08:01 PM  
It depends on how hard you want to spin the engine and how long you want it to live. If it's a hardcore race engine then yeah - pistons, rods, or crank change = balance job. If it's an engine that you are only twisting 5000rpm, going to change bearings at the end of the season, and willing to risk it, then no you don't need to do a balance job for the pistons. What do you feel comfortable with? If you only have $200 in the parts that you have and don't have any more money then throw it together. If you already have $2500 in the engine then an extra $300 is just a drop in the bucket. You get what you pay for.

While everyone else is on the Summit ripping trend - I like them.

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