Getting ready to purchase a Scat 306 rotating assembly

5.02GO

Founding Member
Jun 26, 2001
308
0
16
Ky, Blue Sky Country
Hello,

i am getting ready to purchase a scat forged 306 rotating assembly from summit. i have talked to summit a little bit about the kit.

The kit comes with Mahle pistons and file to fit rings. Summit told me that they would switch to JE pistons and to different rings for the same price.

Summit also mentions a two piece rear main seal. Does the crank determine what rear main to use? I though you could only use a one piece?

Here is a link to summit. http://store.summitracing.com/partd...825031+4294891093+4294870276+115&autoview=sku
Questions:

Do i have to use file to fit rings?
Can i use other rings? If so, what should i get?
JE good pistons?
Have to use a two piece rear main seal?

Befor i spend the money on this kit, i would like your opinions.

I did do some searching on this, but couldnt find exactely what i was looking for.

thanks guys
 
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I believe its the block that will determine what seal you need to use, you can pick a one piece up at a parts store...a late model 5.0 will take a one piece. You don't have to use file fit rings, it just takes more time to assemble but you also can get the exact gap you want. JE are GREAT pistons...I have them in my motor. And I hate to do this whole 'if it were me' thing, but for the money of spending a new rotating assembly for a 306, why not get a 331/347? Good luck.
 
Jason 302 said:
I believe its the block that will determine what seal you need to use, you can pick a one piece up at a parts store...a late model 5.0 will take a one piece. You don't have to use file fit rings, it just takes more time to assemble but you also can get the exact gap you want. JE are GREAT pistons...I have them in my motor. And I hate to do this whole 'if it were me' thing, but for the money of spending a new rotating assembly for a 306, why not get a 331/347? Good luck.


Thanks for the reply. I was thinking that the block was what determined the one or two piece seal, but wasnt sure. The rotating assembly mentioned the two piece.

As for the file to fit rings, i just dont feel like i need them. This is the first motor that i will be building and hopefully my last.

The stroker 331 or 347 is just something i dont need. I would buy a ford 302 short block but ford has discontinued them. So, i'll have to build one. A 306 is what i need. Plus the price is better for me.

thank you.
 
A 331/347 assembly is cheaper than what you listed above for the 306. It will fit right inside your stock block with the same machining as needed for the 306. A good cast steel crank 347 kit goes for $800-$1000. No clue why you'd waste $1100 on a forged 306 assembly when the stock crank and rods will work fine, but too each their own I guess?
 
You can hand file the rings if you are careful with hand tools, although the ring filer is recommended.

I would recommend ready fit rings instead, and then just checkthem before you assemble. That way you only have to file if a couple are too tignt. All 8 holes worth of my Speed Pro's were right on.

Pricey or not, it won't hurt to put quality stuff in. Best thing would be to have it balanced also. That is worth every penny.
 
Ok, I just have to put my .02 worth in for doing the 351 swap instead. Huge gain in torgue if take the swap option!

Don't take my word for it, search the forums. You'll find that those of us who went 5.8 absolutely love it.

To anyone out there looking to do a block swap all I'm asking is that you direct a little of your research into getting a 351w. Decision is totally yours, just get all the first.

The cost is usually about the same, or cheaper even.
 
I realy like the quality of the Mahle pistons (not saying JE isn't a quality piece as well). I used them in a 2000 camaro SS LS1 build up...it made a little over 500 rwhp on all motor before nitrous and I could spin it to 7200 rpm all day long..it had seen as high as 7600 rpm before. I was a little hesitant about Mahle pistons but after talking to many VERY well know speedshops in the LS1/LS2 and some mustang market...they convinced me that they were a very good product. I used a stock crank, Scat rods, with Mahle pistons....with excelent results. I too was leaning to JE pistons but went with Mahle and would use them in any of my future builds as well. I know this doesn't exactly help you out since im talking from LS1 experience but it should translate to the 5.0 as well. The speed shop that did my balancing and assembly was highly impressed with Mahle as well. By the way I liked the rings as well...they gapped them perfect (set up for a 200 shot)...it comes with a spec sheet for gapping them according to what kind of power adder and how much you plan to run, if any at all. By the way....sold the SS and bought a 93 SSP 5.0 coupe....with only 91,000 miles on it...I always wanted a coupe car.
 
I would rather stay away from the file to fits. Being my first motor build, i would rather use the regular type.

Mahle, JE , SRP, Probe etc....Was just curious about the quality and longevity.

Does the pistons normally come with a set of rings? Mahle pistons with Mahle rings? JE pistons, JE rings?
 
I agree, go with a 331 or 347 kit, Scat 4340 crank, Scat or Probe 4340 lightweight I beam rods w/ 7/16" rod bolt, Probe, Ross or SRP pistons, dish 9:1CR for a blower later, Romac ultralight 28oz damper, Fidenza alunimum flywheel, lightweight rotating assembly balanced to 28oz spins up real fast. Rotating assembly good to 1000hp.