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Discussion Starter · #1 ·
Hey guys im in the process of building a 557 and I need help and advice with parts. I plan on using kaase sr-71 heads with a hydraulic roller setup. Currently I have my block machined/bored ready to build and all of my parts to my rotating assembly (Rings have been gapped to handle nitrous). I have nothing else purchased or set and stone. I will be using nitrous for an occasional shock factor to the ride and my rotating assembly is forged. Im not very educated on the science part to all of this so im mainly looking for direct pointers to parts that will work well with each other with what im wishing to accomplish. This is my first complete engine build.
 

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whats it going in?what rpm do you need to run it?whats the hp goal?sr-71 heads are bad *** heads for a high rpm drag engine or truck puller etc,so a matched combo is the most important factor.
do you have the heads?
 

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Discussion Starter · #3 ·
whats it going in?what rpm do you need to run it?whats the hp goal?sr-71 heads are bad *** heads for a high rpm drag engine or truck puller etc,so a matched combo is the most important factor.
do you have the heads?
Its going in my 71 F250 and im building a street monster. Im going to back it with a built c6. Im not planning on building a dedicated track truck just something to blow peoples mind on the streets. Hp goal is at least 750+ N/A. RPMs aren't a goal im after just whatever is safe so like 6000 to 6500 id be plenty happy with for max. I have not purchased the heads. Im just trying to get a solid plan to stick to so when I get funds I can purchase whenever.
 

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1990 Ford Mustang LX 351M powered!! Project Cherry Bomb!!
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Did you purchase the pistons with the SR-71 heads in mind? Those heads do require their own fly cutting on the pistons due to different valve placement than stock heads. As @hbboss1 stated above SR-71 heads are some serious hardware.. They really are designed for larger displacement engines (yes like yours) that are gnna be turning between 7000-8500 rpms. A 750 HP all motor piece is no joke, as you have stated you need a game plan.. you've already bought a rotating assembly, which includes pistons. Usually when purchasing a stroker kit and pistons you've got the heads in mind. Now depending on what pistons you have will depend on what heads you will be able to run. Pick the wrong head, you will have 13-14:1 compression. Pick the wrong head you wind up with 8:1 compression. See what I mean? Since you've already got the parts we need to see what we can come up with to make a streetable combination. 750 HP is a great number to shoot for.. but in actuality making a drivable 750 all motor is a different story. There are a lotta ppl here who will help you get your combo a good streetable ride but you just have to set the proper expectations..
 

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Discussion Starter · #5 ·
Did you purchase the pistons with the SR-71 heads in mind? Those heads do require their own fly cutting on the pistons due to different valve placement than stock heads. As @hbboss1 stated above SR-71 heads are some serious hardware.. They really are designed for larger displacement engines (yes like yours) that are gnna be turning between 7000-8500 rpms. A 750 HP all motor piece is no joke, as you have stated you need a game plan.. you've already bought a rotating assembly, which includes pistons. Usually when purchasing a stroker kit and pistons you've got the heads in mind. Now depending on what pistons you have will depend on what heads you will be able to run. Pick the wrong head, you will have 13-14:1 compression. Pick the wrong head you wind up with 8:1 compression. See what I mean? Since you've already got the parts we need to see what we can come up with to make a streetable combination. 750 HP is a great number to shoot for.. but in actuality making a drivable 750 all motor is a different story. There are a lotta ppl here who will help you get your combo a good streetable ride but you just have to set the proper expectations..
Ok that helps greatly. Like i said im not set and stone on anything thats why im reaching out for help and advice. My pistons are CP Forged Dish Pistons at 4.440" -38cc

If this helps any this is the exact kit that I bought: Scat 1-47618BI BB Ford 557 Competition Balanced Rotating Assembly - 9.9:1 CP Dish Pistons

I didnt buy from CNC i bought directly from SCAT, but this is the same kit and model number
 

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thats a great kit,but you will have to run a standard valve location head.edelbrock,trick flow power port 325,ford a429 cobra jet.with some porting on them that will get you there.
 

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I think the AFR heads have a different valve location on em, similar to the Super Cobra Jet aluminum heads.. but like @hbboss1 said you can make great power with the other heads. I'd look towards the TFS if you're really serious, but yeah make a call to the piston manufacturer just to double check and make sure before you spend any $$$ on a set of heads..
 

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Discussion Starter · #13 ·
If your going with TFS head check this build out, exactly what you want.


Cheers, Bob
Found out that im able to use Kaase P51s with my dish pistons because they have a stock valve location so im gonna do p51 with either a victor or if i can get my hands on one a mafia intake and ill be touching or just shy of 800hp NA according to Kaase
 

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Discussion Starter · #14 ·
I think the AFR heads have a different valve location on em, similar to the Super Cobra Jet aluminum heads.. but like @hbboss1 said you can make great power with the other heads. I'd look towards the TFS if you're really serious, but yeah make a call to the piston manufacturer just to double check and make sure before you spend any $$$ on a set of heads..
I ended up finding out Kaase P51s will work for me since they are stock valve locations. According to Kaase ill be touching or just shy of 800hp NA with a 557ci
 

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Discussion Starter · #16 · (Edited)
the p51 heads do not have stock valve locations.i dont know who told you that but they wont work if your pistons have stock valve locations
My pistons were designed to use factory 460 iron heads which have a CJ standard valve layout and location. the p51 heads are the same valve layout and location as SCJ heads and the SCJ heads have a standard valve location and layout. It says so on Kaase's website when you click on the p51. And if im not mistaking the SCJ from ford motorsport on summit shows they have a standard intake and exhaust valve location
 

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you are confusing the stock ford scj DOOE heads with the ford racing SCJ heads.the p51 and ford racing SCJ heads have the same valve location and WILL NOT fit a stock vale location 460 iron heads.you can try it,but be sure to make a video on first start up.
better yet,call the people you bought the kit from and ask them if that piston will fit p51 heads!
 

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Discussion Starter · #18 ·
you are confusing the stock ford scj DOOE heads with the ford racing SCJ heads.the p51 and ford racing SCJ heads have the same valve location and WILL NOT fit a stock vale location 460 iron heads.you can try it,but be sure to make a video on first start up.
better yet,call the people you bought the kit from and ask them if that piston will fit p51 heads!
Ohhh that makes more sense ok thank you for clarifying that. You said the TFS 325 have a standard port location then?
 
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