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Discussion Starter · #1 ·
hey guys im new to the forum, and ford perfomance, this is what i have and want to do, any help would be appreciated.

i have a 75 351w that i would like to turn into a 408 Stroker. i was going to get the kit from CHP unless there are better ones, i already have an Edelbrock Performer intake,(came on the engine) but would like to switch, looking at the performer air gap my gaol hp is somewere between 450 and 550hp, and id like to keep the compression around 10.1, i want to be able to run mid grade or premium fuel, and i was looking at the kit with flat top pistons with valve reliefs to run the Twisted wedge heads, but im not sure those have the compression i want.. so im stuck on heads and cam. but i do know that i want a hydrolic roller cam. i want one that has a noticible idle everyone loves a cam that lopes! or atleast i do! but it stil needs to be streetable. and one last thing. with my combonation work with a built C6 Trans?
thanks guys
 

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Can you post a link to the parts you are talking about?..It's much easier for everyone that way so they don't have to go searching to help you out....When I was researching my 408 alot of the combo's listed did not have the correct compression ratio..You have to do the math and make sure the numbers are correct....Having said all of that I think your goals are pretty easily attainable..
 

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If those numbers are accurate at the bottom of the page those pistons have much more compression than you are looking for...Most heads for the smallblock are in the 58-64cc range and require a fair sized dish in the piston to run in the 10ish:1 range..Also the twisted wedge 170s are a little on the small side for a 408..The 190s would be a much better fit..
I would select the head you are going to run and then we can try and find a piston that will work..
 

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Discussion Starter · #7 ·
so would i be better off witha different set of heads? not the twisted wedge? they do have a 54cc chamber as and option i believe. so what do you think i should go with?
 

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Discussion Starter · #8 ·
but if there alittle small for a 408 i should go with a different head right? what about edelbrock or something
 

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Those are good heads for a 408, BUT that 64cc combustion chamber will give you too much compression with the stroker kit to meet your original goal. Check out the bottom of the link you provided for the crank kit and it will tell you the approximate compression ratio with a given CC head. You can see that the -4.0 kit will give too much compression with almost any head.

You should be looking for a dish or a reverse dome piston with around a 19-24cc dish.

Here are a couple of examples that are in your price range and they contains good parts for street/strip build:

http://www.coasthigh.com/Ford-408W-Reverse-Dome-22cc-Scat-Based-Kit-p/12360-sca-600-f408-1.htm

OR

http://www.coasthigh.com/Ford-408W-Reverse-Dome-22-0cc-Street-Fighter-Kit-p/12360-sf-f408w.htm

I would specify that you want a piston for use with the trick flow heads (I am sure that Probe has one) if that is the direction that you go with (which is what I would do.) Since CHP is owned by the same guy as Probe, it should not be a problem for them to give you the right piston.

The RPM Air Gap would be miles better than the base Edelbrock Perfomer manifold and that is what I would consider. If you need hood clearance or want a little more low end torque at the cost of a little HP, you could also consider a Performer RPM or a Stealth.

Although quite strong, a C6 wastes a lot of usable HP compared to a C4.

With the proper camshaft selection, this combo should meet your HP goals and not need more than mid grade fuel.
 

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Discussion Starter · #12 ·
one of my consers though is that it is only a cast steel crank. with that hold up or should i try and get a forged crank? oh and that made up my mind on the intake.. im getting the air gap. will order it next week
 

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I chose the above kits based upon the cost of the kit you mentioned. Of course you can pay more for better parts.

You really don't need a forged crank in a stock block and a good cast crank is fine for street with some strip use. I ran a cast Scat with 500hp at the track for many years with no issues or concerns. I suspect that the RPM crank would be just as strong. I would be more concerned about the rods in those kits than the cast cranks and would probably upgrade to an H beam rod (which is available in other kits from CHP.) With the Probe SRS pistons (a good choice) and proper assembly, you will be good at 500-600hp for many, many years.

Nothing wrong with using the H beams with a cast crank either. Not only are the H beams stronger in most cases, they typically come with capscrew instead of traditional bolts/nuts(which require additional block clearancing.)

By the way, CHP is a good source for parts. I also like dealing with CNC Motorsports. Be careful of many kits found on various sites as there are some parts that have poor quality and you will want no part of.

You can see all the 408 CHP kits with 22cc dish pistons here: http://www.coasthigh.com/Ford-408-Windsor-engine-kits-reverse-dome-s/130642.htm


http://www.coasthigh.com/Ford-408-Windsor-engine-kits-reverse-dome-s/130642.htm
 

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Discussion Starter · #14 ·
thanks for the help dennis. that answered a good question for me.. i am probably going to go with the pro street kit so i can get the H beam rods but then i get a forged crank as well.. unless i can swap rods in the prostreet kit, but i dont want my internals hitting there max hp rating. not a good idea.
 

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Those rpm heads are also on the small side for a 408...I think the slight loss in compression would probably be made up for with the superior flow of the bigger heads...There are other heads that would work for your application as well such as an AFR 185,205 or edelbrock vic jr just to name a couple..I would try to stick with 185cc runners or bigger for an engine that size.The bigger they are the more power you will make but it also gets more expensive..
Here is a compression calculator that you can use to try the various combo's....A felpro 1011-2 head gasket is .039 thick...I came up with 9.88 using the 64cc heads..
http://www.csgnetwork.com/compcalc.html

I am running a scat rotating assembly that came with Keith Black forged KB750 pistons..They have a little smaller 15.8 cc dish but that puts your compression at about 10.25 or so with the 64cc heads.
 

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Frdnut is steering you right. The RPM heads are certainly not the way to go to make 500hp. Every point increase of compression is worth 3-4% more HP so even with the 66cc 190's, you are loosing only 7 or 8 HP over having a true 10:1. Good heads will make more HP than the compression that you will loose will.

BTW, for best HP, always buy the best heads possible as there is more HP to be found there than with any other component. Then design your motor around the heads. For a 408, the TW 190's are a good start. The Vic Jr.s are decent too. I also like the TW205's or AFR 205's if you want bigger and need stock height exhaust ports. If your vehicle is not limited by narrow shock towers, then there is a whole new world of heads available (that I won't mention now) for tremendously more HP. It all depends on what your intentions are for your ride. You never have said what vehicle you are putting the 408 in and what your intentions are, except to build around 500hp so I am assuming street.

As far as compression goes, everything is not black and white. There are many variables with blocks, cranks, rods, and pistons. IIRC correctly, Probe compression specs the pistons @ .010 in the bore. Other manufacturer's have their own installed specs. My new build using SRP pistons specs their pistons @ .020 in the bore. There are also variations in production block deck heights and installing the pistons does not necessarily ensure that you will get the desired compression. Unless you have a 69' or 70' block, chances are your compression will be less than advertised.

To compensate for the difference in blocks, you can have the block zero decked. This will bring the top of the pistons equal to the top of the block. Doing this will increase the compression over manufacturer's specs and doing so will get you closer to 10:1.

Also you can vary the head gasket thickness and IIRC Probe specs a .039 head gasket to get the rated compression. Since it is not normally safe to go below .035 I would just go ahead and use the head gasket that Frdnut mentioned.

Another way to increase compression is to have the heads milled. TF heads are great in this respect and you could easily have enough milled off to get the desired compression.

All of the above methods have their pro's and cons, but a good builder always takes this into consideration. You can either throw it together and hope that it is good or you can have everything measured and then intelligently compensate to get the desired results. Most people do the former, but the smart ones do the latter.

There are other things that affect static compression, including where the top ring is located on the piston. A good compression calculator takes all these variables into account. I like the one that Diamond piston's offers: http://www.diamondracing.net/tools/

As far as cam choice, I will leave that to others as that is not my area of knowledge. I will tell you that since you didn't mind running either mid or high test gas, it is possible to run higher compression than 10:1 with the right cam choice--even over 11:1 is possible depending on the engine and how the vehicle is setup (including weight and rear gears.) I do build at these higher compression levels, but I normally have a custom cam spec'ed for my vehicle to allow for pump gas.
 

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Doh.. I thought that you said that you wanted to run regular gas and that was the concern for keeping the compression low..If you are willing to run mid or high test fuel I wouldn't worry about being a little over 10:1 like Dennis said..As for the camshaft I am no expert in that area either..To get a knowledgeble answer though people will want to know as much info about the vehicle and how you intend to use it as possible..A few important parts of the puzzle are..
Vehicle weight
rear end gearing
trans type
intended use of the vehicle..
 
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