408 Cleveland

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wrobinson

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My 13 year old wants to build a 1971-73 Mach 1 Mustang for his first car. We have found a Grabber Blue with white interior base model 1971 Mach 1 to start on.
I am considering stroking the Cleveland to 408 CI with a Scat rotating assembly. I would like the engine to make more torque down low in the powerband. The compression will be around 9:1-9.3:1 depending on deck height and completed combustion chamber size. I think the cam kit is  a Comp Cam Magnum hydraulic roller with 224 duration and 566 lift. This build will be a daily driver on regular unleaded fuel, probably 87-89 octane. The motor is out of a numbers matching 1973 Q code Mach 1 with factory 3.25 gearing and C6 transmission. Do you think this combination will support 350-375hp and 400-425tq?

 
There is a serious issue you need to be aware of regarding the Scat crankshafts and probably all the stroker cranks in general.

The rear main seal will almost certainly leak if you stick with the factory 2 piece style. While some of us have managed to make them work with premium 2 piece rear main seals, most will leak. The solution is to have the block modified to use a 351W 1 piece rear main seal. This machining operation will need to be done while the rest of the machine work is being done to the block.

Comp Cam lifters are causing more than one person problems. I suggest Morel for lifters

Your cam looks to be on the small side for a stroker. I admit my build is pretty radical and I would not recommend it for the street, but I am at .641 lift on intake and exhaust and a lot more duration.

a 408 may very likely overwhelm the stock fuel pump and lines. 3/8 lines are good to about 500 horsepower beyond that 1/2 lines become desirable, but unless you change the pick up, you are restricted by its diameter.

Stock fuel line size is 3/8ths so you are okay with a mild build, but if you drive it like you stole it, you may run the bowls dry which will lean out the engine and burn stuff that isn't supposed to burn

 
I am considering stroking the Cleveland to 408 CI with a Scat rotating assembly. I would like the engine to make more torque down low in the powerband. The compression will be around 9:1-9.3:1 depending on deck height and completed combustion chamber size. I think the cam kit is  a Comp Cam Magnum hydraulic roller with 224 duration and 566 lift. This build will be a daily driver on regular unleaded fuel, probably 87-89 octane. The motor is out of a numbers matching 1973 Q code Mach 1 with factory 3.25 gearing and C6 transmission. Do you think this combination will support 350-375hp and 400-425tq?
Unless you're already there on the bore I wouldn't touch the block. A 351 could make those numbers on pump gas easy. Is there any reason you want to run 87-89 besides availability?

 
There is a serious issue you need to be aware of regarding the Scat crankshafts and probably all the stroker cranks in general.

The rear main seal will almost certainly leak if you stick with the factory 2 piece style.  While some of us have managed to make them work with premium 2 piece rear main seals, most will leak.  The solution is to have the block modified to use a 351W 1 piece rear main seal.  This machining operation will need to be done while the rest of the machine work is being done to the block.

Comp Cam lifters are causing more than one person problems.  I suggest Morel for lifters

Your cam looks to be on the small side for a stroker.  I admit my build is pretty radical and I would not recommend it for the street, but I am at .641 lift on intake and exhaust and a lot more duration.

a 408 may very likely overwhelm the stock fuel pump and lines.  3/8 lines are good to about 500 horsepower  beyond that 1/2 lines become desirable, but unless you change the pick up, you are restricted by its diameter.

Stock fuel line size is 3/8ths so you are okay with a mild build, but if you drive it like you stole it, you may run the bowls dry which will lean out the engine and burn stuff that isn't supposed to burn

Remember this build is a first car for a first time driver. I was thinking of stroking the motor for the torque. Yes I agree the camshaft is pretty tame for a 408 but then again building for a young driver. The factory fuel lines should suffice being that we are leaning toward an EZ EFI or FiTech system. I appreciate your comments, thanks.
 
My 4V has plenty of torque off the line, but I have a 3.73 rear end. A 3.50, or lower, ratio rear end and an overdrive transmission will give you the kick in the seat of the pants and a highway cruiser at a lower cost and still be reliable.

 
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