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408 Or 421 Stroker Dd


built04SS

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depending on the block i wouldnt use more than a 4.00 stroke.

 

you may not be able to re use your stock block again so depending on which route you go there are many options

 

6.2 blocks can go 427

 

on a 6.0 block id depending on cylinder condition id start at 402 and then go 408 if you needed to clean up the bore.

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Well i was planning on using my stock 6.0 block and doing either a 4.00 or a 4.125 i believe it is stroke with a 30 over piston .... im just trying to get some hlp from people like bf i order bc i was planning on ordering this week

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So far what i have that i was gonna put on my motor till it lost oil pressure the other night is i have a set of 799 heads i just had done they were shaved 15 thousands, also a victor jr intake with a 90mm vette tb,44 lb injectors, truck currently has lng tubes with true 3 inch dual all the way, im having the tranny built when the motor gets done and torque converter, stock rocker arms? (will they work) truck also has a custom.ground cam in it right now but will be having another one done for the new motor.... any help would be good chase bc i see ur truck and looks like u have everything down patt

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i would not put a victor on a DD truck. The victors short runners tend to raise shift points and reduce torque in the low rpms. A fast intake can produce less hp but what it loses in hp it will gain in torque and be a more driveable set up, and put down better ETS with a tighter converter and lower shift points, all better for dd truck....and stop light to stop light racing. However for a an all set up its a good choice.

 

427 is possible with your stock lq9 block, 4.125 stroke with a .060 over piston. The cylinder walls are at the max so if something goes wrong the block is junk, but really if something goes that bad....the block is junk is no matter what bore. The thin walls are also not as good for boost, but NA should hold up good. Typicaly the 4.125 stroke moves the wrist pin into or close to the rings and the set up tend to use oil. There is a company by me making a 427 lq9 block with their design piston and they say there is no oil use. I know of one of these in a f body and he has not had an issue and one in a SSS but it has low mileage so we can't see any oil use. so that is an option.

 

from a racing stand point i would take the cubes. more cubes can tame down a aggressive cam and make more torque which means less of a stall. however everyone makes a 408 short block so you may be cheaper going that route.

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Well iive jad the victor jr on my truck for a lil over 6 months now and no offense but im not spnding that much on an intake right now ill have to make this one work... but its goona be n/a fuelinjected maybe a lil gas every now and then.... and im not sure if a 427 would be that good for a dd if the cylinder walls are maxed out... i want something practicall that has power when i want it

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how are you getting 421? 4.030 bore with a 4.125 stroke? The 4.125 strokes are said to use oil because of what i said above unless you use a piston with a better design then what i have heard about. So i would assume a 408 would be better for DD but the larger cube motor will be more forgiving on other mods.

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trying to cut cost now will cost you more in the big end.

 

building a budget motor will get you budget results . do it once , do it right and youll be very thankful in the end.

 

imo id get an exact amount you have to spend and decide if a stroker is what you can do or just a nasty higher comp 6.0 or 370 .

 

most of the 6.0 blocks ive seen with spun cam bearing can be fixed but not all .

 

i think the vic jy intake will work ok but there are better options for an n/a build

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Im spending about $4500 im getting the stroker kit for $1800 thats a complete forged rotating assembly i already have the heads ready the only thing i have to do is have the machime work done with is $300 ... im having the converter built for $350 transmission built for $400 have the kits sitting in my closet.... also gotta have my viscous coupler replaced the coupler alone is $400 and i still have to get gaskets new lifter trays and pay for a tune

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And i already tore the motor apart the block is fine not hurt and what would u consider a better designed piston that wont use oil? The kit comes with mahle pistons my cousin is the one doing the motor andhe says it would just be stupid to build a 408 when i can build it bigger for more torque and hp for the same price.... i just dont know much abt stroker kits and what length rods and what stroke crank.. thats what i need the hlp with... the guy that has the kits said i can get a 4 inch stroke with a 6.125 rod or a 6.200 rod

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your asking very good questions. I had to call a wise man to ask about rod length and its affect on stroker motors. Here is what i learned:

 

on a longer stroke motor even with the same size rod, the wrist pin has to be moved up on the piston to retain the stock deck height of 0. It's this that causes the oil use issue because the wrist pin then intersects the rings.

 

the use of a longer rod does not change the displacement of the motor, only either where the piston is in the bore or where the wrist pin is in the piston. Because most builders want to remain as close to a 0 deck height as possible, most of the time they move the wrist pin up. This again causes oil use issues.

 

However, the longer the rod has advantages as well. The longer rod acts like a longer lever, such as a longer pry bar, and is able to turn the crank easier. This means you use less hp to turn the motor over and therefore you gain hp by making it easier for the motor to work.

 

The longer rod also increases piston dwell time. By increasing dwell time you allow the piston to be at TDC longer and it allows for more airflow in and is able to push more exhaust out.

 

On a stroker motor you also want to retain a certain rod length to stroke ratio. This ratio will affect cylinder wear and longevity of your motor. a ratio of 1.65 to 1.8 is optimum, the lowest point is 1.5. The stock lq9 is 1.683. Your options might be: and i'm assuming they make pistons for these combos that will keep stock deck height

6.125 rod on a 408: 1.531

6.200 rod on a 408: 1.550

 

6.125 on a 421: 1.484

6.20 on a 421: 1.503

 

reuse stock rod

6.098 on a 408: 1.524

6.098 on a 421: 1.478

 

So again you faced with a choice, longer rod will produce more power, but be less reliable based on oil use. However the longer rod will be better on cylinder wear.

 

For a DD i would roll the dice on cylinder wear to get rid of oil use. But for my truck, i would shoot for more hp and deal with what ever happens. It also looks like the 408 is better for a DD, but again less hp potential

 

Maybe some one can re-read this to make sure i got it right, and here is an article where i found some good reading. http://www.fordmuscle.com/archives/2003/09/stroker/index2.php

Edited by shadowsniper3006 (see edit history)
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