408 Stroker Motor Build

Discussion in 'Classic Mustang Specific Tech' started by Gailahan, Sep 16, 2006.


  1. Gailahan

    Gailahan Member

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    From what I hear, stock blocks are good to 700hp. With a main stud girdle and a girdle around the rocker arms it should be fine. My combo should make around 550 max NA hp. Forced induction is just something that I might do in the future if I need to feed the addiction further. I don't really plan to make over 800 hp, and if it ever comes to that I'll switch to an aftermarket block after I blow the other one up. =)
    #21
  2. Spoofty

    Spoofty New Member

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    There's also a brace that goes across the lifter valley that helps too. I don't remember who makes it. It requires a little fab to the block. I've only seen one installed on TV though.
    #22
  3. 67Dylan

    67Dylan New Member

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    girdles = band-aid fix

    If you keep the power at 550-600hp and keep the revs low you'll be OK.
    #23
  4. Vinyl66

    Vinyl66 Member

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    302 blocks start splitting apart at 550 HP. Your 351 should handle this without much problem.

    A good dual or a Vic will work well on your stroker engine but
    I am a fan of a larger intake on a stroker engine. Especially if you are wanting to see 550-600 hp. An intake's design was built around breathing capabilities of a certain sized engine. A Vic. Jr. 302 intake may be too much intake on a slightly modded 302 but may be the perfect fit on a 347. I believe the 351 Air Gap is about the same height as the 351 Vic Jr and may have the same runner size as well. If that is true then there may not be as much difference between the dual and single plane on the 351.

    But on my car:
    1966 Mustang with 347. I have a handful of timeslips where my car ran 89-90 in the 1/8 mile and 109 in the quarter with an RPM air gap copy shifting at 6000. I switched to a Vic Jr and immediately picked up to 91-92 in the 1/8 and 112 in the quarter. Still shifting at 6000. That is about a 25 hp increase on my car. Absolutely no driveability problems except that it is scary with street tires (no traction) trying to accelerate quickly.:D

    The AFR205's would EASILY get the nod over the 185's in a stroker that size. I am using the 185's and love them in my 347. I have seen some hard running 302's using the 185's. You will NOT have to run the engine to 8000 to get big power with the 205 head. It will also make major power and torque below 3500 if you do not go WAY overboard on the cam.
    #24
  5. Vinyl66

    Vinyl66 Member

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    There is a 408 build up in the new Car Craft magazine which puts out 520 HP at 6300 rpm and 490 lb-ft at 4200.

    The recipe is:
    AFR 205's
    Crane Hydraulic Roller 248/256 @ .050, 0.595/0.605 lift and 110 lobe center
    1.6 rocker arms
    Victor Jr. Intake
    Holley HP 750 carb
    Reverse dome pistons (9.5:1)
    1 3/4 long tube headers
    #25
  6. bnickel

    bnickel Founding Member

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    comparing an air gap copy cat to a vic jr is just not a good comparo. the fact is that you could have mace the same power with a real air gap as the vic jr made. the copy cat intakes aren't that great really.
    #26
  7. 67Dylan

    67Dylan New Member

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    That & the air gap reaches it's peak around his shift point. The vic jr needs more RPM before it shows who is king between the two. Besides, the air gap needs more carb than the jr does, which could explain some of the hp increase.
    #27
  8. Vinyl66

    Vinyl66 Member

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    Do you know the port runner length difference and the port size difference between the Pro Products Air Gap and the Edelbrock Air Gap?

    I think that I made a perfectly valid comparison between a good dual plane intake against a single plane intake on MY car. I am not saying it will work on every combination but I am still a believer in a bigger intake on a stroker engine.

    The only thing about the Pro Products intake that I didn't like was the casting imperfections or aluminum flash. It took a little while but I was able to smooth out all the flash with my trusty Dremel. The intake looked and performed great for me after a little work. Especially for the price. I would recommend one to anyone who is willing to spend a short time smoothing out the imperfections.
    #28
  9. Vinyl66

    Vinyl66 Member

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    A dual plane does need more carb than a single plane does and that may account for some of my increase. The Vic Jr. did not need more RPM with my combination to obtain the extra mph (HP) though.
    #29
  10. Vinyl66

    Vinyl66 Member

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    There is a guy on Fordmuscle that switched from a genuine Edelbrock Air Gap to a Vic Jr. on his 347 and gained a lot more than I did. He probably gained more due to larger cam, ported Trick Flows, 750 carb, larger headers and exhaust.
    #30
  11. washMO66

    washMO66 Founding Member

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    Pro Products = Sub par Chinese Junk - Can it be cleaned up and made to work, sure, as proven by some people in here. But it makes you wonder if the runners are really the exact same??

    Not saying that from a buy American standpoint, my car had one on it when I bought it back (bought / sold story is long) because my buddy in his infinite wisdom bought cheap because he wanted it to be prettier (polished) and took off my ported and port matched real Vic Jr in favor of the Pro P.

    The Pro products leaked oil out the front and back where it hits the engine block. I took it off, bolted on my old Vic Jr and had no oil leaks and the car felt different, more responsive etc.


    Dual vs Single plane - Your stroker will make so much torque down low you would be sacrificing top end for no usable gain at the low end. If your build is right the car won't hook on any tire you put under a stock suspension from a light - ET Street or anything, believe me, I know. I can start my car in 2nd gear on street tires (don't make a habit of this) and burn them as long as I want, as a matter of fact on street tires 1st gear is about a half second to 6600 RPM and is useless. On ET Streets it is much better but it still will only hook at the track, period.

    The car is not a daily driver, go single plane, I drive mine all the time in town, to work etc with good manners.... lots of stall now because I have more cam, but it works.

    PS - When I went from a Performer RPM to a Victor JR, my short times at the track went from 1.64's to 1.59's (approximate, been a while)?? Explain that??? Shouldn't that low end torque dual plane have better 60'?? ET's and trap times got better too (.2 & 4 MPH) because of the pick up on the high end.

    Food for thought........

    PS - Port polish on the heads like Vinyl said, makes some difference. You should have no problems getting 500FWHP out of a well planned and built 400+ci stroker
    #31
  12. Vinyl66

    Vinyl66 Member

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    washMO66 said:
    The Pro products leaked oil out the front and back where it hits the engine block. I took it off, bolted on my old Vic Jr and had no oil leaks and the car felt different, more responsive etc.


    Lightbulb going off: This is where my oil leak is coming from!! Ever since I installed the Vic Jr intake I have a small oil puddle under the front of the intake on top of the timing chain cover. It looks like the intake didn't seal very well. I have had antifreeze puddle up in that area before but never oil.

    I hate cheap Chinese chit as much as, no maybe even more than, the next guy. Maybe because my company imports almost everything from China and much of it IS inferior and has to be sent back or reworked. So I see the quality of some parts being perfectly fine while others are horrible. I took the chance on the Pro Products intake and think it is a good intake. My little bit of "reworking" with the Dremel was well worth the money saved. Looks good, has consistent runner openings, sealed easily, and performed well. I am cheap so the $100 I saved was a bonus.:D I am actually keeping it for a while in case I start a 302 project for another car.

    But back to the subject. For a 550+ HP 408 stroker use a Vic Jr!!
    #32
  13. dennis112

    dennis112 Active Member

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    Well said, my experiences are similar. I have good street driveability with either the Stealth or the Vic Jr. As you said, I can start out in 1st or 2nd gear with no problems and can still obliterate steet tires by punching it in either gear. What is there to gain by adding more torque on the lower end?

    I do my best pulling in 3rd gear. I shift at 6400 and the engine drops to 5000 after each shift. I want to achieve most of my average power in this range.

    One can say the RPM/airgap/Stealth are good to 6500, (which they may be on there intended engines), but that is NOT true with a big stroker. The rated RPM's are based on a stock sized engine, such as either a 289/302 or a 351w. Adding 40+ more cubes to either engine (347/393) increases the demand on the induction system. Smarter friends than me (at Hardcore50) done the math and determined that the available dual planes mentioned will peak between 5700-5800rpms with the 40 cube increase. Does that mean I still can't reach 6500, no. If the engine is still making good average power it can climb higher even to 7k. That is all related to the engine's combination and each engine is different. Still, that engine's available airflow has achieved its peak at around 5800 and after that there will be diminishing returns.

    The Vic Jr. is rated at 3500-7500 on a 351w. Put it on a 393 stroker and the power band will also drop, much like the dual planes. I don't have any figures, but assuming the same 7k drop as the dual plane, the power band "could" be close to 2800-6800. It could be even less on a 408 which is pushing nearly 60 cubes more than stock.

    I think what it all comes down to is the combination of engine and car. If you already have lots of torque at the bottom end (spinning madly off the line), you will probably see gains on the upper end with a single plane. You might even get gains on the lower end from having "slightly" less torque off the line with your big stroker. Believe me, you will still spin the tires from all the available torque with a big stroker.

    If you are hooking decently and want excellant street manners, by all means a dual plane might be best in your situation as long as you are getting the expectant gain you desire on the top end.

    The original poster is looking for 500-600hp and wants to go fast. His car is not going to be a daily driver. With all the torque the 408 will produce (unless he overcams it), he will not need more on the lower end. The Vic Jr (or other comparable single plane) would most likely be be the best best choice.

    Combination, combination, combination . . . . .
    #33
  14. Max Power

    Max Power New Member

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    I dunno, call me old fashioned, but I would rather spend the $100 extra with an american company that designs and builds quality products that you can bolt on right away rather than spending hours grinding away on a cheap chinese rip-off that borders on trademark infringement.

    There are ways to save $100 in this world, and I think that is one of the poorer ones.

    To each his own.
    #34
  15. 67Dylan

    67Dylan New Member

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    I agree. Although it's easiest to reverse engineer a product, IMO it's one of the shadiest ways. They spent no time designing, crunching numbers, or testing they only stole they idea and want to reap the rewards.
    #35
  16. Vinyl66

    Vinyl66 Member

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    I am glad that there are people out there like you. I like old fashioned. I like when people buy american products as well. However there are TONS of foreign owned companies here in the US that employ US workers and bring in LOTS of income to their communities.

    I certainly did not spend hours grinding on the intake. Maybe 30-45 minutes. Since I do not make $100 an hour it was well worth it for me. It was an easy and good way to save money for me. That way I can use it for things that are even more important to me in this world. Like my 4 year old son's birthday today!!!
    #36
  17. washMO66

    washMO66 Founding Member

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    That's big! My twin boys will be 4 in November... You gotta prioritize... otherwise instead of college money daddy would be getting cutom sheetmetal intakes......:D
    #37
  18. Max Power

    Max Power New Member

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    Don't get me wrong, I am not against international commerce, far from it. We have to make our product in China because no american mfgs will do it anymore. But one of the biggest problems in dealing with China is trademark infringement. They just blatently rip designs off and get paid for it. In industries like DVDs or golf equipment, it is flat out brutal.

    I was talking to the owner of Scorpion Rocker Arms at PRI last year, and he had a prototype Gen III Chevy rocker on his display. Well someone took the prototype off the display, and since the design was unproven, he decided against manufacturing it. Well 6 months later, chinese knock-offs started appearing on ebay with his logo on it. And then HE starts getting calls when they fail and ruin people's motors.

    That is the problem in doing business with China on hard parts. Spend any time in this industry and you will see it.

    Do you think anyone in China will develop new aftermarket cylinder heads for oddball motors like Ford FEs, Olds, AMCs and Buicks like Edelbrock does? Absolutely not. But they will be right there to rip off the R&D once Vic Edelbrock sends the stuff to market.

    If Vic decides to do his R&D here and move production to China, I will be a little disappointed, but I will still buy his products, no problem. I will still send the check to Vic.

    But I will not support some chinese trademark ripoff artists, and if everybody else does, there will be no more Vic Edelbrocks to design and create these new products.

    Think about that when buying from thieves. Do you want Edelbrock still around when your son gets involved in the hobby? Is the $100 you saved really worth it?
    #38
  19. 69gmachine

    69gmachine Member

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    The HP numbers sound reasonable for the combination of parts, but what's missing is a real world assessment of driveability. From my own experience with a smaller, wider cam I don't think that this combination is going to be much fun in traffic. Over 500 NA HP is either going to take a LOT of cubes or a hairy combination. You can't use 500 HP on the street anyway, and most people can't use it on a road course either, much less autocrossing. It's great for a drag car where all you do is mash the gas and hang on, but it sounded like it would only be at the drag strip occasionally. First decide how you plan to use the car, then spend your kids future. Unless you do something really dumb building your 408, you won't have any problem taking out your buddy's LS1 unless it has a blower and big meats.
    #39
  20. Max Power

    Max Power New Member

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    Actually, I have seen more than one Gen II LS motor run mid-lo 12s with only heads, cam intake & exhaust. Those motors are stout!
    #40

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