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Thread: The 351W Long-Rod Thread of Doom.

  1. #1
    Pirate
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    Default The 351W Long-Rod Thread of Doom.

    Due to there being several requests for information about one of my favorite 351W engine packages, the 351W with the longer connecting rods, I decided to put this thread together in the interest of getting some information out there, and is going to be a source of info for this build.

    I am not building one of these engines right now, but have built two in the past, and I would have to say that I was impressed with how they ran. However, before I start tossing part numbers out there, I am going to give you a brief rundown of who can benefit, and who won't benefit, from longer connecting rods, and a simple explanation of just what this is, and isn't.

    Thousands of years ago, Cro-Magnon-era man roamed the countryside, armed with spears and clubs....no, wait, too far back. In an effort to try to squeeze more power out of 2-barrel-carb engine limits, circle-track engine builders went to machining down the connecting rods from Ford 351M/400 engines, along with getting pistons custom-built to put on those rods, and using them. The longer connecting rod works excellent with smaller cylinder heads such as the stock GT40/GT40P, AFR 165's (lethal combo), and Windsor JR's. It also favors small camshafts, which most of us are running, and small intake manifolds, which again most of us here are using.

    Keep in mind, that you will be using the stock crankshaft. Stroke is not affected. You are simply reducing the pin/deck clearance, and putting a longer connecting rod in place.

    Long-rod engines do not work well with larger heads, single-plane intakes, and big cams. In short, long-rod engines need less head, cam, and intake, so they would work well with most of the existing setups here.
    One other bonus? Long-rod engines can run a lot more compression on pump gas. My two that I built? The engine with the AFR 165's ran a calculated 11.1:1 compression ratio....on 87 octane. The Windsor SR headed unit? 10.5:1. I also used stock Mustang 5.0 HO roller cams in both engines. The owner of the AFR-headed motor dynoed it, and it came back with a results sheet, making 449 hp and 451 ft/lbs of torque. Some notes? The engine was above 400 ft/lbs. from 2000 to 5000 rpm. It was the best daily-driver engine I had ever built, even though it went into a full-size 1994 Bronco, with EFI. With the smoked stock traction lock diff and 3.73 gears, you could do peg-leg burnouts at 55 mph, with the 31" tires that were on it. I ended up having to put a detroit mini-locker into it to get it to hook up, because the truck was undriveable in wet weather.
    One other note? With the engine balanced, and side-loading reduced, both engines were pretty much vibration-free, and other than exhaust noise, you couldn't tell the engines were running.

    Now, I am not guaranteeing anything, I am just relaying my experience with my two builds, and feedback from other engine builders (for example? http://www.mustangsandmore.com/ubb/F...02875.html...I don't know this guy, this was just another comment). That being said, I will place product info below.

    Want a kit? Speedomotive sells a 351 long rod kit.

    http://speedomotive.com/ps-105-10-fo...roker-kit.aspx

    Want to make your own?

    Pistons? You have two choices:
    http://www.kb-silvolite.com/performa...tails&P_id=168

    Wiseco used to have a part number for this piston, but I can't find it anywhere...however, since they will custom-build about anything...

    Rods:
    http://waynesengines.com/
    At my last price check, $279-$300 for a set of 351M/400 rods, modified to fit on a 351W crank.


    If there are any questions....ask away. I also know details about a 302 long-rod setup.....

    I am probably forgetting something.
    Last edited by Pirate; 02-19-2008 at 12:13 PM.

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  3. #3
    Working with half my brain tied behind my back just to make it fair Nathan in MI's Avatar
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    Being that this favors smaller-ported heads, smaller cams, and smaller intakes, would it also be advantageous to run smaller valves in the heads and a smaller carburetor up top?

    Also, how does the long-rod setup affect ignition advance curve? How much initial/total timing were you running in the two that you built, and were you running both mechanical and vacuum advance, or just mechanical?

    How well would my ported E7 heads with larger valves (not sure the exact size because I forgot to measure them before I put them on ) work in a long-rod setup?

    Does the block require any modifications for clearance?

    Sorry for all the questions, but I'm really interested in this...

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  4. #4
    Pirate
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    It's designed to work well with stock, or near-stock heads. I think that until you get into AFR 185 head range, you aren't going to have a problem with having something too big.

    The heads you are proposing? Should be fine, although I would prefer a set of GT40's. If I am doing my math correctly, you should be around a 10.5:1 compression ratio with either the E7 or regular GT40 head, or the iron GT40P's 60cc chambered-head (pushing towards 11:1), but you may have to back off advance, and run super unleaded in it 24/7 with the P head.

    So far as ignition advance is concerned...conservative is the key here, with the amount of compression that is in play, I would not go much more over 10 degrees initial, if at all. I would go ahead and make it advance a little sooner, as what you would want with an auto tranny-equipped vehicle, but definitely start small, and work your way up. I disabled the vacuum advance with the cast-iron-headed motor, as it caused pinging.
    From what I remember, the AFR motor was around 10/34 and the cast iron motor was the same , but with no vacuum advance. It will run with 87, I just felt some extra safety in running 89 or 91/92 octane. If you are going to run 91/92 octane only, then you can experiment with bumping it up.

    Intake setup? Weiand stealth, with a Barry Grant 625 cfm Road Demon.

    This motor should have super-snappy throttle response, especially with a small cam in it. My preferred cam is the stock 5.0 HO roller, preferably the 1987-1988 SD mustang/Lincoln MK7 LSC HO cam....


    Keep in mind that you aren't going to be making the same power numbers as the motor I built with the AFR heads, depending on which head you use, you could be 20-40 hp short of my motor.

    block clearance?
    No. Nothing changes, unlike a stroker motor.

  5. #5
    diesels kick ass!!!! sploer4.0's Avatar
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    you may not believe this but i have figured out a way to fit 6.5" rods in a 351w
    Quote Originally Posted by GMGT
    you mangwhore


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    This sounds perfect for my 88 F-250. What kind of mods will have do be done to the EFI system and fuel system?

    I'd be happy as hell to have 300 RWHP outta my truck.

  7. #7
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    I want the details on the long rod 302 setup. Its interests me.
    1989 Grand Marquis LS
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  8. #8
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    Quote Originally Posted by Nitro Blazer View Post
    This sounds perfect for my 88 F-250. What kind of mods will have do be done to the EFI system and fuel system?

    I'd be happy as hell to have 300 RWHP outta my truck.
    If you use the stock camshaft...replace the stock 5.8 truck intake (either buy an Edelbrock, or buy a Price Motorsports 302/351W intake adapter and use a 302 truck intake, remembering to port the lower half of the intake before installation....swap in a 5.0 HO cam...and put a good set of headers on it. Preferably, I would install a set of regular GT40 heads in place of the factory turds....

    The trick here is that long-rod engines don't require as much airflow as a regular-rod counterpart. With the KB pistons that were recommended...comp ratio will be around 10.5:1.


    Quote Originally Posted by Southern_Pride View Post
    I want the details on the long rod 302 setup. Its interests me.
    You have two options:

    1. Common aftermarket 5.4" rods, and custom forged pistons...

    2. 400 Chevy small-block 5.565 rods, with the big ends resized to fit on the 302 crank rod journal, along with Hypereutectic KB pistons.

    To be honest, I would go with a custom set of forged pistons on the 400 chevy rods, because the flat-top pistons don't allow for much of an increase in compression. I'd shoot for the same 11:1 pistons with aluminum heads, or 10.5:1 with cast iron...then it would be worth doing, unless you are supercharging the motor. Otherwise....there isn't going to be much of a power difference with going to a long-rod 302 with the existing off-the-shelf hardware that's out there now.

  9. #9
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    Just curious. I have high hopes for my crappy heads. Its not so much the power gain that interests me as much as the less vibration. May make the block hold up better. I may do one one day. Are you talkin 400 pistons in a 302? KB doesn't list 302 pistons for that rod length in a 302 but then again why would they. Just want to be clear on the details.
    Last edited by Southern_Pride; 02-12-2009 at 12:59 AM.
    1989 Grand Marquis LS
    flat black, 650 double pumper, random cam, hei, stealth intake, Police front springs, Wagon rear, Police rear bar, wagon front ,exploder wheels, 205/60-15 fronts 275/60-15 rears, 1 5/8" headers, 2.5" offroad x pipe, Eclipse front bucket seats, Custom floor shifter, 4.10 gears, aluminum driveshaft and daily driven. 16.77@83mph

  10. #10
    Pirate
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    Quote Originally Posted by Southern_Pride View Post
    Just curious. I have high hopes for my crappy heads. Its not so much the power gain that interests me as much as the less vibration. May make the block hold up better. I may do one one day. Are you talkin 400 pistons in a 302? KB doesn't list 302 pistons for that rod length in a 302 but then again why would they. Just want to be clear on the details.
    No, they are 302 pistons....and after checking the KB website....they look like they are no longer available.

    Well, unless you find a set on Ebay, or if summit has a set....the 5.4 route, or custom forged piston route is the only way to go.

    EDIT:

    Summitracing.com:
    http://store.summitracing.com/partde...6&autoview=sku
    Last edited by Pirate; 02-12-2009 at 06:23 PM.

  11. #11
    Member Nitro Blazer's Avatar
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    So I can build that motor and drop it right in the truck and go? No bigger injectors, pressure regulator, fuel pump?

    I think I'm going to get started on this right away.

  12. #12
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    Quote Originally Posted by Nitro Blazer View Post
    So I can build that motor and drop it right in the truck and go? No bigger injectors, pressure regulator, fuel pump?

    I think I'm going to get started on this right away.
    As long as the camshaft isn't changed to something that screws up the vacuum signal, or requires bigger injectors...no. I would recommend that the injectors be professionally cleaned and flow-tested, however. In addition, if you are going to be doing this right, I would seriously look into getting some basic GT40 heads, at least the 302 truck EFI intake (hogging out the lower manifold) with adapter, and a set of headers. A Mustang HO roller cam would also be a nice addition.

  13. #13
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    If I were to do it I would certainly get the edelbrock intake and the GT40 heads. I would probably stick with shorty headers to save a little cash on the exhaust. I'd probably use the stock y pipe and remove the giant cat and use two high flows with an x pipe and flowmaster 40's for true duals.

  14. #14
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    Quote Originally Posted by Nitro Blazer View Post
    If I were to do it I would certainly get the edelbrock intake and the GT40 heads. I would probably stick with shorty headers to save a little cash on the exhaust. I'd probably use the stock y pipe and remove the giant cat and use two high flows with an x pipe and flowmaster 40's for true duals.
    Just make sure to get 351W-specific truck headers...To be honest with you, I'd just use that Y-pipe and make a 2-into-1 exhaust system, using a Flowmaster Y-junction, and run a 3" single out the back. If you are supposed to have cats on it...some states don't like it when you put duals on a vehicle equipped with a single exhaust...and that keeps it cheaper, running the single, not to mention works better with the rpm range that this motor will make power in.

    Having personally installed dual 2 1/2" exhaust on a similar-year Bronco...without a tubing bender...the single is less grief to install, also.

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    Well in that case I might just leave the exhaust like it is. It's somekind of shorty headers into the stock cat and out to a hooker muffler which I believe is 3 inch.

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    Member of the Orb Alliance packman's Avatar
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    Seeing as this set up has a lot of potential in our cars, I'm wondering if the shortened piston deck height (especially with the pin located in the way of the oil ring) is gonna wreak havoc with emissions? Other than that, this engine should have a lot more accelaration than a standard 351W.



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  17. #17
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    Howdy, gang.....

    I have some more 302 long-rod information handy.....and have located forged pistons for this setup.

    http://www.kb-silvolite.com/feature....n=read&F_id=21

    Of interest is the KB747; it's for a stock stroke 302, with 5.4 rods. In addition, it produces 10.6:1 compression with 64 CC heads....with a little smoothing of the dome, this piston, coupled with a 5.4 rod, should let you get away with around 10:1 compression with either E7 heads, or regular GT40 units.

    Concerning rods....you don't really need much of a connecting rod with this setup, I've located some from Ebay:
    http://cgi.ebay.com/ebaymotors/ws/eB...link:middle:us

    Yeah, it's the chinese rods, and I need to do some background checking on whether or not they're worth a damn....but it's a start.

    A set of Scat I-beam 5.4 rods would work well, also.

    To be honest with you, I'm pondering building one, as I already have most of the equipment fresh and ready to go. So far as what heads to run....I'm finding a lot of AFR 165's out there that would be perfect, or maybe even just clean up my existing GT40P heads, and do some more smoothing of the pop-up dome on the KB747 pistons....

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    i have a few questions pertaining the 351w long rod setup.

    1.) as far as efi is concerned, what kind of fuel system (injectors, maf, pumps) does it require and im assuming the tuning process would be different than that of a typical performance 351. if theres an article or thread on some site about this please lead me to it.

    2.) how exactly does it let you use that kind of compression on pump gas?

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    Quote Originally Posted by 70torino429 View Post
    i have a few questions pertaining the 351w long rod setup.

    1.) as far as efi is concerned, what kind of fuel system (injectors, maf, pumps) does it require and im assuming the tuning process would be different than that of a typical performance 351. if theres an article or thread on some site about this please lead me to it.

    2.) how exactly does it let you use that kind of compression on pump gas?
    bump.

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    Why screw around with a small block??? 385 FTW!!!!!

    nothing against small block Cleveland's but everything else is a planter or boat anchor...
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