1. TheSkunk

    TheSkunk Active Member

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    Alright guys I’m having difficulties deciding what route to go..

    Needs:
    Run on pump gas
    Streetable/daily (more weekend toy but girlfriend drives every now n then)
    Be rather budget friendly.


    what I have:
    Complete Roller 360
    Complete Magnum 360

    set of j heads (1.88s)

    what yeah got? Been looking into swapping the mag heads onto the roller la? Will be going in my Lebaron looking to get some fun pony’s while still maintaining manners not afraid to port or mill the heads would prefer to leave bottom end alone as long as they are good..
     
  2. Duke5A

    Duke5A Well-Known Member

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    What transmission is in the car? Only way I'd entertain an LA over a Magnum (assuming both are in good shape) is if I had to worry about the balance. B&M makes a weighted flexplate to mate a Magnum to a 727, but not a Magnum to a 904. Of course this can still be overcome by just welding the appropriate weight to the converter, so it still might be a non-issue for you.

    Magnum doesn't have provisions for a mechanical fuel pump either. You would just need to get a fuel pump eccentric for the end of the cam and use the LA timing cover you have, but you would lose the serpentine belt setup. Might want to run an electric pump.

    But yeah, Magnum all the way. The heads in factory form will support 400HP. You probably don't need do anything to them beside freshen them up. If the bottom end is fine, then just toss new seals at and leave it alone. I wouldn't go anything over 230 degrees @ .050" on the duration for the cam for a street driver that sees GF duty. It'll still have plenty of lope though, but you can use 3.5x gear.

    What gear is in the car?
     
  3. TheSkunk

    TheSkunk Active Member

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    Car will have a 904 type trans behind it I can’t remember what the other trans I have is out of..? A Cordoba maybe idk. Currently has original 8 1/4 with 3:?? Gears. Will be looking into swapping to 3:55s this winter.

    I’d really like a stout 360 but don’t know where to begin.. I really like the number from this build but am cautious of just how streetable it would be? Any opinions?
    “360 rebuilt with 9.5 to 1 cast pistons, original crank, rods and windage tray. 202 heads with competition valve job and ported to flow 260 cfm. Edelbrock RPM intake, Holley 750 rejetted, Large tube headers and Mopar Performance P4120231 cam with .484" lift, 284 duration, 108 lsa, installed at 106 intake centerline.
    460 h.p. @6000 rpm
    486 lbs. of torque @ 4,250 rpm” I think that torque number would really liven the big girl up but I don’t wanna go too radical..
     
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  4. TheSkunk

    TheSkunk Active Member

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    I’m really looking into all options at this point. Magnum engine entirely mag heads on the la or..??? Lol I hate having options n just don’t wanna be disappointed when it’s all said n done.
     
  5. Opticon77

    Opticon77 Well-Known Member

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    Then I'd be careful of those stock Magnum head castings with their cracking problems. If you were planning port work anyway just spend the extra cash on aftermarket heads. I think the Edelbrocks do 250cfm @ .500 out of the box.
     
  6. TheSkunk

    TheSkunk Active Member

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    I can get the heads checked milled and bowl work for $530 from a well reviewed shop so if they were good I was gonna try n run em unless it will cause issues?

    I don’t really have any numbers in mind I’m just looking for a very healthy yet reliable motor. Idk maybe my expectations are to high and I’m better off just keeping it closer to 350hp. but I see builds claiming it’s easy to make 400-450 n still have manners?? that’s why I’m here asking for some real world experience
     
  7. Duke5A

    Duke5A Well-Known Member

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    350HP is a cakewalk.
    400HP is doable while maintaining street manors, but involves careful parts selection.
    450HP out of a stock stroke smallblock is beyond what a lot would consider to be a street friendly car.

    Define some parameters for the build. A street car lets say 5500 RPM max, no more than a 3.55 gear to make highway trips tolerable and 93 octane friendly. Now work within those limits. 370HP with that in mind is doable. Little over 1HP per cubic inch.

    ....and the most important question: what is your budget?

    A factor rotating assembly on either block, Edelbrock heads, an RPM intake and a roller cam of somesort (don't use a flat tappet) will get you there pretty easily.
     
  8. TheSkunk

    TheSkunk Active Member

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    Gotcha and I would say I’m trying to stay under 3500 I think is realistic. I’ll do everything I can in house. Not scared to do the work I’m a diesel mechanic during the day n hot roder by night lol.

    And I figured I could get 1hp per cube rather easily with today’s cams n re working the heads but idk if my goal of a streetable stock stroke motor was out of touch or was a mater of sitting down n picking the right parts. Thanks for all the replies guys keep it coming
     
  9. 79410aspenrt

    79410aspenrt Well-Known Member

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    i ran this engine on the street for a few years. solid flat tappet over 600 lift, super victor single plane intake, 4500 rpm stall, 3.55 gears. i would say it was close to 500 HP. it was a blast to drive on the street. i live 30 minutes from town and it made lots of hwy miles. i've used SFT on the street for 20 years, never had a problem
     
    Last edited: Apr 15, 2020
  10. 79410aspenrt

    79410aspenrt Well-Known Member

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    Hughes Engines

    i would get this cam, have compression around 9.5, air gap intake, 750 DP holley, 1-5/8 headers, hughes 1.5 roller rockers, leave bottom end stock, get a good valve job done. you do not need big valves in heads for what you are doing. 3.55 gear with a 3500 rpm converter.

    i ran something very similar back in 2006 in my R/T. ran 13.2 in the 1/4.
    don't bye into all the ''don't run a SFT on the street or roller rockers always need adjusting'' crap. the first thing i have always done was put a SFT cam in and min 3500 rpm for the street.
     
  11. TheSkunk

    TheSkunk Active Member

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    you wouldn’t happen to have more detailed specs on that engine do ya? If I can find a rather cookie cutter recipe that be even better. I’ll also talk to my machine shop and see what they recommend but am happy to see some ideas coming in
     
  12. Mikes5thAve

    Mikes5thAve Well-Known Member

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    Id plan on changing to a 727. Next to the 7 1/4 axle that's the weakest link. Actually it might be comparable because I've blown up more 904s then axles.
     
  13. 79410aspenrt

    79410aspenrt Well-Known Member

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    i disagree with this. 904 all the way. i finally switched from 727 to a 904 and will never go back to 727. if the 904's are blowing up that frequently, i would wonder about the transmission builder instead of the actual transmission
     
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  14. Mikes5thAve

    Mikes5thAve Well-Known Member

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    I've gone thru enough of them over the years to never want to touch one again unless it was in a car making minimum power.
    One look at the smaller size of the parts inside them shows where the weak links are.
    Now if it was in a car that mainly sees strip use it would be 904 all the way for the weight savings but in a driver I'd take reliability of a 727 or 518 any day if someone wants to go OD.
     
  15. Duke5A

    Duke5A Well-Known Member

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    I'm sorry, I just can't agree with this. That cam you recommended has 242 degrees of duration @.050". It's going to develop very low vacuum. Non-Chinese adjustable roller rockers required for that mechanical cam will run you $700 (Do not buy Chinese rockers unless you want to be doing this all over again).

    Good converters cost money. You can drop $800 on a piece that has good cruising manors with a high stall number. Cheap ones will not have lockup and will feel like a wet noodle under cruise.

    You want to build something more oriented to low end torque - especially for street duty.

    You can see that everyone's idea of a street car can vary wildly.

    You have two factory roller blocks to choose from. Use a roller cam with no more than 224 degrees of duration at .050". Maybe even a little less. Reuse the factory rockers and maybe even the roller lifters if they're in good shape. Use the money saved to pickup a set of alloy heads. Some sort of a vacuum secondary carb like a 770 Holley Street Avenger.

    Don't go more towards the realm of a track car for your first build.
     
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  16. TheSkunk

    TheSkunk Active Member

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    Thanks again guys and I agree street car and race car on the street are two different things. I like all the feed back keep it coming
     
  17. 79410aspenrt

    79410aspenrt Well-Known Member

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    it all boils down to what you want to do. have a stock very boring no fun to drive frown on your face car or do you want some rumble from the mufflers put you in your seat on acceleration smile that never goes away people look at your ride car. it's your choice.

    this combo is very street-able and will have you smiling. do it once and done has always been my way of thoughts. i have run way more cam, compression, stall, gears, on the street for many years from big blocks to small blocks.
     
  18. Mikes5thAve

    Mikes5thAve Well-Known Member

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    The magic phrase that was mentioned was budget friendly.
    It comes down to what this car is really going to be used for. Lopey cam and loud exhaust is fun but can get tiring after a while if it's a daily driver or a crusier when you want some peace. At the same time in close to stock form what's the fun in driving an FMJ when a new 4 banger econo box has better performance.
     
  19. 79410aspenrt

    79410aspenrt Well-Known Member

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    the combo i mentioned above is no where near a strip only car. entry level performance street/strip car at best. not much $ invested and still performs well enough to keep the smile on the face. a set of dynomax ultra flows will be awesome on the street
     
  20. TheSkunk

    TheSkunk Active Member

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    Alright so iv been mulling it over.

    I’m contemplating going with kB 107s to try n help gain some compression vs the stock pistons. Is there anyway to improve compression ratio with stock pistons without mill the heads or deck to death, and is it worth it vs going new pistons and a slight mill on the heads? I guess I’m a little confused how the kB pistons raise compression so much without mill work (might just be over thinking and am replacing the light bulb before flipping the switch)
    Also Is it really worth going to different heads if my factory mag heads check out well? Or even my 1.88 J heads?

    I like the idea of the rpm air gap intake and am waiting to decide on the cam atm due to trying to figure out what works with stock magnum valve train (if I go mag head) or other depending on what heads I use. I am looking at getting the tti long tubes as well.
    I hope these questions are to simple minded I’m just kinda flooded with info right now and being first engine build I’m double/triple checking. Thanks!