79 R/T. 360 to replace 318...

Engine Swaps

  1. MBDale

    MBDale Well-Known Member

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    Hey guys, just joined the forum and have always loved the aspen body style and how they are a totally underrated muscle car from mopar. Anyway I've got a 71' 360 block from a friend. It was rebuilt 10+ years ago with TRW hyper eutectic Pistons with the skirt coating and 1.88 "J" heads. It's never ran in a car but it was uncovered and all dirty. Now it's at home and apart in the basement. Block needs a good cleaning and I'll probably go with 2.02's. Thinking of a cam comparable to the mopar 450/455 . I had that cam in a 360 with 2.02 heads and these same pistons and was happy with it in a '72 Swinger. I've got the 360 oil pan and a new MP distributer kit that I was going to use on my 340 Duster but went with a fancy MSD. Also a Holley 670 street avenger. So that's the engine I'd like to put in a 79 R/T that's for sale nearby. It's a orange car, black interior. 318. Buckets-console.Don't know if it's a 727 but suspecting a 318 car would be a 904 trans with it. Would this car have 3.21 open diff?? I can get a 8 1/4 from buds '73 Dart sport, 3.55's. How hard would it be to fit it? Custom drive shaft? I've got Cop rims cause their way cool. Headers of course. Will the 318 radiator hold to a 9.5 compression 360? I'm thinking of the car running and driving with a valid vehicle safety for less than $5000. Thoughts?? Advice??
     
  2. greymouser7

    greymouser7 Well-Known Member

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    Welcome aboard!
    I have heard mix reviews about some of the street avenger carb's.
    I think there is a dealer ship in Colorado that has one, or check Idaho craigslist.
    shop around for deals to keep it well under $5K
    my-craigs-finder.com
    for example:
    http://columbus.craigslist.org/cto/5172872875.html
     
  3. greymouser7

    greymouser7 Well-Known Member

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  4. Captain Caravelle

    Captain Caravelle Moderator--Mopar Maniac

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    Welcome aboard.
     
  5. Superpac Ninja

    Superpac Ninja Well-Known Member

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  6. Superpac Ninja

    Superpac Ninja Well-Known Member

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  7. lowbudget

    lowbudget Well-Known Member

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  8. jasperjacko

    jasperjacko Well-Known Member

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    A-body is narrower on both counts.
     
  9. MiradaMegacab

    MiradaMegacab Well-Known Member

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    318 is internal balance
    360 is external balance
    Dont swap dampers or flex plates.
    I have my 360's internally balanced, you might want to verify yours as it was rebuilt.
    The drivers side motor mount is different too.
     
    dodger roger likes this.
  10. MBDale

    MBDale Well-Known Member

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    Thanks Mirada, I'd clean this block first. Was thinking it'd be worth my time to balance rods, crank, and Pistons before assembly. Since its a whole can of worms for the external balance 360 thing should I just go with a B+M flex plate? If so what kind of balancer too??
     
  11. MiradaMegacab

    MiradaMegacab Well-Known Member

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    Are you planning on doing an internal or external balance?
     
  12. MBDale

    MBDale Well-Known Member

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    I'm unsure of matching balancer to flex plate to torque converter. So to answer your question, external.
     
  13. MBDale

    MBDale Well-Known Member

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    Slight damage to front drivers fender.

    image_1440225123072.jpg

    image_1440225142543.jpg
     
  14. MiradaMegacab

    MiradaMegacab Well-Known Member

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    So you need a 360 harmonic balancer. (External balance) ATI makes a nice product.
    Id run a neutral balanced (internal balance) torque converter with an offset weighted B&M flexplate.
    The converters arent interchangable between 904 and 727.
    For your application Id run a non lockup 904/999 with the low first gear. That will help with off the line acceleration, over the 727. Plus you can keep your driveshaft and yoke. The yokes are different between the 904 and 727.
     
  15. MBDale

    MBDale Well-Known Member

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    I'm out of town for work and won't be home for a month. But when I get to the car I'll be removing the 318. It's siezed anyway and I'll check if the diff is an 8 1/4. Also going to remove the seats and get them recovered.

    image_1441709595394.jpg
     
  16. MBDale

    MBDale Well-Known Member

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    This is when I got the car to a friends.

    image_1443922161671.jpg
     
  17. kimrpaige

    kimrpaige Member

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    Great thread, as I am in the same boat. I am going to put a 360 in my 77 Aspen which has the original 318. I am retiring in a couple of months so this is my "retirement" project, LOL The 318 runs perfect but I want a 360. My Aspen has a 904 and a 8 1/4 with 2.94 open diff. I have two 360 blocks, one out of a Lil Red Express along with the 727 that came on it and a short block that came out of a 83 Motorhome with 12K on it. I too am going to use the 904 as it has less rotating weight, I know I will either have to get a 904 converter with weights or use the B&M flexplate. I am a bit confused if I use the flexplate, does that mean I can use my 318 converter? I also thought that the pass side mount is different, so I need to find one of those either the right or left whichever one is different. I also need a pan as both my 360's are truck/van pans. I am trying to figure out which pistons and cam to use also. I am getting a pair of reworked 360 J heads sometime this week, not sure of the casting numbers. I will probably start a new thread and see where it goes. Sounds like a lot of gurus here to help us out :) Kim
     
  18. NoCar340

    NoCar340 Well-Known Member

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    Neither block is better than the other. A 360 block is a 360 block; the old wives' tale about early ('71-'73) blocks using the 340 water jacket cores, giving them thicker cylinders, is total bunk. The higher-mileage block would technically be a more-stable platform due to heat cycling, but a 12K-mile block won't even have ring ridge and should be able to be built with standard-bore pistons after a quick hone to renew the crosshatch. It's win-win, really. Neither block is a bad choice; personally I'd probably use the low-mile virgin.
    Good call on the 904, but have it rebuilt with cast-iron bands and Alto Red Eagle clutches. Put a shift kit in it, lose the accumulator spring and loosen the line-pressure adjustment until only about 1.5-2 threads are showing on the back side of the plate. Use Type F or FA fluid only. It will live a long and happy life this way, and give you a screech into 2nd on full-throttle upshifts.
    Use a B&M flexplate and you can use the stock 318 converter. However, to get the most out of your engine build you'll want something with more stall. How much? Well, that's going to depend on your engine build, but it's safe to say 2,400RPM would be minimum based on the fact that you mention worked J heads.
    Driver's side only. It's the same mount used on any 360-powered car with spool-type mounts ('73-'79 B-body, '79-'80 R-body, and any F/M/J '76-'80). It's narrower than the 318 mount.
    Summit sells an inexpensive center-sump pan that's a stock replacement. It's a good-quality piece. Any parts store should be able to get you the appropriate pickup; just order one for your car as if it were a factory 360 and you're good to go.
    Pistons are going to depend on the compression you want and where your heads measure for chamber volume. I've seen the 3418915 J heads (casting numbers may end with a letter, like 3418915D, etc.--makes no difference) with chambers ranging from 70-76cc so it's best to measure (cc) them before deciding on a piston. A few cubic centimeters can make a big difference in compression. 9.5:1 is a very happy ratio on 91-octane pump junk. If you're not willing to pay for premium, I'd say stay around 9.0:1 which should keep you safe when you get some of that really-bad reformulated crap that passes for gasoline these days. The 916Js are great heads, even with the 1.88" intake valves.
    Once you know what compression you're going to have, call a cam manufacturer. Tell them what you've got, and what you want it to do. Answer their questions honestly and don't try to make it sound like you've got better stuff than you really do. Follow their recommendations. They offer this service for free and they're almost never wrong. Bigger isn't better, and these guys live, eat, and breathe cams. Cams pay their bills. Don't second guess them. If you are 100% honest with them about what you have and what you want, you will be 100% happy with the cam they choose, guaranteed. If you prefer Comp or Crane or Howard's or Cam Motion, it makes no difference. None of 'em are going to steer you wrong. Call--don't fill out a form or e-mail. Get a voice on the phone. If they don't want to talk about it, take your business to someone who does.
    Nobody here but us chickens. :D
     
  19. 80mirada

    80mirada Well-Known Member

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    If you have a lock-up converter 904, there is a decent selection of aftermarket converters now, and they help fuel mileage. The 318 driver side mount can be used with a shim between the block ear and the rear ear on the mount.
     
  20. kimrpaige

    kimrpaige Member

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    Nocar,
    I understand about the blocks all being the same, I will probably dis-assemble it take it to a machine shop and boil it out , replace freeze plugs and install new cam bearings, and like you said, hone it and buy new std. size pistons. I will research the 904 rebuild parts you mentioned, that is a bit out of my realm so a good tranny shop will do the labor, LOL. I am thinking if I am going to purchase a new stall converter, I should by one for the 360 with weights on it rather than the new flex plate. I am still a bit confused on the drivers side mount as I look at parts like from Rock Auto, they list the same mounts for 318, and 360. What am I missing? the bracket that mounts to the block? So I am folowing you on the cam selection. I do not have the heads yet so I do not know the specifics. So do I have the machine shop cc them or do i or can I do it like the How to hot rod small block mopar book telll how to do it. I have been a mechanic for over 40 years, but believe it or not never a hot rodder. So once I got the compression down and the stall converter determined, tire size, rear axle ratio, The cam company will tell me what cam. I understand about too much cam, as most people use too much carb also. I am using a Performer intake, 600 cfm Edelbrock carb, MSD ready to run distributor (already on my 318) Thanks so much for all this info. This is what great about a forum. Thanks again, Kim