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Project 1950 Pontiac straight 8 to a small block V8 chevy. What do we need to know?

Discussion in 'The Hokey Ass Message Board' started by Jay Tyrrell, Jan 4, 2012.

  1. Jay Tyrrell
    Joined: Dec 9, 2007
    Posts: 1,631

    Jay Tyrrell
    Member

    Hey,
    I have a buddy that we have finally convinced to do a motor swap on his 1950 pontiac torpedo back straight 8 to a small block chevy V8. The straight 8 was great. It got us back and fourth from Chicago for the Hunnert car Pile Up a couple years ago, but it is starting to get really tired and it is burning way too much oil. He also wants to be able to hang with the pack, go on longer trips, and needs it to be more reliable. He also does not want to be adding oil every stop to it. So a small block chevy motor is a good option for him I think. I was wondering if anyone has done this before and what helpful hints, ideas, or snags that you can share before we jump into this project. Here is a pic of the car.
    Thanks
    J
    016.jpg
     
  2. 50'SilverStreak
    Joined: Sep 12, 2015
    Posts: 12

    50'SilverStreak
    Member
    from Alabama

    Did you get the engine swapped in the car? I have a 50 silver streak I am thinking about making the conversion on. Any advice you can give or threads you can point to? I have been doing research and see people talking about converting to sbc, but have not seen any tech info on the swap.
     
  3. TudorJeff
    Joined: Feb 13, 2007
    Posts: 1,132

    TudorJeff
    Member

    Miscellaneous things I’ve learned since buying a 1951 Chieftain

    · Don’t let the “Pontiac guys” know it has a SBC. When rarely asked, I tell them it has a “Corporate GM Engine”. Even though most of them drive Aztec’s and Sunbirds.
    · There is a lots of room to put an SBC in the engine compartment since it originally held a straight 8.
    · A mechanical fan on an SBC winds up being toooo far from the radiator to do much good. A good electric fan is recommended
    · The stock shifter for the original auto trans connects to a TH350 very easy.
    · The stock rear ends have pretty low gears 3.63:1 with some all the way up to 4.30:1 making a 350 / TH350 not too great on the highway. They would be better if using a 700r4.
    · The stock rear ends leak, bad
    · An aluminum radiator for a 1947 to 1954 Chevy truck (like the $200 ebay specials) fit perfect in the stock location with just making some minor brackets. Even the drain plug lines up with the stock location. The V8 ones will have the hose locations correct as well.
    · A 1979 Firebird rear end (GM 10 bolt) with 2.73:1 highway gears makes for a nice replacement and compliments the 350/350 combo nicely. They are 62.5” wide.
    · A 1979 Firebird rear end (GM 10-bolt) “fixes” the clearance issue and rubbing of the driveshaft on the bottom of the floor in a lowered car. The output of the pinion to the driveshaft is lower than on the stock rear end.
    · A 1979 Firebird rear end requires that you replace the rear wheels to match the new smaller 5x4.75 bolt (instead of the stock 5x5 pattern).
    · Most new steel wheels are more positively offset than the stock Pontiac steel wheels (the new wheels stick out further), about .75”
    · If I were to do it again, a 68-79 Nova might be a better replacement if you are going to buy new stock steelies. They are 60.25” wide.
    · I replaced the stock steelies with custom 4.25” back spaced 15x6 wheels from The Wheelsmith.
    · I am not sure which rear end would be a good replacement if you want to keep the 5x5” pattern.
    · St. Louis Spring makes some great rear leaf spring replacements. The 4” drop worked for me.
    · New shackles (RP35455) and bushings make a huge difference in how the car handles.
    · Replacing the bushings in the frame will make you use curse words that haven’t been used since the dawn of time.

    Other stuff
    · California Pontiac Restoration sells good stock fuel sender and pickups.
    · A 1950 instrument panel can fit new style round gauges (Autometer) with just a little bit of work.
    · A 3-3/8” tach (Autometer) will fit where the stock clock goes, with a little trimming and cursing.
    · Autometer will recalibrate their fuel gauges to work with the stock sender for just a few dollars. But it’s weird. You have to buy the gauge somewhere like Summit, then send it back to Autometer (where the gauge was originally made) to have it recalibrated.
    · Newport wiper kits (Tanson Enterprises) for these cars are awesome, you can even mount the switch in the stock location at the center of the dash.
    · A tapered front wheel bearing kit is a good investment and cheaper than the stock roller bearings.
    · A Lokar or some other spoon pedal replacing the stock pedal gives you much more leg room and allows your knee to not be seized up after a multi hour drive.
    · A Gen IV Vintage Air system fits behind the dash as long as you don’t mind losing your glove box.
    · Once you have installed AC, electric fans, an new wiring harness, electric wipers, led backlit gauges, extra courtesy lights, etc., a 140 amp alternator make a nice addition.
    · Even rebuilt and reasonably adjusted front drum brakes on these cars leave much to be desired. Scarebird looks to be the next good investment.
     
    Last edited: Oct 1, 2015
    50'SilverStreak likes this.
  4. 50'SilverStreak
    Joined: Sep 12, 2015
    Posts: 12

    50'SilverStreak
    Member
    from Alabama

    Thank you both for your responses. They are very helpful and give my a lot to work with. My first upgrade is going to be front brakes. I have the Scarebird kit and I'm in the process of gathering up the rotors, caliphers, bearings, etc. needed for the job. I will be posting pictures of that project in a few weeks. Any info on which master cylinder to use?
     

  5. 50'SilverStreak
    Joined: Sep 12, 2015
    Posts: 12

    50'SilverStreak
    Member
    from Alabama

    Tudor, thanks for all the details. There is much there that I will use and it will make things easier. Greatly appreciated.
     
  6. Nikkerton
    Joined: Dec 5, 2019
    Posts: 197

    Nikkerton
    Member

    Hey did you ever end up getting your SBC in? I am about to pull my inline six and have a 350/TH350 waiting but I haven't gotten mounts yet. Any advice on your mount choice and placement?
     
  7. zinbobwy
    Joined: Mar 25, 2011
    Posts: 8

    zinbobwy
    Member

    I am getting ready to do the 350/350 in my 51 streamliner, first going to modify the frame so I can use a jag from end, I have the front clip and straight 8 out, looking at the frame and doing a little coffee shop engineering, dosent look too bad, plus I like fabricating.
     
  8. FXN2XLR8
    Joined: Jun 17, 2010
    Posts: 8

    FXN2XLR8
    Member
    from Texas

     
  9. FXN2XLR8
    Joined: Jun 17, 2010
    Posts: 8

    FXN2XLR8
    Member
    from Texas

    Howdy, Mr. Tudor Jeff from San Antonio. I hope this text finds you in the VERY best of health. I recently purchased a 1950 Pontiac 2dr Streamliner because I REALLY can't remember the last time I saw one " Live " I read your information about various projects with this particular car. I CANNOT thank you enough for ALL your help with this project. One question I have is ....I purchased the ...Universal Cross members for the Engine and Transmission that slide in between the frame rails because I just ....assumed....that the engine and transmission mounts won't line up with the Straight 8 cross members so I thought ....let me get these so I can put this 327 engine and 700R4 transmission ( like you suggested ) in this car........does this make sense? AGAIN.....Thank you so VERY much for ALL the information with this project.......An incredible amount of help to me ! ! ! ! ....TRULY hope to see you sometime in the future cruising around Texas.......Oh...also are there any Pontiac clubs that I can join around San Antonio, New Braunfels, Canyon Lake ?
     
  10. TudorJeff
    Joined: Feb 13, 2007
    Posts: 1,132

    TudorJeff
    Member

    I saw someone "quoted" my post. I had actually forgotten about this post, hell I'd kinda forgotten about my Pontiac for a while. For the other vehicles I have, it winds up sitting for 6-8 months at a time. However I've recently started playing with it again and have had the following completed... So here is another round of "What I've learned from owning my '51 Pontiac".

    Got the Scarebird kit installed and added a Speedway swing pedal, booster and MC. The kit is great and could work just as well (and easier) without the booster but it stops good and is super easy. It takes just one toe to bring the heavy car to a halt, straight and no pulling too. As you probably know the kit comes with caliper brackets and a list of stuff to buy from the local auto parts store. I like this because it makes your stuff super serviceable. Besides the brackets and some spacers, you need to buy stuff like Chevy truck rotors, Cadillac calipers and pads, Buick Riviera bearings and seals, and it even tells you what hoses to buy. I also had to buy new metric lug nuts to go with the new rotors.

    I also bought some new steel wheels to fit over the rotors.

    The swing pedal & booster (dual diaphragm) came from Speedway and were for GM disk / drum. Had some trouble getting it dialed in and I even reached out to Scarebird "tech support" who suggested that I "get rid of that piece of shit booster". Haha. But we finally got it working great.

    I also bought some new shocks, bump stops and had the center link rebuilt, tie rods replaced, and a new pitman arm installed.

    Honestly if I had to do it over I would have the car clipped or have someone way smarter than me just put a MII in it. I still might do that anyways just for kicks and to have a power rack.

    In other fun news I also put a new PPI amp to power a Kicker 8" sub my buddy handed down to be. It was going to go in my c10 but it sounds pretty sweet in the old Pontiac! Especially since it's just a headphone cable straight in to the amp from my phone or iPod.

    Next up for me is to install my new TH350 from Phoenix Transmissions I've had a few months and swap in some new Thornton Chevelle shorty headers I just got. Headers have been a hassle on this car. It had what I thought were truck manifolds on it, but they turned out to be Chevelle manifolds. These new headers look to be an exact fit for the manifolds so I will report back in a few years to let you know how they turned out! haha.
     
    TinoOrtiz likes this.
  11. TudorJeff
    Joined: Feb 13, 2007
    Posts: 1,132

    TudorJeff
    Member

    Hi there! The universal mount should work ok. I bought my car with the SBC already in it so it just has some home grown mounts and stuff so I don't know much about how they were engineered. I can say that the motor is sitting way back since the HEI is close to the firewall and the water pump is a long way from the radiator.

    The only Pontiac club I am aware of around here is more of a muscle car / restored / resto mod club so they may not appreciate the 327 swap. Maybe if you had a 421 in there instead, haha.

    If you have specific questions, it's easier to just PM me since I don't get on here too often. Good luck with your project.
     
  12. MeanGene427
    Joined: Dec 15, 2010
    Posts: 2,307

    MeanGene427
    Member
    from Napa

    Why not just put a big Poncho in there? 389-400-428-455 are the same size as a base 326, and would drag that beast around very well. A decent Poncho also has a much better sound than an average SBC, and they look great when dressed up
     
  13. jimmy six
    Joined: Mar 21, 2006
    Posts: 14,795

    jimmy six
    ALLIANCE MEMBER

    Better give that barge some cubic inches with some stroke to get it out of its own way. I’d be looking close to 400”. Pontiac has a few from 389 to 455.. good luck.
     
    Unique Rustorations likes this.
  14. LOL know what I have learned from Pontiac guys and corvette guys and MOPAR guys and just brand conscious guys in general? Labia against my glutei maximi is extremely pleasant.

    Old thread, and I can't imagine that it takes much of a show horn to get an SBC where a straight 8 once resided. :D
     
  15. Essex_29
    Joined: Dec 27, 2007
    Posts: 145

    Essex_29
    Member
    from Finland

    As MeanGene427 says, the sound from a Pontiac V-8 is much better than that from Chevrolet small block. I had a 400 cubic engine in my '70 LeMans. It sounded great, was nicely powerful, and had great mileage. So, yes, I'd go with a Pontiac engine, in part because it would be so cool. Everyone's got an sbc...
     
    Guy Patterson likes this.
  16. MeanGene427
    Joined: Dec 15, 2010
    Posts: 2,307

    MeanGene427
    Member
    from Napa

    And they all stink- sorry, couldn't resist lol. I had a sweet 72 Grand Prix for a while, with the 400, best sound I ever heard from Flowmasters- almost like an FE
     

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