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Thread: Olds 455 buildup for jet

  1. #1
    Boostedballs
    1975 Kona 20' semi-daycruiser 455 olds, berkley jet-
    I recently found that someone installed pistons that were too small into my standard bore 455 olds. I can see almost 1/6 inch of ring from the top! Compression is still good but the pistons started to contact the head. I'm pulling this engine out this weekend to go through it and see what I need.
    I have some mildly-ported /polished G or Ga heads (don't remember which) at the machine shop, I have an edelbrock dual plane performer, edelbrock 730 performer carb and new edelbrock performer cam kit.
    What pistons should I use? I would like this thing to scoot pretty good but I also want to use pump gas. I'm guessing that something in the ballpark of 9.5:1 would be good?
    I have read a little about what Mondello does to these engines but what else should I pay attention to when getting this thing back together? I have a bunch of chevy experience but not much with olds. I'll probably do some work on the rods and balance the assembly. Maybe some oil pump and rear main cap porting, detail block for oil drain, rustoleum lifter valley, drill oilers for timing chain, intake splash guard. How about crank scraper and/or windage tray? I have a stock pan that has been extended to 10 quarts. Should I run an oil cooler? What spark plugs in a jetboat?

  2. #2
    BrendellaJet
    Normally I would advise people to just go with the chevy, but you sound like you have an idea of whats going on so you can handle the olds.
    A set of resricted push rods is in order. The oiling mods you are planning sound good. The olds likes to send all the oil up top and then starve the crank. Need to make sure the oil has a way to get back to the pan, and quick. Make sure you drill the heads for the oil drainback into the pan. I'd ditch the modified pan and buy something quality that will give you some oil control.(try armando's, the price is comparable with a dooley I believe and is far superior). If you do go with a new pan, make sure it has the bungs for oil drain, temp sensor & the drains from the heads.
    The olds can be made to live. Good machine work and researching how to make them run and you will have a good performer. An oil cooler would be a wise investment too. The biggest pan you can find would help also.

  3. #3
    Boostedballs
    I found that I have a spun rod bearing in #3 and 5. This is the crappy crank and I can't seem to find a nodular 455 crank anywhere local. I have found a 425 forged crank. Would it be worthwhile to build my 455 as a 425?

  4. #4
    Boostedballs
    I just bought a 454 and stand for $350 because it has a cracked starter boss. If I get the bell housing that has the reverse starter on it, I should be in business.
    Anyone interested in some Olds jetboat parts?

  5. #5
    DOZZR
    Sell them on E-bay, you will get top dollar just be sure to "know" what to charge for the shipping I did really well selling the parts, but I lost my ass when it came to shipping.
    Do you have any pics you can post ?

  6. #6
    Mark Sims
    Go to realoldspower.com If you dont build the olds correctly, you will need a corn scoop shovel to scrape up the parts.Stay away from mondello! you will pay twice what it costs. My olds runs strong and has for years but they must be machined to last and clearances are critical.

  7. #7
    Boostedballs
    Go to realoldspower.com If you dont build the olds correctly, you will need a corn scoop shovel to scrape up the parts.Stay away from mondello! you will pay twice what it costs. My olds runs strong and has for years but they must be machined to last and clearances are critical.
    I decided to go with a BBC. Now I'm just gathering the parts up for it. I'll be selling all of my olds parts in the SPAM section soon.

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