IMP Boats Information

Discussion in 'Powerboats' started by JKE, Jan 17, 2005.

  1. ozark69
    Joined: Jun 2018
    Posts: 2
    Likes: 0, Points: 1
    Location: climax springs, mo.

    ozark69 New Member

    Thanks Steve,I'll let you know what I find out. It will be a couple of weeks as I am working out of town just now.
  2. Inca Hoots
    Joined: Apr 2019
    Posts: 1
    Likes: 0, Points: 1
    Location: Southwest US

    Inca Hoots New Member

    Been the better part of a year since the last post...hopefully many of you guys are still around.

    Just picked up a 1971 Inca Hardtop 23', with twin Mercruiser outdrives and twin inline 6 165hp GM 250ci engines (240 hours displaying on one, 220 hours on the other). It hasn't been "stickered" since 1999, and thus I'm assuming it's not been in the water since then. Bought it at an auction from a charity donation, and paid $900 including all fees. Fig'rd I could part it out and get my money back if I had to...but would love to get it back on the water and make some fun memories with my family. This is my first boat, but I'm a reasonably good shadetree mechanic, so I should be able to get most of the mechanical work done myself and with the help of my buddy who knows far more about both boats AND mechanics than I do.

    We got the starboard engine to fire and run for a minute or two on a gas can. The port engine's carb has a stuck float, so I pulled it and am soaking it in carb cleaner now. Will almost certainly rebuild both of them.

    Port stern drive is several years newer than the starboard for some reason, and appears to be stuck in gear. Starboard stern drive is frozen up due to rust, so we pulled it, and will tear it down and diagnose. Purchased a Mercruiser manual PDF online ( DOWNLOAD 1963-1973 MerCruiser Engines & Drives Repair Manual | eBooks | Automotive ) , and also just paid for the original 1973 hard copies of the Mercruiser Factory Repair Manual off eBay yesterday...and those should be delivered next week.

    I'm posting some "before" photos. Boat was REALLY dirty from sitting around Arizona for so long, but appears to be complete with original interior that's in good condition for it's age, and also came with quite a few fun 70's/80's period-specific owner upgrades (marine radio, CB radio, depth-finder, cassette deck, etc.).

    Still on the to-do list:
    R&R both carbs and get both engines timed and running properly.
    Diagnose and repair outdrive issues (both sides)
    Flush all four fuel tanks
    Repair hull (3' long starboard-side scrape that was repaired poorly)
    New trailer tires and tongue jack installed
    ...and then, take it up to the lake and see where we're at

    My buddy thinks it's plenty workable, and doesn't believe I purchased a "basket case"...but it's going to require quite a bit of love to get it back to operational. I'm enjoying the journey so far... :)

    How are you guys doing with YOUR vintage projects?

    All the best,

    Attached Files:

  3. djamson
    Joined: Jun 2019
    Posts: 12
    Likes: 0, Points: 1
    Location: Fl

    djamson Junior Member

    I replaced my ironman tires with Goodyear Endurance and I noticed a great improvement. These tires seemed to help my trailer sway less. They also offer a smooth ride.
  4. Ike
    Joined: Apr 2006
    Posts: 2,448
    Likes: 315, Points: 83, Legacy Rep: 1669
    Location: Washington

    Ike Senior Member

    In the photo pic-06 I see squeeze bulbs and inline auto style filters. You don't need those and they shouldn't be in the fuel system anyway they are not safe. They aren't rated for inboard fuel systems and they aren't needed. Just replace the fuel lines with USCG type A hose. I have the same engine on my 1972 Sea Ray SRV 190. They are really great engines and almost unkillable. The 1972 one in my boat lasted 45 years before the head rusted out from the inside. The one I have now is a 77 or 78. it came out of a 78 Fiberform. There are lots of parts available for these engines.

    As for the drives they are probably MC-1 drives (pre-Alpha) Parts are available as well. Actually the hardest thing to find is a tech who knows how to work on these engines and drives. So if you are a DIY guy so much the better. I noticed you purchased the service manual. There are actually two volumes. The whole manual is available on-line (not to download though) Boatinfo - Mercruiser Service Manual nr. 2 - 1974-1977 All Engines & Drives

    If the carbs are Rochesters, they could be 2-jet, twin jet, Quadra jet. They are all pretty similar. If you are really lucky you may have gotten the few of these engines that had Holleys. Anyway the rebuild kits for the Rochesters are readily available on line from multiple sources, and you can get new clones of them. The Rochesters are not bad carbs. They do the job.

    The first change I made was to the distributor. I put an electronic distributor from Mallory on mine. It solves a lot of problems, it runs smoother and starts quicker.

    The only warning I would give you is to look out for automotive parts. This engine is the GM-250. They made millions of them, All the parts from the 250 fit and work on the 165. However they don't last and aren't safe. Make sure you get marine parts. Yes they cost more but it can save your life. The previous owner put some GM 250 parts on mine, mostly in the cooling system and they were all a pile of rust when I got the boat. The whole cooling system was clogged with rust from those parts. Plus that the fuel hose was automotive hose which has no place in a boat. Use only USCG type A hose.
  5. GeorgeG
    Joined: Dec 2020
    Posts: 1
    Likes: 0, Points: 1
    Location: Comfort,TX

    GeorgeG New Member

    I recently obtained a INCA by IMP cabin cruiser boat. I cannot find a number plate anywhere on the boat.
    The boat has a chevy 350 OMC motor (siezed) and a 898 mercruiser outdrive (looks OK)
    The motor seems to be a 1971 model. The dash board is frabicated out of mahogany boards, it is not
    molded f/g.
    There is no glove box
    I am seeking any info as to where to trey to find a hidden number on the boat so I can register it.
    Thanks, GeorgeG DSCN8644.jpg DSCN8655.jpg DSCN8652.jpg DSCN8646.jpg
  6. Ike
    Joined: Apr 2006
    Posts: 2,448
    Likes: 315, Points: 83, Legacy Rep: 1669
    Location: Washington

    Ike Senior Member

    It doesn't have a Hull Identification number . It wasn’t required until 1972 and many manufacturers didn’t start doing it until 73 or later. Not to worry. The state will assign one when you register it. They are required by the Coast Guard to do that. For example, my 1972 Sea Ray doesn't have one. The state assigned one about 4 years ago when the USCG changed the rules and started requiring them to assign HINs to old boats. Some states were doing it already but a lot of old boats that didn't have an HIN were still floating around.

  7. Ike
    Joined: Apr 2006
    Posts: 2,448
    Likes: 315, Points: 83, Legacy Rep: 1669
    Location: Washington

    Ike Senior Member

    By the way if you read through this whole thread you will find a lot of info on IMP and see links to other sources. They were good boats, built to last.
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