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Thread: Log Style to Center Rise Manifold Conversion

  1. #1

    Log Style to Center Rise Manifold Conversion

    Thought I would start a new thread focusing on the manifold conversion.

    To recap, water in the oil from a bad manifold, struggles to get milkshake oil out. Three oil changes later it looks like oil again.

    Concerns about low oil pressure, 20 psi with a bare priming tool. We then tried the priming tool with the block off bushings [thanks guys] and got 38 psi, so maybe we're not quite putting lipstick on a pig but we shall see. There's still no oil from the pushrods so it looks like they will need to be removed and cleaned manually.

    I contacted Basic Power Industries to order the center rise manifolds and they "strongly" suggested replacing the OEM Log Style with replacement log style. This would eliminate issues with mounting the raw water pump and the alternator as the bracket for these are bolted to the front lower bolts of the port side log style manifold.

    This also eliminates issues with the pulleys as these are propriety and won't work with replacement alternator and water pump brackets.

    I did additional research and I believe my manifolds are 3 pass, and the replacement log style are 2 pass and won't work.
    In addition my end caps were shot, and no one makes them, and my thermostat housing is shot and no one makes them either.

    So, we are back to replacing the log style manifolds with the center rise.

    The first order of business was making up a bracket to eliminate the need for the mounting bolts on the end of the log style manifold.
    The parts were bead blasted and primed but won't be painted until I'm sure everything fits.

    This ended up being easier than anticipated. Both the 350 crate engine and the original 305 have 3 bolt holes on the port side cylinder head. I'm not positive if all SBC have these holes, but the 305 and the 350 did.

    I was able to make a flat bracket from 1/4" steel using these 3 holes with an arm to the 2 holes formally attached the log manifolds.
    All in all, pretty straightforward.


    Attachment 4163

    If you look closely the attaching points have spacers between the head and the plate. These are 5/16" s.s. spacers from McMaster-Carr. https://www.mcmaster.com/#catalog/123/3292/=16icrnw


    So far the pulleys seem to line up great. Before painting anything I'm waiting on the replacement alternator, [bearings on ours were growling] and a body for the raw water pump. I bought the major rebuild kit for the pump but on ours the front casting was shot.

    I'll update with the alternator and the pump progress. I have not yet ordered the manifolds as I wanted to make sure all of this worked out first.
    Last edited by tricyclerob; 02-25-2017 at 03:25 PM.

  2. #2
    Looking good Rob. Getting the correct angle of the pulleys so your belts won't fly off is tricky.

  3. #3
    I guess I should clarify, the grey parts are the original brackets for the water pump and alternator and the blue dyed part is the new bracket to eliminate the need for the attaching points on the log style manifold.

    Opps…I just realized the last shot where I mentioned the spacer bushing was the shot without the bushings. I guess you would have to look really, really hard to see them.

    Also, again from McMaster-Carr, I got some thicker 5/16 ID, s.s. washers for the water pump and alternator adjusting bolts. The old ones were just standard washers and were bending in the adjustment slot.


    After the water pump is rebuilt and installed and the alternator hung I can make sure everything aligns and paint the parts.
    Last edited by tricyclerob; 02-26-2017 at 06:19 PM.

  4. #4
    Quote Originally Posted by andybuzz2u View Post
    Looking good Rob. Getting the correct angle of the pulleys so your belts won't fly off is tricky.
    Everything is in the same position as OEM so as long as the pulleys line up I should be good.

  5. #5
    Wow, cool project! Are we talking about a 280 series boat? From the pic, The engine's out of the boat. Putting the engine back in, Will there be good clearance at the engine compartment's forward bulkhead?
    Sorry, dumb question, but Thought I should ask before, as the saying goes: one paints oneself into a corner.
    All the best, diver

  6. #6
    Hey Diver. Yes it is a 280, 1982. The engine is a 350 crate motor we, [my son-in-law and myself] were contemplating installing to replace the original 305. [it was left from a Jeep project my oldest son had going, but new house, and new baby has that stalled indefinitely]. Right now I'm using it to mock up the new brackets.
    For simplicity sake, and as we were eventually able get good oil pressure readings from the 305, we're putting new manifolds on that engine [the 305] to possibly get us through next season.

    The compression is good across the board and the water jacket held 10psi for 2 days so I think we are good there as well.
    Not like there's any shortage of other things to do on the boat, seacocks are inoperable, wiring is a mess, 2 of 3 bilge pumps don't work, more water in the bilge than I would like, etc, etc..

    If/when we replace the engine I looked at removal and it looks like it will come right out, and as my son-in-law is an operator for a crane company we have that covered. I think we will need to remove the cabin top, but that's a few bolts, no biggie.

    Next order of business is to rebuild the raw water pump and for that I'm waiting on a new pump body.

    There's really no loss using the old 305 as all the new parts on the 305 will bolt on the 350 if/when that goes in. And if it takes a dump mid-season, I have a 19' sailboat a few slips over.
    Last edited by tricyclerob; 02-26-2017 at 06:44 PM.

  7. #7
    OK, coming along…
    One small thing, the raw water pump pulley didn't line up exactly with the crank pulley. I ordered a piece of 7/8" S.S. bar stock to drill out and make new spacers slightly longer than OEM. This may have been due to replacing the harmonic balancer as everything else is bolted to the stock location. All bolts are stainless.
    When this is all finished I'll post part numbers and links. I may try to get my son the smart engineer to do something with the pattern for the alternator support so it can be printed out to actual size.


    Below are the water pump spacers, with 2 thin washer added for exact alingment. Making new ones from stainless bar stock.

    Next order of business. Can anyone point me to a hose diagram for Barr manifolds?
    I googled images but nothing is really jumping out.


    p.s. A slight delay in progress due to getting my 59', BMW operational. It sat for 6 years and old fuel had done it's dirty deed. Clean and re-line fuel tank, disassemble carbs, lots o' wax on wax off. Can't have too many projects…I guess.
    Last edited by tricyclerob; 03-27-2017 at 10:57 PM.

  8. #8
    Looks great
    1982 Catalina 251 "OLD SCHOOL"

  9. #9
    That it starting to look finished

  10. #10
    Next order of business. Can anyone point me to a hose diagram for Barr manifolds?


    Oh, and links or part numbers if they are moulded hose. I googled for a while but really couldn't find anything specific.
    Last edited by tricyclerob; 03-28-2017 at 04:56 PM.

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