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  1. #1
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    Aug 2017
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    southern California
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    Default help with identification and source for exhaust part 454

    Guys, on my older (80's vintage) 454's, I have the pictured exhaust collector on each engine, going into muffler. They are looking suspect and I want to replace them. I looked at fiberglass elbows and various tees to fabricate something, but I was absolutely shocked at the expense of the fiberglass parts to assemble one.
    I am not sure what these parts are called. On a sterndrive, I would have called them a y-pipe. I'd love to be educated proper term for these. Again, this is on a 80's vintage 454, carbed. The hose coming off manifold riser is 3" (so I am assuming the od of the pipe is 3") but visually, the end going into the muffler looks slightly larger, maybe 4".
    Can anyone tell me the proper term for these "elbows" and also if there is a source for exact metal replacement? I am even open to used pieces in good shape if I can find them. Thanks
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  2. #2
    Join Date
    Aug 2008
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    Fairport, NY
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    Default Re: help with identification and source for exhaust part 454

    Quote Originally Posted by realcaptron View Post
    Guys, on my older (80's vintage) 454's, I have the pictured exhaust collector on each engine, going into muffler. They are looking suspect and I want to replace them. I looked at fiberglass elbows and various tees to fabricate something, but I was absolutely shocked at the expense of the fiberglass parts to assemble one.
    I am not sure what these parts are called. On a sterndrive, I would have called them a y-pipe. I'd love to be educated proper term for these. Again, this is on a 80's vintage 454, carbed. The hose coming off manifold riser is 3" (so I am assuming the od of the pipe is 3") but visually, the end going into the muffler looks slightly larger, maybe 4".
    Can anyone tell me the proper term for these "elbows" and also if there is a source for exact metal replacement? I am even open to used pieces in good shape if I can find them. Thanks
    My opinion is to take them off for inspection. The little bit of rust visible on the outside is not very indicative of useful life. Look for material loss on the inside; might not be too bad. If OK, then a good sandblasting and primer/topcoat may work for many more years.
    I had stainless ones on mine, and eventually the welds started to drip water at a few places. Coal tar epoxy kept them going for a number of years.

  3. #3
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    Sep 2008
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    Maryland - USA
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    Default Re: help with identification and source for exhaust part 454

    I'd suspect they are Y-pipes....though they come in many different configurations....based on your description, that's a reasonable conclusion...

    Personally, I think that configuration has too much back pressure; that said there are many still running today, from that era.

    Like DD suggested, make a good inspection....We opted to replace ours ~ 11 years into their use....they were disintegrated, from the inside. We opted for the newer center-riser manifolds and 4" elbows....turned out there were reducers in the mufflers....so what was a 3"-3" into 4" became a 4"-4" into 5" setup....Finally, I just bought the fiberglass exhaust tube and made my own elbows and y-pipes....that approach lets you build what you need without any limitations imposed by the tube maker...

  4. #4
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    Aug 2017
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    southern California
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    Default Re: help with identification and source for exhaust part 454

    Hey Dave and Mark....you guys seem to be the ones who have been helping me most since my fairly recent purchase of this older boat. Thanks very much for that. Got another question.......You may recall that I recently replaced automotive hei distributors in this boat with new delco voyager marine units. I basically just dropped them in with engine not moved and sort of roughed the timing in by ear without a light. The port side seems to be better tuned, and since I dropped in the new distributor(s) the starboard motor starts up kind of like choke is staying closed for too long or something is off a little. I have to use throttle control to keep it above 1000 rpms for maybe 30-45 seconds before it seems to warm enough and the engine rpms increase by itself and I pull it back. Also, this boat has vacuum gages on the dash and prior to changing the distributors, both gages held steady at about 17 or 18 without fluctuation. The port side still does but the starboard side vacuum needle is bouncing between maybe 14-18 with idle at 700. When i increase rpms the gage stops bouncing around and the engine sounds ok and seems ok. Both engines idle without threat of dying even in gear at 700. In fact, when shifting in or out of gear, my rpms do not appear to move at all. Could this stubborn, cold start and vacuum gage fluctuation be related to improperly timed distributor?

  5. #5
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    Fairport, NY
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    Default Re: help with identification and source for exhaust part 454

    The correct timing is really important with a highly loaded marine engine, that may run on 93 to 87 octane gas. I would not trust my ears, got to have a light. Dial that in, and see what happens.

  6. #6
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    Default Re: help with identification and source for exhaust part 454

    could be a few things but 2X what DD suggests - make the timing 'correct and go from there....with the EST systems, I'd concentrate on setting the total advance and 'live with' the resulting timing at idle - as long as it restarts ok when hot....some modules have more advance than others...

  7. #7
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    Default Re: help with identification and source for exhaust part 454

    Quote Originally Posted by makomark View Post
    could be a few things but 2X what DD suggests - make the timing 'correct and go from there....with the EST systems, I'd concentrate on setting the total advance and 'live with' the resulting timing at idle - as long as it restarts ok when hot....some modules have more advance than others...
    what is total advance?

  8. #8
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    Default Re: help with identification and source for exhaust part 454

    Here's a quick overview....

    The spark needs to occur at the 'proper' place in the engine's cycle to make the most power....it takes a finite amount of time between the spark occurring and the resulting pressure increase.....as the engine RPMs increase, the spark needs to occur earlier in the cycle.

    The timing curve for a given engine will have an initial amount - the base timing - and will then increase to a total value, usually between 3000 and 3600 rpm. In the EST system, the advance is controlled by the module, electronically, and is best set to match the total advance called for by the engine OEM and then live with the resulting initial timing...

  9. #9
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    Default Re: help with identification and source for exhaust part 454

    Quote Originally Posted by realcaptron View Post
    what is total advance?
    Defined as the maximum advance through the rpm range. For you, that should be around 30 degrees. The crusader operators manual only specs the "base" advance, to be 10 deg BTDC. But, with commonly available advance timing lights or a timing deg decal on the harmonic balancer, there is no good reason to not use "total" advance. People may decide to advance a little more or less (+/- 2 deg or so) based on the gas octane they are running.
    Note that to get full advance, you need to run that engine, in neutral hopefully, at 3500 rpm or so. You should verify that the advance "tops out" with rpm, before you lock down the dist bolt. Should occur just over 3krpm.

    I was typing with Mark. What he said too!

  10. #10
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    Default Re: help with identification and source for exhaust part 454

    sorry to keep asking questions.....on my engines, the timing marker over the balancer is a metal piece with a squared off end and a series of sawtooths leading to the other end which is more tapered. I have surmised that the squared off end would be 0 degrees at tdc, and the sawtoothed end represents degrees of advance. If I am correct on that assumption, how many degrees does each tooth represent?
    also, when I changed out the distributors and replaced with new marine ones, the vacuum advance tube that had been connected between the old automotive hei's and the carburetors remained. Having nothing handy to plug the carb vacuum inlet, I just folded the vacuum tube in 1/2 and taped it shut. What about that? Should the carb inlet where the old vacuum advance entered from hei distributors be plugged or left open, sucking air?
    Thanks you guys. You are being very helpful.

  11. #11
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    Default Re: help with identification and source for exhaust part 454

    There have been a variety of timing tabs used by GM thru the years....zero is usually NOT on the end but offset closer to an end. Each tab typically has scribed lines at (even) two degree increments. The 'teeth' peaks and valleys line up with the scribed lines. It is best to get out a flashlight and examine what is on your engine. You can google gm v-8 timing tabs and likely get a few decent examples....The RH engine should be laid out opposite from the LH engine.

    Which carb do you have? On the q-jets, there's usually only the vacuum port for the pull-off....never leave unused ports open - cap them off.

    The fold and tape approach should work until the tape fails....most auto parts stores sell a pack of block off caps if you want something more permanent....

  12. #12
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    Default Re: help with identification and source for exhaust part 454

    Quote Originally Posted by makomark View Post
    There have been a variety of timing tabs used by GM thru the years....zero is usually NOT on the end but offset closer to an end. Each tab typically has scribed lines at (even) two degree increments. The 'teeth' peaks and valleys line up with the scribed lines. It is best to get out a flashlight and examine what is on your engine. You can google gm v-8 timing tabs and likely get a few decent examples....The RH engine should be laid out opposite from the LH engine.

    Which carb do you have? On the q-jets, there's usually only the vacuum port for the pull-off....never leave unused ports open - cap them off.

    The fold and tape approach should work until the tape fails....most auto parts stores sell a pack of block off caps if you want something more permanent....
    Thanks Mark. I have Holleys on both motors. Not sure which model. Still haven't found numbers on them. Electric chokes. As far as timing the engines, I know I need to do that since replacement of the distributors. I took family out for a harbor cruise couple days ago. Both engines seemingly purring like kittens without any stumbling or threat of stall. I did notice that the starboard exhaust smells a little gassy (not terrible but a little), and when I checked my tanks for consumption (only have dipstick, no gages) after doing about 20 miles at 1400 rpms the whole time (approx 2 hrs at that speed), the port side appears to have used about 7 gallons but the starboard side 20 gallons, which I find almost unbelievable difference. I know that before I changed the distributors, both engines started up immediately without cranking. Port side still does, but starboard side starts up a little more stubbornly and smooths out as soon as warmed up.

  13. #13
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    Default Re: help with identification and source for exhaust part 454

    If the choke adjustment is too rich (after warmup), fuel consumption will increase....but I'd start with the timing first....and then verify the chokes are fully open by the time the coolant gets to operating temp....also, if the choke adjustment is too tight (way too rich - fully closed), hard starting can result...

    If they are marine rated, they should have J shaped bowl vent tubes....model numbers typically get stamped on the air horn...and they make mech and vac secondary marine units...

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