I'm going to try the 4.1->4.9 conversion - Page 2
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HT4100 4.1, 4.5, 4.9 Discussion, I'm going to try the 4.1->4.9 conversion in Cadillac Engine Technical Discussion; From what I have read, the 4.9 intake is the least restrictive, and I do not want to make things ...
  1. #16
    ehall's Avatar
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    Re: I'm going to try the 4.1->4.9 conversion

    From what I have read, the 4.9 intake is the least restrictive, and I do not want to make things worse by using a lower-flowing intake.

    If you look about halfway down http://forum.britishv8.org/read.php?6,13482,page=1 there is a picture showing the TBI vs MPFI intakes. The latter has slightly wider runners.

  2. #17
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    Re: I'm going to try the 4.1->4.9 conversion

    There's some interesting reading here. Scroll down to the bottom of the page for an in-depth description of changes between all 4.x's:

    http://www.fieroaddiction.com/caddy49b.html

    If you read pages 8-10, you'll find that the in 1988, the new 4.5's TBI intake was the last time it was revised for flow, being changed to a dual-plane from the 4.1's-single plane. The only modification to the 4.X intake in following years was the simple addition of the injector holes for the 1990 PFI 4.5. The 4.9 used the same 1990 4.5 manifold.

    For the easiest swap with maximum compatibility, you might find it beneficial to seek out a TBI 4.5 intake manifold. You could plop on a TBI throttle body and everything else (like throttle cables and detent cable routing and bracketry) would fall into place and look very professional.

  3. #18
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    Re: I'm going to try the 4.1->4.9 conversion

    I saw that, but as I read it they were talking about the 4.5 MPFI changes. I'll have to look at the intakes the next time I at the yard. car-part.com shows 1990 4.5 MPFI is the same intake as the 4.9, so it seems the MPFI intake is all the same, but the 4.5 TBI intake is exclusive to 88-89 which suggests that it is different from the 4.1.

    The only thing I am kind of concerned about with the 4.9 intake is that I'm not sure how the 4.1 injector firing will work with the dual-plane setup. I may actually open the throat into a single opening

    edit--I found a picture of what was labelled a 4.5 intake and it appears to be a dual-plane intake that is not MPFI, so perhaps it is the TBI intake



    Hard to tell but I don't see port injector holes. It does seem that the runners are as wide as the 4.9

    edit x2--the Rebuilder article scans have a table of casting numbers and it confirms the MPFI is the same unit, but it shows 2 different numbers for 4.1 and for 4.5 TBI so there are four possible intakes on those



    Also interesting is that the line art in my FSM shows two round holes on the intake instead of the oval shown in that other pic. And the footnotes in the article refer to tapered versus stepped intakes, so it may be that the very early FWD intake had the oval and everything after that was a pair of round holes.

    At this point I think I'm just going to epoxy the MPFI holes.

  4. #19
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    Re: I'm going to try the 4.1->4.9 conversion

    ehall,
    How about tapping those injector holes with a pipe tap and using some plugs instead of the epoxy. I have a small lathe, so I could machine some plugs with a oring groove, and that could be an alternate if you could find a machine shop to do them affordably. That's a pretty big hole to fill with epoxy tho.

  5. #20
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    Re: I'm going to try the 4.1->4.9 conversion

    Right now I am thinking I might use some oil galley/freeze plugs in combination with some gasoline-safe silicone. I want a smooth seal at the bottom which is why I'm looking at the filler material, but I don't want to permanently modify the holes either. Some aluminum rod cut into plugs might also work.

  6. #21
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    Re: I'm going to try the 4.1->4.9 conversion

    I am very interested in what you are doing here. I am a fairly new member with an 84 Eldo that runs fine but does have that familiar 4100 thump (very minor) and would love to upgrade to a more powerful, reliable engine that would look stock. Keep us posted!

  7. #22
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    Re: I'm going to try the 4.1->4.9 conversion

    Does the 4.9 have the same mounting points as a 4.1? I know the 4.9 is mounted transversely so how much of an issue is this?

  8. #23
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    Re: I'm going to try the 4.1->4.9 conversion

    The 4.1 in my 85 DeVille is transverse mounted the same as the 4.9 in the 91-93 DeVille (same motor mount part numbers). I don't know what the longitudinal mounting pattern looks like.

  9. #24
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    Re: I'm going to try the 4.1->4.9 conversion

    Does anybody know what parts are different between C-body 91-93 DeVille 4.9 vs other platforms? Near as I can tell the only differences are mounts and exhaust manifolds, but I am wondering if anybody knows of anything else

    The problem I've got is that I am trying to bolt a 4.9 into my 1985 C-body DeVille so I am pretty much stuck with C-body 4.9 so that the stock exhaust manifolds will mostly work with the exhaust that I already have. But that limits me to 91-93 DeVille which is only a subset of the available pool. I just bought a pair of exhaust manifolds on eBay, and I'm hoping that I will be able to use them with a 4.9 from the Eldorado/SeVille or the 94-95 DeVille which would open up a much larger pool of options. But I don't know if that's the only problem... Does anybody know if anything else is crazy different?

    Thanks

    ps--I have confirmed that A/C compressor is the same for the years, so the lower mounting should be alright. I have also confirmed that the oil pan is the same, so no surprises with exhaust routing either.

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    Re: I'm going to try the 4.1->4.9 conversion

    Just about everything is the same across platforms except for the items you've mentioned, as well as dipstick tubes for both trans and oil. Even if you do find some tiny things that are different, bosses for mounting hardware are identical across platforms and years, making transfers easy. For example, even if you found out that they changed the AC compressor between years or models, the brackets for all compressors would bolt to the block.

    But yeah, because nothing changed, pretty much the only way to identify what car a 4.X came from is by looking at the exhaust manifolds - they are THAT similar.

  11. #26
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    Re: I'm going to try the 4.1->4.9 conversion

    I bought an engine today. It's from a 91 Deville so I got lucky on the interchange. The car must have been garage kept, it was a very clean engine with just only surface rust on the lower steel. Oil in the filter looked deep brown so it had been changed a few hundred miles before the accident. Almost no varnish on the rockers and what little was present was very light golden color with no deep brown or black staining. Water pump spun easily. Spark plug tips were grey and no particulates. EGR had some some buildup but not clogged up so it was either well maintained or very low miles. Even the rubber seals on the weatherpack connectors were still soft and limber. Best part is that it was just $300! The downside is that I'll have to figure out the brackets and accessories since it didn't include any.

    I'll post up some pics when I get it into the shop and we start studying on it.

  12. #27
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    Re: I'm going to try the 4.1->4.9 conversion

    Sweet.



    Hope all goes well. Its a shame that the entire assembly cant be dropped in there. PFI to TBI will cost you a few ponies.

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    Re: I'm going to try the 4.1->4.9 conversion


  14. #29
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    Re: I'm going to try the 4.1->4.9 conversion

    Quote Originally Posted by ehall View Post
    I looked on rockauto and brought up the 85 4.1 and 95 4.9 in two windows. The water pumps are identical (same part num) so now I know why you guys complain about them so much (I've gone through three or four on my 85 too). Alternators are different, with the 4.9 having a 140 amp box versus the 108 amp unit on the 4.1 (not a problem). Exhaust manifold gaskets have identical hole patterns but the filler shape is different and have different part nums--the 4.9 has a solid gasket while the 4.1 has an outline gasket with big openings--but as long as the openings are identical it should not be a problem. The power steering pumps are different which worries me a little--I should probably reuse the 4.1 pump to ensure that it works with my steering setup. The serp belts and tensioner pulleys are slightly different as expected.
    i took a 86sdv 4.1 alt and turned the rear casing and it fit only difference is your going to need a special brace for the old alternator to fit but the voltage in the alts is different but mine was a high output but i have no problems out of it. i also want to see pics

  15. #30
    ehall's Avatar
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    Re: I'm going to try the 4.1->4.9 conversion

    Yep the alternator housing looks identical in the catalog pics. I would like to upgrade to 140 amp and this would be a good excuse to do it but I have to look at it in detail, things like rear brace might not work, and the connector pin-out is different from what I remember.

    I would like to use the newer power steering setup since there is actual aftermarket support for it (you can buy a pulley for it). I'm pretty sure I can bolt it on but I don't know what kind of hard line work will be needed. I don't know if the brace is the same or not either.

    The A/C is a bit of a challenge. The only significant difference I can see from the catalog pics is that the 85 compressor has an extra mounting ear for the smog pump to bolt onto, so I should be able to bolt it to the block and just leave that ear unused. If I have to swap compressors I may have to change hoses and such due to differences in the fittings (haven't looked yet but its very common for fittings to change between R-12 and R-134a systems). I still have the original R-12 charge (26 years!) and am trying to figure out if I can keep it during the swap somehow

    I am hoping to be able to keep my 4.1 valve covers and air filter so that it looks stock

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