I'm going to try the 4.1->4.9 conversion
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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; I have looked around and it seems that 1995 was the last DeVille with a 4.9 engine. Jasper wants $4k ...
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    ehall's Avatar
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    I'm going to try the 4.1->4.9 conversion

    I have looked around and it seems that 1995 was the last DeVille with a 4.9 engine. Jasper wants $4k for their kit. remanufactured.com wants less than $2k. I suppose I can get a junkyard mystery motor to test with and see how hard it is to hook up my 4.1 intake. If it works then I'll look around for a hotrod reman.

    I am going to autozone on Monday to buy intake manifold gaskets for my 85 4.1 and the 95 4.9 and see if the ports are way different.

    Any other hints before I do that? Should I ask for parts from a different year or model than the '95 4.9 engine?

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

    What did you find? The only difference you'll probably find is the water port. It is slightly different but can be made to line up with a bit of grinding and filling with epoxy. No need to ask for different years of 4.9. They're all basically the same except some minor changes with the crank bearings to prevent knock.

    Just find a 4.9 out of a wrecked Cadillac with less than 100k miles. That way, you know that it had to be running prior to the wreck. These engines are very long lasting with their hardened wet sleeves. If you're concerned about it, you could put in new rings and new crankshaft bearings. I have a 4.5 motor in my Eldorado with 240k miles and it still is easy on the oil. The engine has not been touched other than new waterpumps and sparkplugs.


    What are you going to do about the transmission? It may not last with the torque of the 4.9. Yes, they can be built up.

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

    It's not Monday here yet so I haven't found out anything. I'm going to do this outside the car first, and if that gets running then I'll start looking at options to install it. I probably won't start on this in earnest until February since I have two other projects going that are going to suck up my free budget for January.

    I'll use the stock transmission to begin with but I have those other notes about the buildup kit bookmarked.

    What about exhaust manifolds, will I have any issues there?

    What about accessories? From what I have read on the forums, the stuff that is taped onto the 4.9 is at least a little different and some of it looks very different.

    So all this stuff will take time to figure out, budget, find and install. Then I will put it in.

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

    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.

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

    Quote Originally Posted by ehall View Post
    What about exhaust manifolds, will I have any issues there?
    You can use either manifolds but the 4.9 manifolds breathe better.

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

    There are a lot of differences in the intake manifold kits. Some stuff like front and rear seals are the same but then something like thermostat housing gasket is different. I am going to have to get my mechanic to look at this stuff.

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

    Talked to my mechanic and his senior monkey, who is pretty well informed about these engines. He said the same thing, that the blocks are interchangeable. I did not even ask and he said to use the 4.1 intake gasket. I am going to take them to lunch and go through a list of everything (distributor, EGR, etc) and see what we need to buy or what we can reuse.

    I am a bit confused about the tranny requirement. When I read the Wikipedia entry it seems to indicate that the same basic tranny was used for all of them (not counting the change to electronic control), with just a couple of beefier units for high output systems:

    link

    A 4-speed version of the 125 was created for the 1985/1986 GM C platform (FWD)/GM H platform (FWD) cars, the Turbo-Hydramatic 440-T4. Many parts were identical to the 125, though it was generally stronger and included an overdrive fourth gear. This transmission was first used in GM's 1985 Buick Park Avenue, Oldsmobile 98, and Cadillac Deville. In 1986, after switching to FWD, the Buick LeSabre, Oldsmobile Delta 88, and later, the Pontiac Bonneville also used this transmission. A special strengthened F-7 version was also used for the 1987–1992 Cadillac Allanté.

    One unique feature of this transmission is its use of both a modulator valve and a throttle valve (TV) cable. Most transmission either use one or the other to control shift points and shift smoothness. On the Turbo 440-T4, the TV cable exclusively controls the shift points, while the modulator valve controls the shift feel. This feature makes it very easy for a home, "shadetree" mechanic to adjust the transmission shift points with minimum affect on the shift feel.

    The 440-T4 was later renamed the 4T60.

    The electronically-controlled 4T60-E was introduced in 1988. By 1991, all 4-speed front wheel drive automatic GM cars used this unit. It would become the basis of the GM 4T65 transmission, still used today.

    A heavy-duty version, the 4T60 HD was introduced in 1991 and produced through 1995 for the supercharged GM 3800 engine.

    Applications:

    * The GM LG3 and LN3 3.8L V6s
    * THM 440-T4
    o 1984–1990 G-body
    * 4T60-E
    o 1988-1999 most front-wheel drive GM cars
    * F-7
    o 1987–1992 Cadillac Allanté
    It seems that the 4T60-* was used in all FWD Cadillacs from 1984-1999 with the only difference being electronic control... Was the 4T60-E a lot beefier?

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

    Quote Originally Posted by ehall View Post

    It seems that the 4T60-* was used in all FWD Cadillacs from 1984-1999 with the only difference being electronic control... Was the 4T60-E a lot beefier?
    Generally speaking, it is the same thing with the same ratios. However, the E has upgraded valve body components as well as clutch pack updates. Even later versions of the E were updated from the earlier E models. Also, the later E models had different final drives because of changes in the sun and planetary gears for whatever reasons. Hmmm...I guess they're more different than I thought...


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

    I talked to a couple of tranny shops and they said that the changes between the 4T60 flavors were pretty minor and that it shouldn't be necessary. One of them said that the whole tranny has to be disassembled to swap in the shift kit (it goes in through the side apparently) so it would cost the same either way to install the shift kit first or repair it after/if it breaks. Sounds good lol

    The other item I have to figure out is distributors. If I can plug the 4.9 distributor into my existing 4.1 harness then I'm pretty much golden but if I have to do rewiring that is going to be a big stumbling point. The 4.1 and 4.9 are clearly quite different in terms of physical shape, but the ignition control modules are identical which is good. My mechanic said that if they have the same electrical hookups then it won't matter. Anybody else have any thoughts on this? Just looking at the physical differences it seems that I will have to use the 4.9. Will my ECM still work?

    BTW I found a really low mileage 4.9 at a local yard for cheap. Unless it's a rusted hulk, I'll be good to go after getting this last issue figured out. Looks like my total cost including engine and install will be less than $2k.

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

    Just got the oil analysis in the mail for my 4.1. Looks like my existing intake manifold gasket is almost shot so the swap is now a "need" item instead of a "want" item.



    Double those numbers (the mileage on the sample was very low) and you see that the aluminum and iron are both pretty elevated, while the potassium and silicon are astronomical. When this is added to the problems I've posted about elsewhere--hesitation at warm, throwing lean codes at hot, low compression in a couple of cylinders, random oil consumption at high temperatures, etc.--it makes sense that a leaky intake is allowing air into the engine after it warms up (the high silicon numbers), and is probably where the oil is blowing out.

    I'm going to order the 4.9 block next week hopefully.

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

    So after seeing that the '89 4.5 intake has some additional performance improvements I spent some more time on rockauto looking at key parts. The 4.1, '89 4.5, and 4.9 have slightly different parts in the intake gasket set but the front and rear seals are all the same (the primary difference appears to be water housing gasket). The '89 4.5 and 4.9 have identical port openings but the 4.1 is a little different (still in the right place though). The 4.1 and '89 4.5 use the same distributor part number (and same coil), while the 4.9 is slightly different distributor and coil (but same ignition module however). The '89 4.5 has different injectors than the 4.1, but they are probably just higher flow.

    Looks like most of this stuff is interchangeable, although some questions about the distributor remain though.

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

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

    The ignition distributor is the same as the HEI unit used in the previous TBI engines, but a Hall-effect cam position sensor has been added to provide the engine control module with information necessary to time the PFI system.
    This kind of change means that that it becomes more likely that I will have to use the old distributor. Physical shape is only slightly different and the gear looks the same so hopefully it will not be an issue.

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

    Had another dialog with the engine mechanic. He said that if the distributors are incompatible then they will take the guts out of the 4.1 and use them in the 4.9 but he does not think that is necessary. They will reuse the 4.1 EGR system and it should be direct since head ports are the same. They will remove the smog/air pump since the 4.9 did away with the valving for it and the ECM does not complain when it is disabled or disconnected. Finally the differences in the water ports on the intake are not a big deal, and we can use the 4.1 gasket set to create a seal around the 4.1's larger opening. I think that is pretty much everything and it should be a go once I get the parts together.

    However... given the amount of hackery involved I think it would be a mistake to rush this. So I think I am going to just replace the intake gasket on my existing engine and build up the replacement on a stand over the course of a couple of months. I will be able to afford new parts if I take my time so it will give a better result, and I won't be as likely to find myself needing a mystery part. I am going to get a leak-down test and will make a decision based on that. Currently my cams are not showing any signs of significant wear so unless I have secondary problems with rings or head gasket I will do the immediate repair and slow replacement.

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

    I am very close to doing this now ... Yes 3 years later but I have taken care of other priorities, have more experience after swapping engines in my Jeep, and work is picking up so I have the extra cash to do it

    The basic plan now is to take the entire 4.9 engine from a 91-93, plug the MPFI injector holes, and then put the 4.1 TBI throttle body and distributor on the 4.9 intake.

    The 4.1 throttle body lets me keep the ports and linkages that I already have, without having to worry about things like cruise control or whatever. However the throttle body will have to be bored out to support the 4.9 airflow requirements and I will have to put Chevy 305 injectors in the TBI to get the fuel rates to match the increased displacement. There is a pretty good pool of experience in the Chevy performance world with doing 305 to 350 conversions and this approach is pretty similar to that, so I'm not particularly worried about this part of it. Actually it's easier for me since I only need to worry about air/fuel/spark which is all right there, and they have to worry about ESC controls and engine sensors that my Cadillac doesn't have. I may get a wideband O2 with an AFR gauge to watch air-fuel ratio but I don't think it will be necessary.

    For spark, it looks like the 4.1 and 4.9 distributors have the same profile, so I should be able to install a 4.1 distributor in the 4.9 and be done with it. Here are pics from A1-Cardone showing 4.1 (left) and 4.9 (right) and the profile seems identical



    The 4.9 added a cam sensor to the distributor but my 4.1 ECM can't use it, and swapping in a 4.1 dizzy will delete it so it's non-issue. The 4.9 also added a knock sensor but my 4.1 ECM doesn't know about that so I will just plug off the hole and forget about it. All of the other engine controls will stay with the 4.1 where possible (such as TPS, coil, etc), and a lot of them are the same anyway (coolant temp, oil pressure, etc.). Assuming the bosses on the intake are basically the same, I will keep my existing accessories. I may switch to the 4.9 power steering if it still on the engine but I will almost certainly have to plumb new steering lines for that and I'd like to minimize that kind of change. The AIR/smog pump seems to have been deleted from the 4.9 so I will have to do some mods there--I may have to add a resistor to the harness to fake out the valve sensor and keep the check-engine light from coming on.

    One open question right now is how I will block off the MPFI injector holes in the 4.9 intake manifold. Since the only real force is the vacuum draw, I suspect that some basic rubber stopper plugs would work fine (rubber O-rings work for the injectors...) however I don't like the idea of parts being able to vibrate loose so I am also thinking about JB Weld or some other kind of semi-permanent solution.

    Exhaust is also an open question. I looked at some trademotion catalog pictures and it seems that the 91-93 4.9 used the same exhaust manifold as the 4.5 engine, and since my 85 is the same C-Body as the 4.5 and early 4.9 then I should be good there. I will probably be able to keep my 4.1 exhaust from the cat converter back but I assume I will need the 4.5/4.9 manifold if my donor doesn't come with the setup. Since the AIR/smog will be deleted, I will have to plug off the side port on the cat converter. I may use the EGR valve from the 4.9 to allow for changes in exhaust pressure.

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

    No knock sensor on the 4.9, or any variant of the 4.X.

    May I ask, any reason you don't want to use a TBI manifold for your 4.1 throttle body instead of modifying a PFI manifold?

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