Cadillac Owners Forum banner
42K views 151 replies 13 participants last post by  ehall 
#1 · (Edited)
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?
 
#58 ·
I got the 4.5 TBI intake manifold today and spent some time studying on it. For reference, here are pics of the top and bottom, with the 4.5 intake on the left and the 4.9 on the right.





The bore on the 4.5 throttle body and manifold both measure at 45mm, while the 4.9 throttle body and manifold measure at 47-48mm. The size of the intake ports for head are also larger on the 4.9 (pics below). I don't know if the runners inside the intake are larger, but the exterior casting looks the same. I could bore the 4.5 intake and throttle body to 4.9 sizes (or even larger I suppose) but all of the ports would need to be made bigger to get equal amounts of airflow. I suspect the intake port is the real limit, so there would probably be some gain from making the throttle body and intakee bores larger (maybe up to 49mm or thereabouts). On the other hand, the SBC 305 and 350 TBI engines used the same bore size as the 4.5 setup. I imagine that any benefit would show up at higher RPMs and would have no affect below 4000 RPMs. I might call a machine shop tomorrow and ask what they would charge to bore out the intake.

Look inside the 4.5 intake and you can see little ridges in the chambers. My assumption is that these are to help direct fuel towards the ports and keep it from pooling up. The 4.9 is smooth inside and since it doesn't move fuel it probably helps airflow to have a smooth surface.

The EGR tubes are rusty on the 4.5 intake. The hex-head button-head screws on the bottom provide access to the tubes but the tubes are crimped in from the top and bottom, and cannot be easily removed. This is another thing to talk about with the machine shop--perhaps they could press in some stainless tubing for me. Also note that the 4.9 only has one EGR supply port, and there is not a runner for the other port (which is blocked off inside with a dummy plate)--while the EGR supply ports on the 4.5 are both present.

As mentioned above the 4.9 has larger ports going into the heads. As was also discussed earlier in the thread, the 4.5 has larger coolant ports. Here is a pictures showing the 4.9 intake gasket on the 4.5 intake manifold.



As can be seen the 4.9 ports are significantly larger (and why the whole manifold would have to be shaped to match the overall airflow), while the coolant ports are somewhat smaller. In order to ensure that the gasket is sandwiched between the head and manifold, we will be using the 4.9 gasket, and then padding the inside edge of the intake manifold's coolant passage to guarantee a good seal.

So the final decision is to use the 4.5 intake and throttle body with the 4.9 long block.

I bought a TBI rebuild kit for the 4.5 throttle body and will be cleaning that up over the weekend. The only other part that we are waiting on is the front timing cover.
 
#60 ·
I took the throttle body apart to replace the o-rings and gaskets and decided to go ahead and streamline it with my Dremel. I used a reinforced cutoff wheel to remove the raised lip (I left little sections by the edge to help center the intake collar), and then used a couple of grinding stones to shape a radius, and some polishing pads to smooth it all out. This is the way that most of the SBC TBI throttle bodies are shaped, and it's interesting that the 4.9 throttle body comes this way from the factory.



I wanted to clean up the rust on the butterfly shaft, but the little screws all sheared off. I will get the machine shop to drill the tiny screw parts out of the shaft so I don't mess it up, then will detox and paint the thing after I get it back.

I cleaned up the 4.5 intake manifold some as well. The Berryman's carb cleaner in a spray can is really good stuff, FYI
 
#61 ·
I closed up the sides of the water ports today. First step was using a wire brush attachment on the Dremel to clean off the dried coolant, then measure and mark the new edge. Then I used blue painters tape along the edge to form pockets, and then gooped in enough JB Weld to fill the pocket. After about 5-6 hours it was firm to the touch, and I pulled away the tape.





After it fully sets up overnight I will put the gasket on it and see how close I got. I went over the line a little bit (you can see the marker in the 2nd pic, it's the black shadow spot right past the seam), so I may use the sanding disc to form a lip, or I may leave it alone. Pretty happy with it so far though.
 
#63 · (Edited)
I mentioned earlier that I had broken the screws for the butterfly valve plates on the 4.5 TBI throttle body. Based on what I have read in some of the SBC throttle body discussions this is "normal" since the screws are peened after install to keep them from walking loose, and I needed to cut the back of them beforehand. Something to keep in mind. Anyways the garage owner was able to get 3 of the screws by pulling them out from behind, and a clock repair place got the 4th screw by drilling it out. After that I painted the throttle body shaft, and have ordered some new 2.5mm screws. The shaft is loose in the throttle body, so I have also ordered some 3/8 OD 5/16 ID brass bearing sleeves to use as bushings/seals.

After all that I looked at the 4.1 throttle body today and noticed that it has an additional pole on the main armature--3 poles on the 4.1, vs 2 poles on the 4.5. Based on pictures I have found online, it looks like 2 of the cables are stacked on a single pole in the 4.5 setup.

Here's a pic showing the 4.1 (top) and the 4.5 (bottom) and it looks like the 4.5 cables are stacked onto the single main pole





Can somebody confirm or better yet post a close-up picture of the cable hookups? I will need to adapt or pull the shaft out of the 4.1 and I would much rather do the former!
 
#65 ·
Thanks for the pics but that's the PFI throttle body which is quite a bit different. Here's a pic of the 4.5 TBI setup



The large main arm has the throttle linkage and cruise control cables stacked somehow. I think the cruise cable is drilled and on the large part of the main shaft, but I don't know for sure. Here's another installed pic



I think I will just drill the cruise cable and put it on the main shaft
 
#67 ·
The hardware from McMaster showed up in today's mail (overnight!) so I reassembled. There is very little play in the shaft when it's fully together so I think I will run it like this for a little while and keep the bushings for later if they are needed.



Tapered and polished inlets, replaced o-rings regulator and gaskets, new 305 fuel injectors, and new TPS and ISC
 
#68 ·
The front cover came in last week and we did all the gaskets and seals today. Here's a pic of the engine put back together and with the new parts installed. I need to move the valve covers off my 4.1 before we can start putting the accessories back on.



One of the shop workers is going to be out of town for a bit so we may not get to the swap until late next week or even the week after. Bummed but I don't have control over it.
 
#69 ·
Can one of you with a 4.9 FSM look up the torque specs on the intake bolts? There are 16 of them in 3 different sizes, and you are supposed to tighten the 4 center ones first, then do the others, then retourque, etc. What is the final torque spec? Alldata for the 4.9 showed a number that way way lower than the FSM showed for the 4.1 so I used the 4.1 numbers but now I'm curious

Thanks
 
#70 ·
i might be wrong but im looking at page 6a-13
the sizes are 30mm 40 mm 55mm
tighten bolts in this order

from left to right top of the manifold and bottom the numbers in() are the bolt size in MM
this is the orientation from the from of the engine
15(55) 9(40) 5(30) 3(55) 1(55) 7(30) 11(40) 12(55)
16(40) 14(40) 8(30) 2(55) 4(55) 6(30) 10(40) 13(40 w stud head)


bolt in order 1 2 3 4 in sequence 12.0 N m 8ft 12 lbs
tighten bolts 5-16 in sequence tot 12.0 N m 8ft 12 lbs
retighten ll bolts in sequence to 16.0 N m 12ft lbs
repeat step 3 until torque level is maintained


hope this helps
 
#78 ·
Looks like we will do the swap next week. I have been doing some more research and making some junkyard runs during the downtime and everything is pretty much figured out at this point. My 85 has the studs on the firewall in the same place for the 4.5 vacuum canister so vacuum is going to be easy with that canister. The outlet sizes on the exhaust manifolds appear to be the same size on the 4.1 and the 4.9 so I think my crossover and intermediate pipes will also bolt right on with no modifications, which means I will be able to keep my intake with the thermac working. 4.1 valve covers bolt right up to the 4.5 intake, so my accessory mounting should be alright. The only thing that doesn't work easily is that the 4.9 spark wire loom won't directly mount to the 4.1 valve covers--I may use some sheetmetal screws with some spacers to get the 4.9 loom on there as a secret handshake to other enthusiasts.
 
#79 ·
Got wheeled into the shop this afternoon and immediately ran into a problem--some of the bosses are different on the 4.1 and 4.5 intake manifolds. Specifically the alternator mounting bosses are different and one of them is even missing. In one of my trips to the junkyard, however, I grabbed a 4.9 accessory bracket for future reference (this was when I was thinking to use the PFI intake) and test fitting showed that it has the same bolt pattern as the 4.5 TBI intake but as was already discussed in this thread the mounts on the alternator are different between the 4.1 and 4.9. A quick trip to autozone and I see that the 4.5 alternator is the same physical layout as the 4.1 (third bolt in same place). So... in theory a 4.5 TBI accessory bracket will bolt to the 4.5 TBI intake (duh) and have the same bolt pattern as the 4.1 alternator so I should be golden. The ECU connector on the 4.5 and 4.9 alternator is a a little different but worst case scenario I should be able to hack the wiring, at which point I would be able to run 4.9 alternators going forward.

Sorry I forgot my camera
 
#80 ·
I was looking at the same problem. I am trying to decide weather to use 4.1 or 4.5 heads and intake manifold on my Allante 4.1 build up. I also had some concern with the throttle cable mounting bracket. (Thought that i could use the 4.5 cables in the 85 if necessary) I am planning to use the 4.1 throttle body. I like the idea of a duel plane manifold. I also like the change in the intake manifold water passages on the 4.5. I do not want to change the Volumetric Efficiency to much. Fuel mileage and reliability are my main concern. Anything else you find that may be a problem, Please give me a heads up. You are about 2 to 3 weeks ahead of me.
 
#81 ·
This morning very early I went to a junkyard about 40 min up the road where they had a 4.5 TBI and a 4.5 PFI still in the cars. Both of them use the 4.9 style alternator and bracket, with the 3rd bolt hole in the center. I don't know what I was looking at in autozone last night. Anyways I grabbed a 4.5 bracket just in case and the alternator too so I could figure out how to modify wiring, and the yard monkey let me out for $20 when I told him what I was doing.

I got back to the shop and started moving parts off the engine. Everything went pretty smoothly using a mix of older and newer parts based on what works better. When I got to the alternator I decided to try mounting just the two ears (leaving the 3rd bolt in the back empty), and it seems perfectly stable to me. IIRC the CS-style alternators have always just used two anyway and while the 3rd certainly provides some stability I doubt it's absolutely necessary for moderate load. So for now I'm using the 4.1 with just the two ear bolts, and later on will convert to the 4.9 alternator wiring and upgrade then.

Here's a couple of pics of the transformation so far. The big open spot in the left rear corner is where the cruise servo assembly goes.





Vacuum integration is more complicated than I thought--I might pull the pump entirely until I can get it rewired, then stick it back in when I figure out what to do. I have not started working on the coolant or power steering lines yet. The crossover exhaust on the 4.1 is off a hair on the 4.9 manifolds, we may cut the pipe and weld it back, or I think we can just bend each ear by half an inch and get it there. Tomorrow we will do all of that and replace the transmission mounts too.

Here's some pics of the old 4.1. Gonna junk it because of low compression on #2 cylinder and issues with some of the components.







Power steering fluid leak and dust from belt wear (pulley wobble) made a nice black goop over everything
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top