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Discussion Starter #1
i have a 4.9 but need to know if putting the intake off the 4.1 and placing it on the 4.9 is better. or swapping in the new wire harness wire harness or if is not going to make much of a differnce not planning on keeping the car i have been asked to do this job
 

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kpobrien said:
i have a 4.9 but need to know if putting the intake off the 4.1 and placing it on the 4.9 is better. or swapping in the new wire harness wire harness or if is not going to make much of a differnce not planning on keeping the car i have been asked to do this job
Any clue as to what the car and year is....???

Those engines all had speed density fuel injection systems so replacing a 4.1 with a 4.9 will cause all sorts of driveability issues as the system willl not be able to compensate for the additional displacement and it will run very lean and drive poorly.

You really cannot replace the 4.1 TBI system with the 4.9 PFI system as the electronics in the car will not recognize the other system. I assume the car is an 85/86/87.....and the 4.9 is a 91-95?? All the 4.1's had TBI so you cannot easily put the PFI engine (4.9) into the car.
 

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Discussion Starter #3
but if i used the computer from the 4.9 it should work.

also would it be better to put in a 4.5 i can also get one of them

i was told if you change the intakes it would work just fine
 

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kpobrien said:
my eldo is an 85 the 4.5 is a 88and the 4.9 is a 92

Your response is what I was afraid of.... You got some bad info. Those parts will not interchange.

Your 85 Eldo has the engine mounted longitudinally in the chassis....or "north-south" in the conventional fashion. All of the 4.9 engines were in transverse FWD cars...with the engine mounted transversely or sideways. The cranks are different and the accessory drive is completely different...as well as the block and many other parts.

The 4.1 was the original displacement of both the longitudinal and transverse engines. That family of engines went to 4.5 with a larger bore....and then to 4.9 with a longer stroke crankshaft. There is no such thing as a 4.9 crank that will work in a longitudinal application. Not to say that something couldn't be cobbled up....but it would require adapting the 4.9 crank to fit in your longitudinal block....not easy at all......lot of machine work.

You need all of the block and external parts from your engine to still fit in the car. 4.5 pistons and cylinder liners would fit into your engine I think if you use 4.5 pistons from an 88/89 engine only.....rods/pistons are different for the 90 4.5.

In any case, the switch to the 4.9 is not that simple as you describe. Your 4.1 is a TBI system and the 4.9 is a port fuel injection engine. Extensive changes to the wiring harness in the car and the engine compartment would be required.....not easy at all....and the cars electronics on the dash and such would never talk to the PFI PCM.

There is no easy way to do what you describe ....not even a hard way to do what you describe. The simplest thing to do if you want to improve performance is to put the 4.5 pistons/liners/rods into your engine and rebuild it as is otherwise. The TBI system will still not recognize the additional displacement so the driveablility will not be perfect and nor much more performance will be realized unless you can find someone to reprogram the chip in the ECM....
 

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Discussion Starter #6
so sorry I feel like a total idoit i hit the 5 instead of the six. It is an 86 eldo front wheel drive with a 4.1 in it. soory for the inconvience
 

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Uh....yea....that does make a difference.....LOL


It is more possible to put the 4.9 in an 86 transverse Eldo....it will bolt in in some respects....but the issue with the displacement change from the 4.1 to the 4.9 will still make the engine drive poorly as the original TBI system will be very lean unless you can get the chip reprogrammed.... Switching the car over to port fuel injection is a huge task as many things have to be changed....the PFI system on the Cadillacs is not just a simple standalone box and harness like some of the other cars. It is well integrated into the car and is almost impossible to just plug in.

I am not sure that your original 4.1 manifold will bolt onto the 4.9. I tend to think it would although I know the coolant ports will not match at the coolant crossover at the front of the engine. The ports in the head (for the coolant) are different shaped than the ports in the manifold....I think that they will still seal up, though....with some liberal use of RTV/silicone. Just glue the manifold in that area with the RTV and let it set up for at least 24 hours before filling with coolant. If you take the intake gasket and line them up to the ports on the head and intake it would be obvious. Use the 4.1 intake gaskets as they would fit the best.

You could install the 4.9 engine with the 4.1 TBI system and the bump the fuel pressure up 2 PSI by shimming the fuel pressure rgulator in the throttle body. There is some adjustment in the fuel pressure by preloading the fuel pressure regulator adjustor....take the throttle body off and look up from the bottom between the fuel line fittings....the small squarish "screw" will adjust the fuel pressure but will probably not be enough to completely compensate for the 4.9.
 

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Discussion Starter #8
thank you so just for the hell of it would the 4.5 work better then the 4.9 like i said i have both @ my disposal
 

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Either the transverse 4.5 or transverse 4.9 would bolt in the same. Both will have a problems running on the TBI calibration in the 86, though...the 4.5 would be less effected by it. The 4.5 was available in TBI form in 88 and 89 so it would swap in the easiest and the 88/89 PCM could be made to work as it was still for a TBI system like the 86 had. If it was me I would try to find an 88/89 4.5 TBI engine and put that in. Much less to do and much greater likelyhood of something in the end that would be better than what you started with. Putting the TBI on the 4.9 PFI engine would not work so well in the long run I don't think.... BTW....there is a 1990 4.5 that is PFI that I would put in the same league as the 4.9's. It has different heads and many other parts that would make it difficult to adapt to the 86.
 

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Putting in a 4.9 might not be so hard after all. You might want to investigate a completely programmable fuel injection system called Megasquirt. What would be really nice is to run your stock fuel injection system in conjuction with the Megasquirt. The 4.5 has only 25 more horsepower than your 4.1 where as the 4.9 has a whopping 70 more horsepower!! Keep us posted on what you decide to do.
 

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Discussion Starter #11
If this is true that using the 4.1 manifold and tbi set up on a 4.9 you play with the presure regulator screw and shimming the regulator to get it to run better. Than on a a 4.5 it would probable work better and you could theoreticlly advance the timming and run 91 and higher octane to make it run a little richer. From what i here, getting a chip repogramed will cost around 4 big bills(400 hundred). And it is going to do all that i decribed.
 

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kpobrien said:
If this is true that using the 4.1 manifold and tbi set up on a 4.9 you play with the presure regulator screw and shimming the regulator to get it to run better. Than on a a 4.5 it would probable work better and you could theoreticlly advance the timming and run 91 and higher octane to make it run a little richer. From what i here, getting a chip repogramed will cost around 4 big bills(400 hundred). And it is going to do all that i decribed.
The higher octane fuel will NOT make it run richer....it would be required to bump the timing up as has been described....but the octane rating of the fuel has nothing to do with the richness of the mixture.

What you said is what I said above....yes. You can accomplish the fueling compensation for the larger displacement by bumping up the fuel pressure by adjusting the fuel pressure regulator spring preload and/or shimming the regulator spring in the throttle body. It won't be perfect but it will probably work for you. It will be closer on a 4.5 than on a 4.9 but either could probably be made to drive OK with some fiddling with the fuel pressure.

The additional timing will help with either...but will certainly require premium fuel and careful listening for detonation as the engine does not have a knock sensor to protect the engine.

That is why I mentioned that if you find an 88 or 89 4.5 it will be TBI already and you will not have to swap intakes and put the TBI on....plus....if you are after performance the 88/89 4.5 TBI has a larger throttle body and better intake manifold than the 86/87 4.1 did ... something that you want anyway.
 

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tacoma said:
hi all im looking to swap my ht 4100 in my 83 eldorado with a 4.9 will this work?
NO. See the second answer I made to the original post....that one applies to you....the other posts should provide enough info to answer your question.
 

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thanks for the reply
will a mid to latter 80s transverse 4.1 work as a replacment for a earlier in-line 4.1 or can the 2 just not mix?
 

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tacoma said:
thanks for the reply
will a mid to latter 80s transverse 4.1 work as a replacment for a earlier in-line 4.1 or can the 2 just not mix?
They do not mix. The longitudinal (RWD) engines and the transverse (FWD) engines are quite different due to the block design and cooling sytem.
 

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probbaly doesnt make a differance but my 83 eldo ht4100 is a longitudinal fwd not rwd but if it wont match it wont match thanks again :)
 

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Your response is what I was afraid of.... You got some bad info. Those parts will not interchange.

Your 85 Eldo has the engine mounted longitudinally in the chassis....or "north-south" in the conventional fashion. All of the 4.9 engines were in transverse FWD cars...with the engine mounted transversely or sideways. The cranks are different and the accessory drive is completely different...as well as the block and many other parts.

The 4.1 was the original displacement of both the longitudinal and transverse engines. That family of engines went to 4.5 with a larger bore....and then to 4.9 with a longer stroke crankshaft. There is no such thing as a 4.9 crank that will work in a longitudinal application. Not to say that something couldn't be cobbled up....but it would require adapting the 4.9 crank to fit in your longitudinal block....not easy at all......lot of machine work.

You need all of the block and external parts from your engine to still fit in the car. 4.5 pistons and cylinder liners would fit into your engine I think if you use 4.5 pistons from an 88/89 engine only.....rods/pistons are different for the 90 4.5.

In any case, the switch to the 4.9 is not that simple as you describe. Your 4.1 is a TBI system and the 4.9 is a port fuel injection engine. Extensive changes to the wiring harness in the car and the engine compartment would be required.....not easy at all....and the cars electronics on the dash and such would never talk to the PFI PCM.

There is no easy way to do what you describe ....not even a hard way to do what you describe. The simplest thing to do if you want to improve performance is to put the 4.5 pistons/liners/rods into your engine and rebuild it as is otherwise. The TBI system will still not recognize the additional displacement so the driveablility will not be perfect and nor much more performance will be realized unless you can find someone to reprogram the chip in the ECM....
Hi Guys,
I am new here and I am not a HT 4100 or 4.5 or 4.9 guru, but I have contemplated and read other threads on this swap.
When I was younger I had a Seville with a CB and I drove a lot and one day i heard the truckers talking and I heard "here comes the Cadillac Kid" so that's how I got this name.

There is an upgrade to a 4.5 for the 4.1 sold as re manufactured long block assembly. Looking at the 4.9 there is a difference in cranks one is listed as 3 bolt and the other a 6 bolt. Not sure about the length of crank and the blocks being different. The transmission 325-4L has a metric bell housing, this is also listed as the same bolt pattern on the Deville. There are TBI 4.5 intake manifolds, the only difference I see is the water jacket port on the 4.1 please notice on 88-89 4.5 intake that there no injection ports. Here is a pic of 4.1. The 4.9 intake is almost Identical to the 4.5 except it has ports for the injectors. One person attempting the 4.9 swap said he was going to plug off the ports.

My personal motivation is to use a latter model Block that has extra ribbing that remedied the leaking intake manifold problem. I have read that the TBI injectors and the ECM is a simple pulse signal. I will try to confirm the crankshafts are different lengths, if so, then I would have a custom made crank patterned off the 4.1 and increase the stroke 5 liter and use Chevy 305 TBI injectors nozzles. I think this would be my approach, if the crankshaft has the same spacing in journals then look at what machine modifications would need to address 3 bolt vs 6 bolt to make it work.

I really cannot see GM making different length crankshaft as main bearing journals and front and rear seal would need to remain the same spacing. I can see the end of the crankshaft being different. I would like to know where I can find the specs on the 4.1,4.5 and 4.9 cranks to see the difference.

I welcome any correction and information. Thanks Truckers Cadillac Kid or TCC
 

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Hi Guys, I have looked into and there is 2 differences in the crankshafts. The 4.1 rear is 3 bolt and 3 inch center hole the 4.9 is a 6 bolt with a 1.09 center. This problem could be easily remedied as some the Fiero guys cut the pattern center out both flex-plates and machine weld the correct 6 bolt 1.09 center hole. The front of the crankshaft is reported to be shorter and will not accommodate the V belt system. I am not sure why the Serpentine Belt and accessories could not be used by custom hoses etc. The only other way would be to have a billet crank made to order. BeelzeBob mentioned that it would not recognize the new flow rates and one is PFI and the other TBI and nothing would communicate. Perhaps I missing something here but I am using a 4.5 TBI manifold and Throttle Body from an 1989. I checked the ECM P/N and they are the same for the 1985 4.1 and 1989 4.5 so I am little lost as to why it would not communicate. I put a question into the Reman asking if there is any internal difference. If all the sensors are hooked up and sending the Info to the ECM and the ECM is telling the TB Injector (5L Injectors that fit into the TB and have same connections) to supply fuel. I cannot see the problem.
 

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Hi Guys, I have looked into and there is 2 differences in the crankshafts. The 4.1 rear is 3 bolt and 3 inch center hole the 4.9 is a 6 bolt with a 1.09 center. This problem could be easily remedied as some the Fiero guys cut the pattern center out both flex-plates and machine weld the correct 6 bolt 1.09 center hole. The front of the crankshaft is reported to be shorter and will not accommodate the V belt system. I am not sure why the Serpentine Belt and accessories could not be used by custom hoses etc. The only other way would be to have a billet crank made to order. BeelzeBob mentioned that it would not recognize the new flow rates and one is PFI and the other TBI and nothing would communicate. Perhaps I missing something here but I am using a 4.5 TBI manifold and Throttle Body from an 1989. I checked the ECM P/N and they are the same for the 1985 4.1 and 1989 4.5 so I am little lost as to why it would not communicate. I put a question into the Reman asking if there is any internal difference. If all the sensors are hooked up and sending the Info to the ECM and the ECM is telling the TB Injector (5L Injectors that fit into the TB and have same connections) to supply fuel. I cannot see the problem.
Are you attempting to install a 4.9 liter in a car with a longitudinal Ht4100 in it presently?
 
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