I finally decided to take the plunge and do a swap.
I am not partial to computerized car stuff, and I do prefer to tune up my engine with a screw driver instead of a laptop, so after consideration of my driving requirements, and my budget, I decided to carb a 4.9. I also wanted to keep my 4 speed Muncie
First, finding the donor. It was a 1992 Seville that had been stored for 9 years, 120 k kms on the clock and was driven to where it was parked. So, home it comes.
This is an edit after dyno tuning.
1. The Moroso distributor advance spring kit has 3 springs. I was initially advised to use the lightest spring which brings in the full advance quickest. This did not work well on the dyno. We found the 3rd spring (heaviest) is the best choice. The 3rd spring is lighter than the stock Olds spring.
2. The jetting on the 2 barrel Holley OE is #73. This leaves the engine slightly rich. By dropping the jet size to #70 the mix evens out and the engine is brighter and more responsive.
3. Using the crossover and single out as I did initially, causes thermal conjestion and a "true dual" system is needed to lower engine temps and smooth out the exhaust flow. I will be modifying the exhaust using the stock exhaust manifolds and 2.5" pipe in a true dual setup. Dyno guys give me the opinion that at the horsepower level of the engine, headers are not needed. I may still make headers though.
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[This message has been edited by Arns85GT (edited 07-11-2014).]
I first have to thank some people who were of invaluable assistance so far.
Bubbajoexx knows the carb'd 4.9 the best and fortunately for me, he is just a couple of hours down the road. He provided me some technical help, and even some steel.
PBJ is a true tech and also an invaluable resource. Of course there are more guys on the list and their help one and all has been greatly appreciated.
This spaghetti had change. No power steering, and no A/C so it starts.
Arn
[This message has been edited by Arns85GT (edited 03-31-2013).]
The stock cross over pipe will not clear the shifter cables, so I fabbed up a mod for it.
Edit
3. Using the crossover and single out as I did initially, causes thermal conjestion and a "true dual" system is needed to lower engine temps and smooth out the exhaust flow. I will be modifying the exhaust using the stock exhaust manifolds and 2.5" pipe in a true dual setup. Dyno guys give me the opinion that at the horsepower level of the engine, headers are not needed. I may still make headers though.
I also decided not to try to modify the thermostat housing to accept the fan switch sensor and temperature sensor.
This required a conversion plate to use the Fiero Thermostat Housing
I also had to make a decision on the oil cooler. I had advice that it was necessary, however, after some research it began to look like I might not need it. The Northstar engines have not had an oil cooler since 1997. So I decided to at least try it without the oil cooler and I got one of the oil cooler lines modified so I could loop it. I'll check for any burning in the oil on a regular basis, and if I need to get a cooler, it won't be a big job, but in the meanwhile, it is cheaper not to have to buy one.
BTW, after a search through the wrecking yards, the oil coolers there are generally in poor condition and not worth the effort.
I have installed the Fiero oil temp sensor in place of the Caddy sensor which just runs an idiot light.
Also, the main exhaust pipe on the Cadillac extends too far out back to clear the trunk wall, so I used the flange and conversion disk and welded in a tighter down turn to create an exhaust pipe that will clear the trunk.
It goes down to a T joint so I fabbed up one of these
It flows into 2 Cats, which will exit to my Spintech mufflers.
Arn
[This message has been edited by Arns85GT (edited 07-11-2014).]
This is the Spintech muffler setup currently there. A pretty easy switch over.
With Bubba's help I did up hard motor mounts.
There are a couple of reasons I went to hard mounts. First off the engine is a smooth running engine. Second, the cradle is already rubber mounted, and third, I did not want the engine to shake from torque. I also added, just to be sure, a support strut made out of a Fiero dogbone strut. Funnily enough, with just adjusting the holes a bit, it mounts right up. I then just have to weld a mounting plate to the cradle.
One decision is how much air to give the engine. I decided on 500 cfm. That will provide adequate air for the rpm range this engine will operate in, and provide decent gas mileage.
However, the carb fits differently than the throttle body. This requires a conversion plate.
In my case, 1/2" aluminum hand shaped.
As you can see, the 1&5/8" venturi don't mate up to the 1&7/8" intake holes which are spaced 1/2" apart to the bargain.
I RTV'd the plate down and mounted the carb the usual way.
The biggest secret to the carb conversion is the distributor.
Bubba was a real font of knowledge on this one and was indispensable for it.
Not wanting an ECM, the distributor needs to be mechanical. This involves small springs with spinning weights for those guys who aren't familiar with standard distributor technology.
In the case of the 4.9, the distributors from the 4.1 and 4.5 fit the 4.9, however, the interior of the 4.1 and 4.5 distributors has a critical difference. It will accept an Olds or Pontiac guts. So, in this case, the guts from a new Olds distributor was put into the 4.1 Caddy distributor and a set of Moroso springs were purchased to modify the advance.
The shaft is shortened, and one of the plugs is not used.
The ring inside is removed
The springs are swapped out
The reason for this is that the torque curve and power curve of the 4.9 shows that your usable rpm are actually 0 to 4.000, with the power dropping of substantially before you get to 5,000. So, you want your full advance at 4,000. Also, the ECM of the 4.9 does not give full advance at lower rpms for emissions reasons. With this setup, you can see how you can modify the advance according to what you want.
As you can see, the module for the Olds pretty much fits right in to the Caddy frame.
Arn
Edit
1. The Moroso distributor advance spring kit has 3 springs. I was initially advised to use the lightest spring which brings in the full advance quickest. This did not work well on the dyno. We found the 3rd spring (heaviest) is the best choice. The 3rd spring is lighter than the stock Olds spring.
[This message has been edited by Arns85GT (edited 07-11-2014).]
The engine had been sitting for quite a while, so to do the compression check, we forewent the dry compression test and went straight to the wet test.
Over 200 psi. Not bad for an old Caddy.
Now I have to wait some. I don't plan on putting the car in the air without an extra guy around for safety. So I have to wait until friends are available, probably the last week of the month. Oh well
The vacuum advance is only necessary for automatic trannied cars. The mechanical advance will give me 40 degrees overall with a 10 degree base. This is plenty for the engine. The question will be whether to set up the engine for high test gas, or regular. I may need to set the base closer to 8 degrees, depending on the quality of the gas.
Well, it's running. The new clutch has a bit of slip, but I'm assuming it is a breakin issue. My short exhaust (2.5" into Spintechs) sounds really good. I won't know the performance until the clutch seats, but it starts real good and I'm over 20 inches of vacuum at idle. Not bad.
Well so much for the Rochester carburetor. It seems they work OK with an automatic choke in stock configuration, but, when converted to manual choke you can't get the idle down to the 600 mark the engine wants. So, I have a Holley 2300 on order. Manual choke and I know for sure I can set the idle.
Another thing. The timing marks are non-existent on this engine as it was computer run. So, the timing is set with a vacuum gauge. That works too. All old school.
Also, the jury is still out on the Centerforce II clutch. It hasn't seated yet, at 75 km. running, and I may have to get the Archie pressure plate.
Well so much for the Rochester carburetor. It seems they work OK with an automatic choke in stock configuration, but, when converted to manual choke you can't get the idle down to the 600 mark the engine wants. So, I have a Holley 2300 on order. Manual choke and I know for sure I can set the idle.
Another thing. The timing marks are non-existent on this engine as it was computer run. So, the timing is set with a vacuum gauge. That works too. All old school.
Also, the jury is still out on the Centerforce II clutch. It hasn't seated yet, at 75 km. running, and I may have to get the Archie pressure plate.
Always something.
Arn
Looking good! Keep in mind that the 4.9 seems to have low oil pressure at idle and sometimes the light comes on when the engine is hot and I'm sitting at a red light. I had the guy who programmed my chip up the idle for the standard trans to help keep the oil pressure higher at idle. I think it was set to 800 rpm at his recomendation. I'm running the centerforce dual friction clutch for the V6 fiero without any problems so far. The guy at the counter said it was good for something like 285ft lbs. The pedal is easy to depress but the clutch seems to grab fine. I think the instructions said do take it easy for 400kms so I did.
No low oil pressure with mine at all. I used the Fiero oil pressure sensor so I don't have the idiot light.
I also have it set up without the oil cooler. Taking temperature readings on the intake manifold and the oil filter housing, it appears to be about a 10 degree F. difference. One thing I am watching though, is the amount of time my fans are on. The jury is still out on whether to get a bigger rad or add the oil cooler.
The Centerforce II is firming up gradually and I have not yet reached 100kms
Here is something you'll want to know. The distributor weights bring the advance up at least 10 degrees automatically. So if you are using a timing light, your timing target will be at least 2" to the left of the 10 degree timing mark.
The weights should not be in play at idle. The MOROSO instruction sheet shows the weight/spring combos to tailor your advance curve. The advance should happen gradually as the rpm increases, with full advance at some higher rpm. Older cars used the weights/springs as well as a vacuum diaphragm to advance the timing, same principle here except the ECU replaces the vacuum...
Originally posted by Arns85GT: Another thing. The timing marks are non-existent on this engine as it was computer run. So, the timing is set with a vacuum gauge. That works too. All old school. Arn
The timing is computer controlled but it still has a distributor that can be turned so there has to be timing marks. It's located on the inner lip of the harmonic balancer / crank pulley.
[This message has been edited by Zac88GT (edited 05-16-2013).]
The timing is computer controlled but it still has a distributor that can be turned so there has to be timing marks. It's located on the inner lip of the harmonic balancer / crank pulley.
My engine has a replacement water pump with no timing marks on it. There is a small bolt head at 10 degree mark and it can be used for reference. The initial advance built into the distributor of 10 degrees, makes that mark a bit useless though. The actual timing mark is about 2" to the left of the 10 degree mark.
As for the vacuum advance, it can be of use in higher rpm applications or with an automatic tranny, but for a stick shift car, the weights do the trick nicely.
The used Rochester carb didn't work out. Too lean, trouble regulating the idle and not able to retard the distributor enough due to leanness.
Seeing as how I just don't know Rochesters, and didn't feel like the learning process and experimenting, I went to Nationalcarburetor and got a rebuilt 500 cfm Holley 2300.
These carb's are benched and flowed before sending them out, so it was ready to run the engine. I had to do some things different for fit, and I needed to set up the fast idle the way I like it, but, HUGE improvement. It now idles down nicely, has gobs of torque and is behaving the way it should.
So if anybody wants to put a Holley on their 4.9 here is a few hints.
First off, the intake is pretty much crowded by the EGR. There is no where to move the EGR, so the answer is a phenolic spacer. In my case a 1.5" oak spacer.
It is a piece of 1.5" red oak drilled and shaped to fit. The mounting screws for the intake are countersunk. The two venturi holes are coated with JB Weld epoxy so the wood doesn't absorb the gas.
The result is very good. The carb clears the EGR and the spacer makes sure the gas stays cool in the carb. Bonus
Edit
2. The jetting on the 2 barrel Holley OE is #73. This leaves the engine slightly rich. By dropping the jet size to #70 the mix evens out and the engine is brighter and more responsive.
Now I just have to finish breaking in the Centerforce II. BTW, I used the Centerforce because I had it on hand. I'd recommend more clutch next time.
It sounds great, goes like stink, and I am basically pleased.
Now I am working on a "batmobile" look for the exterior. I'll post a pic tomorrow.
Arn
[This message has been edited by Arns85GT (edited 07-11-2014).]
I would never have thought of using an oak block. Isn't there some advantage to having a carb raised up in terms of horsepower? Something like it gives the the fuel more time to mix with the air? I'd say the oak block is thinking outside the box but I'm willing to bet that it's an old hot rodder trick.
So how far are you going with the batmobile look? Just a flat black or full on bat wings and fake jet exhaust?
This is the car fresh out of the shop. Lots of dust and smears. I can't quite make up my mind whether to leave it mat coated or give it a shiny clear coat
It is sort of the "rat rod" vs the dressed out rod theory I'm considering. I'm open to suggestions.
To be honest, I would like to see MORE pics of the car as it is with the mat finish. Thinking of doing this with my '87 Base Coupe with a carb'd 4.9! My car is already black with custom faded clearcoat, lol. Is it difficult to keep clean?
-Gary
quote
Originally posted by Arns85GT:
This is the car fresh out of the shop. Lots of dust and smears. I can't quite make up my mind whether to leave it mat coated or give it a shiny clear coat
It is sort of the "rat rod" vs the dressed out rod theory I'm considering. I'm open to suggestions.
This is a Duplicolor lacquer finish. Lacquer takes a few days to cure hard, but it dries fast.
The base coat was Jet Black lacquer, however, when I touched up the hood and top, I used black primer and then cleared over it.
You cannot tell the difference at all.
If you go to a car shop that sells Meguiar's they should have the high cut and fine cut cleaners. They are in a bottle and you use a cloth with them or a buffer. I did not use the buffer because it tends to give a sheen to the matte finish which causes unevenness.
I am not sure how much work it will be to keep looking nice. Time will tell. It likely will be no worse than any black car, is my guess.
