Transmission swap
Thread Starter
Racer
Joined: Jun 2009
Posts: 302
Likes: 2
From: Milton Delaware
Transmission swap
My '73 is finally going in for its new paint job. Yup, finally was able to save up enough money. Going to take the engine and tranny out,so we can do the engine compartment. While the engine is out and the shop is getting the body ready, I'm going to go over the engine.
1. Need to replace the rear main bearing seal.
Should I replace the front too? I have a 1988 "Mexico 350 crate engine". Does it have a one piece seal or halves? If it is the one piece and since I have to take off the pan and loosen the crank bolts....should I replace the main bearings?
2. The front bearing and rear seals of the tranny is leaking, so those are being replaced. Have a quick shift in my TH400 and I want to get rid of it. What needs to be done for that? No matter what, I do not want the quick shift.
3. Just wondering...... is there another auto tranny, newer, that is 4 speed, that will fit in my vette without too much alterations. Have access to a auto salvage yard that might have a tranny available if some one has done this with success.
4. Going from a Eldelbrock 600 carb back to the Qjet carb. Better gas mileage and performance. But this "1988 Mexico 350 crate engine" intake manifold does not have the correct configuration for the choke assembly. Where the choke springee bolts to the manifold it is on a slant instead of being flat like the original '73 manifold. What intake manifold and to what year can I replace this with that will look like the original?
5. Not doing a body off resto, but I am going to replace the 4 on each side body mounts with the polyurethane type. Any ideas about doing them. Know of any videos of that being done?
6. Have a slight smoking when I first start the engine up, and I am thinking of it is in the valves or heads. What you ideas? and to do what?
I know this was long, guys, and thanks for being patient. I hope a lot of you reply and give me good tips of what to do to those questions and for whatever else I should do. All is appreciated. Please answer the question by the number so I refer back to them
Will keep everyone posted on how this project is going. Thanks
Jim
1. Need to replace the rear main bearing seal.
Should I replace the front too? I have a 1988 "Mexico 350 crate engine". Does it have a one piece seal or halves? If it is the one piece and since I have to take off the pan and loosen the crank bolts....should I replace the main bearings?
2. The front bearing and rear seals of the tranny is leaking, so those are being replaced. Have a quick shift in my TH400 and I want to get rid of it. What needs to be done for that? No matter what, I do not want the quick shift.
3. Just wondering...... is there another auto tranny, newer, that is 4 speed, that will fit in my vette without too much alterations. Have access to a auto salvage yard that might have a tranny available if some one has done this with success.
4. Going from a Eldelbrock 600 carb back to the Qjet carb. Better gas mileage and performance. But this "1988 Mexico 350 crate engine" intake manifold does not have the correct configuration for the choke assembly. Where the choke springee bolts to the manifold it is on a slant instead of being flat like the original '73 manifold. What intake manifold and to what year can I replace this with that will look like the original?
5. Not doing a body off resto, but I am going to replace the 4 on each side body mounts with the polyurethane type. Any ideas about doing them. Know of any videos of that being done?
6. Have a slight smoking when I first start the engine up, and I am thinking of it is in the valves or heads. What you ideas? and to do what?
I know this was long, guys, and thanks for being patient. I hope a lot of you reply and give me good tips of what to do to those questions and for whatever else I should do. All is appreciated. Please answer the question by the number so I refer back to them
Will keep everyone posted on how this project is going. Thanks
Jim
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
My '73 is finally going in for its new paint job. Yup, finally was able to save up enough money. Going to take the engine and tranny out,so we can do the engine compartment. While the engine is out and the shop is getting the body ready, I'm going to go over the engine.
1. Need to replace the rear main bearing seal.
Should I replace the front too? I have a 1988 "Mexico 350 crate engine". Does it have a one piece seal or halves? If it is the one piece and since I have to take off the pan and loosen the crank bolts....should I replace the main bearings?
Very very very high likelihood of 2 piece. The 1 piece was just barely out at this point, in the form of the L98.
2. The front bearing and rear seals of the tranny is leaking, so those are being replaced. Have a quick shift in my TH400 and I want to get rid of it. What needs to be done for that? No matter what, I do not want the quick shift.
3. Just wondering...... is there another auto tranny, newer, that is 4 speed, that will fit in my vette without too much alterations. Have access to a auto salvage yard that might have a tranny available if some one has done this with success.
700R4 and 2004R will fit, you'll need a custom crossmember, add TV linkage, and shortened driveshaft.
4. Going from a Eldelbrock 600 carb back to the Qjet carb. Better gas mileage and performance. But this "1988 Mexico 350 crate engine" intake manifold does not have the correct configuration for the choke assembly. Where the choke springee bolts to the manifold it is on a slant instead of being flat like the original '73 manifold. What intake manifold and to what year can I replace this with that will look like the original?
If you're doing a divorced choke carb, the only real options available are the factory iron intakes. You can and I recommend using a late 70's quadrajet - that probably has the correct heat riser choke for the intake you've got, or you can forget about a heated choke entirely and run an electric choke. The later quads are actually a bit more reliable and have an easier-to-adjust APT, which will let you dial cruise in like setting an idle mixture.
5. Not doing a body off resto, but I am going to replace the 4 on each side body mounts with the polyurethane type. Any ideas about doing them. Know of any videos of that being done?
6. Have a slight smoking when I first start the engine up, and I am thinking of it is in the valves or heads. What you ideas? and to do what?
Could be weak valve seals leaking down...
I know this was long, guys, and thanks for being patient. I hope a lot of you reply and give me good tips of what to do to those questions and for whatever else I should do. All is appreciated. Please answer the question by the number so I refer back to them
Will keep everyone posted on how this project is going. Thanks
Jim
1. Need to replace the rear main bearing seal.
Should I replace the front too? I have a 1988 "Mexico 350 crate engine". Does it have a one piece seal or halves? If it is the one piece and since I have to take off the pan and loosen the crank bolts....should I replace the main bearings?
Very very very high likelihood of 2 piece. The 1 piece was just barely out at this point, in the form of the L98.
2. The front bearing and rear seals of the tranny is leaking, so those are being replaced. Have a quick shift in my TH400 and I want to get rid of it. What needs to be done for that? No matter what, I do not want the quick shift.
3. Just wondering...... is there another auto tranny, newer, that is 4 speed, that will fit in my vette without too much alterations. Have access to a auto salvage yard that might have a tranny available if some one has done this with success.
700R4 and 2004R will fit, you'll need a custom crossmember, add TV linkage, and shortened driveshaft.
4. Going from a Eldelbrock 600 carb back to the Qjet carb. Better gas mileage and performance. But this "1988 Mexico 350 crate engine" intake manifold does not have the correct configuration for the choke assembly. Where the choke springee bolts to the manifold it is on a slant instead of being flat like the original '73 manifold. What intake manifold and to what year can I replace this with that will look like the original?
If you're doing a divorced choke carb, the only real options available are the factory iron intakes. You can and I recommend using a late 70's quadrajet - that probably has the correct heat riser choke for the intake you've got, or you can forget about a heated choke entirely and run an electric choke. The later quads are actually a bit more reliable and have an easier-to-adjust APT, which will let you dial cruise in like setting an idle mixture.
5. Not doing a body off resto, but I am going to replace the 4 on each side body mounts with the polyurethane type. Any ideas about doing them. Know of any videos of that being done?
6. Have a slight smoking when I first start the engine up, and I am thinking of it is in the valves or heads. What you ideas? and to do what?
Could be weak valve seals leaking down...
I know this was long, guys, and thanks for being patient. I hope a lot of you reply and give me good tips of what to do to those questions and for whatever else I should do. All is appreciated. Please answer the question by the number so I refer back to them
Will keep everyone posted on how this project is going. Thanks
Jim
Does your heat riser setup for the choke look similar to this one?
(center of passenger side manifold, aluminum blockoff plate)
Drifting
Joined: Jul 2007
Posts: 1,889
Likes: 23
From: Kansas
Buy a new 330 H.P. crate for around 3K & be done with the motor problem. Find an 1982 that has the cross member, drive shaft, shift cable bracket, & shift unit set up. Buy a 1987 or newer 700R & run wiring so you can shift it into Overdrive when you want to. I know there are Corvette Forum members who know a lot more than I do about this. Find one of those members also. Oh with that new 330 H. P. motor, you will need a later model flywheel. Have a great day. Gene
Melting Slicks
Joined: Feb 2006
Posts: 3,428
Likes: 5
From: Japan
The first thing I'd do to verify the condition of the engine is a compression check. If that turns out OK then you can safely move on to the next thing(s).
If you just want to kill the leaks without an undue amount of hassle, then replace the front/rear seals, intake manifold gaskets, pan gaskets, and valve cover gaskets. There are 'sleeves' available that you can put over the harmonic damper hub that will make the front seal work a lot better.
If I remember correctly, a Weiand 8004 intake has a mounting provision for the old-style QJet choke spring, and it has a spread-bore mounting flange.
As for the bearings, while you've got the pan off, pull a couple rod caps off the rear journal and see how they look. Look at the crank journal as well. If it's at all scored up, and if the bearings are worn through the top (white-colored) layer of metal, you've got problems there, especially if you've been getting low oil pressure numbers at idle, like, say, less than 15 psi.
If your compression numbers were erratic or low, putting new bearings in it (not really advisable anyway with the motor in the car) will be comparable to putting lipstick on the proverbial pig. Those Mexican castings are also crap metal, low nickel content, prone to cracking, etc.
At that point I'd be looking into motor replacement. Like I said, check the compression (or better still, do a leakdown test) first. If you get the pan torn off and those two rear bearings still look OK, the motor's still got some useful life in it. Seal it up, put it back together, and run it.
If all else is good (a big if) the most likely cause of the smoke would be worn valve guides+ worn stem seals. The seals can be fixed in the car, and will at least stop the smoking for awhile...
Enjoy!
If you just want to kill the leaks without an undue amount of hassle, then replace the front/rear seals, intake manifold gaskets, pan gaskets, and valve cover gaskets. There are 'sleeves' available that you can put over the harmonic damper hub that will make the front seal work a lot better.
If I remember correctly, a Weiand 8004 intake has a mounting provision for the old-style QJet choke spring, and it has a spread-bore mounting flange.
As for the bearings, while you've got the pan off, pull a couple rod caps off the rear journal and see how they look. Look at the crank journal as well. If it's at all scored up, and if the bearings are worn through the top (white-colored) layer of metal, you've got problems there, especially if you've been getting low oil pressure numbers at idle, like, say, less than 15 psi.
If your compression numbers were erratic or low, putting new bearings in it (not really advisable anyway with the motor in the car) will be comparable to putting lipstick on the proverbial pig. Those Mexican castings are also crap metal, low nickel content, prone to cracking, etc.
At that point I'd be looking into motor replacement. Like I said, check the compression (or better still, do a leakdown test) first. If you get the pan torn off and those two rear bearings still look OK, the motor's still got some useful life in it. Seal it up, put it back together, and run it.
If all else is good (a big if) the most likely cause of the smoke would be worn valve guides+ worn stem seals. The seals can be fixed in the car, and will at least stop the smoking for awhile...
Enjoy!
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
3. The 200-4R will use your same driveshaft and same cross member. You can find a 200-4r at the wrecking yard and beef it up a little or have it done. If your pockets are deep, get one from BTO. If you do your own trans build, be sure to install a hardened stator support, wide alto band, trans-go shift kit and a super servo, be plenty tough for 350 hp.
Thread Starter
Racer
Joined: Jun 2009
Posts: 302
Likes: 2
From: Milton Delaware
So I take it guys, that there is no other existing car transmission with at least 4 speeds auto that will fit in this vette. Do Not have any deep pockets at all to buy a new auto tranny. I need to find another method. (hopefully a lot cheaper) Thanks
