Need help w/ a few things! 🙏 TBI conversion to Carb.

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CopperNick

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DSCN2874.JPG


on the premise that at this point a few pictures might be in order, I dug my just pulled 350-E out of its current corner and took some close up of the various identifying aspects.

Here it can be clearly seen that the ATF pan has its passenger corner clipped to create an angle to the oil pan. As the thread above commented this is what he found when he managed to slither his way under the car to look. Also visible in the picture is the vacuum module c/w its vacuum line that would be attached at the other end to a fitting on the manifold if this unit was in a vehicle.


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These show what typically would be seen if looking at driver's side of the E or lock up version of the 350. The first pic is nothing unusual, just the gear selector lever.

PIC Two shows the external clue that this transmission is not a normal or standard version. This is the plugin into the wiring harness shown in the next picture would be attached. This is power gets to the transmission to initiate the lockup of the converter in third gear. Visible are the four sockets in the female body but if you look closely you will only see one pin in the male fitting. Not sure why but suspect that what was actually happening was that the lockup occurred due to input from other sources and this is the circuit that is attached to the brake pedal to break or shut down the lockup during braking or declerating.

To answer your question about the need for the lockup. Yes, you can live without it; the e-version of the 350 will happily move from gear to gear without issue and exactly like its non lockup cousin would do. The concern is internal heat that the transmission can generate while going about its business. If you surf sites that deal with transmissions you will discover that transmissions possessing the lockup capability but having it disabled will run hotter and require more frequent ATF changes.


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Okay, this being the passenger side of the 350-E what you see is nothing unusual or different between it and its non-zapped cousin. The open port showing the red ATF is where the dipstick tube plugs in. Both pics also show the demand downshift cable, aka the passing gear cable location with the cable still installed.

DSCN2882.JPG


Finally a detail shot of the carburetor end of the downshift cable. This one has a custom created extension/adapter attached to it to allow it to be fitted to a Holley 4 Barrel that I used to run. I went EFI a few years ago but needed to keep the adapter at the time. My new 700R4 doesn't need it so it will come off this cable and get parked (and probably eventually lost.)

So about the only visual cue that would tip you to having the E variant is the plug in on the transmission case. As I noted, apparently as far as the 350 goes you can live without the lockup. I did with this unit for over thirty years but most of that was stop and go commuter traffic. Had I been running the highways or interstates it likely would have failed years ago. By the way, this unit was not original to the vehicle it came from, Its predecessor blew its guts out and all over the concrete pad at my service station. Good thing they were an understanding and sympathetic bunch. The box was done; a Total DOA. Lost the entire contents of the pan. T-mission shop owner took one look at the corpse and turned and walked over to his shelves to see if he had a rebuilt replacement. Lucky for me he did.

One thing to note here. I cannot honestly state that the first transmission blew up because i had been running it on the interstate with the lockup disabled. The vehicle itself was a used unit and I got a "good" deal on it because they didn't want to do the regular maintenance.

I can say that the replacement unit never saw any interstate time.

Most of the time what the lockup will do is add a few miles to your miles per gallon and take some of the stress off the drivetrain in the process.

Good luck with your project and welcome to the forums.



Nick
 

MonteLS_84

Apprentice
Jul 28, 2021
63
10
8
View attachment 181364

on the premise that at this point a few pictures might be in order, I dug my just pulled 350-E out of its current corner and took some close up of the various identifying aspects.

Here it can be clearly seen that the ATF pan has its passenger corner clipped to create an angle to the oil pan. As the thread above commented this is what he found when he managed to slither his way under the car to look. Also visible in the picture is the vacuum module c/w its vacuum line that would be attached at the other end to a fitting on the manifold if this unit was in a vehicle.


View attachment 181365


View attachment 181366


View attachment 181367


These show what typically would be seen if looking at driver's side of the E or lock up version of the 350. The first pic is nothing unusual, just the gear selector lever.

PIC Two shows the external clue that this transmission is not a normal or standard version. This is the plugin into the wiring harness shown in the next picture would be attached. This is power gets to the transmission to initiate the lockup of the converter in third gear. Visible are the four sockets in the female body but if you look closely you will only see one pin in the male fitting. Not sure why but suspect that what was actually happening was that the lockup occurred due to input from other sources and this is the circuit that is attached to the brake pedal to break or shut down the lockup during braking or declerating.

To answer your question about the need for the lockup. Yes, you can live without it; the e-version of the 350 will happily move from gear to gear without issue and exactly like its non lockup cousin would do. The concern is internal heat that the transmission can generate while going about its business. If you surf sites that deal with transmissions you will discover that transmissions possessing the lockup capability but having it disabled will run hotter and require more frequent ATF changes.


View attachment 181370 View attachment 181371

Okay, this being the passenger side of the 350-E what you see is nothing unusual or different between it and its non-zapped cousin. The open port showing the red ATF is where the dipstick tube plugs in. Both pics also show the demand downshift cable, aka the passing gear cable location with the cable still installed.

View attachment 181372

Finally a detail shot of the carburetor end of the downshift cable. This one has a custom created extension/adapter attached to it to allow it to be fitted to a Holley 4 Barrel that I used to run. I went EFI a few years ago but needed to keep the adapter at the time. My new 700R4 doesn't need it so it will come off this cable and get parked (and probably eventually lost.)

So about the only visual cue that would tip you to having the E variant is the plug in on the transmission case. As I noted, apparently as far as the 350 goes you can live without the lockup. I did with this unit for over thirty years but most of that was stop and go commuter traffic. Had I been running the highways or interstates it likely would have failed years ago. By the way, this unit was not original to the vehicle it came from, Its predecessor blew its guts out and all over the concrete pad at my service station. Good thing they were an understanding and sympathetic bunch. The box was done; a Total DOA. Lost the entire contents of the pan. T-mission shop owner took one look at the corpse and turned and walked over to his shelves to see if he had a rebuilt replacement. Lucky for me he did.

One thing to note here. I cannot honestly state that the first transmission blew up because i had been running it on the interstate with the lockup disabled. The vehicle itself was a used unit and I got a "good" deal on it because they didn't want to do the regular maintenance.

I can say that the replacement unit never saw any interstate time.

Most of the time what the lockup will do is add a few miles to your miles per gallon and take some of the stress off the drivetrain in the process.

Good luck with your project and welcome to the forums.



Nick
Thanks for all of the info. A bit of an overload but I'm dealing with it. 😅

So, doing some research on my end...it seems the electric hook-up is indicative of a lock-up. Okay...I don't see any sort of vacuum canister as in the photo you shared (other than the photo I shared of an unidentified canister looking item).

I'll have to continue investigating. My question now is...would an aftermarket torque converter make all of this irrelevant? Or would the trans. still be dependent on the electronic and vacuum controls? 🤔 And where in the heck would I order those vacuum related controls, what are they called, part number? 😬 I can only find the modulator itself.

Google says I will benefit from an aftermarket TCC unit. What the heck is that? 😂
 

ELCAM

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Jun 19, 2021
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Nicks first image is the modulator valve. Same valve as in your pic. A TH 350 has to have the modulator valve it is already present and hooked up on your car removing the computer will have no affect on it. The reason one asks about it is that the 200-4R does not use this since it is present we know it is not a 200-4r.

The reason the lock up converter is important is it is operated by the computer in your car, if you remove the computer you will need a different way to operate the circuit if you want to use it.

You can convert a 350c to a 350 but you have to take the pump out of the transmission and drill a hole in it, modify the auxiliary valve body and remove a check ball from the main valve body. Something like that, a bit of work and you need to know how to take a TH350 apart. See last 2 pages of attached pdf file.


The TCC kit is something like this https://static.summitracing.com/global/images/instructions/tci-376600.pdf that is for 200-4R and 700- R4 but can be made to work with the 350c.
 

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MonteLS_84

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Jul 28, 2021
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Nicks first image is the modulator valve. Same valve as in your pic. A TH 350 has to have the modulator valve it is already present and hooked up on your car removing the computer will have no affect on it. The reason one asks about it is that the 200-4R does not use this since it is present we know it is not a 200-4r.

The reason the lock up converter is important is it is operated by the computer in your car, if you remove the computer you will need a different way to operate the circuit if you want to use it.

You can convert a 350c to a 350 but you have to take the pump out of the transmission and drill a hole in it, modify the auxiliary valve body and remove a check ball from the main valve body. Something like that, a bit of work and you need to know how to take a TH350 apart. See last 2 pages of attached pdf file.


The TCC kit is something like this https://static.summitracing.com/global/images/instructions/tci-376600.pdf that is for 200-4R and 700- R4 but can be made to work with the 350c.
Getting a new torque converter will still rely on the computer, vacuum, etc.?
 

Wageslave

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Jan 25, 2017
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Does your distributor have a vacuum advance port on the side of it? And if so, is it connected to the carburetor? I didn't see one in any of the pictures and if it is still running the computer controlled distributor without the computer hooked up, it will not be advancing your timing. You may need to purchase a non-computer controlled HEI distributor to give you proper timing control. Luckily, they are pretty cheap on eBay.
 
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CopperNick

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In no particular order, that TCC unit sounds like it would be employed when assembling a mismatched combination of engine and transmission. One example would be using a late series 4L version transmission which is totally computer dependent, such as the 4L60E and mating it to an early vortec or iron block first gen. In this case only the t-mission needs computer guidance so that TCC unit is a standalone black-box that takes on the role of the computer for the transmission by itself. It's partner, whatever that turns out to be, can be retrofitted with a carb and distributor that don't need a computer to function so only the t-m gets one all by itself.

Getting a new torque converter won't solve the lockup problem because it isn't the converter itself that does the locking. That is done internally as noted and explained above.

The pic you posted that shows the top of your distributor tells me that your unit is a large head HEI. If you were to look at it from the driver's side you would see a small square projecting out from the main body of the cap. That actually holds all the electrical contacts to actuate the timer. Plugged into it will be a three wire connector that sits in the back row and comes from the base of the distributor. The front row has only two plug ins, each in a separate socket, the battery, and the tach. Battery is straight forward; power in to the timer (same-same as distributor or dizzie). The tach, short for tachometer, is the feed to the gauge that, if you have it on the dash, shows you your engine rpm. If that socket is empty, no problem, you have idiot lights on the dash and no tach.

The suggestion here would be to get your buddy to get the beast running correctly and take notes. If he has a shop with a lift and will allow non-employees access for show and tell, then you can get a better idea of how everything looks from an underneath perspective. Otherwise the first shop accessories you ought to be investing in are a set of 4 (four) 3 ton jack stands and a 2,5 ton minimum floor jack. Having these will let you lift the vehicle properly and secure it in position while lifted. NEVER, NEVER, rely on just a jack and bumper jacks and baby bottle jacks don't cut it on slippery or uneven terrain. There are a unlimited number of videos showing stupidity in action like "using a baby's swing set to pull an engine" for example, quickly followed up by "my day at the hospital" and "Ma, ma, look at all the stitches I got". Think there is even a sub forum on this site that chronicles misadventures and their consequences?
 

jiho

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Jul 26, 2013
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Just to add a little more to the overload .... :mrgreen:

I think the light spark knock -- that you mentioned way back in the beginning -- is probably due to the disconnected EGR. Probably combined with vacuum leak(s) from disconnected hose(s) causing it to run lean.

Your "flipper" really did a hack job, BTW.

Does your buddy know how to tune the computer-controlled Qjet and HEI?
 
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ELCAM

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My opinion is do one of two things.

Fix all the computer stuff and get it back to original. I think it still has the original intake, carburetor and distributor. This could be a real bear since they did such a butcher job (think the streached out wiring on that temperature sensor) the computer its self may be damaged.

OR

Get a non computer distributor and carburetor. Get all that hooked up properly and tuned and see how it really runs. Then proceed from there.
 
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MonteLS_84

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Jul 28, 2021
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Hey everyone. I finally have some updates. My buddy still hasn't found time to come out, so I had to dive in. I attempted to set the timing a few times...but never got passed finding a mark on the balancer. So, I gave up and waited. Well, until recently, that is.

I figured I could play with rotating the distributor every which way, and take it for a spin to see how she would run. Here's the funny part.......the distributor was loose! The whole time!

So...tightened her up...went for a ride...no more spark knock. 🥳 Unfortunately, I still had some hesitation and stumble, so I continued to blindly turn the distributor and repeat the process what seemed like 100 times. It's still not "perfect"...but I got it to where she starts easy, runs...and hesitation is at a minimum. Sometomes I floor it, and it's instant...sometimes I get a little bog before the launch. 🤷‍♂️

I'm deleting the EGR, and plan to buy a few upgrades. After tons of reading and watching videos, I'm still a but clueless on a few things.

From what I've learned and plan to do:

Connect green and black wire (in 4 pin) to distributor - will eliminate ECM control of distributor. Will be getting a new HEI.

Will be getting new heads (vortec), cam flat tappet (xe268h), intake (vortec rpm airgap), 600 edelbrock carb. (maybe bigger, waiting on a reply from edelbrock), and a 2500-ish stall torque converter for th350c.

My unanswered questions:

1. Being that the ECM will technically still be hooked up (just not controlling distributor/carburetor)...will it still lock up the trans? Or is that dependent on the ECM getting info from the distributor/carburetor?

I know I've been told about the manual trans switch route - I'm trying to avoid that if possible.

2. Does anyone know what size push rods are needed to run vortec heads with a flat tappet cam? The block is 1995 (former TBI engine). I've seen 2 answers for this.

*If anyone sees any other potential issues I may face, please let me know.

I'm also swapping out the 2.29 gears for a 3.73, 3.42 or 4.10 posi (undecided). 10 bolt, 26 spline. I weighed the cost of upgrading the whole rear end...and I think I'll just run this for now. I'll just be playing and taking short cruises...no drag racing.
 
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