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Old 04-10-2010, 06:01 PM
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th 350 modulator erupts

I started my car for the first time after the engine and tranny rebuild. The modulator and a metal stem blew out. Did I ruin the tranny and were there other parts I didn't see that came out? The car ran for less than 10 seconds and I shut it off.

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Old 04-10-2010, 10:23 PM
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Quote:
Originally Posted by stevekz
I started my car for the first time after the engine and tranny rebuild. The modulator and a metal stem blew out. Did I ruin the tranny and were there other parts I didn't see that came out? The car ran for less than 10 seconds and I shut it off.

there would be an inner valve and then the vacuum modulator installs in the hole. There would be an O-ring seal on the mod stub that fits into the case.

There would be a bracket and retaining bolt that holds the modulator into the case

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Old 04-11-2010, 02:25 AM
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inner valve

which way does the inner valve go in? thanks
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Old 04-11-2010, 02:26 AM
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Quote:
Originally Posted by stevekz
I started my car for the first time after the engine and tranny rebuild. The modulator and a metal stem blew out. Did I ruin the tranny and were there other parts I didn't see that came out? The car ran for less than 10 seconds and I shut it off.
The retainer probably got left off. Other than if you lost the valve, you did no damage.

The modulator, o-ring, valve, etc. is #46-50.

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Old 04-11-2010, 02:40 AM
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follow-up

I understand what happened now, thanks to the input(the students left off the retainer.)My follow-up is this;the vacuum line that goes from the modulator to the intake manifold does go to the fitting(has a vert and horiz. 1/8" nipple) that feeds the distributor vacuum as well...right?
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Old 04-11-2010, 02:52 AM
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Quote:
Originally Posted by stevekz
I understand what happened now, thanks to the input(the students left off the retainer.)My follow-up is this;the vacuum line that goes from the modulator to the intake manifold does go to the fitting(has a vert and horiz. 1/8" nipple) that feeds the distributor vacuum as well...right?
The modulator has to have manifold (aka full time) vacuum.

It can share the same port as the vacuum advance w/o issue- as long as the vacuum advance is manifold vacuum and NOT ported vacuum.

If the vacuum port is plumbed directly into the intake manifold, this will work fine for the modulator, although it might not be the best place to take the distributor vacuum advance from- there's variations in the vacuum- IF the port is in a runner, and not in the plenum area of the carb, or from the carb base or other carb port. The carb's ports will supply a steady vacuum signal, which is what you want for the dist. vac. advance.
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Old 04-11-2010, 08:05 AM
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new problem

There is a hole in front of the tranny dipstick and a wire sticking out of it,when I tried to put in fluid it poured out there. Is there something else they didn't do?
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Old 04-11-2010, 11:59 AM
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Quote:
Originally Posted by stevekz
There is a hole in front of the tranny dipstick and a wire sticking out of it,when I tried to put in fluid it poured out there. Is there something else they didn't do?
This is the where the detent (kick down) cable goes.
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Old 04-11-2010, 12:14 PM
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Before you ask- yes, you can run w/o the cable attached. You will not have a "passing gear" when you floor it; you need to manually select the next lower gear.

If you don't want to run the cable, the hole needs to (obviously) be plugged. THIS is the plug that's used- or fabricate one for yourself. Some people just cut the stiff wire off, I wouldn't do that, personally- I'd remove the pan to remove the wire from the valve, plug the hole and leave the rest as-is.

If you want to run a cable, you need the 'bottom' linkage at the carb to have the correct pin that pulls the cable out. Then, you'll need a cable and will need to connect it @ the tranny. The cable is held in the tranny case by one small bolt located very near the opening where the stiff wire is protruding.

Good luck.
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Old 04-11-2010, 12:31 PM
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ive never had or seen this happen but im curious now so i must ask,

is there pressure exerted from inside the trans that pushes on the valve that would make it fly out of the trans case?

trans parts are so alien to me. i dont know how ppl learn them.. insane..

thanks
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Old 04-11-2010, 12:47 PM
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one cool cobalt

I feel like a little kid in awe. Can you buy a cable that goes there and is it a threaded opening? I am so hyped to run this thing but stuff like this just keeps happening to prevent it.
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Old 04-11-2010, 12:54 PM
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Quote:
Originally Posted by stevekz
Can you buy a cable that goes there and is it a threaded opening? I am so hyped to run this thing but stuff like this just keeps happening to prevent it.
The cable looks like THIS. There's no threaded opening- the end that goes into the tranny case has an o-ring that seals it, the other end has a long, slotted end on it that attaches to the carb linkage.

If you have a Q-jet carb for an AT, it'll have the correct linkage already. Most Holley and Edelbrock carbs are easily adapted w/the correct pin to hold the slotted end of the cable.

You will also need the throttle cable/kick down cable bracket that mounts to the intake- there are aftermarket brackets available from the aftermarket from Edelbrock and others, or you can modify a stock bracket.
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Old 04-11-2010, 01:03 PM
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sorry ..none of the above

I bought a rolling chassis,then I bought a 4-bolt main 350 and did an overhaul,after that our mechanics teacher at school had an old th-350 he gave me and I bought a master kit for it. The missing parts(modulator retainer-which I made and have secured) were overlooked by him but in all fairness he has 40 kids with less knowledge than me...enough said.So I would like to just plug it by the easiest means possible. Thanks very much for your help.
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Old 04-11-2010, 02:13 PM
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Quote:
Originally Posted by stevekz
I would like to just plug it by the easiest means possible.
Pull the stiff wire out as far as it will go w/o forcing it, cut the stiff wire off flush w/the case so the wire (what's left of it) will recede back into the case. This will give you some room to plug the hole.

Find a suitable cup plug, dowel, etc. that fits the hole and plug it. Use sealer, etc. to keep the leakage at bay.

Do not overfill the tranny. Add some fluid, start the engine, run it through all the gears, back to park and check the level- engine running.

Repeat this until it's full cold or hot, depending.
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Old 04-11-2010, 02:29 PM
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sooo.. much thanks

you have made it possible for me to sleep tonight(knowing it will be okay) thanks for your help. Hopefully I will get it going this week and write a post
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