300 hp N/A carb 2.8 V6 engine

[SappySE107]

What size is the hole on the 3400 heads?

[veekuusi]

I think that the thread is 1/8 NPT in the 3400 heads.
The hole in the 3100 heads is 2 mm bigger , some 11 mm.

[34blazer]

1/4 npt

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[SappySE107]

Learn something new every day. I have never seen a 3400 with that coolant temp sensor in the cylinder head.

[Guest]

Learn something new every day. I have never seen a 3400 with that coolant temp sensor in the cylinder head.

Neither have I.

[veekuusi]

I found a suitable fitting today.
"Reducer" , or what you call it.
I quess it is 1/8 NPT to 1/4 NPT ?

And there certainly was a 1/8 NPT thread in those 3400 heads , that I was using.
The thread was only in one cylinder head (for coolant temp sensor) , I had to make
the 1/8 NPT thread to the other head by myself (first drill a hole of course).

I need those fittings , because the water outlet is in different place in head , I think otherwise
there can remain air in the head .

[Guest]

That must have been something you did then, is that what youcre saying?

The small port 3100 heads had a temp sensor located in that position in many applications.

[Will'sFiero]

I found a suitable fitting today.
"Reducer" , or what you call it.
I quess it is 1/8 NPT to 1/4 NPT ?

"Reducing bushing"

[veekuusi]

I got the engine running all right.
But it made an interesting sound.
It took a while to figure out , what was wrong.

Starter motor gave up.
Bendix in the starter motor do not work.
The gear of the starter jammed to the fly wheel .

It takes a few days to get a new starter motor.

[Purple pit]

3400/newer style starter? Just put on a gear reduction myself and now have some teeth missing on the flexplate. Not sure if a shim would do anything for us. Bendix is not a cheap starter, my Airtex kind of was.

[veekuusi]

I got a new 3400 reduction gear starter.
150 euros (including tax) , something like $ 170.

[Purple pit]

Do you think it needed a shim or was it not lined up somehow? Or was it a bolt torque problem and the bolts came loose just enough to take it out of line? Hard to blame the starter, those two look the same.

[ForcedFirebird]

How many engine starts did that starter have? seems premature.

[veekuusi]

How many engine starts did that starter have? seems premature.

You are right.
Maybe hundreds of starts. There has been big difficulties to get the engine running in
the past few years.I mean long starting times. The starter has suffered a lot.
It has taken a beaten.

Certainly not loose bolts is the cause of the damage.

But now with the new starter, everything is OK.

[padgett]

Long starting in a GM car is usually the fuel pump relay. When it fails you have to crank until the oil pressure comes up before the fuel pump will turn on.