T4 Tear Down / Rebuild in Jax FL

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Clatter
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Re: T4 Tear Down / Rebuild in Jax FL

Post by Clatter » Sat Sep 30, 2017 9:26 am

That's why it's important to not listen to most experienced old-timers..

They say stuff like_
"Oh, you don't have to do all that"
and
"It'll work fine"
and
"Just put it together".

Those days are gone.
"Oh, You don't need to do all that... The valve seats are just going to fall out of it anyway!"
- Doug Ellsworth

Beginners' how-to Type 4 build thread ---> viewtopic.php?f=1&t=145853

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Clatter
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Re: T4 Tear Down / Rebuild in Jax FL

Post by Clatter » Sat Sep 30, 2017 9:27 am

"That's your size"..

:roll:
"Oh, You don't need to do all that... The valve seats are just going to fall out of it anyway!"
- Doug Ellsworth

Beginners' how-to Type 4 build thread ---> viewtopic.php?f=1&t=145853

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analogtherapy
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Re: T4 Tear Down / Rebuild in Jax FL

Post by analogtherapy » Sat Sep 30, 2017 4:22 pm

Clatter wrote:
Sat Sep 30, 2017 9:24 am
See why this is so much harder to do now?
Used to be that you just put these together!
Now, you have to check, and often adjust, everything.
I'm really starting to understand that now :?

But, new bearings did the trick (John you're a genius)! Just got them in the mail, mocked em up, and it was a huge difference. I still need to do a mockup with both crank and cam installed, and see how the crank rotation feels now, but outlook is good!

By the way: the original cam bearing set I got were Kolbenschmidt, the 2nd set were Mahle. There was a noticeable difference in weight and finish between the two brands, with the Mahle being heavier and having a more polished (shiny) look. Both were made in Brazil. Maybe this was just the luck of the draw, but the Mahle's did seem to have an overall higher quality to them even before fitting them up. Just my .02.

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analogtherapy
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Re: T4 Tear Down / Rebuild in Jax FL

Post by analogtherapy » Thu Oct 05, 2017 5:11 pm

Question: Would you run this fan if it were yours?

Awhile back I had taken my crank, flywheel, etc (including this fan) to be balanced, and this is how the fan was balanced. I was shocked when I picked it up, but I'm also pretty ignorant when it comes to this kind of stuff (maybe this is acceptable?) so I just set it aside to come back to it later. I've started thinking about it again. So, is this fan structurally compromised? It seems like an awfully lot of metal removed to me...

Would you run it as is, or get a new one?

Image

Image

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raygreenwood
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Re: T4 Tear Down / Rebuild in Jax FL

Post by raygreenwood » Fri Oct 06, 2017 5:51 pm

No...DO NOT run that....whoever did that is an absolute dumbass. The balance weight is crimped on the inside rim of the steel pulley. Ray

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analogtherapy
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Re: T4 Tear Down / Rebuild in Jax FL

Post by analogtherapy » Sat Oct 07, 2017 1:00 pm

raygreenwood wrote:
Fri Oct 06, 2017 5:51 pm
No...DO NOT run that....whoever did that is an absolute dumbass. The balance weight is crimped on the inside rim of the steel pulley. Ray
Thanks Ray. Your reaction just confirmed my fears. Looking for a type 4 fan now...

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analogtherapy
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Re: T4 Tear Down / Rebuild in Jax FL

Post by analogtherapy » Wed Oct 11, 2017 11:44 am

Moving on to crankshaft end play...

Image

Image

I've repeated this a number of times, and...if I'm reading this correctly...I've got end play of .0025 (I zeroed the dial with the flywheel pushed close to the case, then pulled away from the case). Each time, it measured riiight between the .002 and .003.

Is this too tight to proceed?
Last edited by analogtherapy on Wed Oct 11, 2017 5:35 pm, edited 1 time in total.

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Clatter
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Re: T4 Tear Down / Rebuild in Jax FL

Post by Clatter » Wed Oct 11, 2017 5:27 pm

If that was how your fan was balanced,
I wouldn't be trusting their job on the crank/flywheel, etc.

Best be getting all of that back out and apart for a re-balance with your new fan..

Sorry,
But the truth hurts sometimes.
Good thing you caught it!
"Oh, You don't need to do all that... The valve seats are just going to fall out of it anyway!"
- Doug Ellsworth

Beginners' how-to Type 4 build thread ---> viewtopic.php?f=1&t=145853

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Clatter
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Location: Santa Cruz

Re: T4 Tear Down / Rebuild in Jax FL

Post by Clatter » Wed Oct 11, 2017 5:37 pm

WRT the end-play,
Being on the tight side is good, but requires diligence.

Ultimately, tight is good,
it allows a good long time before everything pounds itself out to loose.

On the other hand,
a smart shop never sends things out on the tight side of spec,
because customers never break in properly.

Are you are going to be in a hurry, and out there running it hard, before it's broken in and dialed on your wide-band?
Then, if so, go looser.
There is a lot at stake if you stick your mains tight..

However,
If you are judicious in your love/care, a tight setting can make the thing possibly last a lot longer.

Most people stick their old gummy distributor, with one broken spring, and holed vacuum can on their new motor.
They put on their old clogged injectors, stiff regulator, and even their half-clogged fuel filter.
Their new motor never has a chance..
After all of this rebuild pain, who can blame them? Enough already! We want to go camping!

That's why the old mechanic always goes to the loose side of spec with the end-play.
They know that the motor will be run hot and hard right out of the gate,
And this helps with CYA..
"Oh, You don't need to do all that... The valve seats are just going to fall out of it anyway!"
- Doug Ellsworth

Beginners' how-to Type 4 build thread ---> viewtopic.php?f=1&t=145853

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analogtherapy
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Re: T4 Tear Down / Rebuild in Jax FL

Post by analogtherapy » Thu Oct 12, 2017 12:57 pm

Thanks Clatter sir. I do intend on treating this engine right. I'll revisit the end play once I'm able to accurately measure my shims...

Moving forward a bit: I've measured my piston height against cylinder height, and (using feeler gauges) I'm at .026":

Image

(I did have this cyl. bolted down using sockets, but I had just removed them prior to this pic)

I've only done one right now, starting with #3. My heads are from Len, and have .8mm raised step in the cylinder registers.

So if I understand this correctly...

.026 in = .66 mm

.8 mm + .66 mm = 1.46 mm, which is .057 in, which is within the .04 - .08 spec mark mentioned in Tom Wilson's book. Assuming all pistons/cylinders are the same (FYI, I will be measuring each individually), then this is a good number and I can move forward on figuring out my CR, right?

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analogtherapy
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Re: T4 Tear Down / Rebuild in Jax FL

Post by analogtherapy » Thu Oct 12, 2017 2:37 pm

OK, I think all this reading is finally starting to sink in!

So, continuing from above (these are just assumptions at this point, based solely on the #3 measurements):

If my deck height is .057...(or 1.46 mm)

Bore: 94 mm
Stroke: 71 mm
Combustion Chamber CC's: 64.5 (49.5 CC's from the head, 15 CC's from the piston dish)

Then CR = 7.6, which is right in line with aircooled.net's statement that the webcam 142 runs best with a CR of 7.5 - 7.75:1 (which is what I'm shooting for).

We'll see if actual measurements end up the same, but I think I'm finally wrapping my head around this stuff.

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