Progress Thread Snow - 93 GT Vert. Prepping for sale

AeroCoupe

lube between the nut and the face. I know my lubes

Founding Member

Oct 28, 2001

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Claremore, OK

Mar 18, 2023

#541

• Mar 18, 2023

• #541

So there are a lot of different grades of lapping compound. Not sure which one you used but check this site out, should give you some insight:

Polishing Paste & Lapping Compounds - Kemet

Silicon Carbide Lapping Compound for precision lapping, cutting and smoothing of metal surfaces. Simichrome metal polish for use after diamond compound. Removes

www.kemet.co.uk

Granted it’s a UK company it’s good info.

 

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JAA

5 Year Member

Oct 2, 2018

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Mar 19, 2023

#542

• Mar 19, 2023

• #542

AeroCoupe said:

So there are a lot of different grades of lapping compound. Not sure which one you used but check this site out, should give you some insight:

Polishing Paste & Lapping Compounds - Kemet

Silicon Carbide Lapping Compound for precision lapping, cutting and smoothing of metal surfaces. Simichrome metal polish for use after diamond compound. Removes

www.kemet.co.uk

Granted it’s a UK company it’s good info.

Click to expand...

I had used the basic stuff: https://www.summitracing.com/parts/ptx-80037

Went with both of these. They will give me a three step process.

• Amazon product ASIN B006ZXZYMA
• Amazon product ASIN B00HC2LNU0

 

JAA

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Mar 25, 2023

#543

• Mar 25, 2023

• #543

Gonna swap to what should be an easy exhaust valve. Will try an extended 3 step process

 

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JAA

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Mar 25, 2023

#544

• Mar 25, 2023

• #544

Lol - that 800 grit certainly puts on a polish!!

 

JAA

5 Year Member

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Mar 25, 2023

#545

• Mar 25, 2023

• #545

Good news

Forgot to take a picture, but that leaking exhaust valve is now good.

Time to hit an intake valve

 

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JAA

5 Year Member

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Mar 26, 2023

#546

• Mar 26, 2023

• #546

30 minutes in, not looking good

 

JAA

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Mar 26, 2023

#547

• Mar 26, 2023

• #547

One thing I am going to do for giggles is to hydro test the stock heads I removed. If my lapping is as good or as better as those it’s a different convo.

 

JAA

5 Year Member

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Mar 26, 2023

#548

• Mar 26, 2023

• #548

Anyone built and used one of these?

 

JAA

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Central MA

Mar 26, 2023

#549

• Mar 26, 2023

• #549

1 hr

 

JAA

5 Year Member

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Mar 26, 2023

#550

• Mar 26, 2023

• #550

Really tried to polish this one up

 

M

Monkeybutt2000

Mustang Master

Aug 11, 2019

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Lafayette,IN

Mar 26, 2023

#551

• Mar 26, 2023

• #551

Again, you've got options. Spend the money at a machine shop, purchase new heads, or send it. If this was my car,I'm sending it.

 

JAA

5 Year Member

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Mar 26, 2023

#552

• Mar 26, 2023

• #552

Monkeybutt2000 said:

Again, you've got options. Spend the money at a machine shop, purchase new heads, or send it. If this was my car,I'm sending it.

Click to expand...

Send it?

 

M

Monkeybutt2000

Mustang Master

Aug 11, 2019

1,387

849

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Lafayette,IN

Mar 26, 2023

#553

• Mar 26, 2023

• #553

JAA said:

Send it?

Click to expand...

Bolt heads on and go.

 

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JAA

5 Year Member

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Mar 26, 2023

#554

• Mar 26, 2023

• #554

Monkeybutt2000 said:

Bolt heads on and go.

Click to expand...

That what I’m thinking at the moment.

 

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JAA

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Apr 1, 2023

#555

• Apr 1, 2023

• #555

Yes I did it. Ive always wanted a vacuum tester and perform a leak-down test

Im going to put in a spark plug and test both valves.

Setup

With vacuum running

Valve shut off

10 seconds after valve shutoff

 

JAA

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Apr 1, 2023

#556

• Apr 1, 2023

• #556

True story - just broke the vacuum gauge. Those plastic things are such garbage.

Here is a cool pic for foxbody folks

 

JAA

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Apr 1, 2023

#557

• Apr 1, 2023

• #557

Initial data
GT heads are 70 and 71. Original e7 are 23 and 24 (for reference). I feel its reasonable to say the GT head I finished and measured this way is better than the e7. Next step is to redo the other GT40 head and measure.

Head	Cylinder	peak Hg	After 10 seconds (Hg)	seconds to 10 Hg
70	1	17.5	16	120
70	2	17.1	15.2	100
70	3	17.5	16	96
70	4	18	16	80
71	1
71	2
71	3
71	4
23	1	17.5	15	80
23	2	13.9	1	1
23	3	19	13	20
23	4	17.1	15.2	53
24	1	18.1	15	44
24	2	18.4	6	8
24	3	18	12	15
24	4	18	8	6

 

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AeroCoupe

lube between the nut and the face. I know my lubes

Founding Member

Oct 28, 2001

5,919

4,040

183

Claremore, OK

Apr 1, 2023

#558

• Apr 1, 2023

• #558

I think you have it whipped man, congrats!

 

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JAA

5 Year Member

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Apr 2, 2023

#559

• Apr 2, 2023

• #559

Final values

Mental note, and for others who stumble on my hot mess here. The torque of the spark plug plays a significant role in keeping vacuum (as you can see by head 71). Do not just hand tighten those plugs. Im confident this directly translates to actual performance also when folks are changing plugs in general.

Head	Cylinder	peak Hg	After 10 seconds (Hg)	seconds to 10 Hg
70	1	17.5	16	120
70	2	17.1	15.2	100
70	3	17.5	16	96
70	4	18	16	80
71	1	18	16.2	105
71	2	19.8	17.3	126
71	3	19.1	17	151
71	4	18.6	16	120
23	1	17.5	15	80
23	2	13.9	1	1
23	3	19	13	20
23	4	17.1	15.2	53
24	1	18.1	15	44
24	2	18.4	6	8
24	3	18	12	15
24	4	18	8	6

 

JAA

5 Year Member

Oct 2, 2018

674

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63

Central MA

Apr 2, 2023

#560

• Apr 2, 2023

• #560

Ok - so next steps

1. Get GT40 heads surfaced
2. Clean surface rust off of engine block
3. Install Gt40 heads
4. Remove old rockers from old e7 on cylinder 1 and install on GT40 cylinder 1 wish pushrods
5. Follow firing order and do each cylinder this way

Thoughts?

 

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