Head Gasket Block Prep Advice

[gruhsy]

Do not use sand paper!
You will make an uneven out of round surface.

Machine shop or replace it.

I have not come across anyone repairing the bore at a shop but it can be done.

Eg cylinder head repair. The mobile site doesn’t have the video of a car head repair but you can find it on a computer web page on the millennium website

https://www.millennium-tech.net/serviceInfo.php?id=1

Yikes! should I be concerned about the scouring on one of the cam tower lifter cylinders? The rest look fine... touch it up with high-grit paper?

[gruhsy]

Found it

Scroll down the list of videos

https://www.millennium-tech.net/video.php

[Mark2023]

Do not use sand paper!
You will make an uneven out of round surface.

Machine shop or replace it.

I have not come across anyone repairing the bore at a shop but it can be done.

Eg cylinder head repair. The mobile site doesn’t have the video of a car head repair but you can find it on a computer web page on the millennium website

https://www.millennium-tech.net/serviceInfo.php?id=1

Yikes! should I be concerned about the scouring on one of the cam tower lifter cylinders? The rest look fine... touch it up with high-grit paper?

OK interesting, I'm assuming they would need to weld the scouring it and re-machine the lifter cylinder?

[Tom]

Totally agree about not sanding. If it's deep enough to catch your fingernail, then I'd also worry about any machine process that does not add back material to keep the lifter-to-bore gap in check. The millennium-tech link looks promising, but with good used cam towers so cheap and plentiful, I'd just do that myself if needed.

I'd be interested to see if the lifter and cam lobe show any corresponding issues. If you do pick up a used cam tower, try to get the lifters too.... New ones are stupid expensive now (over $200). And, to avoid that dry lifter clatter, here's my shade-tree way of priming the lifters.... Works better than months of soaking.

[gruhsy]

Yes weld in to fill. Then machine and hone polish to the correct size.

However used cam towers are so cheap and available.

I would only do it if you have a friend that owns a machine shop like friends shop. I get all the simple work for free

http://www.fidelitymachine.ca/

Do not use sand paper!
You will make an uneven out of round surface.

Machine shop or replace it.

I have not come across anyone repairing the bore at a shop but it can be done.

Eg cylinder head repair. The mobile site doesn’t have the video of a car head repair but you can find it on a computer web page on the millennium website

https://www.millennium-tech.net/serviceInfo.php?id=1

Yikes! should I be concerned about the scouring on one of the cam tower lifter cylinders? The rest look fine... touch it up with high-grit paper?

OK interesting, I'm assuming they would need to weld the scouring it and re-machine the lifter cylinder?

[Mark2023]

Ok, so I did a thing...

My machinist expanded my cam tower bores to fit a larger INA hydraulic lifter. I know the INA replacement lifters for the 944 are horrible but these are supposed to be much better. I think this is a pretty interesting procedure so I will do a full write-up once I get the car back together. I am told this is pretty common on domestic cars but is just starting to be done on 944. The machinist I used is super knowledgeable and has done this on several other 944s.

It's going to be really cool to have brand new lifters in my car

[Tom]

Very cool Mark! Very interested to hear how this works, which lifters you used, bore size, etc. Is this your own approach, or are you following the design referenced in this thread:

viewtopic.php?f=4&t=52

Also, for what it's worth, I never had any problems with the INA replacement lifters, and INA makes OEM parts, so I wouldn't worry about your new lifters just because INA made them. I'm sure some of the 944 replacement lifters by INA had issues, but the whole 'INA lifters are trash' thing seemed exaggerated imho -- mostly by those who were trying to make a buck selling something else.

[gruhsy]

Wasn’t the issue with the INA the 1700.00$ price tag?

[Tom]

Wasn’t the issue with the INA the 1700.00$ price tag?

Yes, but when INA used to sell them in their own box for ~$45 they got a bad reputation that may or may not have been warranted. There were some failures, I'm sure, but a lot of the people beating the 'INA=junk' drum often seemed to be offering their own whiz-bang alternative. I have the $45 replacements in my car, and they've been going strong for 14 years and 40k miles, even though at the time one well-known 944 place told me they were "nearly guaranteed" to fail and take out my whole motor. It's all moot now that INA stopped making them, but I just mention it because Mark seemed worried about INA as a brand. INA makes lifters for some of the biggest car makers on earth, so they are more than capable of making good products (even if something was actually up with their 944 replacements).

[Mark2023]

Very cool Mark! Very interested to hear how this works, which lifters you used, bore size, etc. Is this your own approach, or are you following the design referenced in this thread:

viewtopic.php?f=4&t=52

Also, for what it's worth, I never had any problems with the INA replacement lifters, and INA makes OEM parts, so I wouldn't worry about your new lifters just because INA made them. I'm sure some of the 944 replacement lifters by INA had issues, but the whole 'INA lifters are trash' thing seemed exaggerated imho -- mostly by those who were trying to make a buck selling something else.

Cool, I just read that thread... that's exactly what is being done on my car! The machinist that did the work is partnered with Emanual from 944 store (Joshua at Valley Cylinders). The lifters are out of a 1991 Mercedes 300D INA part #4200001100 I don't think it's my place to release the specs for the machine work just in case it becomes a 944 store product. Those guys did all the R&D in this so I don't wanna release anything I'm not supposed to. I am super excited for this to hopefully go mainstream it would be really cool to finally have a solution. Also it is cool that Joshua skimmed the cam housing so now I have a square surface for the first time in 32 years and on a rebuilt flat head surface!!!!!!