19 replies to this topic

[JonnyAlpha]

Hi

I have been practising head work on, what was sold as scrap, a 12G940 cylinder head, however since cleaning it up, it seems to be free of the normal damaged that would declare a head scrap, e.g. cracks between the valve seats etc. It does have a couple cracks at the bases of the rocker stud holes though.

I am doing this myself with minimal tools, I have just picked up a SH Neway Cutter Set, which came with a Neway 285 - 46 degree cutter and a 7mm adjustable guide, among some other bits.
I have access to a Warco Hobby Lathe and Pillar Drill.
I also have a DTI gauge and Magnetic Stand (Used for setting the engine timing)

I now need some advice in a couple of things:

Valve Seat cutting:

1. How do you ensure that the valve seats are at the same height?
2. Can you use a hand cutter in a battery powered drill (without a flexi drive)?
3. Can you use a hand cutter in a Pillar Drill?
4. If using a pillar drill, could I use a DTI gauge to get the seats at the correct heights
5. What tooling could I use to enlarge to ports to use 35.6mm inlets as opposed to 33.3mm valves?

What tooling could I use to cut a recess around the valve seat area to a specific height, this is to use as a guideline when raising the chamber roof? (similar to the recess that you see around the valve seat on a stock head.

Also:
6. If installing manganese bronze valve guides, where can I get the correct reamer to ensure the correct tolerance with the valve stems? Are these turned by hand or can I use the TailStock chuck on the lathe?
7. Without a hydraulic press, what is the best way of installing valve guides and getting the correct height?


Many thanks

 

[Cooperman]

I have had problems with phos-bronze guides. The reamer size is nominally 9/32", but a couple of valves did seize in the guides and now I will only use the cast-iron ones, even in rally engines.
A vertical mill will enable the throats to be cut for bigger valves, but a hand cutter may not be suitable for cutting completely new seats. You could try and see how you get on.
The throats will need blending after cutting for bigger valves.

[JonnyAlpha]

I have had problems with phos-bronze guides. The reamer size is nominally 9/32", but a couple of valves did seize in the guides and now I will only use the cast-iron ones, even in rally engines.
A vertical mill will enable the throats to be cut for bigger valves, but a hand cutter may not be suitable for cutting completely new seats. You could try and see how you get on.
The throats will need blending after cutting for bigger valves.

Edited by JonnyAlpha, 10 April 2021 - 09:17 PM.

[JonnyAlpha]

I have had problems with phos-bronze guides. The reamer size is nominally 9/32", but a couple of valves did seize in the guides and now I will only use the cast-iron ones, even in rally engines.
A vertical mill will enable the throats to be cut for bigger valves, but a hand cutter may not be suitable for cutting completely new seats. You could try and see how you get on.
The throats will need blending after cutting for bigger valves.

 

Sorry, tried to reply on my phone and the quote messed up.

 

Ref valve guides, my understanding was that for steel valves, such as the 35.6 Metro ones that I intend to use, you needed Manganese Bronze Valve Guides, as they would sieze in cast iron valve guides?

 

I don't have a vertical mill, but I was wondering if a counterbore cutter or something similar in a pillar drill would suffice?

[nicklouse]

I would be getting the head crack tested before going further. 

[JonnyAlpha]

I would be getting the head crack tested before going further.

How do you / they crack test a head? I have heard of the process, is it using UV lighting?

[JonnyAlpha]

Oh and another question, to which I cannot seem to find the answer, what should the dimension of the port throats (if that’s the correct term for the area directly under the valve) for 35.6mm Metro Tripple Grroove Valves? And whilst in the subject, what about the exhaust throats.

[Project_1275_GT]

Hi 

 

I have recently modified a head myself with only hand tools available. I ground the chambers and ports using a standard Dremel type tool with various types of attachments. I purchased a set of valve seat cutters in various angles [ebay]. These were used with the supplied Tee bar tool and correct 9/32 guide. Fitted new bronze guides using a punch set, I uses Facom punches that are shouldered at the top by the handle, the length of the punch was placed through the valve guide and the shoulder used to tap in. Worked well. Reamed by hand after 9/32. I checked each valve depth before cutting and marked depth on the head. Then cut all to the same depth. I checked depth by installing each valve and checking with a Vernier and steel rule across the head. also checked valve guide depth until all were exact depth. Lapped in valves and rebuilt. Not tested yet  

 

Thanks 

 

Rob

[JonnyAlpha]

Hi

I have recently modified a head myself with only hand tools available. I ground the chambers and ports using a standard Dremel type tool with various types of attachments. I purchased a set of valve seat cutters in various angles [ebay]. These were used with the supplied Tee bar tool and correct 9/32 guide. Fitted new bronze guides using a punch set, I uses Facom punches that are shouldered at the top by the handle, the length of the punch was placed through the valve guide and the shoulder used to tap in. Worked well. Reamed by hand after 9/32. I checked each valve depth before cutting and marked depth on the head. Then cut all to the same depth. I checked depth by installing each valve and checking with a Vernier and steel rule across the head. also checked valve guide depth until all were exact depth. Lapped in valves and rebuilt. Not tested yet

Thanks

Rob

Nice one Rob.
Where did you get the reamers from and what valves are your u using?

[Project_1275_GT]

 

Hi

I have recently modified a head myself with only hand tools available. I ground the chambers and ports using a standard Dremel type tool with various types of attachments. I purchased a set of valve seat cutters in various angles [ebay]. These were used with the supplied Tee bar tool and correct 9/32 guide. Fitted new bronze guides using a punch set, I uses Facom punches that are shouldered at the top by the handle, the length of the punch was placed through the valve guide and the shoulder used to tap in. Worked well. Reamed by hand after 9/32. I checked each valve depth before cutting and marked depth on the head. Then cut all to the same depth. I checked depth by installing each valve and checking with a Vernier and steel rule across the head. also checked valve guide depth until all were exact depth. Lapped in valves and rebuilt. Not tested yet

Thanks

Rob

Nice one Rob.
Where did you get the reamers from and what valves are your u using?

 

 

Sorry cant remember where I got the reamer. I opted for a strange combination as its for a turbo engine. St/ST exhaust and Rimflow inlet. 

[JonnyAlpha]

 

 

Hi

I have recently modified a head myself with only hand tools available. I ground the chambers and ports using a standard Dremel type tool with various types of attachments. I purchased a set of valve seat cutters in various angles [ebay]. These were used with the supplied Tee bar tool and correct 9/32 guide. Fitted new bronze guides using a punch set, I uses Facom punches that are shouldered at the top by the handle, the length of the punch was placed through the valve guide and the shoulder used to tap in. Worked well. Reamed by hand after 9/32. I checked each valve depth before cutting and marked depth on the head. Then cut all to the same depth. I checked depth by installing each valve and checking with a Vernier and steel rule across the head. also checked valve guide depth until all were exact depth. Lapped in valves and rebuilt. Not tested yet

Thanks

Rob

Nice one Rob.
Where did you get the reamers from and what valves are your u using?

 

 

Sorry cant remember where I got the reamer. I opted for a strange combination as its for a turbo engine. St/ST exhaust and Rimflow inlet. 

 

 

I do believe you need specific reamers for bronze guides.

 

I would be getting the head crack tested before going further. 

 

Like this: 

 

I believe I need a reamer specific for bronze valve guides. 

[Turbo Phil]

You only need to use bronze guides if you’re using the stainless nitrided race valves. The road spec valves can be run in cast iron guides.
You can knock the old guides out with a hammer/punch but I wouldn’t fit new ones this way it can deform them guides. Always use a press, or as a crude DIY method you could use a large vice.

Phil.

[JonnyAlpha]

You only need to use bronze guides if you’re using the stainless nitrided race valves. The road spec valves can be run in cast iron guides.
You can knock the old guides out with a hammer/punch but I wouldn’t fit new ones this way it can deform them guides. Always use a press, or as a crude DIY method you could use a large vice.

Phil.

Ok thanks Phil so the cast iron ones are ok (and cheaper)
http://www.minispare...|Back to search

[nicklouse]

 

 

I would be getting the head crack tested before going further. 

 

Like this: 

 

 Nope. Either with a crack test fluid or the set up AC uses .

[JonnyAlpha]

I would be getting the head crack tested before going further.

Like this:

Nope. Either with a crack test fluid or the set up AC uses .

Found the sprays online, cleaner, dye and revealer.
What does AC use?