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Still some questions re. Head porting


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Good evening,

Planned to send the head to P. Burgess, but he wrote me, that he has a lead time  of 14 weeks.  Don’t want to wait as long, so I decided to do the porting myself and get the 3 angle job and valve guides reamed by the engine builder  + shaved to 10:1

I read an excellent threads from Neil and Nick for the 6 cyl and the 1500 head preparation thread from Phil The Brookster dated back 2011, where GT stepped in as well.

Had also a look at the Vizard book and bought the P. Burgess book.

At the end I’m still confused about some points and have s few questions:

   1)  Inlet manifold:

·      GT wrote the 1500 twin HS4 manifold would flow so badly. Has anyone adapted and ported an MK3 manifold for HS4s as it is supposed to flow better. GT expected +5 to 10 hp for swapping the stock manifold against a Mongoletsi manifold (similar to MK3). Sounds a bit optimistic, but cheap to do…

1I 2) Inlet port:

·      General consensus not to work on LSR, but Burgess and Niko recommended to remove the boss around the valve guide, this is LSR.  So remove or leave alone?

·      SSR: Templates out of Neil’s  DIY thread are for 6 cyl. ,which has deeper throat. How to proceed with gauging the SSR on the shallower Spit throat? It’s so close to the seats…

2    3) Exhaust port:

·      Should one do the SSR here as well?

  4)   Troats:

·      There are ridges left and right , where the horizontal port penetrates the vertical throat (between SSR and LSR). Should they be removed or do they have a function?

  5)   Seats:

·      Do the exhausts also get a 3 angle job?

   6) Valves:

·      Do the exhausts also get a 30° back-cut?

 

Thanks

Patrick

 

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You could at least clean up the area around the valve guide without removing the boss entirely. I think that's what I did looking at photos but don't have before pics to compare it to.

I used Neil's thread as inspiration for doing the short side radius on mine, as well as other books. I took off 2mm. There is always a risk even if you are conservative, the head has core shift so porting carries a degree of risk.

Ridges, clean up if it's what I think you're referring to but a pic would be helpful.

Won't comment on exhausts as I left mine pretty much well alone apart from ensuring the port was even size throughout. I haven't come across many instances of people advocating doing the SSR on the exhaust.

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I seem to recall I might have smoothed around the valve guide boss, but nothing major? Would need to see my thread to refresh the grey matter!

SSR - only on the inlets (I used the same template as Neil used for the 6 cyls).

Smooth the casting marks on the throats, and any other casting marks you might have. Smooth the main runners. This can be done on both inlet and exhaust.

Neil's advice was to leave the exhaust side mostly alone (other than cleaning up), as to get any real gains here would take major effort.

3-angle seats on all seats, it improves flow which is desirable on inlet and exhaust.

You can match the inlet ports to manifold, but leave the step on the exhaust, this is supposed to work quite well as an "anti-reversion" feature.

Valves - no idea, I never took this step!

If you want, I do still somewhere have the sectioned head, I can dig these out and take some more photos if it would help?

Phil

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Thanks a lot Richard and Phil. I'm more confident now.

Now I need to buy burrs and and probably a new Dremel copy and start  the job.

The old one is a bit knackered... The question is, whether one needs really a strong Makita or whether the 130W Dremel type are not more handy, even though it might take a bit longer. At the end it is not so much material that need to be removed. Will see...and let you know

Cheers

Patrick

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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I recommend Dave Vizard's book, "The Theory and Pratcice of Cylinder Head Modification".    Many others feel the same = you can get a copy from Amazon for betweem £50 and £260!!     Too long to pst here, but have his porting diagrams, for the six cylinder Triumph

Vizard porting diagram 2.jpg

Vizard porting diagram 1.jpg

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1 hour ago, roulli said:

The question is, whether one needs really a strong Makita or whether the 130W Dremel type are not more handy, even though it might take a bit longer.

I did buy a proper Makita die grinder plus a selection of carbide burrs and stones a few years ago. Can certainly move a lot of material fast..... which isn’t always an advantage if you’re not quite sure what you are doing!

Probably a decent size Dremel type tool is enough provided you have some decent carbide burrs. I did the Vitesse head like that. It took a long time. Had the Makita for the PI head - which is the one I did the thread on. It was the better head. I also used the Makita for a really quick an dirty clean up of the 1300 head. It came out ok.

I don’t have much to add to Neil’s original thread, my follow up or Phil’s comments. I wouldn’t do more than knock the corners off/general tidy up of the exhaust ports. I would put a back cut on the inlet valves but not bother with the exhaust.

Sadly I don’t have any pics of the Silverstone Engineering head I had on my Herald 1300. Was bloody expensive, but that engine made good power.

 

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Thanks John and Nick for sharing your experience

Copies of Vizard's book are currently available  for 500 to 800 $ on Amazon.

I'll probably download a pdf. It's just a bit weird, that  these sites promote free download and then one has to register and leave a credit card number..

 

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I read my emails before I logged in on sideways. SO i had already a look at the book :)

Thanks again Nick.

Even that  Vizard book is not for the small engines it's still interesting, as it is really full of details.

Some other books are so disappointing as one expects tangible advice and then it remains rather superficial and at the end one still doesn't know what to do.

@ Millstone10

The Makita has one fixed speed only, doesn't it?  Is that not an issue.

 

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5 hours ago, Millstone10 said:

I burn out a dremel as it ingested the lovely iron filings as it was so close to (inside) the port to get to the SSR.

This is certainly a risk.... I've killed two, albeit cheap B & Q copies.  I would suggest making an adapter for your workshop vacuum and having that plugged into the other end of the port you are working on (and running) wherever possible.  This is good for your Dremel thing, your Makita (yes, they can suffer the same way) and your own air passages.  Doing this sooner would have saved me at least one Dremel.

The absence of variable speed on the Makita isn't really an issue (burrs need high speed to work properly) but as I said above, they do remove material at a hell of a rate, so you might want to practice a bit on a head (or other lump of cast iron scrap) that you don't love too much.  The final point about the Makita (or any other electric die grinder) is than unlike an air powered die grinder, which stalls gracefully when overloaded - the electric ones kick.  Hard sometimes.

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Never tried it, but I can't believe that a Dremel is really the man for the job. or even a Makita.

It demands a bigger investment, in a compressor, but that is so verstaile that you'll never want to be without it.    An air powered die grinder is a third the price of a Makita, and burrs last for ever, nearly.  You can port a head in an afternoon with that kit!

John

 

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7 minutes ago, JohnD said:

An air powered die grinder is a third the price of a Makita, and burrs last for ever, nearly.  You can port a head in an afternoon with that kit!

If you own a compressor...... If you don’t, the Makita is a fraction of the price of a compressor big enough to run a die grinder. Then there is having room for a compressor and putting up with its racket.

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Years ago I did my 6 cyl with a big Black and Decker variable speed drill and carbine burrs. :blink:

I had the drill and no money to buy a big die grinder and/or compressor.

Heavy and tiring but did the job. And as Nick says they kick back when you get it wrong so you soon learn the technique.

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Those are useful, but you really need something higher speed than a drill to drive. This reminds me of a conversation I had with a local gold/silver smith who has a very handy looking variable speed electric motor hung on a stand, driving a similar flexi. Giant dremel really. He got it used from a mate. I did get the details but IIRC the urge to own one left me when I found the cost!

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I already had an air compressor so bought an air powered die grinder.
Didn't like it as my compressor couldn't keep up and found it wasn't very powerful.
Then bought an electric Bosch one 2nd hand, similar to this one:
https://www.amazon.co.uk/Bosch-Langhals-Geradschleifer-KickBackStop-10-000-28-000-Regelstufen/dp/B0057CI8T6
Much more powerful, but you have to be careful or it will kick back like others mentioned.
Don't know how to explain it, but you have to hold it "loose", but firm and be precise" to avoid the kick.

If you don't want to spend that much Lidl has a 500W die grinder for under 20Euro;
https://www.lidl.de/de/parkside-geradschleifer-pgs-500-a1-500-watt/p360324

I have copied the 4 cylinder pages out of the Vizard book a long time ago.
I'll have a look if I still have them.

If you hook the amazon drill extension up to a normal drill, forget it, like Nick just said the speed is much to low.

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Vizard makes the point in his T&P book (page 1!) that speed is an essential.    Stones need at least 3,000ft/min at the surface, and he calculates (and I agree) that a 1" wheel needs at least 12,000rpm.   He further points out that a grindstone will wear out much faster if used at a less than optimum speed.

Burrs on the other hand are less sensitive to speed, although they cut slower if run slower.    A tunsten Cabide tool is very long lasting!

John

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2 hours ago, JohnD said:

Vizard makes the point in his T&P book (page 1!) that speed is an essential.    Stones need at least 3,000ft/min at the surface, and he calculates (and I agree) that a 1" wheel needs at least 12,000rpm.   He further points out that a grindstone will wear out much faster if used at a less than optimum speed.

Burrs on the other hand are less sensitive to speed, although they cut slower if run slower.    A tunsten Cabide tool is very long lasting!

John

Agree with that John. I found stones to be hard work, slow and wear quickly. A burr on the other hand is very tolerant of speed, cut well and like you say seem to last forever. Work in the hand drill at 2000 - 3000 rpm. Just need a bit more physical effort. And more awkward to hold.

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Hmm, looks like my memory is failing, but then I did copy it around 20 years ago.
I did find the copied pages, but it's from a speedpro and not written by Vizard.

The amount of detail it goes into is pretty small.
Just a few lines of text a flow diagram and two pics.
It says to:
- remove the valve guides and use ones that are 7⁰ bulleted.
- modify the combustion chamber.
- cut 3-angled seats.
-modify the SSR with a generous radius.

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