Skimming Chambered Head

Langlia · Post by **Langlia** » Sat Dec 08, 2018 8:13 pm

It it possible to skim down a chambered head till it's flat and install 1.3 pistons with cutouts to increase the compression? I see its 10.3:1 with Flat head and 1.3 Pistons and 9:1 with chambered head and 1.3 pistons..

I have a ported what seems to be 1100 Head with standard sized valves..

Is it better to get the seats recut to suit bigger valves or keep it standard?

Thoughts??

Dave C · Post by **Dave C** » Sat Dec 08, 2018 11:11 pm

That's exactly what I did with the 1600 in my Morgan

711 block, "de-chambered" a chambered 1600 head, 1300 GT pistons, with bigger cut outs for big valves Shadbolt cam, webers, 10.3:1 compression etc,,,sorry, I don't remember what size valves as I assembled the engine in the mid 80's and it's still going strong.
Somewhere I have all the facts and figures as to piston to valve clearances, compressed head gasket dimensions etc.

I seem to remember skimming a couple of heads before we found one that the head gasket would seal...(water passages getting bigger as the chamber was skimmed down.)
Dave.

Langlia · Post by **Langlia** » Sun Dec 09, 2018 1:43 pm

Interesting,

I only have the two heads to play with..

The GT head has the small style chamber in the head, with the 1300 Pistons they still need 2.54mm machined out of them to work with Kent Cams.

Need to check the depth on that chamber but I might be able to run a 244 cam with no additional mods?

s2europa · Post by **s2europa** » Mon Dec 10, 2018 9:33 am

I think you're better off finding an uprated head (they come up for sale quite often on the apexspeed forum or ask for one). Despite Dave's experience, you're taking off 0.100" of the head, making it even more susceptible to warping when it is hot.

Not sure if this one is still available.
https://www.apexspeed.com/forums/showth ... Ford-parts

Brett Wilkie · Post by **Brett Wilkie** » Mon Dec 10, 2018 12:27 pm

Are you sure that you want such a cam with that power range? I know that crossflows thrive on lift but now you have to modify the pistons to suite and you have to think about the strain on your valve gear too. Power range 3000 to 8000 might become tiring to drive on the streets but I could be wrong as I have not tried one on? I drove a Fiesta for a time with this 280 degree cam in it and it was a delight to drive and the engine didn't have to be balanced as the needed revs were not crazy.

I have been experimenting a little with the local Shadbolt cam grinds available and I did put a high lift cam (near .400) in my crossflow with an alloy FLAT head, I did an assembled plasticine valve/piston clearance test and found that it was a little close for comfort so I had the (1300GT) pistons pockets machined down further. I am sorry that I can't recall the figures now? I have not yet had that car out on the road so I can't comment on the performance yet. A couple of years ago I had a discussion with Barry at Shadbolt Cams and we came up with the idea to use the 270 degree .398 lift grind decision for a street car, the duration was the same as a stock GT cam but with higher lift. The hope is for good lower end torque without having to rev the shit out of it on the top end.
Barry has been unwell the last year or so and I am never sure how long Shadbolt will continue to function as a business so I had them do me a few different cams to keep in my parts supply.
I think the next engine I put together will be an uprated/ported flat head1700 and I will use the 280 degree lower lift cam so I can save a bit on avoiding extra machine work, besides it felt great in my old Fiesta. Time will tell.
As far as the cylinder head goes you might find it easier to just bite the bullet and get an alloy one. The alloy head is very easy to port, comes with hardened inserts, bronze guides and the valves are of the uprated GT size. I bought mine from Dave Bean but I think the Canadian Dollar was in better shape when I did.

Langlia · Post by **Langlia** » Mon Dec 10, 2018 5:55 pm

Thanks for the info Brett, no money in the budget for an alloy head at the moment.

I mistyped that originally, looking at the 224 torque cam.

I popped an intake/exhaust valve from the chambered head and put it into the flat head. Seats fine.

How far can these valves stick out?

I have 0.074" on the intake and 0.049" for the exhaust.

Langlia · Post by **Langlia** » Mon Dec 10, 2018 6:13 pm

So..

108.59 Valve Stem Length for 681F Chambered heads

110.56 for Flat head.

1.97mm difference.

Can I use these valves with no modifications?

Brett Wilkie · Post by **Brett Wilkie** » Mon Dec 10, 2018 10:54 pm

I notice that the head in your photo looks like it has valve seat inserts already? What head is that and what are the valve head sizes? I have not experimented with swapping the different valve lengths so I can't say? I know it looks like almost nothing and you would think the 2 MM is easily compensated by the rockers lash adjustment but for some reason Ford went out of their way to make the parts in different sizes and what about rocker geometry? Have you noticed that Burton carries rocker shaft pedestals that are higher by only 50 thou so it looks like they take it seriously. I don't have the answers but I think it is worth some research before you commit to anything.
https://www.burtonpower.com/posts-050-h ... 203as.html
I was looking around the net a bit and came across these sites and thought the opinions were interesting.
https://oldschool.co.nz/index.php?/topi ... ing-guide/

https://www.lotus7.club/forum/techtalk/ ... road-xflow

s2europa · Post by **s2europa** » Tue Dec 11, 2018 9:15 am

Those valves look like they are sitting a little too proud of the head surface. I have an uprated FF head that I can take pictures of this weekend if you want to see what they look like.

Langlia · Post by **Langlia** » Tue Dec 11, 2018 9:50 am

The more pictures the better!

I see I can get 110mm valves for about Â£100 for a new set.

As for the geometry not sure.. I'm sure it could be taken up with the adjustment as well if not taking off a bit of metal from the bottom of the rocker mount?

It's a 1.1 Xflow Head from what I understand based off the original valve sizes.. I don't have the measurements on me but I'll get some. Someone did a good port job on this head, has hardened valve seats and bronze valve guides. Chambered head valves do sit properly against the seats.

Might be worth it just to get the 110mm valves instead of playing with the geometry.

Brett Wilkie · Post by **Brett Wilkie** » Tue Dec 11, 2018 2:04 pm

I had (or may still have) an 1100 head and they are flat but with tiny valves, it would be a candidate for modifying. The 1977 to 1980 Fiestas we have here in North America also have flat type heads but again with smaller valves, there is no reason that head couldn't be done up as well.
When I did my alloy head I just used the stock uprated sized valves, 39.3 mm inlet and 34mm exhaust. I know Burton's carries some nice valves but the stock items helped keep my cost down, I see a set of those are now about 77 UK pounds.

Sideways · Post by **Sideways** » Tue Dec 11, 2018 5:42 pm

Langlia wrote: Might be worth it just to get the 110mm valves instead of playing with the geometry.

Amen to that.

Mind you, I never liked geometry at school, so I may be biased.

Langlia · Post by **Langlia** » Tue Dec 11, 2018 7:24 pm

Brett Wilkie · Post by **Brett Wilkie** » Wed Dec 12, 2018 12:32 am

Those ports look nicely shaped and not overly large but those valves are smaller than GT for sure. Was that head used for a smaller displacement engine? I know you mentioned it being an 1100 head so maybe it was used for a hot 1100??
I am not in Canada at the moment so I can't measure bits in my garage aside from the valve sizes I remember that I mentioned earlier. I do though have my hard dive with me so I can add a few pics of one of my modified heads beside a stock 1600 Cortina head so you can visualise the difference in valve and port size.
I wonder if the valve seat inserts on your head will allow for much increase in valve head diameter? If yes then you should get up to stock GT size at least I would think. You will have to ask a machinist for an opinion on that one.

Brett Wilkie · Post by **Brett Wilkie** » Wed Dec 12, 2018 12:33 am

Those ports look nicely shaped and not overly large but those valves are smaller than GT for sure. Was that head used for a smaller displacement engine? I know you mentioned it being an 1100 head so maybe it was used for a hot 1100??
I am not in Canada at the moment so I can't measure bits in my garage aside from the valve sizes I remember that I mentioned earlier. I do though have my hard dive with me so I can add a few pics of one of my modified heads beside a stock 1600 Cortina head so you can visualise the difference in valve and port size.
I wonder if the valve seat inserts on your head will allow for much increase in valve head diameter? If yes then you should get up to stock GT size at least I would think. You will have to ask a machinist for an opinion on that one.