Big valves in a Fullauto head

I thought I would post this so one of the forum members could see what I did with his head. I installed 3mm oversized intake valves.

The first picture is a new head with one seat cut out and moved toward the edge of the cylinder. The guide hole has been reangled and bored for an 850 guide and the chamber has been relieved around the valve for less shrouding.



While the other side was being cut like the first I put the new seats and the installation tool in the icebox to cool off.



The head was heated to 380 degrees and the raw seats were tapped into place.




Then the head was put back in the mill and the seats were cut to size and the ports are roughed out with a carbide burr.



The a few more hours with a burr and stones and it has a nice finish.



Then the guide hole is honed for .0015 interference fit.



After the guide is pulled into place it is reamed to around .001 smaller than finished size. A carbide reamer is used for the aluminum bronze material.



Next a guide hone is used to take it to final size.



Then a fine diamond brush makes the finish that is preferred for the Black Diamond coated valves.



Now a mandrel is installed in the guide and a cutter is used to re-angle the spring seat so it matches the guide.





Then the same mandrel is used with a cutter to cut 4 angles on the seat.



Then a bit of work was done in the exhaust to clean the bump in the casting on the sides of the guide.



Then the rest of the exhaust port is smoothed and blended.



Now a set of Black Diamond valves is dropped in for a trip to the flowbench.



This head will be used on an 880 cc street bike so maximum flow and velocity at lifts under .400 inch was the target.
The first test shows what happens when the velocity goes too high too early. The turbulence plugs the port and additional valve lift reduces the flow.



After removing another .020 from the short side floor the flow increased up to .400 like it was supposed to. The blue line is the velocity in comparison to the head before I started.



Here is the CFM numbers before and after.



Now after a set of springs it is ready to make some arm stretching torque. Jim

Very cool Jim. Thanks for posting this.
Bill G

My Pavlovian response mechanism is on WOT! Tell us about carb and cam selection. Under.400 lift. Does that mean a stock cam?

Please! And thanks,
Russ

Thanks for sharing those pics Jim. I was wondering what parts of this process would pertain to the work you did on my RH10 thru CNW? Just curious.

rvich said:

My Pavlovian response mechanism is on WOT! Tell us about carb and cam selection. Under.400 lift. Does that mean a stock cam?

Please! And thanks,
Russ

Click to expand...

The cam will be a sporty street cam- likely a Megacycle 5600 or a Webcam 12a. That is the most cam I would ever recommend for the street.
The carbs will be Keihin FCR flatslides. Jim

Snorton74 said:

Thanks for sharing those pics Jim. I was wondering what parts of this process would pertain to the work you did on my RH10 thru CNW? Just curious.

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The work would have been the same other than installing the bigger seats and the porting. And of course I don't flowtest heads for a standard rebuild.

Rebuilding a standard head would include equalizing the squish area with a surface cut and usually installing al-bronze exhaust threads. Jim

For a layman as myself this is a wonderful scienze fiction topic! And Jim is a UFO.

Thanks for posting all that super eye candy it made my day, I'm tired of looking at dirty blackhawk helicopter parts and caught this thread on my lunch break. I want a fullauto of my own Cj

Never saw how the valve seats were dealt with before, nor all the other details to compensate thanks. Question: did the head flow improve with just the big valves over the standard ones before the porting was optimized? Should help use up tires even faster.

Nice !! thanks for putting the info on here , very interesting 8)

I just looked at this again and took my time this time....Man that's nice !!

Very nice Jim. What valve to guide clearances do you use with the al bronze guides?
I have some Terry Prince heads (Vincent) which Terry set up with .001 on intake and. 0015 exhaust. The guides are Colsibro, valves are SS tuftrided. A couple of the locals have suggested I ought to open the clearances up, otherwise valves might stick. Naturally I would prefer not, given that Terry has taken great care to do a similar procedure to the one you have detailed for us, seals installed as well.
The thermal coefficient of the Colsibro is very close to SS, so it seems that if there is clearance cold, there ought to be equal clearance hot. I'm guessing that al bronze is quite similar to Colsibro in make up and thermal expansion.
What material are the Black Diamond valves made from?

Glen

hobot said:

Never saw how the valve seats were dealt with before, nor all the other details to compensate thanks. Question: did the head flow improve with just the big valves over the standard ones before the porting was optimized? Should help use up tires even faster.

Click to expand...

Once the big seat is installed it takes quite a bit of grinding to get the bowl to match the seat. The bowl and how the port enters the bowl are the most important parts of getting good flow.
I only removed material from the seat to about 1 inch before the guide. From 1 inch before the guide to the flange nothing was removed except to clean any rough spots.

Even after doing a lot of them over the years I often end up making two or three trips to the flow bench before it is right. Calipers will get the port shape in the area but the little things that are hard to measure will be what makes the difference between a good port and one that is just so-so. Jim

worntorn said:

Very nice Jim. What valve to guide clearances do you use with the al bronze guides?
I have some Terry Prince heads (Vincent) which Terry set up with .001 on intake and. 0015 exhaust. The guides are Colsibro, valves are SS tuftrided. A couple of the locals have suggested I ought to open the clearances up, otherwise valves might stick. Naturally I would prefer not, given that Terry has taken great care to do a similar procedure to the one you have detailed for us, seals installed as well.
The thermal coefficient of the Colsibro is very close to SS, so it seems that if there is clearance cold, there ought to be equal clearance hot. I'm guessing that al bronze is quite similar to Colsibro in make up and thermal expansion.
What material are the Black Diamond valves made from?

Glen

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The black diamond valves are stainless steel. I don't recall the exact alloy. They have a type of DLC coating on the stems. The guides are similar to Ampco 45. I fit .001 on the intakes and .0015 on the exhausts with this setup.

If I am installing valves or guides other than these I will usually open up the clearance by an extra 1/2 thou. unless they are titanium valves in which case I will open them up by at least an extra .001.

I am not well versed in Colisbro guides or tufftrided stems so I can't really give a good opinion. If I were fitting them I would add an extra 1/2 just due to the fact that I don't know. A little loose beats stuck any day.
If the person that fitted them has experience with how tight they can be run then you may be good to go.

One thing I have learned is to use synthetic oil or prelube on the stems when they are assembled. Regular oil or grease will burn on the stem and cause the valve to stick if the clearances are tight. Jim

Thanks for sharing Jim- Super impressed

Thanks Jim.
I might use a bit of fine emory on a 1/4 rod just to get another half thou. A machinist friend suggested pulling the seals and having at them with a reamer, however I think the Colsibro is like al/bronze in that a reamer might not leave a smooth finish. It would be easy to ruin all of the good work that has been done!
The Si in Colsibro is silicon, which I suspect makes it hard and difficult to cut. The L may stand for aluminum, have to do some reading.

I was wrong, no al in Colsibro

COLSIBRO® is an age-hardened copper-nickel-silicon alloy which offers a remarkable blend of properties. The alloy is characterised by superior strength coupled with good thermal and electrical conductivities and excellent corrosion resistance in a variety of environments, including marine.Additionally, COLSIBRO® possesses excellent bearing and wear characteristics together with very low magnetic permeability, spark resistance, good elevated temperature properties and minimal loss of impact strength at sub-zero temperatures.Columbia Metals supplies the alloy in the fully heat-treated condition and, unsurprisingly, this versatile alloy finds its use in a wide spectrum of engineering applications. These range from valve guides and bearings in high performance racing engines to electro-mechanical components, hydraulic equipment parts, mechanical fasteners and a wealth of other high duty engineering applications.

Glen

Jim, Thanks for the information.

What are the angles of the four angles you are cutting. From this pcture it looks like a sharp transition to the seat.

Also, how do you determine where to set the seat height and how do you know you will not going to have valve clash before you go to the bigger valves, reangle of guides and setting seat height.

comnoz said:

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As a general rule I set the distance between the valves at no closer than they were originally. To go 3mm oversized on the valve then a change of 1 1/2 degrees is needed. When I rebore the seat hole I move it over just far enough so the cutter barley touches the original seat bore on the side next to the exhaust.
If the head is going on a bike with a race cam where valve to valve distance needs to be increased then I will lower the exhaust seat first to gain the clearance because the exhaust flow does not seam to be hurt by lowering the seat. Lowering the intake seat on the other hand hurts the flow considerably.

It is hard to see the actual seat in the picture. It is only .040 wide.
There is a 60 degree cut- then a 45 degree seat- then a 37 degree cut- and leading into the chamber is a 15 degree cut.

I have another Fullauto big valve head here that has had a lot more work done on it for a spare nothing 1007cc motor. I will be posting some pictures of that build soon. Jim

comnoz said:

As a general rule I set the distance between the valves at no closer than they were originally. To go 3mm oversized on the valve then a change of 1 1/2 degrees is needed. When I rebore the seat hole I move it over just far enough so the cutter barley touches the original seat bore on the side next to the exhaust.
If the head is going on a bike with a race cam where valve to valve distance needs to be increased then I will lower the exhaust seat first to gain the clearance because the exhaust flow does not seam to be hurt by lowering the seat. Lowering the intake seat on the other hand hurts the flow considerably.

It is hard to see the actual seat in the picture. It is only .040 wide.
There is a 60 degree cut- then a 45 degree seat- then a 37 degree cut- and leading into the chamber is a 15 degree cut.

I have another Fullauto big valve head here that has had a lot more work done on it for a spare nothing 1007cc motor. I will be posting some pictures of that build soon. Jim

Click to expand...

I seem to recall that there's been attempts at fully radiused seats. You'd probably need a flat where the valve contacts but would it work otherwise?

swooshdave said:

I seem to recall that there's been attempts at fully radiused seats. You'd probably need a flat where the valve contacts but would it work otherwise?

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I have done fully radiused seats. It does seem to help a little to radius the angle from the strait wall of the port to the bottom 60 degree cut. I have not seen any improvement in radiusing the corners leading up to the 45 degree seat and sometimes I have seen some loss in low lift flow.
I have been told this happens because the sharp corners help the air make the turn similar to how the holes in a golf ball help the air wrap around the rear of the ball.
Looks pretty though. Jim