Fullauto Technologies Head

Dkt26 · Jun 6, 2014

I am very excited to announce that I am the proud dad of a new fullauto head.
Could anyone outline what performance upgrades Jim does to them? It looks awesome stock and this is how I will use it in its first iteration but am just a little curious as to what can be done to them.
The D ports look fabulous by the way. Super well done fullauto.
Also with regard the valves, it looks as though they just need lapping and bolt fitting. Is there anything else I need to consider prior to installation?
Also, thought it timely to lift compression a bit. Currently running +20 hepolites with standard cam (which I like and won't be changing till next rebuild) and composite head gasket (no base gasket)
Any advice

comnoz · Jun 6, 2014

The Fullauto works very well right out of the box. It will increase the power in the midrange up through around 6200. I would highly recommend fitting Kibblewhite valves as they will flow better and last very well with the installed guides. If you use plain steel valve stems in the bronze guides they will wear faster.

I can do 3 stages on the Fullauto.

1. Just a port cleanup to make them work a little better in the original powerband.

2. A 1.5mm oversize intake valve along with bowl blending will make them pull harder over 4500. No guide re-angling is necessary if you run a stock or very mild performance cam. [Webcam #12 grind}

3. A 3mm oversize intake with port widening and intake guide re-angling will make them run with the best on the racetrack. Jim

Dkt26 · Jun 7, 2014

Thanks Jim
So do I need only lap the kibblewhite valves? The black diamond 750 valves I checked looked really close and only required a lapping.
Also, any thoughts on compression?

comnoz · Jun 7, 2014

Dkt26 said:
Thanks Jim
So do I need only lap the kibblewhite valves? The black diamond 750 valves I checked looked really close and only required a lapping.
Also, any thoughts on compression?

You should be good with just a light lapping with the Kibblewhite Black Diamond valves. The Fullauto combustion chamber is the same size as a stock low compression head. On a 750 you should be around 9.5 to 1 which is pretty good on the street. Jim

Dkt26 · Jun 7, 2014

Oh I should have mentioned that it is an 850.
I was thinking of raising compression a little with a thinner head gasket. Just not sure which to use. It is an everyday rider so I don't want anything too extreme. Do you or anyone else have any suggestions?

Fast Eddie · Jun 7, 2014

Dkt26 said:
Oh I should have mentioned that it is an 850.
I was thinking of raising compression a little with a thinner head gasket. Just not sure which to use. It is an everyday rider so I don't want anything too extreme. Do you or anyone else have any suggestions?

It seems almost universal on 850s that the CR was lower than claimed, but with a FA head being a far more precisely machined component, this may not be the case.

Unless you know your starting point, you can't predict what CR you will get with any given work. I would drop the head on, get the pistons to TDC, carefully measure how much oil it takes to fill the combustion chambers and calculate your current CR.

I think that with an 850, for every mm you take out of the head to block gap, you raise the CR by nearly one point.

olChris · Jun 7, 2014

Dkt26 said:
Oh I should have mentioned that it is an 850.
I was thinking of raising compression a little with a thinner head gasket. Just not sure which to use. It is an everyday rider so I don't want anything too extreme. Do you or anyone else have any suggestions?

Use the "KISS" method. Unless you have the experience.. (or the $$$$$)

Hobot · Jun 7, 2014

A compression test with some oil to help cheat on ring seal will give ball park effective/dynamic CR with the cam type fitted then can decide from there which gasket thickness to get from JSM and then check & fiddle the push rod geometry for the final engine stack height. The higher the CR the faster the kick'er off parts wear.

Matt Spencer · Jun 7, 2014

Could measure chamber volume with burette or syringe , and calculate piton to top face volume ( inc. valve cut outs ) .

Them plus cyl swept volume plus that , divided by them , gets the x : y bit .

http://skrunkwerks.com/skrunk/measuring ... n-ratio-1/

Think you can ignore the gnats dicks stuck between the cylinder wall and piston over the top ring .

Hobot · Jun 7, 2014

All methods of measuring and objective calculations are not as good as the real time compression testing with cam installed so only good to get both sides equalized in CR and to ball park final effective-dynamic CR to determine ign advance with the octane available. Alas even kicker rpm type compression testing has its errors too.

Matchless · Jun 7, 2014

I am in the process of building my new strong engine. Maney cases, crank, 920 barrels, J.S. Motorsport rods & medium comp. pistons & a Fullauto head re worked by Jim Comstock with 3mm inlet valves & port work (very nice job). I have measured the combustion chambers & they are 60 cc each. With a .040" head gasket & no base gasket it would give 7.9:1. I have opted to use a .021" gasket & mill .025" from the head to get just over 9:1. This should be a good starting point for pump fuel. As soon as the bike is finished I'll report back if anyone is interested. Also, I can't say I am overly impressed with the finish of the Fullauto casting for the price but with Jims mods the performance is bound to be better.
Martyn.

jseng1 · Jun 7, 2014

Matchless said:
I am in the process of building my new strong engine. Maney cases, crank, 920 barrels, J.S. Motorsport rods & medium comp. pistons & a Fullauto head re worked by Jim Comstock with 3mm inlet valves & port work (very nice job). I have measured the combustion chambers & they are 60 cc each. With a .040" head gasket & no base gasket it would give 7.9:1. I have opted to use a .021" gasket & mill .025" from the head to get just over 9:1. This should be a good starting point for pump fuel. As soon as the bike is finished I'll report back if anyone is interested. Also, I can't say I am overly impressed with the finish of the Fullauto casting for the price but with Jims mods the performance is bound to be better.
Martyn.

You can avoid milling the head and use a .003" head gasket ring and .005" wire (smashes flat) around the pushrod tunnels and oil return and get close to 9:1 C.R.

Hobot · Jun 7, 2014

Don't sweat too much on not obtaining 10 CR as only 3% gain over 9 CR and some maybe better idle and slow hi throttle steady lugging on a fairly aggressive cam that you ain't having to worry with. It sounds like you will have to use caution on entering roads not to give much throttle at all till lined up pretty straight or just spin right out. When instant torque on tap its hard not to tap it as soon as ya like for the pulling sense high till throttle experience sinks in.

Matchless · Jun 7, 2014

Jim,
Steve Maney leaves the liners proud of the top deck by approx. .004" & because of this I preferred to use a .021" gasket which you are currently sending to me. Leaving the liners proud is good practice in my opinion.
Martyn.

Fast Eddie · Jun 7, 2014

Matchless said:
Jim,
Steve Maney leaves the liners proud of the top deck by approx. .004" & because of this I preferred to use a .021" gasket which you are currently sending to me. Leaving the liners proud is good practice in my opinion.
Martyn.

Martyn, that sound like an interesting motor you're building there. Out of interest, what cam are you going to use? And out of further interest, if the liners are proud, how do you seal around the pushrod holes?

cjandme · Jun 7, 2014

Fast Eddie said:
............... if the liners are proud, how do you seal around the pushrod holes?.........

Also curious about the above, & +1 on the interesting engine combo (very jealous of the various components your putting together :mrgreen: )

Hobot · Jun 7, 2014

JIm uses un waxed dental floss + favorite sealer around push rod tunnels and oil drain hole. Silk or cotton thread would work but synthetic will melt into globs that leave voids in the sealant. Some run sans gasket so why not all thread and Hylomar if things clear ok?

Dkt26 · Jun 7, 2014

Yes very cool combo martyn
I have stock compression with the comp gasket and am interested in the 21thou copper gasket. I don't want to have to do anything else like milling pistons etcetera.
Will I be fine to just assemble with the thin 21thou copper gasket from JS?
I would imagine my comp would come up a bit to say 8.5:1 or thereabouts.
Also with fitment , I've never done this before with copper gaskets. Done heaps of cars and trucks but never annealed a gasket before.
If I am going to be right just fitting the 21thou gasket with no other mods required, how do I correctly anneal the copper gasket? My limited understanding is that I just heat it with a handheld gas torch until it changes color then fit. Is this correct? Also do I need to do bolt up while the gasket is hot? Do I use any goo like hylomar?

phil yates · Jun 8, 2014

olChris said:
Dkt26 said:

Oh I should have mentioned that it is an 850.
I was thinking of raising compression a little with a thinner head gasket. Just not sure which to use. It is an everyday rider so I don't want anything too extreme. Do you or anyone else have any suggestions?

Click to expand...

Use the "KISS" method. Unless you have the experience.. (or the $$$$$)

Yes, KISS is always a safe way to go, especially if dollars are an issue and you are doing the work yourself, or at least what you can do. I have done a lot of research on the matter of performance upgrades and concluded that Jim knows more about the subject than anybody else in the Norton world. And he gives out free information in a most unlike business fashion, which is rare indeed. Most will want dollars for the sort of information Jim offers.

My Fullauto head and complete engine will be shipped to the USA for Jim to do the work. The rest of the bike will be stripped and re built here in Australia, not that it needs much, it has already been restored once, but I am extremely pedantic in this area. I have confidence there are plenty of good Ozzie restorers to do that work. But engine performance upgrades go to Jim, he has probably forgotten more about Commandos than most people know.

Enough said, I don't want to be running an advertisement for Jim, but every single PM I've received, and they are many, has Jim Comstock at the top of the list.

Phil

Fullauto · Jun 8, 2014

[quote="Matchless] Also, I can't say I am overly impressed with the finish of the Fullauto casting for the price but with Jims mods the performance is bound to be better.
Martyn.[/quote]

Er, in comparison to what? I think they are beautifully finished and I haven't had any complaints before. They are a complex sand cast item after all. And so far in front of the originals that they are out of sight.

Fullauto Technologies Head

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