Atlas head commando head

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Can a late type atlas head IE non spigoted be converted to fit a commando ?
Is it just the oil feed that would need matching in the side?
Presumably you could do the rocker spindle conversion and feed it from one side?
Is the oil feed the only difference? Cheers
 
Can a late type atlas head IE non spigoted be converted to fit a commando ?
Is it just the oil feed that would need matching in the side?
Presumably you could do the rocker spindle conversion and feed it from one side?
Is the oil feed the only difference? Cheers

One "problem" you will run into is that the 4 head bolts on either side of the sparkplugs are 5/16 on the Atlas and 3/8" on the Commando. But I don't think it would be difficult to enlarge the through holes on the Atlas head if necessary.

Ed
 
One "problem" you will run into is that the 4 head bolts on either side of the sparkplugs are 5/16 on the Atlas and 3/8" on the Commando. But I don't think it would be difficult to enlarge the through holes on the Atlas head if necessary.

Ed
Oh yes I'd forgotten that one cheers
 
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you will need to come up with a way to plug the two original oil feed holes in the top of the head so they will not leak and tap the plugs to fit the bolts for the commando haedsteady bolts
 
Some very late 20M heads are original factory no spigot AND 3/8 head bolts...it seems they are rare, but I have one for my combat tune atlas using NOS std bore commando barrels.
P11 guys and one of the knowledgeable guys from NOC verified it for me. I originally thought I had a very neat home conversion.
or
are you just to cheap to get a proper commando head?
 
Some very late 20M heads are original factory no spigot AND 3/8 head bolts...it seems they are rare, but I have one for my combat tune atlas using NOS std bore commando barrels.
P11 guys and one of the knowledgeable guys from NOC verified it for me. I originally thought I had a very neat home conversion.
or
are you just to cheap to get a proper commando head?

I have a 1969 R engine with 5/16 head bolt and oil feeds on the rockers side.
May be not original!
Piero
 
Some very late 20M heads are original factory no spigot AND 3/8 head bolts...it seems they are rare, but I have one for my combat tune atlas using NOS std bore commando barrels.
P11 guys and one of the knowledgeable guys from NOC verified it for me. I originally thought I had a very neat home conversion.
or
are you just to cheap to get a proper commando head?
Some very late 20M heads are original factory no spigot AND 3/8 head bolts...it seems they are rare, but I have one for my combat tune atlas using NOS std bore commando barrels.
P11 guys and one of the knowledgeable guys from NOC verified it for me. I originally thought I had a very neat home conversion.
or
are you just to cheap to get a proper commando head?
I guess I must be too cheap,the cost of parts is a big issue for me, I was considering buying one and converting it to commando spec
 
I have a 1969 R engine with 5/16 head bolt and oil feeds on the rockers side.
May be not original!
Piero
Your situation is the opposite from the OP, 20M atlas head on a engine claimed to be commando.
You have atlas barrels on what you think MIGHT BE a 20M3 commando R engine
 
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Your situation is the opposite from the OP, 20M atlas head on a engine claimed to be commando.
You have atlas barrels on what you think is a 20M3 commando R engine

Hi.
From engine numbers NOC says it is a R.
It has the thin Atlas head studs but the head is a Commando type with oil feed on the rockers dide and studs holes sre not worked.
Piero
 
Hi.
From engine numbers NOC says it is a R.
It has the thin Atlas head studs but the head is a Commando type with oil feed on the rockers dide and studs holes sre not worked.
Piero
piero are the holes in your cylinder head 5/16 or 3/8 ?
 
above link post #3
https://www.accessnorton.com/NortonCommando/atlas-rockers-in-a-commando-head.7354/

then this post from that thead indicates a commando head on a 66 atlas engine using 68 atlas rocker bits
https://www.accessnorton.com/NortonCommando/atlas-rockers-in-a-commando-head.7354/#post-91727
It depends on the specific year of the atlas head, but yes. The rockers and spindles changed a few times over the life of the atlas but you should be safe if you're looking at taking from a later atlas head. My 66 atlas is actually running a commando head with rockers and spindles I took out of a 68 Atlas.

then valves & pushrods are diff sizes, but
https://www.accessnorton.com/NortonCommando/atlas-rockers-in-a-commando-head.7354/#post-91733
Commando valves are .100 in. longer and the pushrods are .060 to .080 shorter. The length is added to the area above the keeper groove on the valve.

A common Atlas upgrade is to use the longer Commando valves and shorten the pushrods as this improves the valve train geometry and makes the guides last longer. Jim

pretty sure high pressure oil feed can remain at the top of the atlas head at the same time adapting a head steady,

changeover lnfo from low to high oil pressure feed
69 mercury 750 posted 02-10-2006 10:11
In 66 Norton switched to a high pressure system which came off the lower bolt on the timing cover. In addition, the oil pump was changed (faster, bigger holes), the oil worm gear and corresponding gear on the crank were changed from three start to six start, a number of oil passageways and galleries in the crankcases were enlarged, and the rocker spindles were changed from scrolled for oil flow to plain for a measure of restriction (this change may have arrived prior to 66.)
 
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