Standard head cylinder bolts: too big!!!!!!!

pierodn · Oct 7, 2013

Please, i need your help.
As in the pictures atthached, i found a problem whit the head cylinder bolts: infact the standard cylinder head bolts n. 060402, the same i used well on the other cylinders of mine, have the thread too big for this the cylinder thread that is too small!
Let me please know how it is possible: maybe this cylinder could be of non Commando type?
Can i find a smaller 4 head stud that go well with the head fitment?
Ciao.
Piero

Standard head cylinder bolts: too big!!!!!!!

bill · Oct 7, 2013

you need part # NM24253 you have an atlas cylinder.

pierodn · Oct 7, 2013

bill said:
you need part # NM24253 you have an atlas cylinder.

Hi,
But if it is an Atlas cylinder, can i use it on a 72 Commando engine?: i need to fit the Commando lifters (cams follower) or can i leave those of the Atlas cylinder?
Ciao.
Piero

bill · Oct 7, 2013

there is a couple of options. you could use the smaller head bolts BUT they will be loose in the head and should need special washers with the smaller ID and proper OD or have the cyl drilled and taped for the 3/8 bolts. you also need to make sure the camshaft will not hit the cyl at the tappets. it should be OK with the std cam but anything with more lift you will have issues. also tappets and camshaft should be a matched set unless all is new parts. the atlas tappets (lifters or followers) will work.

pierodn · Oct 7, 2013

bill said:
there is a couple of options. you could use the smaller head bolts BUT they will be loose in the head and should need special washers with the smaller ID and proper OD or have the cyl drilled and taped for the 3/8 bolts. you also need to make sure the camshaft will not hit the cyl at the tappets. it should be OK with the std cam but anything with more lift you will have issues. also tappets and camshaft should be a matched set unless all is new parts. the atlas tappets (lifters or followers) will work.

Hi Bill, thank you.
I have the Atlas tappets into the Atlas cylinder.
I have a 72 engine with 72 head and 71 camshaft and pushrods.
The Commando pushrods work well with Atlas tappets?(they seems to be equal like Commando tappets!)
Ciao
Pieto

Rohan · Oct 7, 2013

Have you tried to bolt your cylinder head onto this cylinder ?

pierodn · Oct 8, 2013

Rohan said:
Have you tried to bolt your cylinder head onto this cylinder ?

Yes, i bolt this cylinder (may be Atlas??) on the 72 crankase (it bolts very well) and onto the 72 head (all the bolts go very well, not only the four 060402).

pierodn · Oct 8, 2013

bill said:
there is a couple of options. you could use the smaller head bolts BUT they will be loose in the head and should need special washers with the smaller ID and proper OD or have the cyl drilled and taped for the 3/8 bolts. you also need to make sure the camshaft will not hit the cyl at the tappets. it should be OK with the std cam but anything with more lift you will have issues. also tappets and camshaft should be a matched set unless all is new parts. the atlas tappets (lifters or followers) will work.

Hi Bill,
I have this idea.
I would use the standard Commando bolts and Re-thread the final part of the 4 studs to screw it onto the cylinder Atlas.
Please let me know if you know the measurement of internal thread of the Atlas bolts cylinder.
Thanks,
Ciao.
Piero

marinatlas · Oct 8, 2013

Hi Piero, I am interested also into your modification, as I have an Atlas barrel I want to modify to accept trhe 3/8
commando head bolts , they are normally 3/8 by 26 tpi (cycle threads ) but I intend to use 3/8 24 tpi (unf ), easier to find out , but wondering if a time serts is not better ??

pierodn · Oct 8, 2013

marinatlas said:
Hi Piero, I am interested also into your modification, as I have an Atlas barrel I want to modify to accept trhe 3/8
commando head bolts , they are normally 3/8 by 26 tpi (cycle threads ) but I intend to use 3/8 24 tpi (unf ), easier to find out , but wondering if a time serts is not better ??

Hi,
I will use the standard commando head bolt that i will rethread only in the cycle thread side from 3/8 to 5/16.
Cio.
Piero

Standard head cylinder bolts: too big!!!!!!!

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