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Head Bolts Arp


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#16 Spider

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Posted 06 August 2017 - 11:36 PM

If the block is already drilled, fit the studs and go about life as usual.

 

I know many say the Extra studs help in regards to holding the head gasket. I can't say I've had one go from having them, but, when lifting heads that have had them, there also seems to be evidence that cylinders 2 and 3 have less clamping than from those without. Just what I've seen.

 

The A Series block, when you look at is pretty dumb quite frankly in it's head stud arrangement. It has less studs (the 4 long ones) to cover a much bigger area than the 5 (shorter) ones across the dist side of the block. It really should be the other way around, however when all the other bits are taken in to consideration, that's not easily achieved. I'm also minded that the arrangement was originally for an engine of around 25 HP and a BMEP (average cylinder pressure) of around 30 PSI.

 

 

 

Yeah, that 11th one, be it a bolt (which was 5/16" originally) or stud - the deck is pretty thin there - 25 ft / lb MAX.
 
Just as a side note, if the blocks aren't already drilled for the extra 2, I don't drill them at all. I think / feel it not only doesn't help, but actually makes matters worse. Just my thoughts on them.

Too late, it's drilled and tapped now for two studs the same size as the others, so are you saying keep those two to 25lbs?

 

 

As Phil says,,,,,,

 

 

Yeah, that 11th one, be it a bolt (which was 5/16" originally) or stud - the deck is pretty thin there - 25 ft / lb MAX.

 

Just as a side note, if the blocks aren't already drilled for the extra 2, I don't drill them at all. I think / feel it not only doesn't help, but actually makes matters worse. Just my thoughts on them.

i was going to ask you guys that might know the blocks that were originally 11 "stud" did they have more material under the stud or was there no difference?

 

was there a difference there A to A+?

 

 

The original Cooper S Blocks, that had the tappet covers on the back, and finished circa 1970 had them as standard. The (ADO16) 1300 GT also had them, but it appears these or at least the very early ones, also used the Cooper S Blocks, these had the (if memory serves) 12G engine prefix. We didn't get the 1300 GT here, so I don't know a lot about them, nor did we get any souped up versions of the ADO16 so again, I don't know a lot about what was actually done and what wasn't, though I do have some info on them, it's not stuff I've read up on (at least in a while).

 

So in regards to the solid chest type 1275 block, I don't think there were many types that came out standard with the 11 studs. I do know the last of our Aust Clubman GT had that style block, but fitted with Cooper S bottom end, had these extra holes drilled from the factory (and fitted with the extra stud & bolt).

 

There's never been a lot of meat up that end of any block. Some, not all, of the drillings for the extra Bolt at the water pump end, broke through in to the water jacket.

 

It was not only the 1275 engines that had these additional holes, the (big bore) 970 and 1071 blocks also had them (these were also Cooper S Blocks), however, these fared even 'worse' than the 1275 block as they have 3/8" less meat on their decks than their 1275 cousins.

 

<EDIT:  Sorry, still too much sand in the head from the last trip away,,,,

 

Coming back to A vs A+ and 9 vs 11 studs.

 

I don't know of any A+ that came from the factory with 11 studs, as far as I am aware, they all only had 9, including the Metro Turbo and that made the highest BMEP of any factory engine. It also used the tapered type head studs (that I mentioned earlier - P/N CAM150 and CAM151, however those currently being sold under those numbers are not them) and flanged nuts as used on all engines at that time, the only change was to a better head gasket. >


Edited by Moke Spider, 07 August 2017 - 12:57 AM.


#17 carbon

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Posted 07 August 2017 - 05:46 PM

The 1300GT 'solid chest type blocks' I have seen with 11 studs all look like they started from a standard 1275 block.

 

The other reason for keeping the '11th bolt' to 25 ftlb is that the bolt shears off before you get to 45lbft...



#18 Spider

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Posted 07 August 2017 - 07:58 PM

Cheers carbon.

 

Yip, my (late) brother found out the correct torque for the bolt after breaking one.

 

When I did used to fit them and in the Race Car, I drilled & tapped it to 3/8" and fit a stud. Looking back, there was no advantage what so ever to doing this.



#19 carbon

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Posted 08 August 2017 - 06:17 PM

Thanks Moke Spider,

 

The only upside to having the bolt shear off is that it typically happens flush with the deck of the block. Using a small punch I have twice managed to unscrew the remaining threaded part of the bolt without damage. It also helps that the original blocks are helicoiled for this bolt.



#20 Cooperman

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Posted 08 August 2017 - 07:21 PM

The Innocenti Cooper 1300 had a solid back block with 11 studs (10 + 1 bolt).

 

The 11th hole usually breaks through into the water jacket and it is a good idea to use some RTV sealant on the threads of the 11th bolt to prevent water seepage.



#21 tiger99

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Posted 14 August 2017 - 07:52 AM

In some engines other stud holes also break through into the water space. I have seen coolant leaking from at least two of the front row of studs on an A+. It generally finds it's way up through the root clearance of the thread in the nuts and dribbles out of the top. Easily fixed, and it soon became something that I always look for. It can happen to the top steady fixings too.

Edited by tiger99, 14 August 2017 - 07:53 AM.





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