9 replies to this topic

[jd lj]

Should the original V8 exhaust manifold to head bolts be grade 5 (3 lines on the head) or grade 8 (6 lines on the head)? The torque specs of 20-25ft pounds would suggest grade 5. Do they have an approximately 3mm thick flat washer? Any pics of original ones would be appreciated.

Thanks

[Shiney005]

They had a flat shim that fit over each pair of bolts up until at least HQ.  I haven't seen any on a motor since the early '80's.  I can't find any mention of them in the 75 parts book.

 

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[arrimar]

^french locks

[arrimar]

One of my cars, I added the repro french locks, they weren't there when I got it.

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[yel327]

Here is my HJ Premier. This is an original engine, although the heads were taken off to do head gaskets. This is a 12/74 car so it is a 9.7:1 250hp engine but the same dress as all HQ and LH from 8-9/73 to 12/74. Those exhaust manifold set screws and washers under them will be original. Washers are thick. I have seen earlier 253/308 like Laurie shows, not sure when those stopped being used.

 

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[jd lj]

Thanks for the pics everyone. It's interesting that GMH used grade 8 bolts with a relatively low torque setting of 20-25ft pounds.
Does anyone know the length of these, 3/8 unc x 1 1/4" possibly?

[yel327]

It looks like the earlier ones were 186619 which come up as: Bolt, 3/8 in.-16x1-1/8 in

 

That changes in later books to 106331 which has the same specs.

 

The thick washers are 3836710 which look to be: 12/32 x 11/16 x 1/8". There are 12 of these on the pre ADR27 engines and 10 on the ADR27 engines (those with stoves on the exhaust manifold).

 

The lock plates are listed in all HQ parts catalogues as 7437450, only 4 of them though.

 

HT-HG also list the 4 x lock plates and 12 x washers. So the lock plates must have gone on after the washers on the front and back ports. 

Edited by yel327, 11 May 2024 - 04:06 PM.

[jd lj]

Thanks for the information Byron.

[jd lj]

Has anyone got any of these original bolts that they'd be willing to sell even if it's not a full set?

[Shiney005]

What car is this for James?