Hello all,
I have a couple of Holden heads here which do not comfirm with the more common models.
I suspect that they were fitted to late HG models, how rare are these now days?
The 173 2811929 cast head and the 202 2811930 head both have the large spark plugs and the adjustable rockers.
The 2811929 HQ and the 2811930 HG heads have the small plugs and non adjustable rockers.
Mike
1971 HG Heads
Started by
_Mike73_
, Aug 18 2011 01:18 PM
10 replies to this topic
#2
yel327
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Posted 18 August 2011 - 06:56 PM
HG's had HQ heads afaik. The only difference that I was aware of was the sumps hence the G prefix. I didn't realise that they would have the earlier plugs and rocker studs? I wonder if they were spare part heads built for early cars using HQ castings?
#3
_wix2250_
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Posted 18 August 2011 - 07:19 PM
Hi I have the same head on my torana its a small chamber head with big spark plugs and adjustable rockers, its number is 2811929 it now has roller rockers yella terra yt5007, it has the small oval holes where the push rods go through. its cast date is - D211 what type do i have ?
#4
yel327
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Posted 19 August 2011 - 07:46 AM
If HG are like that, then late LC engines should be too as they also ran HQ engines. Interesting stuff. I'll ask Dr Terry.
#5
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Posted 19 August 2011 - 07:54 PM
If HG are like that, then late LC engines should be too as they also ran HQ engines. Interesting stuff. I'll ask Dr Terry.
GMH Dealer Service letter says that all HG Holden GE, GD, GM, GL and LC Torana CE, CD & CF engines have tapered seat spark plugs and non adjustable rockers.
#6
Dr Terry
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Posted 19 August 2011 - 09:26 PM
Hi Guys.
Yes, I've come across quite a few HG 186/161 heads that have the HQ casting numbers.
From what I've worked out, the 930 & 929 casting number began around Feb/Mar 1971. So most late HG & LC will have these numbers, even though they are still machined in the early style. So this isn't just restricted to the 173/202 HG ute/van engines & the 2850 LC type engines.
Maybe they are different in port shape or volume, why else would the casting number be different.
The only 'real' differences for HQ were the machining changes for the tapered seat spark plugs, the studs for the adjustable rockers & the shape of the pushrod holes.
One of life's great mysteries.
Dr Terry.
Yes, I've come across quite a few HG 186/161 heads that have the HQ casting numbers.
From what I've worked out, the 930 & 929 casting number began around Feb/Mar 1971. So most late HG & LC will have these numbers, even though they are still machined in the early style. So this isn't just restricted to the 173/202 HG ute/van engines & the 2850 LC type engines.
Maybe they are different in port shape or volume, why else would the casting number be different.
The only 'real' differences for HQ were the machining changes for the tapered seat spark plugs, the studs for the adjustable rockers & the shape of the pushrod holes.
One of life's great mysteries.
Dr Terry.
#7
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Posted 19 August 2011 - 10:53 PM
Hi Dr Terry
Just a theory.
GMH would have started volume casting 173 and 202 blocks and heads early in 1971 for the upcoming HQ release.
As the foundry was focused on casting the 173's and 202's it could be plausible that volume production of 161's and 186's was scaled back as GMH would have theoretically had a 3 to 4 month stock pile of 161 and 186 components to see out production requirements until the HQ came on line.
Maybe they found they didn't have enough cylinder heads so they grabbed some of the new 173 and 202 head castings and machined them up to suit the 161 and 186 engines.
Cheers
Dave.
Just a theory.
GMH would have started volume casting 173 and 202 blocks and heads early in 1971 for the upcoming HQ release.
As the foundry was focused on casting the 173's and 202's it could be plausible that volume production of 161's and 186's was scaled back as GMH would have theoretically had a 3 to 4 month stock pile of 161 and 186 components to see out production requirements until the HQ came on line.
Maybe they found they didn't have enough cylinder heads so they grabbed some of the new 173 and 202 head castings and machined them up to suit the 161 and 186 engines.
Cheers
Dave.
#8
yel327
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Posted 20 August 2011 - 12:20 PM
Possibly also replacement heads for HK-HG made from HQ castings? Terry, did you see them on really original cars?
#9
_Mike73_
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Posted 21 August 2011 - 07:23 PM
Hi I have the same head on my torana its a small chamber head with big spark plugs and adjustable rockers, its number is 2811929 it now has roller rockers yella terra yt5007, it has the small oval holes where the push rods go through. its cast date is - D211 what type do i have ?
Adjustable rocker heads I have are;
2811929 small chamber head B 17 1 mould 1, C 19 1 mould 2, & D 7 1 mould 6, D 19 1 mould 6, D 19 1 mould 2, D 19 1 mould 6.
Then there is the 2811930 C 23 1 mould 1 large chamber.
Sorry its raining cats and dogs and I didn't get the number under the coil boss.
You might find that the LC GTR 173S CF engine had the 2811929 adjustable head.
Mike
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Posted 21 August 2011 - 08:39 PM
Hi I have the same head on my torana its a small chamber head with big spark plugs and adjustable rockers, its number is 2811929 it now has roller rockers yella terra yt5007, it has the small oval holes where the push rods go through. its cast date is - D211 what type do i have ?
Adjustable rocker heads I have are;
2811929 small chamber head B 17 1 mould 1, C 19 1 mould 2, & D 7 1 mould 6, D 19 1 mould 6, D 19 1 mould 2, D 19 1 mould 6.
Then there is the 2811930 C 23 1 mould 1 large chamber.
Sorry its raining cats and dogs and I didn't get the number under the coil boss.
You might find that the LC GTR 173S CF engine had the 2811929 adjustable head.
Mike
GMH Dealer Service letter says that all HG Holden GE, GD, GM, GL and LC Torana CE, CD & CF engines have tapered seat spark plugs and non adjustable rockers.
#11
Dr Terry
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Posted 22 August 2011 - 11:17 AM
I've seen several on original untouched cars, with casting dates as early as Mar & Apr 1971.Possibly also replacement heads for HK-HG made from HQ castings? Terry, did you see them on really original cars?
Mike, I'm pretty sure the 173S (CF) engine had tapered seat spark plugs & non-adjustable rocker gear.
Dr Terry
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