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Would anyone know what difference there is in a 179 head to a 186. I have been given a warmish 179 and want to put it in my 186. Will it fit without any mods????? Do I need to anything to get it to fit
Thanks.....

Dave, not exactly sure on this so am happy to be corrected by someone with the exact info.

138 reds,149 reds and 161 reds all share the same small chamber "kidney" shaped combustion chamber heads.

173,179,186 and 202 all share the larger combustion chamber heads.

There would be some exception to this in some of the factory performance applications I'd guess.

X2 engines may have had the small chamber from 138,149,161 heads and 161S,173S,186S etc and XU1 engines may also have used these heads to increase compression.

A lot of blokes actually use the small chamber heads in the 173 to 202 engines to increase compression.

Like I said above, I'm not knowledgeable so much in the factory applications of the various heads but someone would be able to correct any inaccuracies I've written and I'm happy to be corrected.

I'm sure the modified 179 head will go alright on a 186.If it ran well on a 179 I'm sure it will do well on a 186.There wouldn't be much decrease in compression ratio as there isn't really much of a swept volume difference between the two engine sizes.

Thanks Terry.....

Hi Guys

FB MAD is pretty well on the money, I'll just clear up a few things.

Firstly there are only two different combustion chamber sizes, the smaller 'kidney shaped' & the larger 'open chamber'.

The 'open' type is fitted to 179, 186 & 202 engines including X2 & S versions.

The 'kidney' shaped type is fitted to all 138, 149, 161 & 161 S engines as well as both the 186 & 202 XU-1s. There was also a 130 ci (export) engine which used this head but most Australians would have never sighted one of those.

The other rare exceptions are the 149, 161 & 173 low compression versions, which used the open chamber head to lower the compression. The 186 & 202 lo-comp just had their pistons dished (or in the case of the 202 lo-comp, further dished).

The is no gain or loss by fitting a 179 head on a 186 short motor. They both share the same size combustion chamber & adjustable rocker gear etc. The only difference that matters is that the 179 heads do not originally have the extra water outlet hole which lines up with the later (HR onwards) lower thermostat housing. This can be easily drilled, though.

Dr Terry

Thanks DR T ,

Have you ever seen an example of the export 130 reds?

I guess being export only they would only go on export models but you never know what the factory may have done with excess leftover unused 130 engines near the end of production.

Other thing, which head did the 173 use??

Cheers,

The other Terry

Good point about making sure the oil and water channels line up......

We once put an inlet manifold from a 308 onto a 253, and found out the hard way the water inlets/outlets didn't match up

FB MAD wrote:Thanks DR T ,

Have you ever seen an example of the export 130 reds?

I guess being export only they would only go on export models but you never know what the factory may have done with excess leftover unused 130 engines near the end of production.

Other thing, which head did the 173 use??

Cheers,

The other Terry

Hi Terry.

I've never personally seen a 130 ci engine in the flesh. I don't know why Holden bothered with both 130 & 138 engines. It might have been one of those minimum capacity legal requirements in some countries, like "engines over 2.2 litre get double tax' or similar. Most items (except pistons & rings) are interchangeable between the 130 & the 138.

There wouldn't have been many left over at the end of production. In similar fashion to the low-comp motors they were only made in small batches.

The 173 head had the smaller (kidney-shaped) chambers, like 138, 149 & 161 but had fixed rocker gear, like a 202.

Dr Terry.