729 replies to this topic

[claysummers]

Planning on a mild cam and running 98 no issue Byron but I don’t want to create a pig hand grenade. Got 179 heads but can’t run the lower thermo housing coolant feed from them.

Yeah Dave my thinking on the crank pn but at least says they are both the earlier steel billet I suppose.


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[yel327]

You won’t have any trouble finding a 186 head if that is what you want. They are still cheap and always around. Often see whole motors for $150. If you can’t find one I’m sure Greg at Classicozwreck would have one on an old motor, will look next time I’m there if you want.

[claysummers]

All good Byron. I will prolly just use the 202 low comp as it has already had work done, dual springs etc. See what the builder says.

Cam and lifter packages don't seem real cheap........

early Holden nut

[claysummers]

No advice on running the high comp head? Will be using a mild cam. Standard lift, bit more duration.

early Holden nut

[yel327]

That is what an XU1 is. A 186 with a 161H head. XU1 has the head modified a bit so probably had slightly less compression than what you will end up with. XU1 was just on 10:1. I’m not sure I’d be running that high with a small cam, but others here will have a better idea than me what you can get away with, or if there are thicker head gaskets available to drop it a bit.

[claysummers]

Dropped disassembled 179 at Lonsdale engines for them to measure up. New pistons advised so if any boring required at all will probably go out to 3 5/8”for standard 186 pistons. Plenty of meat in the walls as the castings are from the same moulds I believe. Block will be decked.

They will balance as well and now I’m thinking I should give them a flywheel and pressure plate.


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[73SUNBURSTEXYOUWON]

Dropped disassembled 179 at Lonsdale engines for them to measure up. New pistons advised so if any boring required at all will probably go out to 3 5/8”for standard 186 pistons. Plenty of meat in the walls as the castings are from the same moulds I believe. Block will be decked.
They will balance as well and now I’m thinking I should give them a flywheel and pressure plate.
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Hi, 11 years back, my 179 needed boring oversize, std.186 was all that was available then. Maybe the same now ??

[claysummers]

Same casting moulds I believe so no brainer to go to 186


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[claysummers]

173 HC used the small chamber head with stock cam I believe. Not much less displacement than 179.


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[yel327]

Yeah, they must have had a compression limit for the red 6 with the standard camshaft to run on both Super and Standard fuels. To make a low comp 149 or 161 they just put the 179/186 head on it but the 173LC used a 202 head plus dished pistons. They appear to have been happy with the increased compression with the standard 202HC at 9.4:1 and it had the tiny cam except for the auto pollution engines but you’d imagine that was the limit and it is also what the 173HC was. If you stuck the small chamber head on a 179 you are probably up around 9.7-9.8.

[I'm a Red Motor fiend]

Same mold. A 179 will take a 120 thou over bore which puts it at the same size as a 186 out 60 thou.

Definitely give them your flywheel and pressure plate.

I wouldn't be too concerned about using the hi comp head.
I doubt your slugs will be at zero deck and with a thicker head gasket and even with only a small cam I think you'll be fine.

[yel327]

Not quite. 186 is 179 plus 0.0625”. 179 plus 060 pistons are slightly smaller than 186 STD. The bores mostly go up by 1/8” (0.125”) other than 179 which is the odd one out that sits in between 173 and 186 (62.5 thou either side).

^^That advice about the head is what I meant Clay, others out there will have valuable feedback for you about what you can get away with. I’d decide though if you are going to do it and get Crow to make you a cam to suit so you don’t have too much dynamic compression.

[claysummers]

Thanks Adam. Block will be decked but just minimally.

early Holden nut

[claysummers]

Thanks Byron. I'll look in to the cam.

early Holden nut

[claysummers]

Reading old Jonno's bible lends to the speculation the 161H head will be okay with a mild cam but for now I will concentrate on the bottom end and probably just fit this 202 head after a valve grind. Intakes have been improved, so called double springs, and big intake valves. Was advertised as a yellaterra for $250. Just a mildly worked head priced accordingly.

early Holden nut

[claysummers]

Got a cam here it's a dynotec CM205D. I wouldn't call this a mild cam. I think the lift is a bit high for stock valve train and don't want to lash out on roller rockers or have a cranky beast. Any knowledge on this cam oh gurus?

early Holden nut

[S pack]

Doesn't sound like it's too wild with duration of 214/214 @50 but it does have a good amount of lift at .429/.429" at the valves.

Ensure the valve springs in that 202 cyl head can handle that amount of lift without coil bind.

[claysummers]

Thanks Dave. Yeh it's the lift I'm not sure about. Easy enough to check bind I suppose. If I get what you are saying the shorter duration will allow a tolerable ramp to full lift that won't be too taxing on the rocker setup?

Thinking to reuse crank gear with a new ally cam gear. The crank gears I have are original and only run with fibre gear. Should be fine?

early Holden nut

[S pack]

I was actually thinking the opposite. The short-ish @50 duration and high lift is going to open and close the valves a poofteenth faster than a cam with more @50 duration for the same amount of lift.

You shouldn't need roller rockers but I personally prefer at least having adjustable rockers over the non adjustable fare.

[claysummers]

Rocker on the right has me thinking i should build up the metal on the rest of the set.

early Holden nut

[claysummers]

Inlets 1 5/8"
Exits 1 3/8"

early Holden nut

[claysummers]

Yeh adjustable I agree. This will do until I get the 7438296 head done.

The springs bind at 18mm.

early Holden nut

[claysummers]

The 429 lift comps out at 17.43mm. Bit close for my liking. 1:5 ratio would be 16.34mm.

early Holden nut

[claysummers]

Now apparent corresponding valve stem seized in guide

early Holden nut

[claysummers]

Bent valve stem of course

early Holden nut