663 replies to this topic

[claysummers]

Might hve a look at the other head I think.

early Holden nut

[S pack]

.429" lift (1.5:1 rocker ratio) at the valve is only 10.9mm so you have heaps of wiggle room if the maximum compression of the valve springs is 18mm

Edited by S pack, 05 March 2021 - 09:08 PM.

[claysummers]

Ok so valve lift for 1.6 ratio is 0.429" sweet. Misunderstood the spec. Thanks again Dave. I'll prolly use this cam but really I just want it to idle and sound bit raunchy but be tractable afront a grey crash box. Torque more important than power.

early Holden nut

[S pack]

Holden 6cyl engines have 1.5:1 ratio rocker arms. If you use 1.6:1 ratio rockers arms the lift at the valve wil be .457"

[claysummers]

thanks for the schooling


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[yel327]

Here’s a cheap 186 with 40 thou pistons, if you can’t get any might be worth it for a cheapy rebuild on your 186:
https://www.gumtree....opytopasteboard

Another two or three 179/186/149 by the text:
https://www.gumtree....opytopasteboard

[claysummers]

Looks like my shed.

Will be going new pistons in the 179 with auto crank I know that much.

161 head is in usable condition with a valve grind but the cam needs the double spring set up I feel. May just tidy up the 202 head for now.

early Holden nut

[claysummers]

Took flywheel and pressure plate to the shop and got some advice on cam and heads. As a result I am going with the duratec gumtree cam and the ported low comp head gets a tidy up and run with stock non adjustable tappets.


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[claysummers]

Shop didn’t like the valve seats on the 202 head. Now have a 186 head to have a look at during the week. I could use one of the two 179 heads I have but they don’t allow use of the later thermostat housing with separate outlets for the manifold.


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[claysummers]

He also thought the size of the valves would detract from low rev tractability. Car is a cruiser, tall diff, crash box.


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[S pack]

Shop didn’t like the valve seats on the 202 head. Now have a 186 head to have a look at during the week. I could use one of the two 179 heads I have but they don’t allow use of the later thermostat housing with separate outlets for the manifold.


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Pretty sure it is a only a matter of drilling two extra holes and tapping a thread in one of them to modify the 149 & 179 head heads to accept the later thermostat housing.

I'm sure Dr Terry will be able to confirm if it can be done.
 

[claysummers]

The housing can be fitted yes however been told it won’t flow coolant. Later heads have a short passage that allows this. Dr T?


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[claysummers]

Later heads have short passage which mates another short passage in the block, feeding in to water pump inlet. All blocks have the same passage, but not the heads. The early heads don’t have the metal cast in place to drill the passage either.

Just tidier with the hoses. They are messy enough already by the time you run heater as well. Planning a trip Adelaide Toowoomba in June. I want a heater.


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[claysummers]

Red 173 202 have it. I don't recall that the blue motors have coolant heated manifolds. They are connected to exhaust for EGR circuit.

early Holden nut

[yel327]

XT4 and XT5 engines are exhaust heated, these started in July 1976.

[claysummers]

173 and 202 from late HG/LC to HX/LX were all water heated I reckon.

early Holden nut

[yel327]

Yes they were, actually HQ to HJ, HG and Torana just followed HQ. So were 253 and 308. Although there were some XT4 engines during HJ but only at Pagewood I think, around the same time the pilot HX’s were made. Only 350 in that period had an exhaust heated intake.

[claysummers]

Got a my 202 head back cleaned and crack tested but rejected due to seats too recessed. Put on gumtree for what I paid for it $250 though was complete assembled, now bare head. Some one snapped it up. Now I notice numbers stamped at the back making me think could have been a Yella Terra after all. Didn't have the yt embossed valves but du ask springs so what. Here is the stamping what say you gurus?

early Holden nut

[warrenm]

Most companies that reco heads stamp the back of the heads with their own number system.

[claysummers]

Thanks Warren.

early Holden nut

[claysummers]

Another dumb question to the wise. JP HV pump? Been told they starve the bottom end or something, but anyway I've got one here new in the box. Or should I be better to use an original that meets spec?
TIA
Clay

early Holden nut

[LJ RB30]

High volume pumps are not needed for most standard-mild even hot Holden 6's.

They take more hp to turn them.

They can produce excessive high pressures on engines with tight bearing clearances that can possibly cause bearing damage.

A stock pump with standard clearances is more than capable for most engines, turboing being the only exception that comes to mind 

Starving the bottom end?  would be more to do will the poor drainback ability from the rocker cover especially after a long hard thrash & crankcase pressures holding oil up in the rocker cover.

Personally a stock pump in good condition is fine, especially with normal bearing clearances.

[claysummers]

Thanks for confirming Trevor 8)


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