Author Topic: 69Z with 186 heads and 1.94 intake seats ????????????  (Read 2090 times)

svtrich

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69Z with 186 heads and 1.94 intake seats ????????????
« on: August 04, 2009, 06:07:09 AM »
I tore my orginal DZ motor apart and ??? The guy doing my heads called and told me I had to come and check this out. This is the first time the motor has been apart so here gos.the heads are 186 castings,1.94 intake seats and 1.60 exhaust seats.strange,its gets worse.the combustion chambers are for 2.02 valves,now the kicker,it has 2.02 and 1.60 valves in the head?If I didnt see it for myself I would never believe it.could GM have screwed up when they built the engine? ???
                                         Richard

aaronz28

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Re: 69Z with 186 heads and 1.94 intake seats ????????????
« Reply #1 on: August 04, 2009, 11:45:57 AM »
i'm not sure i follow... the 69 Z did have 2.02 and 1.6
so did the 67 and 68.

GM did produce the 186 heads in 1.94/1.5 versions... but not installed on Z28s.

How can you tell that it has the 2.02 combustion chamber vs the 1.94?

i'm not sure there is  difference.

thanks

Aaron


Jerry@CHP

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Re: 69Z with 186 heads and 1.94 intake seats ????????????
« Reply #2 on: August 04, 2009, 11:46:10 AM »
Were the intake valve areas of the combustion chambers machined around the valve pocket?

Jerry

JohnZ

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Re: 69Z with 186 heads and 1.94 intake seats ????????????
« Reply #3 on: August 04, 2009, 02:18:20 PM »
Here's a photo of the unshrouding cut in the chamber wall adjacent to the 2.02" intake valve in a 186 head. Are you saying that your chambers are machined like that, have 2.02" valves, but the intake seats are for 1.94" valves and it has 1.60" exhaust valves and seats?
'69 Z/28
Fathom Green
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X66 714

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Re: 69Z with 186 heads and 1.94 intake seats ????????????
« Reply #4 on: August 04, 2009, 02:27:44 PM »
What type of head gaskets were on it? Joe

Jerry@CHP

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Re: 69Z with 186 heads and 1.94 intake seats ????????????
« Reply #5 on: August 04, 2009, 03:20:03 PM »
Could have the GM 711, #5117 or the .040" Felpro.

Jerry

svtrich

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Re: 69Z with 186 heads and 1.94 intake seats ????????????
« Reply #6 on: August 04, 2009, 07:15:56 PM »
What type of head gaskets were on it? Joe

it still had the steel shim
               Rich

svtrich

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Re: 69Z with 186 heads and 1.94 intake seats ????????????
« Reply #7 on: August 04, 2009, 07:19:11 PM »
Were the intake valve areas of the combustion chambers machined around the valve pocket?

Jerry
Jerry,they are just like Johns pic.I wish I took some pics befor he finished the heads

Jerry@CHP

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Re: 69Z with 186 heads and 1.94 intake seats ????????????
« Reply #8 on: August 05, 2009, 12:46:19 AM »
If the intakes are unshrouded, then they would be factory 2.02's unless a machine shop has done this machine process sometime in the past.

Jerry