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chevsen
Mark Basile
Woodland Hills, CA
(3 posts)

Registered:
02/19/2020 04:18PM

Main British Car:


4.0/4.6 heads - dropped guides?
Posted by: chevsen
Date: March 20, 2020 01:03AM

I recently picked up a set of 4.0/4.6 heads. I didn't notice until I started removing the valves that all of the intake valve guides have dropped toward the chamber by about .150 -.200". Is this a common problem? Are the guides THAT loose from the factory? And on that note, I only removed one intake and one exhaust valve, but the intake guide appears to be bronze and the exhaust is cast iron? Are these the factory guides or did someone possibly replace the intakes this deep (these heads have been hot tanked and I cannot see any witness marks on the intake guides to validate that they have dropped). Also, the intake stem seals look to be identical to the exhaust, so that leads me to believe that the bronze guides are factory? Any insight here is appreciated.


minorv8
Jukka Harkola

(199 posts)

Registered:
04/08/2009 06:50AM

Main British Car:
Morris Minor Rover V8

Re: 4.0/4.6 heads - dropped guides?
Posted by: minorv8
Date: March 20, 2020 03:24AM

The 4.6 heads I had did not have bronze guides. Intake and exhaust were both cast iron.


turbodave
dave cox

(31 posts)

Registered:
04/30/2018 03:00PM

Main British Car:


Re: 4.0/4.6 heads - dropped guides?
Posted by: turbodave
Date: March 24, 2020 09:15AM

no factory head had bronze guides.


roverman
Art Gertz
Winchester, CA.
(3031 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: 4.0/4.6 heads - dropped guides?
Posted by: roverman
Date: March 25, 2020 07:55PM

Perhaps "crafty" installer pushed in deeper to avoid cutting on top for higher valve lift ? I find no logic in bronze int. and iron exh.
Check how much effort to push bronze guide up to proper location. Art.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5911 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: 4.0/4.6 heads - dropped guides?
Posted by: BlownMGB-V8
Date: March 26, 2020 12:35PM

It might work well with teflon intake seals and umbrella seals on the exhaust. Less vacuum on the exhaust side to suck in oil. The cast iron being more porous could hold the oil better.

Jim


chevsen
Mark Basile
Woodland Hills, CA
(3 posts)

Registered:
02/19/2020 04:18PM

Main British Car:


Re: 4.0/4.6 heads - dropped guides?
Posted by: chevsen
Date: April 07, 2020 11:57PM

Upon further inspection, they are not bronze and highly magnetic, sorry for the confusion. The end profile of the guide (slightly "chamfered" on the port end) is different from the exhausts and they are bronzey colored which is what threw me. But....they are definitely dropped. I pushed one of the guides back into approximate position on a 20 ton press and it took quite of bit of force. Stumped at how they could move so much given the apparent interference fit on the one I moved back up away from the port??


minorv8
Jukka Harkola

(199 posts)

Registered:
04/08/2009 06:50AM

Main British Car:
Morris Minor Rover V8

Re: 4.0/4.6 heads - dropped guides?
Posted by: minorv8
Date: April 08, 2020 12:27AM

They are not original so maybe whoever did the job simply installed them deeper in the head. Are they shorter than ex guides.



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