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Dan Jones
Dan Jones
St. Louis, Missouri
(259 posts)

Registered:
07/21/2008 03:32PM

Main British Car:
1980 Triumph TR8 3.5L Rover V8

New-old-stock Rover block needs align honed?
Posted by: Dan Jones
Date: September 25, 2018 07:12PM

I finally got around to working on one of my Rover/Buick engine projects. This one uses a new-old-stock Rover 4.2L short block, along with a set of ported Rover 3.9L heads, an Edelbrock Performer Rover intake, tri-y headers and a solid lifter cam. I purchased the engine as a long block from a local guy and later noticed the main caps were not torqued down. Initially, I wanted to check the piston-to-valve clearance so the cam was installed and degreed. I had a set of ARP main studs which were installed and torqued. This caused the crank to lock up. Took things apart, washed out the grease and checked the clearances. Initially, it appeared as if the crank might be above the high side of the tolerances and need to be turned. BTW, the crank sort of looks like it was nitrided which can cause it to grow a little.

Engine is now at my machinist and he checked the housing bores with a dial bore gauge set to the middle of the spec (set at 2.491", range is listed as 2.4906" to 2.4916"). All of them are 0.0015-0.002 under that value so it looks like the block will need to be line honed. BTW, the spec values came from the King bearing catalog which are the same as listed in the Clevite catalog for a Rover 3.5L. I have the Rover 3.5L, 3.9L and 4.2L V8 engine overhaul manual (circa 1996) but didn't see anything listed for the housing spec. I still need to check the TR8 ROM.

Anyone run into something like this before?

Thanks,
Dan Jones


minorv8
Jukka Harkola

(127 posts)

Registered:
04/08/2009 06:50AM

Main British Car:
Morris Minor Rover V8

Re: New-old-stock Rover block needs align honed?
Posted by: minorv8
Date: September 26, 2018 01:27AM

Not with 4.2 block but with 4.6 litre cross bolted block the ARP torque values will lock the bottom end solid. I assembled a 4.6 short block for a friend and he insisted in using ARP hardware. I did not really understand the excessive (compared with factory values) torque values provided with the main studs so I torqued the mains in specific steps using factory tightening sequence (mains/cross bolts). Way before the ARP torque value was reached the bottom end was solid. I removed the ARPs and fitted STD bolts. No issues when torqued to factory specs.

So, ARPs back in, torqued to Rover values and no issues whatsoever. I called my friend and asked what he wanted. Finally we decided to keep the ARPs torqued to factory specs. The engine has now seen fairly hard use and no issues with our decision.

It is evident that when using ARP values the block will distort. Factory uses bolts whereas ARPs are studs. When torquing they behave differently but still the APR values sound excessive.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5658 posts)

Registered:
10/23/2007 12:59PM

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

authors avatar
Re: New-old-stock Rover block needs align honed?
Posted by: BlownMGB-V8
Date: September 26, 2018 11:22AM

I suspect the ARP values are the ones specified for iron blocks. I have used them in iron with no issues, using the recommended values.

Jim


Dan Jones
Dan Jones
St. Louis, Missouri
(259 posts)

Registered:
07/21/2008 03:32PM

Main British Car:
1980 Triumph TR8 3.5L Rover V8

Re: New-old-stock Rover block needs align honed?
Posted by: Dan Jones
Date: September 26, 2018 12:42PM

Even with the stock fasteners torqued to 90 nm, it's still under the minimum clearance and locks up. It gets worse with the ARP fasteners. There's not enough stretch with the ARP studs at the lower OEM torque value so I think I'm going to stick with the OEM fasteners and get it align honed.

Thanks,
Dan Jones


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