Engine and Transmission Tech

tips, technology, tools and techniques related to vehicle driveline components

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mabie1978
Michelle Pierce
Elyria, OH
(111 posts)

Registered:
08/25/2008 07:47PM

Main British Car:
1978 MGB 3.5 Rover V8

Question about Rover heads
Posted by: mabie1978
Date: June 10, 2009 01:20PM

I know there are some Rover guys out there, so my question is, could I put heads off of a '92 3.9L on to an '88 3.5L block? From my understanding they were built back to normal spec but with upgraded valve stem oil seals. The guy said they will fit a 3.5 without any issues, but can you think of any problems I might have? Thanks!



Edited 1 time(s). Last edit at 06/10/2009 01:22PM by mabie1978.


castlesid
Kevin Jackson
Sidcup UK
(361 posts)

Registered:
11/18/2007 10:38AM

Main British Car:
1975 MGB GT Rover V8 4.35L

Re: Question about Rover heads
Posted by: castlesid
Date: June 10, 2009 08:06PM

Michelle,

They will be a straight swap for the 3.5 heads.. The only difference will be the cut outs in the inlet ports for the injector spray pattern and they will probably have waisted stem valves so will flow a little better.

Use with tin gaskets to maintain compression ratio unless they have been milled to use the thicker composite gaskets. and I would recommend using the non stretch type of head bolts.

Double check whether they are 10 or 14 bolt heads, if 10 bolt then they are the later type and require composte gaskets unless you want to raise the compression ratio to approx 9.8/1 assuming your block has high compression pistons 9.35/1

Kevin.


mabie1978
Michelle Pierce
Elyria, OH
(111 posts)

Registered:
08/25/2008 07:47PM

Main British Car:
1978 MGB 3.5 Rover V8

Re: Question about Rover heads
Posted by: mabie1978
Date: June 10, 2009 08:54PM

Hey Kevin,

My engine still has stock size pistons, and will remain that way I believe since there is no apparent wear to the cylinder walls. So they are the stock size for the '88 3.5, I would prefer to keep a lower compression as it is going to be a daily driver. Unfortunately I don't know what the original compression was without a lot of research. So far the plan is to use the stock crank and cam shafts, having the block cleaned and re-plugged. New bearings all around along with new rings on the pistons. Found these heads already built for probably what it would cost me to have the machine shop do it for me. So that is why I was trying to figure out if I could use these and still build a low compression engine.
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castlesid
Kevin Jackson
Sidcup UK
(361 posts)

Registered:
11/18/2007 10:38AM

Main British Car:
1975 MGB GT Rover V8 4.35L

Re: Question about Rover heads
Posted by: castlesid
Date: June 11, 2009 05:02AM

Michelle,

If its an 88 Rover block the engine number and compression ratio is stamped on the block by the dipstick. if it High comp it will be 9.35/1 and low comp probably 8.3/1, if low comp definitely use the tin type gaskets. if high comp you should be fine also using the tin gaskets to retain the 9.35/1 ratio.

Another point is if you use the thicker composite gaskets you will change the lifter preload and it may be insufficient.

Do check whether the heads are 10 bolt later type or 14 bolt earlier type as the combustion chamber size is different, the later 10 bolt heads have 28cc chambers and will require composite head gaskets, the earlier heads have 36cc chambers and use tin gaskets.

Kevin.


mabie1978
Michelle Pierce
Elyria, OH
(111 posts)

Registered:
08/25/2008 07:47PM

Main British Car:
1978 MGB 3.5 Rover V8

Re: Question about Rover heads
Posted by: mabie1978
Date: June 16, 2009 11:19AM

They are the 14 bolt and they have been decked. How will I know which gasket I need? I know that the thickness will need to change most likely since some of the metal has been removed. Oh have I told you guys that this is my first engine :)


castlesid
Kevin Jackson
Sidcup UK
(361 posts)

Registered:
11/18/2007 10:38AM

Main British Car:
1975 MGB GT Rover V8 4.35L

Re: Question about Rover heads
Posted by: castlesid
Date: June 17, 2009 01:25PM

Michelle did you check the block face by the dipstick, the compression ratio should be stamped there just above the engine number.

If the heads have had a lght milling they should be fine, you don't need low compression the Rover engine should run fine with up to 9.75/1 + on pump gas being an all alloy engine.

If your concerned about how much has been milled from the heads take them into a local Auto engineer and ask them to cc a couple of chambers which will give an accurate figure and if only 28-30cc you can use the cvomposite gaskets for peace of mind.

Kevin.


NixVegaGT
Nicolas Wiederhold
Minneapolis, MN
(659 posts)

Registered:
10/16/2007 05:30AM

Main British Car:
'73 Vega GT 4.9L Rover/Buick Stroker

authors avatar
Re: Question about Rover heads
Posted by: NixVegaGT
Date: June 18, 2009 09:54AM

It's not hard to cc them yourself too. You just need a simple graduated container of some kind. I used a large syringe from the pharmacy. It cost like $6. easy.

When I cc'd my heads they turned out to be 45cc (300 heads) instead of the stock 54cc. I think they have been worked on before... I think they took only 5 thou.



BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6469 posts)

Registered:
10/23/2007 12:59PM

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

authors avatar
Re: Question about Rover heads
Posted by: BlownMGB-V8
Date: June 18, 2009 10:51AM

You can use a square of clear plastic with a hole in it, seal it to the head (or block) with a smear of grease and fill through the hole. Works like a bubble level, when the bubble is gone see how much fluid you used. If you do both the chamber and the cylinder at TDC it's easy to calculate compression.

Jim


NixVegaGT
Nicolas Wiederhold
Minneapolis, MN
(659 posts)

Registered:
10/16/2007 05:30AM

Main British Car:
'73 Vega GT 4.9L Rover/Buick Stroker

authors avatar
Re: Question about Rover heads
Posted by: NixVegaGT
Date: June 18, 2009 11:21AM

Good point. I should have said that... I just used a piece of plexy I had laying about.


mabie1978
Michelle Pierce
Elyria, OH
(111 posts)

Registered:
08/25/2008 07:47PM

Main British Car:
1978 MGB 3.5 Rover V8

Re: Question about Rover heads
Posted by: mabie1978
Date: June 22, 2009 10:46PM

Hmm, you guys are way to smart.


NixVegaGT
Nicolas Wiederhold
Minneapolis, MN
(659 posts)

Registered:
10/16/2007 05:30AM

Main British Car:
'73 Vega GT 4.9L Rover/Buick Stroker

authors avatar
Re: Question about Rover heads
Posted by: NixVegaGT
Date: June 23, 2009 12:58PM

Or destructively obsessive. LOL.
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BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6469 posts)

Registered:
10/23/2007 12:59PM

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

authors avatar
Re: Question about Rover heads
Posted by: BlownMGB-V8
Date: June 23, 2009 03:17PM

And sometimes obsessively destructive ;-)

Jim


roverman
Art Gertz
Winchester, CA.
(3188 posts)

Registered:
04/24/2009 11:02AM

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

Re: Question about Rover heads
Posted by: roverman
Date: June 23, 2009 06:12PM

Oh and did we mention, put the barely adequate size hole near top or bottom edge of chamber or bore? Hole in the middle will just make you crazy trying get the last bubble out. While were being soo technical, did we mention what a low surface to volume ratio the Buick/Rover-semi hemi, has? Not as good as a "sphere", mind you but way better than a Hemi with a pop-up piston. Low "S/V" will burn more properly atomized fuel as will higher surface tempeture in the boiler room. This all equates to more power from the calories. This design, first lid-out in the late fifties, is still used today, even on aftermarket, "racing" heads. Changed here and there but never abandoned.roverman.


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