Engine and Transmission Tech

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

Go to Thread: PreviousNext
Go to: Forum ListMessage ListNew TopicLog In


harv8
Martyn Harvey
Waterloo, Ontario, Canada
(179 posts)

Registered:
10/23/2007 10:09PM

Main British Car:
MGB Rover V8, TVR Chevy V8, MGB GT Ford V8

authors avatar
Rover 3.9
Posted by: harv8
Date: October 23, 2007 11:41PM

I'm building a Rover 3.9 for my 1980 MGB V8 this winter. I currently run a Rover 3.5 that produces 184 HP at the wheels. I would like to have over 200 HP at the wheels with the new 3.9 engine. Does anybody have any advice / tips for me before I begin. I'd be particularly interested to hear details of cams used, head modifications and HP/torque numbers from different configurations. I was planning on using the usual carb set up on an edelbrock performer intake.


StagByTriumph
Glenn Merrell
Colorado
(37 posts)

Registered:
10/25/2007 12:11PM

Main British Car:
1973 Stag Rover SD1 3.5 w/ 3.9 EFI

authors avatar
Re: Rover 3.9
Posted by: StagByTriumph
Date: October 25, 2007 01:30PM

What do you want to do with the car? Race, rally, Sunday driver, daily driver?


Moderator
Curtis Jacobson
Portland Oregon
(4411 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

authors avatar
Re: Rover 3.9
Posted by: Moderator
Date: October 25, 2007 02:32PM

Martyn, you mean this one don't you? [www.britishv8.org]


MGBV8
Carl Floyd
Kingsport, TN
(3791 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB, Buick 215

authors avatar
Re: Rover 3.9
Posted by: MGBV8
Date: October 25, 2007 06:10PM

Hi Martyn,

I'll be real interested in this thread since I've been planning a 3.9 for a while.


harv8
Martyn Harvey
Waterloo, Ontario, Canada
(179 posts)

Registered:
10/23/2007 10:09PM

Main British Car:
MGB Rover V8, TVR Chevy V8, MGB GT Ford V8

authors avatar
Re: Rover 3.9
Posted by: harv8
Date: October 26, 2007 12:14AM

Yes Curtis, that is the car I want to fit the 3.9 into.
I've really enjoyed my 3.5 for the past 10 years. Forrest Racing built me a well balanced engine that has performed well as a fast road car. It has the Isky 262 cam and is fitted with Vittesse pistons +20 thou.
I'm thinking that a well balanced 3.9 should give me a few more HP and some more useful torque. I'm not building a race car though. I guess I need to update the specs on this car now it has Fast Car's crossmember under the front.
HARV8 Sept 2007 (4).JPG


Moderator
Curtis Jacobson
Portland Oregon
(4411 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

authors avatar
Re: Rover 3.9
Posted by: Moderator
Date: October 26, 2007 01:42AM

Martyn, the car is exceptional already! Personally, I think a car that already exhibits such refinement and sophistication would really benefit from electronic fuel injection and maybe even programmable electronic ignition. You'd get better gas mileage and you might feel a little better about pollution. You'd enjoy the smooth driveability. The challenge of learning new tricks might be fun. Installing EFI is a little easier now than it was your first time around too, if only because information about setting it up is more readily available. It might be fun to make a custom plenum... something that looks unique and still performs well. (If you have to machine the Rover 3.9 plenum top-casting anyway to get it under an MGB hood, why not fabricate or commission something a little different?)


harv8
Martyn Harvey
Waterloo, Ontario, Canada
(179 posts)

Registered:
10/23/2007 10:09PM

Main British Car:
MGB Rover V8, TVR Chevy V8, MGB GT Ford V8

authors avatar
Re: Rover 3.9
Posted by: harv8
Date: October 27, 2007 01:42AM

Fuel injection is very tempting! I'll need to re-wire the car and upgrade my cooling system.



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: Rover 3.9
Posted by: NixVegaGT
Date: October 29, 2007 03:12PM

Martyn,

Nice car. I'll be using a Crower cam:

Cam is a Crower 50232 with an intake lift of 0.488", an exhaust lift of 0.490", Duration 276, Duration at 0.05": intake 214 degrees, exhaust 218 degrees. Lobe separation angle: 112 degrees.

I'm building a Rover/Buick stroker... I'm not sure how that translates to your 3.9 project but it can't hurt. It's supposed to be pretty hot for the 215. I won't be able to give feedback on this cam with 4.9l until spring... I was planning on building a MegaSquirt EFI for the engine using a Rover intake but opted for a Q-jet carb initially. If you don't know about the MegaSquirt yet it's some pretty interesting stuff. Check it out:

[www.megamanual.com]

Keeping stuff under the hood on a Vega is pretty tough bit It's got to be worse for you MG guys. I'm lucky to be able to fit a carb on top of the engine and still be underhood. Like I said I opted for the Q-jet for starters and plan to upgrade to EFI later. I landed on the Q-jet for the versatility of tuning for different applications. It's a pretty nice design. Variable CFM and infinite rod/jet combos for good mileage and power... Interesting stuff.

Are you planning on building the 3.9? Have you found a block yet? Maybe you could score one of those later blocks (like I have) with the cross-bolted mains.

I bought some of D&D's rocker shaft supports:

[www.aluminumv8.com]

I think that could open up some HP at the higher end too... Something to think over.


harv8
Martyn Harvey
Waterloo, Ontario, Canada
(179 posts)

Registered:
10/23/2007 10:09PM

Main British Car:
MGB Rover V8, TVR Chevy V8, MGB GT Ford V8

authors avatar
Re: Rover 3.9
Posted by: harv8
Date: November 22, 2007 09:50AM

I'm looking for a complete Rover 3.9 fuel injection system. Anybody have one for sale?


MGBV8
Carl Floyd
Kingsport, TN
(3791 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB, Buick 215

authors avatar
Rover 3.9 Pistons
Posted by: MGBV8
Date: February 08, 2008 05:55PM

Hi Martyn,

Here's some info I meant to add to your thread back in the fall. Wish I had. It might have helped Kevin Jackson a bit.

This is an exchange from our V8 email list about 3 years ago.

------------------------------------------------------

Kevin: Hey all, Currently taking a 3.9 0.020 over. I'm interested in opinions and experiences of high compression pistons for this -- at least higher compression than the wimpy Range Rover pistons!


Carl: I have spent waaay tooo many hours looking thru piston catalogs trying to find an alternative for those truck slugs. I believe I actually hit on something.

Since the compression height seems to be the problem, I found a piston that would fit in the 3.9 bore, then started working on stroke & rod lengths to get the piston up closer to the top of the deck.

My solution: 305 Chevy piston with a 6" Chevy rod. This combo will put the piston .001" above the deck. Check out the specs on the KB145 piston
(hypereutectic, not forged) and try out the calculators at United Machineswebsite:

[kb-silvolite.com]

By shaving the top of the piston (or not), like Glenn mentioned, I should be able to have anywhere from 10 to 11.5:1.

BTW, I'm using the newer, small cc heads. You may need to shave your's a bit or use a thinner head gasket.

I ran this by Dan LaGrou. He said he hasn't tried this combo, but thought it would work.


Kevin: Fantastic lead! I'll run this by my machinist...

Are any mods needed for the 6" Chevy rod? I'm sure those are pretty common.

When was the change to the smaller combustion chambers made? I'm mostly familiar with the 3.5 and '89-'90 3.9 engines... and far more familiar with Austin "A" and "B" series engines.


Carl: I am currently running a '63 215, but I have 2 '89 3.9L blocks (& pieces parts).

A stock small block Chevy rod is a 5.7" The 6.0" is an aftermarket rod commonly used in performance circles. Some brands and types (aluminum or forged) are quite pricey. We aren't building an all out racing engine (at least, I'm not or I would find a forged piston, too). Therefore, we can use the budget rods, like Eagle & Scat. I'm leaning toward the Scat because the small journal is only available in the more expensive H-beam. Which, I failed to mention. Older small block Chevys (283, 327) used a small journal crank (2.0"), others used a large journal (later 327, 350, 400). We need the small journal as it matches the Buick/Rover. The Chevy rod is .100" thicker than the Buick/Rover so .050" must be machined off each side of the big end.

The heads on the new 4.0 & 4.6 are factory built to compensate for the thicker composite head gasket. I played around with the calculators and to get the compression number you want, you will have to use the thin steel head gasket or skim the head a bit. Or use KB143 & be right at 11:1. Be sure to check valve to piston & rod to block clearances.

Another important number for your machinist: Deck Height is 8.960" on a stock, never decked block (per Dan La Grou).

Good luck!

Carl














-



Edited 2 time(s). Last edit at 06/07/2016 01:02PM by MGBV8.


harv8
Martyn Harvey
Waterloo, Ontario, Canada
(179 posts)

Registered:
10/23/2007 10:09PM

Main British Car:
MGB Rover V8, TVR Chevy V8, MGB GT Ford V8

authors avatar
Re: Rover 3.9 Pistons
Posted by: harv8
Date: February 11, 2008 10:26AM

Thanks Carl. My engine is still laying on the floor at the engine shop. No decisions made about building it up yet.

Cheers,
Martyn


Sorry, only registered users may post in this forum.