Engine and Transmission Tech

As the the title alludes to, I read over the past week that the Rover blocks up to the modern day versions, are all based off of and have the same engine mount location dimensions as the old GM 215 cid family of engines. I mention this as I'm finding it very difficult to locate a 215 cid motor in any condition anywhere. If differences exist, other than the obvious that one is a 3.5 and one is a 4.6 therefore the 4.6 is bigger as other forums have stated, I'd love to to find out what the differences are from the guys / gals in the know. I'm attempting to sort out which engine I would want in the B-GT. I'd like to keep it British. Thanks all for any insight you'd like to bestow.

Ken, Welcome to our forum.4.6L is set-up for crank trigger ignition. May be retrofitted back to distributor,requires early cam, chain set,timing cover,drive gear and correct pullies.Block has same deck height and length. Crank has longer snout(drives oil pump directly). Considerable stonger, with all (5) mains cross bolted, crank rods all up-gaded.No rope seals.3.7" bore standard. Good Luck, roverman.

Using the Google search box in the graphic header at the top corner of this page, you can easily find a mountain of information on this topic... but I'll get you started.

GM made about three quarters of a million 215's. If you want a genuine GM 215, IMHO they're NOT hard to find - you just need to know where to look. You're far more likely to find them in a rusty Buick Special in some senior citizen's backyard than you are to find them in your local junkyard. (Why are people so shy about knocking on doors these days?) You're also more likely to find a 215 in a "Thrifty Nickel" classified ad than on Craig's List. (Thrifty Nickel is chain of regional newsprint classified ad listings you can pick up for free as you enter local diners or convenience stores...) When Buick 215's show up on eBay, the price is usually too high. As recently as October 18 2010, a complete Buick 215 was listed for sale in the classified section of this very website - for only $185! - here's a link to the ad: [forum.britishv8.org] (It's probably still available.)

So... they're out there and after all these years they're still bargain priced.

Front cover and water pumps are basically similarly sized and even interchangeable between 215, 3.5, and 3.9 versions of the engine. The 4.0, 4.2, and 4.6 are quite different up front. Different oil pump and filter provisions. Totally different water pump. Serpentine belt. The later engines have no distributor because a crank driven ignition was used instead. Summary: any Buick or Rover aluminum V8 will fit in an MGB, but they each require different work on the installers part.

The original Buick/Olds 4-barrel manifolds work pretty well, yet position the carburetor lower than aftermarket manifolds. Rover never sold their engines with four barrel manifolds.

Displacement is a factor of cylinder bore and crankshaft stroke. The 215 (i.e. 3.5L) engines have a bore of 3.5 inches and a stroke of 2.8 inches (i.e. 88.9 x 71.1mm.) If you're willing to collect esoteric parts and do a lot of machine work, it's feasible to rebuild these engines to pretty much any displacement up to about 310cid (i.e. >5.0L) - the biggest Buick "215" I've seen was in Ken Biermann's: 3.800" bore by 3.400" stroke => 308.45.

Rover 3.9 (241cid) engines look like 3.5's except for cylinder bore (3.70 in / 94.0 mm)... and that they mostly came with fuel injection. The 4.2 is a stroker version of the 3.9 (3.03in / 77.0mm). These engines are much harder to find, and harder to find pistons/rings for, and generally they're not very popular... A short stoke is one of the great charms of these little V8's. 4.0 and 4.6 engines have beefed-up engine block castings, four bolt mains, etc. Arguably, the later blocks are stouter, but in fact they have a worse reputation for service issues. (Not reliability issues per se... but some proportion of engines suffered loose cylinder liners and/or cracks in the aluminum block castings behind the iron sleeves. By now, the bad engines should mostly be out of service - but you still need to be cautious not to get a bad apple. Even if you do get a bad apple, it might work out to be a good deal because the later heads have the largest valves and ports and the smallest combustion chambers.) The 4.6L engine was another stroker... this time the stroke was 3.2in / 82mm.

To take it one step further, the BOPR (Buick, Olds, Pontiac, Rover) engine (215, 3.5 etc.) spawned a progeny that includes the Buick 300, 340, 350 and the Buick V6 lines, 198, 231, 252, 3.8L and 3800. The 300 has been used in a number of MGB's and is only externally distinguishable by it's iron block and later BOP corporate bellhousing pattern. It has about a 5/8" taller deck. Painted or powdercoated silver it takes an experienced eye to tell them apart. Heads and valvecovers are interchangeable.

JB

Buyer beware, 1964 Buick 300 engine had a genuine problem with electrolysis,(corrosion). The combination of iron next to aluminum, less than optimal formulation of antifreeze and lack of proper changing by owners all contributed to corroded aluminum heads. This is most visible at coolant transfer ports,(dog bones), at the ends facing the deck.Worse problem is what you "can't see" ! Many of these heads are so eat-up,when porting the bowl areas,they become too thin to be reliable. roverman.



Edited 1 time(s). Last edit at 10/30/2010 01:29PM by roverman.

This site has some side-by-side photos of the Olds, Buick, and Rover motors:

[www.roversd1.nl]

Thanks Joe. Pretty knowledgeable site. Not knowing the casting thickness of the "4.4" head, in the seat/bowl and guide area, I wondered about feasability if making it "splayed valve" ? Obviously since it uses stud mounted rockers @ 5/16 dia, idea of off-set, with larger dia stud, without welding. Cheers, roverman.

Wow you guys are great. Thanks so much for getting me started on the right track.