From rovernet-owner@ganglion.anes.med.umich.edu Tue Nov 14 08:41:40 1995 From: Kurt Horton email Subject: [Rovernet] Rover 3.5 cousin engines
I had two people ask me for info on 3.5L rover engines and their Buick siblings. I will try to give a quick rundown on the buick family. Accuracy is not my strong suit so if anyone sees flaws or additions let me know. The Buick "Fireball" 215cid was born to bridge the early 60s oil crunch gap. The US market had large cars with large engines that guzzled lots of gas. Buicks solution was to design a smooth V8 powerplant that could be dropped into some of its then "smaller" car styles like the Skylark as an economy option.
Well gas soon became plentifull and while the engine was high tech for its day it was underpowered for pushing heavy american steel, Plus the muscle car days were dawning and the new way was heavier cars, heavier engines more gas and more ponies. The engine died on the vine.
The english were at this time past there Hay days of 4 cylinder engines but didn't have any new powerplants that compared to the US V8's. Nor did they have the size vehicles needing such large engines on the hole. Engine development seemed to have died in the UK for anything beyond the straight 6. (Triumph tried with the V8 Stag engine but it failed quickly due to mechanical problems.) BL was selling some of its old engine designs to the Japanese but had only a few new and heavy 6 cylinder engines to put into new vehicles. At this time Rover motor company was looking for a new powerplant for its sedans and managed to buy the rights the the GM 215 cid.
The newly aquired engine was redesigned from an investment casting to a sand cast aluminum block making it slightly heavier but it is said to be 'less prone to bridge cracking and better at vibration damping'. The basic engine dimensions however remained the same: Bore, stroke, bearing sizes, distance between bores, etc. US 215 manifolds still fit 3.5L blocks as do all the 215 aftermarket upgrades such as Eidalbrock (sp?) manifolds, Malory ignitions Crane roller rockers, Keane Bell oil pump kits etc. As I believe do US bearings and internal components such as connecting rods, pistons, gaskets, etc.
The 215 itself became popular in the off road race world as well as some boats and experimental aircraft because it was light, dependable and could be built to a good extent. Mickey Thompson Used the 215 block along with his own forged crank and aluminum pistons to make an off road race engine. The crank was 3.5" stroke, quite a bit larger than the 2.8" stock one still used to power the 3.5 liter Rovers. The bore was kept at 3.5" stock diameter but the Buick rods were box welded to increase strength. I think that this brought the engine up to about a 250 cid. that had a higher lift higher rev cam. and Mallory Dual point ignition.
Meanwhile Buick having given up on the 215 had recast the block as a cast iron version having the same general dimensions, the Buick 300. (Slightly taller and larger bore but same bore to bore and bearring placement) This engine was equipped with a 3.4" stroke crank that had larger bearrings and a different rear seal assy. This makes the crank a half inch or inch longer out the back side and the flywheel bolt pattern different. Many articles have been written on installing this crank into the 215 case to get the 215's light package with the increased stroke and displacement of the 300's crank. It does require engine rear seal remachine, crank grinding and some funny buisness to get a transmission housing to bolt up properly. I think most people bolt up an automatic transmission easiest. The 300's timming chain cover should match the 215 as will its crank pulley/harmonic balancer and cast iron cylinder heads which do have larger valves and ports. Since the 300-310-340 is a taller engine family the manifolds do not exchange to the 215cid-3.5L family.
Now GM realizing it was giving up performance on its vehicles because its engines were so heavy decided to redsign the 300's heads (which were redesigns from the 215's heads for larger bore and valves) back into aluminum. This was done and aluminum heads were born onto a cast iron block. This was a bad idea. After numerous problems with blown head gaskets etc. I think they gave up on it but these heads will fit the 215, 3.5 etc. engines. They do have one extra head bolt per cylinder. (Another long story but: if you find the mystical detuned Oldsmobile engine block it should have the extra outboard cylinder head bolt boss alowing you to use all the bolts including the extra. Those of us without just go without.)
Are you confused yet?
The story is not over yet. Volvo gets involved. Yes many years ago people found out that Volvo valves could be fit to (what was it?) 310 Aluminum heads to increase the valve size even more. Just in case you want more flow.
Chevy got into the story because people were looking for stronger rods to go with there incresed displacement when they put 300-310-340 cranks into there little 215 blocks. They found that instead of box welding the rods like M.T. did chevy Carrera(sp?) or stock small block rods would work with some modifications. They are lighter stronger especially the famed Carrera rods and almost the same length, and hell they were throwing in all kinds of pistons from who knows where because they were opening up bore diameters to 3.8" and using big valve aluminum heads for drag racing.
Buick, Buick, Buick, Yes GM still keeps them around. And guess what they have done. Well while making smaller more fuel efficient cars they decided that they needed a new powerplant. "How can we do this?" they must have asked. First it has got to be light so lets make it out of aluminum. Second it has to be small so lets go use that old 215, 300, 310, 340 bore to bore dimensions. Maybe not quite small enough for transvese mounted useage plus people think gas hog if it says V8 so lets chop off two cylinders (reduce part count) V6, and leave the bore a little larger than the 215 so it weighs in at (I am really pulling here for a good number) 3.0L-3.9L-4.0L V6 and more upgrades comming.
In reality Buick had developed a cast Iron V6 using the same 215 base dimesions prior to making it out of aluminum. It powered late 60's early 70's GM cars. The new ones are fuel injected with crank triggers and use all the modern accessories. Also the front covers of these engines mate up with the old 215 blocks or 3.5 Rover blocks.
So if you want you can take a 3.5L block bore it out to 3.8, Stroke it from 2.8" to 3.5 using a Mickey Thompson crank, put Big Aluminum heads on it and Volvo valves to make it even bigger valves, a 4.0L front case w/ crank trigger or similar 3.0 w/ HEI ignition and still be able to hang a serpentine belt w/ all the modern accessories on the outside of it all.
Meanwhile over across the pond in the UK. People have been playing with the engine with and without the help of BL/Rover. The Brits like classify there engine building into stages and many aftermarket parts have been made to increase engine performance. Pistons, cams, valve swaps etc. The most interesting one that I know of is the use of a Factory made Crank. Rover appearantly made the engine into a diesel for a vehicle known as the Tundra [LA: Iceberg engine.] something or another. The resulting crank was larger in stroke and therefore very desireable to engine builders. This seems to be the basis for many of the extreme English 'tuned' engines of 4.5 to 5.0L or there about.
The Engish have worked more on packaging than here in the states producing such things as new manifolds and headers for different applications. If you want to put a V8 in your MGB they can sell you the bits. Yes I know BL did it, but they didn't put 5 speed gear boxes or four barrel carbs on them. You can. (if you want.)
The point is (if I have one) that many engines have developed from the 215 basic layout. I don't really remember which came first the Al.V8 or Fe.V6 but the designers have been very engilish about re-using bits in developing new engines and this has been the basis for some very good interchangeability and therefore engine building.
Hardcastle has some books out on history of the V8 going into the English side of the story and Hot Rod magazine had some articles about the featherweight 215V8's a few years past and I am sure there is some mention of The Mickey Thompson 250's in off road racing magazines.
Let your Imagination be your guide. Good Hunting!