Engine and Transmission Tech

I have just one question, and it is one you really should take seriously. Is all of this really worthwhile for an 80 lb weight advantage? Because that is the difference between a BOPR block and a 300 Buick iron block, and even less for the later Rover blocks which weigh more. A 300 block can easily be built as a 5.6 or a 5.7 liter engine using the 350 Buick crank. The block is stiffer/stronger and will handle 700 hp without reinforcements. The threads will not pull out. Torquing of fasteners is more positive. Reliability is improved. Fit and appearance is almost identical. If you really want it to look like an aluminum block you can have it ceramic coated.

To my mind it is the obvious choice for a big inch motor. Why build a Dixie cup when you can have something reliable?

OTOH if max hp and minimum weight is your game, it would seem that either the LS or turbo4 is the way to go. YMMV

Jim

Why not a 300? For starters, I like the characteristics of a shorter stroke (2.8" vs 3.36") and I like later-model Rover intake manifolds (for EFI). One day I'll build a new short-block and I might have it sleeved/bored for 3.75" (Chevy 305) or 3.78" (Ford 2.3 Turbo) pistons - so I've been very interested in this thread.

Plus thousands of crossbolted blocks going to waste! Curtis, you need one of the latest 3.9 that had the casting for crossbolts. There is enough meat in the stock sleeves to go .036 over for standard 305 pistons. I think if we put our heads together we will find a solution on the sleeves. Rover dropped the ball on that. The 300 Buick is great, I just wish they made more of them.



Edited 2 time(s). Last edit at 10/16/2013 12:26PM by mgb260.

Jim B., perhaps we can have a write-up of this 700 hp.,300" sbb, with NO reinforcements" ? Who built it ? Got dyno sheets and durability ? Is it possible this is derived from "Buick V8 forum, bench racing developement" ? Availability of these oem. pieces that will reliably sustain these impressive #'s ? Cheers, roverman.

Like Curtis, I prefer the short stroke engine in a MGB. Feels proper for the sports car character.

Over the past several years I have pondered how to best do better pistons for my 3.9 project. I have spent hours pouring thru piston catalogs, calculating different rod lengths to match the compression height, etc. Keith Black 305 Chevy pistons, small journal 6.0 Chevy rods machined .050 each side with bearings dressed to match. Bore the block, cross your fingers. What a pain. May be cheaper & faster to just order overpriced custom pistons and be done with it.

Or, skip the whole thing & jump on the LS bandwagon. I would do it with some sort of 4.8L mongrel since it is the shortest stroke LS.



Edited 1 time(s). Last edit at 10/16/2013 03:30PM by MGBV8.

Okay, it was a bit more than a few years ago. This was an exchange from the Buick Rover V8 email list over 8 years ago:


Keith: 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.


Keith: 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

I suppose you could destroke a 300 as well as any other engine. You'd need main bearing spacers to fit the 215/3.5 crank, but the bores are integral to the block so there are no liner issues. A 3.80" bore is usually pretty reasonable.

Art, you don't have to believe me. You spend time on the Buick forum. and you've read what those boys have done with the SBB. You also know that there isn't a whit of difference between a 300 block and a 350 that would affect how much power the block can handle, and that with boost and nitrous you can still exceed what the equipment will bear. So quit busting my chops on this OK? ;-)

Jim

Destroke a 300? Hmm.

The 4.0L Rover has larger mains than the 215/3.5/3.9. May be the same as the 300. Be fun to play around with the numbers.

Yep, same mains. Could be interesting!

[www.gomog.com]



Edited 1 time(s). Last edit at 10/16/2013 06:06PM by MGBV8.

I guess I wandered off a bit, but these subjects are conducive to that. What I have exactly, is a 1963 Olds Jetfire block. Sleeves are grooved o.d. and cast in place. I have had it 30 yrs. I am putting 3/32 sleeves in the block. Had them 20 yrs. Using 6" forged H beam small-journal sbc rods and TRW forged std. 305 Chevy pistons. Landrover heads with lower head bolt added. Would like to use all 6 head bolts, but heads would have to be modified. Front cover from Buick 3800 series II. Northstar dis ignition. Landrover 4.0 intake manifold and fuel injection system modified for dual throttlebodies. Twin KKK turbos with water-alcohol injection. And the roller cam that I bought, as soon as I can decide how it should be ground for this set-up. I will have to make the girdle myself, Art, on a Bridgeport, since that is what I have. Then, a hacked-up GM LS ecm to control the mess.
All of this goes into a 2700lb. Fiero.

As for the sleeves and the leaks, the only reason for a leak is if there is no head gasket that the firering will bear on the top of the sleeve. A lot of the large diesel engines have wet sleeves and no top seal at all except the head gasket. I am an automotive machinist, and sleeve engines everday, some with large pieces of the cylinder wall missing from catastrophic damage, and never have leaks. I have not done late model Rover blocks, but they are just engines. I will call Lee, at English-Swedish Spares near Atlanta, (good source for parts) and get my hands on one of those blocks. 4.0 ? What years?

The Rover 4.0 is regarded as the one with the most sleeve issues. It was built from 1995 to 2003.

Jim B., not wishing to bust anyones chops, but if you feel slighted, I apollogize. I felt to be asking pertinent questions of a presented build, that seems to be elusive. Back in 82', I put a 300" crank,(std mains), in a 215 Buick. I wanted the stronger crank,(crank pin overlap). This resulted in making billet 7075 T6 main caps, with studs. Re-sleeved block with 305" sbc forged pistons, big valve 64' sbb heads. A lot of work, with a reliable result,(likely around 300 hp) ? Cheers, roverman.

It's all good Art. You know I have not built that engine but the drag racers on BuickV8 have gotten up to as much as a thousand horsepower out of their SBB 350s (700 on Sean's turbo'd stock motor that wasn't even torn down for freshening up beforehand I believe) and it is the same block as the 300 except for the bore, the deck height, and the lifter spacing. But it's worth noting that Perry S. has now hit over 500 with his 3.9 Rover as well. My efforts are small potatoes by comparison. I'm perfectly happy with what I got out of the 215 which I guestimated at around 300 hp. That's my target for the 340 also, and since I don't know a dyno guy I'll just compare it to how the 215 ran and if it does that good or better I'll be happy. I think an honest 300 hp at the rear wheels is more than plenty for a street driven MGB.

Larry, you might need wheelie bars on that Fiero. ;-)

Jim

Underestimate & overdeliver, Jim? :)

I think 300 RWHP is plenty, as well. Until Calvin motors by on the long straightaway.

Actually, I am a very careful, conservative driver. The car has a 4 spd., but I am changing to automatic. If I were looking for big inches and big torque, and cast iron, I would build a 427 sbc with a turbo and nitrous. (YUK!) If I had my druthers, I druther have a Lamborghini. (but I don't) What I do have is a pile of oddball somewhat unique parts, some of which I have had for years, that I am go
ing to build a small, lightweight, powerful, reliable engine with. And besides, it will give me an incentive to set up my chassis dyno.



Edited 1 time(s). Last edit at 10/18/2013 06:08PM by quietone.

Carl! Surely you wouldn't accuse me of sand bagging would you?!!? ;-)

Jim

Let's see, you estimated your old Olds 215/blower combo at 300hp (pretty close, I believe). You wrote on your 340 thread that this combo will have 60% more cubic inches & a 25% increase in supercharger. Mike Moor's Buick 300 has been dynoed at 308 RWHP. You have 40 more C.I. & a blower. Yeah, you're sandbaggin' just a smidge. ;)

Larry don't forget to chamfer side of rod by counterweight for filet clearance, just debur other side.

Thanks, Jim.
I am looking for a piece of 7075 alum. plate to make a girdle for the bottom end, but 6061 is all I have found so far. Prices on ebay not too bad. Have a good day.

Check onlinemetals.com. Did you find out anything about the 4.0 sleeve issue?