MG Sports Cars

Another stand would be handy, especially if we decide to do any work on the 430 BBB. The load should be identical otherwise to the one we delivered to him. You might get all that stuff in your white trailer, but I could see a possibility of some of it ending up in the trunk.

Jim

Jim,
What trunk. My BGT has no trunk. I think it will all fit in the white trailer and that would mean protection from the weather.
I'll disassemble on of my engine stands and see if it will fit in the back of the GT.

Steve

I just won an auction for a set of Corvette rear wheels (plus one front which I won't use). They are 17 x 10" and the price was right. They should work just fine for the rear. This pretty well means I've decided to go to the GM bolt pattern, and Jag or Corvette parts may be used in doing it. What I'll do is, buy or make a set of billet spacers/adapters of the correct thickness to let me use these wheels with the stock axle (they have a lot of backspacing) and then make the IRS the correct width to fit them.

For the time being though I will lend these wheels to the Roadmaster project and use them to set up the Jag IRS on that car. Once that is done I will then use them for my roadster.

Jim

Hey Jim, I saw this in the current issue of KitCar... thought it might give some ideas... rear cover for a Dana 44 diff... shown here on the company's aluminum dana 44 housing...





Edited 1 time(s). Last edit at 04/01/2008 01:02AM by rficalora.

Jim, I thought you might get a kick and others out of this youtube vid.... I know it's not british but using an R200 diff in this supercharged ls1( correction LT1) 240z...kind of shows that an R200 can handle the power.

[www.youtube.com]



Edited 1 time(s). Last edit at 04/07/2008 10:40AM by 74ls1tr6.

Jim, Here is a 9 sec. 454 supercharged Z running a R200 diff.

Thanks guys, that's good info. I did a little research on the r200 diff and it's true that some of them are holding up to very high power levels. What I was seeing at that time was their use in a awd configuration and with some incidence of axle breakage and differential concerns. These problems were being addressed with high strength alloy aftermarket parts iirc, which is something I'd rather avoid if I can, but it's still a good idea to follow what's being done there. That last photo is pretty impressive. The alloy D44 housing and hanger are sweet. I'll try to do a little research on that, it'd be nice to know how dearly they like that one. Probably out of my budget, but you never know.

Jim

Don't know what your budget is Jim, but I'd say they like it pretty dearly... [www.newmancarcreations.com] I was thinking it might spur some ideas more than a purchase order :)

I saw Larry Shimp's post on the Jag IRS thread and fired off an email to the recommended parts supplier. I'm considering going that route. Also I just ordered rear tires to fit the Corvette rear rims. Some will no doubt think them a bit excessive but I couldn't resist. Sumitomo HTR-Z's for $99 each in 315/35-17. It'll be a tight fit but I think I can make them work.

Jim

"Sumitomo HTR-Z's for $99 each in 315/35-17"

That's amazing!

Here is a Australian idea for a Jag lower control arm, I would use a brace on both sides. I like the single shock mount also.You would have to use a stiffer coil over spring ,say 350 lb instead of 200.

Jim I almost forgot, I remember your thread on brakes for your roadster. You can get brake drum hubs from early Mustang,Fairlane,Cougar and remove drums and have a nice 5 lug hub, You need a swedge cutter. Then find a slip on rotor.Also you can buy 265-50-15 tires at Summit (Cooper Cobra Gt).The link Larry mentioned on the Jag rear on part 3 tells how to go to Ford pattern.

What I thought was amazing was that they called to make sure those were the tires I wanted to order for an MGB. So I sent them a hyperlink.

Jim, that looks like a pretty good idea. Better than gussets since the coil-over is supported in double shear. I still think something along the line of a radius rod is a good idea though, at least for acceleration. The more I think about the rear strut that Arthur suggested the more I like it, and if the LCA has enough torque resistance to resist twist from axle torque then there's no reason why a 5/16" cable wouldn't be stout enough to handle the tension load on that link. Not saying that would be the best solution, just an indication of the minimum requirement. Thanks for the tip about the tires, only thing is that I was looking for 14 inch. It'd still be good if I could find them.

Converting to the Chevy bolt pattern is going to be a little complicated but not too bad I guess. If I use jag parts on the rear that part will be taken care of and I should be able to use Camaro rotors on the front similar to the Arntz/Butler Cobra. But then I'll also have to find a GM space saver spare and I hate to give up my powder coated aluminum spoked Lincoln one. It's a sweet piece. But, maybe I'll get lucky and run across something suitable.

Jim

Got the roadster out for a drive today and definitely enjoyed the weather and the somewhat softer suspension. I'm not sure the rear leafs have loosened up yet though as the car sits a bit high in the rear but that's better than sitting low. I took a page from Bill G's book and added two half-leafs to the front of each spring pack to control the wrap-up, but I also banded the pack tightly in the front and I believe that's causing it to ride high and stiffer than it would otherwise do. I'll give it a week or two and then consider removing the front clamp. There is no hint of wheel hop, though I did lose some of the even traction I had before and the right wheel is now laying about 3 times the rubber that the left one does. This may also be from the clamps, I really have no way to tell except to remove them and try it again.

Since I won't even be able to start on the IRS for a couple months and my new rear tires are on loan to the Roadmaster project until after the summer meet, I plan to use some of that time to either buy or make (most likely) a set of adapter/spacers to center them in the wheelwells and convert from the ford to chevy lug pattern. That way I can run them on the stock axle while I'm developing the bolt-in IRS package. The extra 2" of fresh rubber may shorten the life of the axle but it's a chance I'll take, there's still one more spare axle in the shed.

Talked to Dale a few days ago and he's going to try to send my 300 heads back with Steve when he picks up the 455 for the Roadmaster. That should get me going on the 340 build, which I can do while waiting on the Jag IRS. Considering the push to get the Roadmaster ready for the meet I may not get much done anyway. But the two cars should end up with very similar rear suspensions.

It doesn't look like I'll be able to bring my roadster to the meet this summer, not unless I can convince Edith to drive the truck and pull a trailer with the Roadmaster on it with me in a different car. That's going to be a real tall order. She doesn't mind driving the truck at all, but towing a trailer by herself isn't something she's going to take to very well. So I'm having just a little trouble resigning myself to not having my car there. At least I'll have the Roadmaster there, but of course it will not be driveable. That was one of the choices I didn't recognize I'd have to make when we started that project. I don't mind doing what has to be done, and it will be a good chance to ride in some fine cars so it's still a good thing, just don't expect to see a certain winged beast.

Jim

Jim, how about a trailer that'd hold both the roadmaster & your car? That way you get the best of both worlds.

Sure Rob, that would work. Unfortunately I do not have such a trailer.

Jim

While Steve DeGroat was up here for Roadmaster Weekend we found time to refine the design of the Jag IRS, which will also be going into my roadster.

In this first photo you can see if you look closely what we'd have if the stock Jag 6 degree pinion angle was used in the install. The interesting thing about this photo is that with the 6* that is machined into the top mounting pad we have an angle of inclination across the LCA of an equal amount, meaning that the LCA is parallel to the pinion rather than to the ground, as all documentation I have seen on this swap had led me to believe. This might translate into a slightly smoother ride over bumps but I doubt it improves the handling any. This angle is too steep for use in an MGB conversion as the air cleaner would be through the hood and the tailshaft resting on the tunnel cross member.



The second photo shows an angle of zero and as you can see the LCA brackets are parallel to the bottom of the car. Again this angle is excessive for a conversion, as the crank would be close to even with the bottom of the differential and no room for the flywheel.



The third photo shows an angle of 4* and I would consider this the practical limit. The universal default is 3 degrees with cars of this type sometimes using a bit less, so I will be aiming for an adjustment range from 1-4* or a 3 degree span. This should mean a slot in the adjustment plate about 3/8" longer than the bolt diameter, and should pose no difficulties. The 4* starting point will be achieved by canting the support beam 2* relative to the end brackets, and the resulting distance from differential pad to the rear shelf in relation to the tire sizes being used and the height setting will give the recommended 1-2* of downward angle of the axle shafts from the diff to the wheels. The pinion angle adjustment range will result in a variance of no more than 3/16" in the height of the differential, well within an acceptable tolerance.



We should be around 2* on the drivetrain angle and as you can see from the photos the LCA pivots are well below the plane of the battery boxes, meaning that there should be room enough for a forward triangulated LCA with a third pivot point attached to the floor and tunnel at a location that is forward of the battery boxes. The brace arm may need a slight bend to clear the boxes but not enough to seriously compromise it.

Jim

The recent work on the IRS has been posted to the Roadmaster thread since we are trying to meet a deadline, but as it stands now parts that are needed for this car as well have been duplicated as work on the other car has progressed. This includes the differential crossmember and a set of custom urethane bushings.





as well as pilot tubes for the LCA shortening operation. While this project benefits from the development of the Roadmaster, that car benefits from materials available for this car as well as time so I think it evens out well enough. The one thing that is different is that the IRS unit for this car is still located in Nashville and will remain there until we can arrange transportation or make a trip to pick it up, so the axle shortening operation will have to be done later.

As for the engine, presently the aluminum 300 heads are being fitted with new valves. I decided not to replace the exhaust valve seats for a couple of reasons. First, a stock type oversize valve was not available. It turned out that the larger valves in that family are a bit longer and I didn't really want to deal with pedestal shims and custom pushrods. Same for fitting valves from another application, as valve length and keepers would have to be jockeyed to get the right combination. So we went with the stock replacement valves. Even at that the valves themselves cost almost $14 each. Secondly, I have never had a problem with valve recession in a 215 engine. So with Dale Spooner on the phone, I took a new chainsaw file to one of the seats in a 215 head I had on the bench and it was definitely harder than annealed cast iron. Dale agreed, and I decided not to replace them.

Now it could be argued that the valves in the '64 300 head are too small for a 340 and I would be the last one to deny it. But according to porting work done in the past by Dale's expert associate (who now limits his work exclusively to hemi engines btw) flow increases in these heads come more from some simple port cleanup than from valve size increases. Since I gave Dale the green light to do some light porting, I'm guessing these heads *may* end up flowing close to what the cast iron heads do, and those heads were used on both the 300 and the 340 without any changes. Another possible potential benefit is that smaller port heads tend to generate more port velocity and can frequently give better fuel economy, and I like that idea. Finally, because this will be a blower engine, port and valve size is less critical. The experts tell us that a blower motor needs to have extensive porting, big valves, and as much flow as possible but these are people who are building things like top fuel dragster engines , and yes if you want the most efficient cylinder filling possible that's the way to go. But the purpose here is quite different. Even without the blower the engine should easily be capable of producing 300 hp and even higher torque figures so we are already past the need for more power. The car is going to be scary fast without another single thing being done to it. Also considering that the valve springs that will go on the heads are good for 7 grand, a 6 grand redline to save the pistons is already well above stock so it will be a motor that's happy to wind up. Limiting the boost to about 12 psi should let the head gaskets stay happy.

So where are we with that? 12 psi and 6 grand on a 347 cid motor with restrictive heads and a stock (or near stock) cam? (Well let's just hold that thought... isn't this the guy that considers a 268H grind to be "near stock"?) Anyway, I really have to go back to my experience with the 215 Olds as a blower motor to draw some comparisons. The Olds heads have the most restrictive intake ports of any SBB/R (Small Block Buick/Rover) derivitive that we are aware of, including the early odd fire V6's. But you take that engine with a stock cam and pump 16psi of boost down the intake and what happens? It behaves quite differently than the typical ported, hot cam big valve drag motor. Where the drag motor is just starting to flow big, this one is shutting down and the charge is stacking up in the intake. Normally we wouldn't consider this a good thing but there are two very significant advantages to it. First and most importantly it boost limits the engine just when it needs it the most, at high (for this engine) rpm and maximum output. By doing this it also limits the pressure the head gaskets are exposed to and extends their life. It is true that this stacking up of the intake charge will generate heat, challenging the intercooler to handle it, but because the application is a street driven car with an 8:1 weight to horsepower ratio it is simply not possible to stay at max boost for more than a few seconds at a time so unless we go racing with it (and that's *really* racing, not playing) it'll be fine.

The second advantage is much more important for a street driven car. Because the blower needs a high drive ratio to produce 16psi in the upper operating range of this engine (between 3 grand and 4800-5200 rpm, limited by the valve springs. Incidentally, CC's new "Beehive" springs may be just the thing for these Oldsmobile 215 heads) this means it is also turning quite fast at idle. Fast enough in fact to begin pressurizing the intake at just about any engine speed if given an unrestricted supply of air. In other words, if you idle off the line and then hammer it, by the time you can look at the boost gage it's in the positive numbers. It then climbs rapidly as speed builds, resulting in a very significant jump in the torque curve. Needless to say, this makes the car very easy to drive, as long as your steering and braking inputs are in order. All this is contrary to conventional wisdom, but again, it isn't a drag racer, though it *is* ridiculously quick. Incidentally, all of this is with stock type cast pistons. To date there have been some issues with head gaskets but reliability has been quite good for the configuration.

Bringing this information forward 4 years to the '67 340 with '64 300 heads, we find an interestingly similar situation. The heads are not big enough for the motor. What to do? Improve on a successful formula perhaps? How about this. In the interest of better fuel economy we increase the CR from 8.5:1 up to maybe as much as 10:1, and reduce the boost accordingly, down around 12 psi. Then just to make things interesting, how about a custom cam grind with a near stock intake lobe and a free breathing exhaust profile with more lift and duration, but reduced overlap? That's my current thinking, all subject to change of course. Anyway, once the heads get here work will resume on the engine. The transmission is currently on hold, waiting for me to compare parts to see if there is a way I can paddle shift a 200r4 automatic, and a little work has been done on templates for radiator shrouding. But the heavy emphasis is on the Roadmaster for the next 2 months. In the meantime that process should result in the IRS for this car being brought close to the swap date for that part of the car.

Jim

Jim, Art Carr does a paddle shift for the 200R4 trans. I just read about Superformance delivering a Cobra Daytona to Carrol Shelby with it.

Thanks Jim. I looked into that and you are correct, so I sent an inquiry to Art Carr. So far everything I've found on paddle shifters uses an external actuator to move the stock shifter arm. I'll need to know what Art does to the valve body if this is what he's doing, the standard Grand National shift body modified for drag racing isn't going to do the job. But we'll see. Maybe someone has adapted internal solenoids. That'd be worth paying extra for.

Jim