MG Sports Cars

Hi folks
Its now time for my Rover V8 to go up for sale. I'm happy that it will run mid 9's on the 1/4 mile but I'm now looking for 8 seconds so a new SBC engine is going in. I'm hoping that someone on here will have some drawings or a link to somewhere that I can buy an engine mount kit? I'm just taking the lazy option at this time to be honest :) If anyone can help it would be appreciated, If not I will drop the SBC in and see what I need to fabricate as required. This is a SBC into a factory MGBV8.

Regards to all.
Perry

Perry, Best setup for SBC is the old style Hurst mount. I think it is still available from Speedway Motors. Or you could make your own.


Here is one in John Fenner's 350 SBC MGB:




Edited 1 time(s). Last edit at 07/17/2015 10:58PM by mgb260.

I'd be very hesitant mounting an engine with any real torque to the flimsy stock frame rails. Most, if not all, conversion kits mount the engine to the modified or replacement front crossmember that has been significantly strengthened.

Jim, Good idea, I'd weld a tube through the frame rail and use a large washer or plate on both sides if not going through the crossmember. John's engine is set way back and is mounted through the crossmember.

< Most, if not all, conversion kits mount the engine to the modified or replacement front crossmember that has been significantly strengthened.>

May be correct for kits, but not for conversions in general. For instance, the MG-Roadmaster Buick 455 conversion mounts the engine to the frame rails via head plates. So does a certain blown Buick 340 I could name, and a stroker 350 cid Buick 300. There are others, and many block side mounts have gone to a weldment on the frame rails. Properly done the rails are quite adequate in strength (the engine torque of a crossmember mount is still transmitted through the same frame rails), and this is a quite viable method, in addition to which it gives engine torque control that is far superior to any other mount. The decision hinges more on packaging and aesthetic factors plus the builder's fabrication abilities than anything else. For instance, when considering a forward frame mount such as a saddle mount or a head mount, consider the routing of your wiring and fluid lines.

Jim

"the engine torque of a crossmember mount is still transmitted through the same frame rails"

True, but it's distributed through a larger area than two small mounts attached to the thin frame rails which also must support the weight of the engine unlike crossmember supported engines. Just because it can be frame mounted doesn't mean it is the best way or even the right way. I've seen some pretty cheesy hack job conversions of all types over the years.

The vast majority of V8/V6 conversions I've seen used motor mounts that attach to the frame rails, either by a welded-on bracket or bolted to the crossmember bolts. I've only seen a few that use crossmember mounts.

Frame rail mounting may or may not be the best way, but experience has shown that it is a fully adequate way.

With the kind of torque Perry will be putting down, though, all bets are off.

" I've only seen a few that use crossmember mounts."

All of Mantell's and FAST kits are crossmember mounted as well as the CCE V-8 conversion kits. Many on the HIWD use one of the three, including yours.

Quote:

All of Mantell's and FAST kits are crossmember mounted as well as the CCE V-8 conversion kits. Many on the HIWD use one of the three, including yours.

Not so. Crossmember mounting is an option on the Fast Cars crossmember and only for the Ford, and mine does NOT use that option. I haven't seen CCE's V8 kit so I don't know what they use.

I don't know of any V6 kit that uses the crossmember mounting. Certainly not CCE's kit.

Why didn't you go with that option? I have CCE's front suspension and motor mount kit for a Ford 302 and it's crossmember mounted. I specifically stated their V-8 kit, not the V-6. Regardless, since I had to cut and weld the frame for my radiator and remote oil adapter, I know how flimsy they are made with very thin material and no way would I want to have it support the weight AND torque of a decent engine without significant reinforcement. Like I stated above, lots of hack jobs running around out there. Having been doing this stuff for 40+ years, I tend to over-engineer and over-build everything I do.

Quote:

Frame rail mounting may or may not be the best way, but experience has shown that it is a fully adequate way.

My car is hardly a "hack job." The guys that build my car, Ted Lathrop and Terry Seneker, both have 40+ years experience building race cars professionally - and successfully - so, combined with my comment above, I trust their judgement.

Let's take a poll: all you v8 converters that have had your frame rails warp from excessive torque please sign up here.

Over-engineering and over-building are the hallmarks of an amateur. A professional builds it just right.

Wow Dan, who pissed in your oatmeal? I never implied your car was a hack job.
Regarding your poll, frame deflection would only be noticeable when the torque is applied but will return to its original position at rest so unless your car is run on a dyno with you watching for it, it won't be noticed.
Your last statement shows that you're a "checkbook builder" instead of someone that actually does the work. Professional builders do overbuild. It's called a safety factor and is required by all racing sanctions. Ask the people who actually built your car. I do ALL my own work with the exception of machine work on engine blocks and chrome plating. I've built National show winning cars that have sold for well into 6 figures. I'm retired now and decided to put a V-8 in a MGB to keep from being bored. I haven't even finished it yet and have had 2 offers to buy it when it's finished.
I certainly didn't mean to step on anyone's toes on this subject but I stand on what I said - without significant reinforcement, I wouldn't use the frame as an engine mounting point and just because it's been done in the past, doesn't always mean it was done correctly. I'm done, build them, or pay to have them built, any way you desire.

P.S. Dan, I looked at the build of your car and there is a picture that clearly shows your engine mounts ARE on the crossmember, not the frame. I guess since you didn't built it, you wouldn't know.



Edited 1 time(s). Last edit at 07/20/2015 11:17AM by JWD.

Over building is great for bridges and daily drivers but for a racecar (what the original poster is talking about) is not going to win you any races. Might be worth doing some simple stiffness testing and moving forward from there (make a jig and mount it to the cross member mounts and hang a long lever off that with a weight and get some torsional stiffness numbers to work from).

Anyways, with a roll cage, I would tie your engine mount into that somehow and then you could pretty much mount it however you need to.

Sorry Jim D., when you put it in the same paragraph, it is easily taken that way.

That thin metal is a boxed section. makes it much stronger than just the metal gauge it is made from. The crossmember bolted to the frame rails adds to that strength. As Jim Blackwood stated, we have a Buick 455 (read gobs of torque) bolted to & supported by those thin metal frame rails. There has been no evidence that the MGB frame rails are not up to the task.

As for Dan's builder, Ted Lathrop, they have been best of friends for many years. Dan has watched Ted build many cars in his shop. Ted would not build Dan a car that was structurally unsound. Ted designed & built this much improved TR6 frame as well as the one under his own car.

[www.fastcarsinc.com]

We weren't talking about show winning cars.......but here are a few from Ted's shop.

[www.fastcarsinc.com]

More pics of the above cars.

[www.britishv8.org]

[www.britishv8.org]

[www.britishv8.org]

[www.britishv8.org]

[www.britishv8.org]

Quote:

P.S. Dan, I looked at the build of your car and there is a picture that clearly shows your engine mounts ARE on the crossmember, not the frame. I guess since you didn't built it, you wouldn't know.

You are wrong. Dead wrong.

Gonna have to side with Dan on this one...

Yes, I saw Dan's car when it was being built also. Definitely frame mounted.
Now, if I may I'd like to present a little history, since I've been there for nearly all of the evolution of this craft with a couple of notable exceptions in the early days. My original conversion used crossmember mounts. At this time I'm not aware of any other conversion that had been done that way. Not the factory cars, not Ken Costello, and I don't think Jim Stabe used them either though I'm not entirely sure about that. However, I believe all of the factory cars, including all MGB/MGC/V8 variants, works cars and specials used frame mounts and while I'll not claim the works engineers were the best that ever were, certainly they were quite competent. My car bucked the trend. Now there are some advantages to a crossmember mount, which I described, and some disadvantages as well which have ultimately led me back to frame mounts. Chief among those is the wider stance of the frame rail mount which controls engine torque, and in this regard there is simply no comparison between the two.

But let's address the stated weakness of the frame mount. The supposedly tissue paper-like construction of the rails, being inadequate to control the twisting moment of the engine. I think we can agree to a practical limit of oh, let's say 600 ft/lbs of torque out of the engine and that is enough to satisfy any but the very most extreme conversion. Max radiator width without cutting is 17" so the attachment points will be very close to 19" apart. Close enough for an estimate. So the torque across those two points will be 380 lbs, lifting on one side and pushing down on the other, or 190 lbs per side. Add in 400 lbs of engine weight and you have about 400 lbs on one side and 10 lbs on the other. So the passenger's side frame rail needs to be capable of supporting a 400 lb weight.

How is this frame rail built? To start with it is not a simple box section It is a deep channel with an additional channel inset in the top, plus it has an additional horizontal wall in the forward section, just about where a head plate type mount would be located. So to fabricate a mounting pad something must be done about the top channel. My recommendation is an additional top plate of 16 gage steel welded across the channel legs, bent down into the channel at the back end, drilled to fit under the nut of the front crossmember attachment bolt and welded at the front to the vertical lip, followed up with a large fender washer under the mount itself spanning the width. But first a vertical tube should be inserted and welded to the top and bottom frame rail surfaces and the extra top plate. This results in a strong and light weight spreading structure which will easily take any force you might like to apply through the engine mount pads. Now the only potentially weak area is the section of frame rail between the crossmember attachment bolts, but you cannot disregard the strength added by the inner fender which is solidly welded to the frame rail and triangulated back to the firewall and the pyramid box structure of the upper inner fender, greatly multiplying it's load carrying capability. The outer fender in turn supports this tall extension of the frame rail outer wall against lateral deflection, rendering the entire structure remarkably stiff.

This method of reinforcement is probably overkill for any engine mount, and massive overkill for the average conversion. But it adds minimal weight and is easy to do so it is very practical. To just drill through and bolt to the frame rail, yes I would agree that method would be inadequate. The disadvantages of this method are: Routing of wiring and fluid lines, and fabrication. But on the plus side, access is as easy as it gets. How can you not like being able to simply reach down and zip out two bolts with the impact wrench to remove the engine? Height adjustments as well are a matter of just adding shim washers.

So anyway, there I had been, describing the crossmember/block mount for the 215 and eventually Fast Cars offered a crossmember mount for the 302 on their custom front end. After that I designed the head plate/frame mount for the Roadmaster and shared the source for the mount cushions with Pete Mantell, after which we began to see the 302 crossmember mounts for the Mantell Motorsports kit.

Both are viable solutions and by now well proven. That does not make them the only solution, or even the best solution, it just means they work well. Personally, I like the head plate mounts the best but I'll use whatever seems most appropriate for the particular application. For instance, we used Land Rover cushions and a crossmember mount for Dan B's TR7/1UZ conversion, and a head plate/frame rail mount for the chump car. Both made sense.

Jim

Actually I did use mounts attached to the crossmember with the stock Buick rubber mounts. You can see them in the top center picture in the attachment. I made two sets since I had to lower the engine in the chassis when I put on the Jetfire turbo. I don't see any issue mounting the engine the way Jim B described either.

Regarding the Speedway motor mounts for a Chevy small-block - it's interesting to me that they are using the motor mount points that were first designed into the Chevy small-block. I've owned 55 and 56 Chevies and they use those front mount points together with a bellhousing that had mount points. The bellhousing mount points were wider apart than the front engine mounts and it was easy to see that engine torque was transmitted through the bellhousing into the frame at a point where the firewall reinforces the frame. In short, the engine torque is resisted by the firewall.

Another advantage of that design, also used by Ford and Studebaker in the 50's, was that it leaves the sides of the engine unobstructed and exhaust manifolds and steering mechanisms have more room. And a further advantage is that there is less block distortion caused by engine torque on side-mounts.

The disadvantage is, of course, trying to work your exhaust system past the bellhousing. Another disadvantage is that the bellhousing and engine become a part of the frame. I'm pretty sure that a truck engine I have in my shop was damaged because the truck, a farm truck, was driven into a field and when the frame was twisted because of driving over uneven ground, the engine bore some of that torque and two of the bellhousing bolt holes on the block were broken off.

If one of our cars goes off-road, we have bigger problems than broken engine blocks, so I think the bellhousing/engine mount design has potential merit.

Your thoughts?

Paul

Here's a picture of an engine mount I made to put a Ford 302 into a TR6. As you can see, they are over-engineered and over-built, but then I am indeed an amateur, if not a - ptui - checkbook builder.