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Cutting the car to make a V8 swap work

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Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd., USA   USA
I never bought the "return to factory" argument either, never gonna happen.

BUT, the less sheetmetal mods required, the more likely the swap is to be done. It's a major reason why Rover and V6-60 swaps are so popular. Two things: people would rather avoid sheet metal work, and a desire to avoid damaging the paint. Both very realistic and reasonable concerns, especially as the supply of solid MGBs with bad engines and pretty good paint dwindles.

Sorry Scott, never meant to put words in your mouth. Just paraphrasing a discussion we had once. Thanks for the clarification. As the only owner of a LS4 conversion I expect you would know better than anyone else.

Now as far as optimizing placement of the engine is concerned, we've seen where moving the engine forward or back an inch or two makes a lot less difference than people want to think, and placement in the Factory V8 cars is already pretty optimal. Plus a more powerful engine is almost always accompanied by a stronger and therefore heavier rear axle. Meaning that your well intentioned setback can actually end up shifting the weight balance too far rearward, and I've seen that happen. Don't recall the car it was on, but the rear weights were heavier than the front. Stock weight distribution is 51/49 and that is ideal for a front-mid engine rwd sports car.

Piont being I guess that there is a lot more than engine placement at play in weight balance. Also, hitting the numbers on the nose is not the only concern in "optimal" engine placement. A lot of other factors come into play and are weighed more or less heavily by the owner as they see fit. Things like shifter placement, footwell intrusion, steering clearance, heater, and a whole list of things at the front of the car that changes with every different engine. And just because there is an aftermarket replacement heater available doesn't mean the owner wants to use that.

I think it is very valid to avoid cutting the firewall. At least as valid as avoiding cutting the hood. And several choices of engine and rear axle allow this to be done in a way that keeps the balance very close to stock.

Jim



Edited 1 time(s). Last edit at 2017-12-06 04:27 PM by Jim Blackwood.

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mster50 Silver Member Mike Sterling/A
Zanesville, Ohio, USA   USA
In reply to # 3632993 by NOHOME I actually did not cut the frame rails. The car was made such that the front end plugs into the main tub and is spotwelded in place. I just picked all of the spotwelds apart, extended the stubs and re-welded everything back together.



If you look at the pic above you will note a few things:

The car is being built on a reference surface that is flat and level with the patient securely attached.

There is a rectangular frame laying on top of the chassis jig. Look carefully and you will see where it is bolted into the lower a-arm pickup point. The frame is a jig for holding the front piece that I cut loose. As long as the sliding jig is square to the reference table when it goes back together, it should be square in 3 dimensions. There were more supports for the loose piece, but it seems that they are already removed in this pic.

Another thing to note is that with the front cantilevered out 7" I thought a bit more support would be a good idea. Note the 1 3/4" roll bar tube that goes from the firewall and the arched section that disappears into the sill structure.

The bit that goes into the sill structure is attached to this lot in order to stiffen the car through the rocker panels



The upper tube curves down and is picked up at the top of the shock mount



The curved tube from the sills is not the most visually charming structure, but it should do the job.



And then you have to fill in the area that was left open from moving the clip forward. Not the best picture...the wheeltubs used to touch the firewall

https://i.imgur.com/9foK7Fq.jpg




Bit of paint and no one needs to know it did not come from the factory this way



This all represents a ridiculous amount of time, effort and $$$. If someone were to tell me they wanted to go down this road, I would be like the audience at the slasher movie when the dumb blond is about to go down the stairs..."DONT GO DOWN THERE YOU STUPID B***H!!!!". Except that every so often the dumb blond actually kicks the monster's ass!

I am still having fun.

What about front wheel well openings in the fenders? Is the body going to stretched also? Is the wheel opening just going to be moved forward and the fender left stock length?

NOHOME P P
O, Ontario, Canada   CAN
1967 MG MGB GT "Maggie (GT From Hell)"
Mike:

In this case, I am putting a Miata chassis under a Volvo P1800. The Miata has a wheelbase of 89" and the volvo is 96. This means that the Volvo body stays the same and only the Miata chassis has to stretch 7" to match the Volvo.



Pete

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mster50 Silver Member Mike Sterling/A
Zanesville, Ohio, USA   USA
In reply to # 3641102 by NOHOME Mike:

In this case, I am putting a Miata chassis under a Volvo P1800. The Miata has a wheelbase of 89" and the volvo is 96. This means that the Volvo body stays the same and only the Miata chassis has to stretch 7" to match the Volvo.



Pete

I was starting to think some of those parts don't look MG, but I didn't catch it until you pointed it out.

BrsMgbv6 Avatar
BrsMgbv6 Bryan Heidtman
SW ohio, USA   USA
1976 MG MGB V6 Conversion "Uknown Cost"
To B or not to B, that is the question?

mster50 Silver Member Mike Sterling/A
Zanesville, Ohio, USA   USA
In reply to # 3641127 by BrsMgbv6 To B or not to B, that is the question?

Either way is OK.

V8MGBV8 Avatar
V8MGBV8 Carl Floyd
Kinggsport, TN, USA   USA
In reply to # 3640943 by MGB GT 4.3 I originally had the MGB rack but switched to a pinto rack. It has a slower ratio and is much easier to turn, you'll be glad you did. Its very similar to MG rack so easy to change over.

Are you aware that MGB has two different ratio racks? The late racks are slower than the CB racks.

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theonlyiceman53 Avatar
theonlyiceman53 Bill Russell
Florida, USA   USA
1974 MG MGB "Frankenstien"
1977 MG MGB "Wicked"
Hi Carl,. I sure didn't know that. Do you know what year they changed or did it coincide with the rubber bumper?
Thank You,
Bill

Richardtherodder Richard Mounce
British Columbia, Canada   CAN
This is the first time I have seen someone who prefers a slower ratio steering. Up until now, the query was all about, how can I get a quicker ratio steering box. Carl it sure looks like the factory was trying to change the MG, to make it less competitive in the sports car market.

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NOHOME P P
O, Ontario, Canada   CAN
1967 MG MGB GT "Maggie (GT From Hell)"
In reply to # 3641670 by Richardtherodder This is the first time I have seen someone who prefers a slower ratio steering. Up until now, the query was all about, how can I get a quicker ratio steering box. Carl it sure looks like the factory was trying to change the MG, to make it less competitive in the sports car market.

If MG had any intention of being competitive in the market, they would have had to come out with the 240Z in 1970 before Datsun did.

The reason for the slower rack was to make the car feel more stable with the raised center of gravity; sudden motions are not good when you are on stilts! It had the added bonus of making it easier to turn the wheel for what was already becoming an older buyer demographic.

Pete

Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd., USA   USA
And speaking of that older buyer demographic, I was out at the pick-n-pull today getting electric window parts and picked up the steering column out of a 2009 Corolla (I think?). A very worthy conversion to the MGB, it both adds power and isolates road noise.

Jim

NOHOME P P
O, Ontario, Canada   CAN
1967 MG MGB GT "Maggie (GT From Hell)"
In reply to # 3641756 by Jim Blackwood And speaking of that older buyer demographic, I was out at the pick-n-pull today getting electric window parts and picked up the steering column out of a 2009 Corolla (I think?). A very worthy conversion to the MGB, it both adds power and isolates road noise.

Jim

Is this for a power steering conversion? Have not heard of the corolla as a donor.

Richardtherodder Richard Mounce
British Columbia, Canada   CAN
How does it isolate road noise?

MGB GT 4.3 AARON F
Costa Mesa, Calif, USA   USA
I should of clarified I was referring to using the MGB rack with the corvette spindles that have shorter arms than the MG. So what happens is you end up with a car that has almost go cart quick steering but its so heavy that it takes too much effort to turn the wheels, especially slow parking. To turn right I only had to turn the steering wheel about 90 degrees. What the slower pinto rack or maybe the other MG rack does is give you a lower gear ratio so its easier to turn the wheel. All its really doing is returning the ratio to what the car had before I added the corvette suspension. I also considered adding an electric power steering assist under the dash which looks really nice. I would of kept the MG rack if I had done that.

Jim Blackwood Avatar
Jim Blackwood * BlownMGB-V8
Gunpowder Rd., USA   USA
Yes, that is confirmed it is a 2009 Toyota Corolla. I have notes that this unit is a bit smaller than the one from the Versa and this is correct. The ring gear housing measures about 4-1/4" diameter whereas the one in the MG-Roadmaster is at least 1/2" larger I think. (hard to get an accurate measurement in the car) The motor is about 1/8" smaller in diameter but about the same length. Not that it seems to make much difference. Maybe you could stretch the wheelbase just to make sure that either unit will fit. devil smiley

The control box sits up under the dashboard pad which has to be removed to get at it. That's the worst part of the removal. The OEM mounting bracket for it is easily removed by flexing the bracket to fatigue the spot welds. No need for an external heat sink.

Jim

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