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MG MGB Technical - Lack of Sympathy

Ok, I have a unique problem. And I wonder if I can get some insights.

I have done a V6 Conversion (Buick 231 V6, Edelbrock intake, Edelbrock 600CFM Carb, Cam, Balance, Blueprinted, Borg-Warner T5, Monza Rear End) and I have a hint of a prob keeping the car from sliding sideways. The car has -so- much power, if I tweak the throttle going around a corner I just spin around.

Any suggestions?

Gord Bestwick

Sounds like an awesome conversion but apart from the obvious like traction bars or , dare I suggest , lifting the right foot a bit I cannot make any useful comments but perhaps someone on the V8 / conversions list can. Try there as well. Any chance of some photos? I too am thinking of a V6 and T5 package. Cheers, Pete, Sydney, Australia.
Peter Thomas

Gord; I guess most people would love to have your problem. I assume you have some
snow and ice in the winter, it should really be a handful on ice. The cheapest way to
handle the problem is keep you foot off the gas in corners. Second, I'm looking in a
JEG'S catalog and see a Holley 390 cfm carb calibrated for 6 cylinder and small V8s
in light vehicles. I'm not sure you want to hear this but I think you have too much
carburetion for regular street use. Oh, dirt track racers will sometimes remove one
spark plug wire on slick tracks. If you just wanted to let us know that you have a
power house of an engine disregard all my comments. It sounds impressive to me.
FWIW, Clifton
Clifton Gordon

Well, I haven't taken many photo's, and the conversion isn't showroom quality, but damn it sure does the trick.


As for a conversion, I actually strongly recomment that combination. (Buick 231 + T5) Although there were a couple of dicey bits. I can talk you through most of what you would need to do to get the conversion done.
(Parts, etc)

Gord Bestwick

Well, I will add while I'm not looking for sympathy, I doubt I would get any! :-)

One thing I've been considering doing is adding a heavily uprated spring on the gas. Next is adding a second spring on it so the second set of barrels doesn't kick open without a great deal of effot.

Actually my question should have been worded better. I'm actually looking for some traction ideas. What I'm looking for are better ways to stick to the ground.

I've totally rebuilt the front end (Its reallll purdy now)

In regards to the carb comment, actually, its the choice carb for this setup. Edelbrock sells a whole package (complete with various bits needed)in which they recommend this particular carb/engine combo. Also, its been polished and ported for better breathing.

Now, just to be fair, with this combo it does make driving a hint precarious. As, on dead dry pavement, in good temp, the wheels do tend to liquify... :-) I was actually thinking of changing the ratio on the carb throttle linkage so I -don't- go all the way down. Another trade off is that there is an air cleaner poking through my nice hood.



Anyways, I am after traction ideas. Also, on a totally unrelated note, I re-engineered the wiring harness. 10 fuses. If this thing catchs on fire cause of electrics, I'll eat my socks!

Well, I must run. Thanks for any input
Gord Bestwick

Gord,

Your basic problem is forward bite, especially in turns.
The first correction is to add a rear sway bar and balance it to the front bar. Secondly, eliminate the rear spring hangers and replace them with sliders. This will soften the rear spring rate, lower the rear end and force the rear wheels in to compliance with the pavement. The addition of a lateral locator (Watts linkage/ Panhard bar/etc.) will reduce the tendency of the rear axle to wander.
I'm certain that there is a community of short track racers in your area. Buddy up to a few of them and they will be more than willing to assist you, especially with examples of how they over came this exact problem. (BTDT: Raced 4 cylinder dirt modified for years !!)
FWIW, Eddie Petty
Ed Meadors III

To me, swapping in a V6 in a "B" would've been a more appropriate factory-installed "next step" in the
long evolution of the MGB (and B/GT), than going to the Buick V8...but that history has already been
set and cured.

In your setup...does the carb clear the hood? ...or did you have to cut a hole to accomodate it?

Anyway, to your handling questions...

I think alot of how your car handles depends on your style of driving, ie:

1) are you an aggressive-style driver? (be honest).
1) do you tend to enter turns late, (too fast)?
2) do you accelerate out too soon?
3) are you applying too much throttle while exting turns?
4) do you attack turns with your steering wheel...or do you
try to flow through them using the least amount of radius?

...etc.

When you say that your car slides sideways...do you mean that it slides evenly on all four tires?

When you say that your car just spins around...do you mean that the rear end tends to swing out?
Oversteer can be a hazardous driving characteristic. Where is this happening? While entering turns
during braking? Entering the apex? Mid-apex? Late apex? While exiting turns under aceleration?
During constant velocity (ie: on a turn pad, or a skid pad)?

Offhand...and this is a very rough guess...I would go to a larger front bar, and maybe switch to tires
with a larger footprint (say, 195 or 205/60 x 15"...??) - and test them - before considering adding
a rear bar.
Daniel Wong

Gord:

Re-build the whole rear suspension to better than new. Any slop is giving you rear -steer. The panhard bar is a very good idea. By the way, the rear is in nice and square right?

Go out and buy a set of R Compound tires. Yokohamas or Toyo might get you through a summer. Have fun!

Pete

PS. All bets are off if you are crazy enough to drive this in the snow.
Pete

I agree with much of the above, especially D. Wong's comments. One other thing I didn't see covered was what gear ratio your running in the differential. Are you running a "posi" rear end or open differential? Did you get the pinion angle correctly located for your torque to spring rate? Do you get wheel spin evenly in a straight line or do you get wheel hop? If your having trouble with the back in coming around TOO quickly, I would hold off on reducing rear roll. It can increase over all cornering speed, but will make the limit less likely to predict. Maybe rethink slip anlges with regards to tire selection. Softer is almost always better (with respect to speed and tire temps), but lower profile makes the limits harder to feel. Go to an autocross and you maybe surprised in how "slow" the new cars look until they spin out. The less the car talks to you, the easier it is to overdrive it. FWIW (I haven't seen that one before but liked it)

Luke
Luke Staley

Gord,

You could always stick in a Jag rear end w/independent suspension. What's a little more cutting and welding?
Mark J Michalak

I didn't see whether you had a CB or an RB. It makes a good bit of difference in deciding what action to take as the RB sits so much higher.
The MGB naturally exhibits trailing throttle oversteer. The MGB with a hot motor naturally exhibits oversteer at the traction limits on hard acceleration. Steady state balance however is excellent. What this means is that it is a wonderful car to steer with the gas pedal, but you have to learn how much is too much. The carb should have some sort of adjustment for the spring on the throttle shaft for the secondaries. If you can, crank that up tight and you'll have some feel for when you start to bring in the power. That will quite naturally lead you to go light on the gas in normal driving, and for more aggressive stuff it's mostly a matter of learning how the car behaves. Autocrosses are excellent for this. Any mid sized city should have them somewhere. You're at the start of a very fun trip. A little restraint now will go a long ways towards making that trip last. TVOE
Jim Blackwood

Wow whatta response! Thanks!

Ok, let me answer all this one at a time.

First some additional specs.

The rear end is out of a 73 Chevy Monza. I believe it is 2.93 Ratio. Next, I forgot to add that on the rear leafs there are anti tramp bars. I don't get -any- axel hop. Its quite nice actually. The rear end isn't posi, its umm, regular? (I forgot what the correct term for it is... :-) )

The specific problem is that because of the power this car produces, and the curve it produces it, it is very easy to be going around a corner all nice and easy, and just give it a hint too much, and much like having the non sequential twin turbos kick in in a Porche 911, the power just liquifies the back tires, and whammo, no traction. I've been considering new tires/rims for the back. WHats the largest you've ever heard of someone stuffing back theres without tubbing? I've heard a 7" wide rim can fit if the offset is perfect.

Now, next, in regards to driving style. I'm actually a fairly well seasoned rally driver (only local stuff tho') With almost a 1,000,000 clicks under my belt. I also had the privelidge of being taught police pursuit driving by an ex instructor. So, driving ability is not in question (or I hope not! :-) )

I considered the Jag Idea, but, money is pretty tight and not feasible at this time.

Also, the front end is very well balanced. Because the motor is only a shave heavier than the BL cast iron brick that came factory, handling is remarkably similiar to factory. Weight ratios are good.

The only "solution" is to add wider tires.

The best way I can describe what happens is this.

Go out on a frosty parking lot. Change your rear tires with really really really bald ones. Go around a corner and hit the gas. Whammo. There you be.

Jim, I think you hit it on the money. I am going to be adding a second spring for the point that the secondaries kick in. I'm gonna make it a tight little bugger too. I have a feeling that the throttle has been so loose, that its having the secondaries kick in at the wrong moment...

Perhaps I should go down to the abandoned oval and giver' hell...

Gord Bestwick

Gord, Suggest you get a lighter weight shoe for your right foot.
Rob

Gord,

Do you have a website or pictures of your car? I have been contemplating the six cylinder swap, but it sounds like you did a little more than that!

Thanks
Zach
'73 B
Zach

Gord, I'm running 14x7 rims with 205/60 tires and no flares what so ever. I rolled the inner lip of the rear fenders, but that is about it. I had some rubbing in the back under heavy cornering, but switched to poly bushings and that cured things. A panhard rod would work even better than the poly bushings. You may need to use a wheel spacer on the back depending on how square your rearend is. Mine was slightly offset to the passenger side.
Too much rear sway bar could also cause oversteer problems, so watch out if you go that route.
Bill
Bill Mertz

Have you thought of changing the linkage on the Holley? There is a kit that converts the ratio of opening of the primaries and secondaries to 1:1. This may make it more predictable, or NOT. Just another idea to avoid over springing the secondaries. Couldn't putting such load on the shafts make a known problem of wear and leakage more probable? Food for thought.

Is this a double pumper? Have you thought of a vacuum secondary, inwhich you could tune the secondaries opening with the spring strength and at what vacuum it would open. I don't prefer the vacuum secondary on a manual transmission, but it sounds as if you have plenty of throttle response. It can also be used to allow a slightly too big carb work more efficiently on a mild/moderate motor.

Luke
Luke Staley

I had a naibor, long ago , dead now , but did the exact samething with the buick v6 and a monzra rear end. and had the exaxct same prop the fix as I remember where anti sway bars AND ( VARY INPORTANT) anti tramp bar ...whats happening is so much power is being applied to the rear leaf springs that they are forming a "s" shape and the power is released after acceleration causing a hop, needless to say when going into a turn your probably under acceleration plus the g-force of the turn is already in the springs is why your being trown around. I think "moss" has an anti tramp bar... but you will have to definatly make your own.I may be wrong on this im going strictly from memory of 20 years ago ( the anti sway bars control side to side and the tramp bar controls the up and down.
prop

sway bars, sticky tires... go down to your local tire shop and get something sticky if you want the traction from them... but keep in mind the softer they are the shorter they'll last.. but if your car has that much punch to it, I'm sure you know all about wearing out tires by now
David Ryzuk

Buy good tires!! Since you are from BC, don't drive hard in the rain, provided you can find a day when it doesn't rain.

Jim
jmlema

I'd first like to thank everyone for at least pretending to have sympathy for my plight! :-) This car -does- handle quite similiar to an original B, because of the weight an everything else. I just need more stickyness is what it comes down to.

I do have anti-tramp bars on the back, and they keep me from hopping quite a bit.


Now let me address everyone in order! (Sorry if I miss you, I'm being harassed by the neighborhood kids for rides right now..)

Rob: Yup... I'm pretty much down to bare feet right now...

Zach: I'm working on some snapshots. I want to clean up my job in the engine bay before I show this to the world. But, if you want I will talk you thru almost anything you need to do.

Bill: Thanks for the tips. Do you know what offset your rims are? My last B I had a set of non stock rims that rubbed pretty bad on the back, and I had to flare out the wheel wells. Any info you could give I'd appreciate.

Luke: I have modified my carb linkage slightly so, the 2 set of barrels kicking in -earlier- That way it develops the power a little lower. It runs a little rich, so I'm going to have to re-jet it, but, eh...

Prop: I only have the Anti-Tramp Bars, do you think the anti-sway bar would help on the rear that much?

David/Jmlema: Big sticky tires are on my list very soon. I need different rims. And rain? Oh, I neeevvveerrr see rain around here.... :-)

Has anyone had experience having the stock rims widened? I know, it sounds like a dumb idea, but, that way, I can be assured that they wont rub!

Gord Bestwick

Y'know Gord, my brother in law had a Spitfire with a 90 degree Chevy V6 in it and he had pretty much the same problem, but maybe a little worse. Downright squirrrrly. He sold it. Not that I'm suggesting that mind you, but I think you need bigger tires. One idea is to play with the air pressure to see if that buys you anything. You can probably get the wheels you need from Weld or Centerline, maybe go to a larger diameter and lower profile tire to stiffen it up, and put that posi unit in there. Splitting the power between the tires should help some.
Several other options exist (you still haven't said if it's CB or RB) but does it break loose purely from torque, or is it from losing all traction on one wheel? How much does body roll contribute? The more you can lower the car the more you can minimize that but then you knew that anyway. One last trick is to set up the rear suspension to plant the tires on acceleration. There are various ways of doing this, the downside being the consequent lifting of the body which does nothing for your roll center but could still help.
Jim Blackwood

This thread was discussed between 26/12/2001 and 29/12/2001

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