BritishV8 Forum

Yes indeed. We have a winner! The "hex" is exactly what is different.

Jim

Hey, wait a minute! - since when did a "Hex' section have 8 sides .....(or are my eyes deceiving me)

Good eyes Graham, it is indeed an octaginal shape on the shaft.

Sent a check to Steve deGroat today to bump up the coffers a bit.

Octagonal? Just because octagons are really cool and go with the whole MG theme? I'm still missing something. Did you cut/grind that section, or was it a feature of some part that you re-worked?

It was made from materials I bought for the Jag IRS conversion. I had bought a 20 ft length of 5/8" 4140 HT and it wasn't available in TGP (turned, ground and polished) but I bought it anyway. When it came in it was a little egg shaped from the heat treatment so I couldn't use it and had to buy drill rod instead. So there was a fair amount of it left over and I've been occasionally using it for other things. It's very strong and tough, but a little hard to machine, although carbide tools help a lot. Since this is probably the same alloy that ARP uses to make studs it seemed like a good choice.

Several features make it much stronger. The allthread broke immediately below the jam nut Here the "jam nut" is a part of the stud itself  and there is a smooth radius transitioning to the shank, which not only is unthreaded in the critical area, but is 10% oversized on the diameter, necking down just above the threads, which are buried well below the region of stress. The shoulder is a full 5/8" diameter, giving a 43% wider seating area than the hex jam nut for more stability side to side, which is the primary axis of vibration, and the shoulder is substantial enough to resist any deformation or flex, giving stability to the whole. This stud also clamps the carb top (air horn) to the carb body. Above the shoulder is a 7/16" octagon which fits either the open or box end of a 7/16" combination wrench, a rather neat feature as it withstands 33% more wrench torque from the box end than a hex nut. Above the octagon the stud for the Big Nut is 5/16" for added strength and stability, and uses a 24 pitch thread, consistent with MG practice and more easily tightened and loosened. The nut itself has a shank which matches the hole in the air cleaner, plus an o-ring on the shoulder to prevent loosening. The flats are cut concave with a 3" radius (6" cutter) providing a natural feel and good grip. Try it out at the BritishV8 meet, you'll see what I mean.

Jim

79% more BS in that post too. (BS = Blackwood Stuff)

Stephen
were do we send donations?  to Jim?

Donations would typically go to Steve as the treasurer, but if you want to send them to me, the bank is just a few blocks away so it isn't any inconvenience to get them deposited.

Jim

Steve/Jim/Rick, et al:

Sent my checque to Jim.  

Cuz... well... his address is right there.   <----  

:-)

M

Has Carl still got the car?  Maybe he's too busy driving it to post....

Too busy coaching baseball & trying to rescue my data from my crashed computer (borrowed wife's laptop to post) so I can get my taxes finished.

Roadmaster is collecting dust in my garage while I find time to piddle with it.  Jim's shiney new air cleaner parts are installed. Had to tweak the carb stud a smidge on my dad's drill press to achieve that Blackwood custom fit.  I think the carb will fly off first, now.    Also, installed a new spring & diaphram in the fuel pressure regulator. It no longer quirts gas towards the exhaust manifold.    Haven't tackled the dash/speedo calibration, yet.

I guess I won't have time to do any more tweaking. Will be handing it off to Steve DeGroat Thursday evening.

Despite losing a freeze (core) plug last night,  Max will sleep better knowing that the MG Roadmaster has been safely handed off to Steve Degroat today in rainy Asheville, NC.

How does THAT make me sleep better?!?   :-)   Besides, I already won my bet.   :-)   (At it's current rate, it's going to "break" something for probably the first half dozen people who get the car! I lucked out that Carl was early in the cue.   :-)    We're still in shakedown mode.... gonna be awhile of sorting before the car is trouble-free.   $.02)  


Any clue on the freeze plug?  When did it occur? (Hammering hard down the highway or light cruising?)   Was it weeping beforehand?  

I mention only because a detonating ("pinging") engine is known to blow out freeze plugs....  (in a 4-cylinder B, usually the inaccessible one in the back!)   WE see this all the time at the racetrack-- someone with just too much timing on the ragged edge.  

I would presume Dale installed those freeze plugs?  That makes me even more suspicious of WHY...   :-/

Cheers,

M

Popped the plug Wednesday night. Wasn't hammering it hard, but I was leanin' on it a bit.    No pinging.  My understanding from Steve is that that plug had been replaced since the rebuild due to cold storage in Illinois.

I've repaired the inaccessable one on my Dad's 63B.  It was actually much easier than I thought it would be.

Update:
We now have a Spare tire and jack.  The wheel will not fit the front, so if you have a front flat you get to change the rear tire first and then put the rear tire on the front.  Spare is a 185/65/15.  Started life as a donut spare for a chevy but the tire was rotted.
The air cleaner is now fixed and back on.  Looks really good.  It cost just what Carl donated.
I cannot install a steel freeze plug so it will have to live with the rubber one.

Steve

Another update:
Replaced the carb with a 750 Quadrojet with a big block calibration.  It seems to run better and doesn't smell like unburned gas.
Hopefully mileage will be up.
The secondaries do not open all the way.  Carl said it felt down on power and he was right.  The new rod that holds the air cleaner in place stops the flappers from opening all the way.  Maybe just 1/3 of the way.
I will try to get a new mpg check on it in the next few days.

Steve

Steve, would it be possible to spread the arms of the metering rod hanger enough that it will slip past the air cleaner rod? But then I guess that would make the rods hit somewhere else. Other than that all I can think to do would be to find a lathe and cut down the diameter a bit.

Such are the hazards of making parts remotely.

But regardless, I'm glad it's running better. The Buick guys say the big block likes the 850 QJ to really run the way it should, even with a stock cam.

Jim

Hey Jim,
What about filing or milling a couple of flats on the air cleaner rod?
Bending the rod hanger probably will result in the rods binding in the main body.
Qjets only came in 750 and 800 cfm sizes. Several methods were used to achieve the different flow ratings. They were further derated as required by secondary throttle opening angles and air flap stops. Fine tuning the secondary and air flap openings will get you up to the 800 cfm range. Removing the outer booster ring in the primarys will get another 50 cfm out of it, but at the expense of poorer fuel mileage.
At the power level that the roadmaster is at, the 750 is a good choice if set up well.
Cheers
Fred

I don't claim to know anything about that Fred. The guys on V8Buick, especially the BB guys, claim there is an 850 QJ that was used on the stock big block Buicks and that this is the one to use. They have the numbers and the specs, I do not. They are very insistent. I doubt you could convince them otherwise but if you like you're more than welcome to try. With all the millions of QJ's GM built, who knows what's really out there? I was just passing the info along and I have no dog in this hunt. I think if you're going to run a carb it makes sense to use the one that is the best possible match for the engine, these are the guys that presumably know what that is, they are at the top of their game, and I'd expect them to know. But personally, I greatly prefer EFI.

I do not believe cutting flats is the answer for the stud, as their orientation is dependent entirely on tightening torque and with a zinc body, crush can change the location. If Steve wants to send it back I can turn the boss down some though, to get clearance, if he can't find a local guy with a lathe of some sort. It's a simple 5 minute job or even less. I bet I could do it in 1 minute. Almost seems a shame to pay postage and risk loss just for that.

Jim

Jim,
I will get it turned down.  Will that weaken it any?
I would hate to loose the air cleaner again.

Steve

Sorry Jim, I wasn't questioning your knowledge at all.
You were just passing along the info.
Some of these "experts" drive me crazy.
The facts are that there were no 850 quadrajets.
The only one that claims to be is the Edelbrock copy and it's air flow data is sketchy.
I won't try to convince these guy's otherwise, it would just hurt my brain.
Like you I much prefer EFI, even though I've been a custom carb builder since 1976.
Cheers
Fred

Steve, if you turn it down to the same size as the corners on a 1/4" hex nut (about a 1/2" dia I think) it will be fine.

Jim

The guys on V8Buick, especially the BB guys, claim there is an 850 QJ that was used on the stock big block Buicks and that this is the one to use. They have the numbers and the specs, I do not.


Ah, I think you're confusled, Jim.

The Quadrajet was available in nominal ratings of 750cfm ( 71 and earlier ) or 800cfm ( later ).  Actual flow capability tends to be ~20-30 cfm below factory ratings in OEM configuration.

I don't ever remember anybody talking about an "850" Quadrajet.

http://www.teambuick.com/reference/library/75_chassis/files/6-e.pdf