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Bugeye Diffy Marking

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erstearns

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Can't find the marks noting what ratio. Can anyone point me to where they might be? I think I am looking for a fraction correct, as in 9/38 etc (or maybe vice versa for 4.22)?
 
Top front side of the lump on pass side as I remember. Yes it is a fraction. There is kind of an ear there and as I remember it is on that.
 
Thanks Jack. Will move around a bit more crud and look there. Was contemplating moving to a lower ratio rear but did not know if PO had done that some time in the past. As you can imagine its kinda crusty and did not want to waste time cleaning if I was not going to use it.
 
It's a 4.22, you're reading the fraction corectly. 4.22 is the stock ratio by the way. You won't always find the ratio out on the diff carrier marked, it depends on how many Guiness the factory worker drank the night before :smile:, but you will always find the fraction on ring gear, that's alway where I look.
 
The fraction if you recall your fifth grade math, will tell you the ratio.
9/38, if you divide 38 by 9 you get 4.22222
If you divide 10/39, you get 3.90
So the small number goes into the big number ??? That is the ratio.
The numbers are always on the ring gear.
 
Further thought always leads to more confusion. What rear-end is desirable for a BE with a 1275 tweaked mildly mated with a Datsun 5 speed?
 
How do you drive it?

I have a 3.9 in mine and I think it works well. I've run it 80 mph for hours on end, but it still has enough grunt to spin the wheel if I mash the loud pedal.

With stock tires, 3.9 rear end and datsun 5 speed... 60 mph is about 3000 rpm in fifth gear.
 
Trevor Jessie said:
How do you drive it?
Click to expand...

Have not driven it yet, purchased as a project. At the end of the day 0-60 is most important but don't want to shake all the bolts loose on the way down the highway to get to the twisty turnies either.

I noticed yours was supercharged. What are you running? Eaton from M or other?
 
Yup, the Moss SC unit. I had a mostly stock 1275 with a 3.9 and 5-speed in a Midget (heavier) and it was quick off the line (obviously a 4.2 would have been quicker), but my issue is the huge jump from 2nd to 3rd. With the SC it is no problem, but with the stock 1275 it really lagged in 3rd gear.

I'd suggest a 3.9, and it is easy to swap in a 4.2 latter if needed.

BTW 0-60 in the Midget was around 13 seconds if I remember correctly.
 
Have you been happy with the SC? Would you recommend it? Anything you would do different 2nd time around?

Don't really care about top end much just on ramp, out of curves and up hill performance thru the gears.
 
I started out with a 5 speed and a 3.9, I didn't like it so I popped in a 4.22.
Much snappier off the line and around my town I have hundreds if not thousands of traffic lights :wink: Gotta show the rice boys who's boss :smile:
 
If it wasn't for the extra grunt of the SC, I might go with a 4.22 as well, but then again ...maybe not. Why? Because I like to run with traffic on the interstate and the slightly lower rpm's helps me relax. I know there is not a big difference, but when the rpms are above 4,000 I notice my knuckles are white regardless of the speed.

How do I like the SC? It is OK. It adds a different dimension to the car. Was it worth the money? Probably not. I'm building an engine for it now. Would I do it again? Nope, I would probably do a throttle body injection, then add a turbo once I add the fuel injection sorted.
 
Was perusing some of the internet chatter about TBI, at the time regarding a TR6, and the maker of one of the TBI kits mentioned that similar improvment could be had by dumping the stock fan assembly for an electric (drag of fan about equal to improvment of TBI). Are you thinking about TBI as the first step prep for a turbo?
 
Yes.

TBI will not improve HP over properly setup carbs, but it can be made more efficient and is more easily tuned if you do not have cheap access to a chassis dyno. And... I would couple it with a programmable electronic ignition.

Once I had the TBI and ignition dialed in then I could add the turbo.
 
Hopefully Ray MCcaleb is reading this, if I'm not mistaken he plans on running a 3.7 with the Rivergate 5spd, that sounded like too tall of gearing with the 5 speed, but I have no experience with the 5s pd., maybe you guys can shed some light on this for Ray.
 
What is the powerband on his engine?
 
Found it Hap, wasn't looking on the edge of the ring gear. Mine is a 4.22. Given that most of my driving will be on the two lanes, sticking with the stock may be the best place to start (bird in the hand......but will keep eye out for a 3.9 to keep on the shelf).
 
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