75 Vega conversion - new to me

[pcguy]

Purchased a 75 Vega with a fairly agressive 350/TH350/3000 converter and 2.73 gears. Purchaased through a consignemnt, the seller was not the builder and the builder doesn't want to communicate, so I'm kind of stuck to find out what it is that I bought.

Have not run this on the track yet, but hope to get it into the 11's - guessing the 350 is putting out 400ish HP - when you fire it up it sounds very much like a pro-street dragster. Confused about the 2.73's and why that ended up in this beast - can't imagine that you could get enough torque off the line to get over 100MPH in 1/4.

Have verified that the existing gears are 2.73 and the spline count is 26 and the carrier is 7.5". What I don't know is if the housing is really a 7.5 S-10 as I have been lead to believe. If it is, the welds were almost top notch and one can not tell by the welds - I have photos.

So some questions:
o is it accurate to assume that 75's had the 7.5 housing and therefore it could really be the stock rearend/housing?
o I had the axles out (all back together now for a test run) and neglected to measure the length - is 26-3/4" the standard length?
o I'm ready to by a refurb Eaton 3.73 posi with a 28 spline count - is this going to fit in the 7.5" housing either way (Vega or S-10)?
o will I need to adapt the pinion gear diameter and bearing?
o bought some 95, S-10, 28 spline, 26-3/4" axles to go with the Eaton and am hoping now that I got the right length - the
local Pick n Pull had a half off sale and I couln't resist.
o what happens if the gears on the Eaton turn out to be 7-5/8"?

BTW, I searched this site for an hour or more looking for answers to these questions and found some, but also found some contradictions.

Anyone guess what this setup weighs?

Nick

[hammerdown7]

Nick, I'll take a shot at these, see below each of your questions. If I'm wrong someone will chime in, this is a great site with great input. Make sure your rear brake shoes are 2 inches wide, that way the backing plates will be correct.

So some questions:
o is it accurate to assume that 75's had the 7.5 housing and therefore it could really be the stock rearend/housing?

I don't believe any '75's came with a 7.5, if it has provisions for a torque arm to bolt to it, it's probably from a later Monza-Sunbird etc. If there is no mounting for the torque arm it is probably from an S10.

o I had the axles out (all back together now for a test run) and neglected to measure the length - is 26-3/4" the standard length?

The axles may be 1/32-1/16 longer, the S10 axles are slightly shorter than h-body 7.5

o I'm ready to by a refurb Eaton 3.73 posi with a 28 spline count - is this going to fit in the 7.5" housing either way (Vega or S-10)?

The 7.5 and 7-5/8 parts work in the same housing, just match 26 spline to 26 and 28 to 28's.

o will I need to adapt the pinion gear diameter and bearing?

I haven't done this but I believe most people recommend turning the 7-5/8 pinion shaft down to fit the 7.5 bearing. They make a special bearing to fit but it is smaller and does not hold up well.

o bought some 95, S-10, 28 spline, 26-3/4" axles to go with the Eaton and am hoping now that I got the right length - the
local Pick n Pull had a half off sale and I couln't resist.

These should fit the Eaton, the other S10 axles are from 4WD and are at least 2 inches longer if not more.

o what happens if the gears on the Eaton turn out to be 7-5/8"?

All 28 spline axles are for 7-5/8 and will mount without difficulty

[pcguy]

Yo Hammer, thanks for that in depth reply.

Anyone got a guess on the weight?

And anyone have any thoughts on the 2.73's that are in this beast? Needs to come out anyway (not a posi), but just trying to understand how someone would have chosen those gears in that setup.

n

[hammerdown7]

My guess on the ratio is that they weren't finished with it yet or they were looking for some fast cruising!

Dick

[HI WINDING MONZA]

Still have the 13" wheels and tires on it? ( reason they kept the 2.73 gears in it)

10's in the quarter have been run by some here with the 13" wheels and tires with a stock rear.

Tire selection is limited though...................................................

Doug in Az

[pcguy]

Pretty sure it's an S-10 5 lug and 15". Bought the Eaton this morning. Cheap tires measure 25" D & 8.5" tread width. With no posi, I'll likely mess them up testing. Leaning towawrd Nittos street slicks, but I gotta see what happens with the current setup, unknown HP and all.

Finally got the name of the guy that built the car and probably who ordered the engine from Britco. Britco said they could tell me more about the engine if I had the buyers name. We'll see.

[my79monza]

Pretty sure it's an S-10 5 lug and 15". Bought the Eaton this morning. Cheap tires measure 25" D & 8.5" tread width. With no posi, I'll likely mess them up testing. Leaning towawrd Nittos street slicks, but I gotta see what happens with the current setup, unknown HP and all.

Finally got the name of the guy that built the car and probably who ordered the engine from Britco. Britco said they could tell me more about the engine if I had the buyers name. We'll see.

Funny, most engine builders stamp their own numbers on a block for reference.
Merle

[monzajer]

PC, here is the e-addy of Jim Schaefer. He is a great Go To guy. He is our rear end & gear guru. He can answer all kinds of questions; pinion bearing size, gearing, all of it.

http://jdrace.com

And maybe you have already looked here. http://h-body.org/library/hbodyfaq/hbodyfaq-3.html

Lots of info here, maybe some help.

There are alot of good guys here to help.

I read the original post and when I got to the part about "...[why the]...2.73s" I thought the same as Dick...not finished yet. The guy could have fallen on hard times.

Anyway, good luck on gaining info.

Welcome aboard! Happy to have another member.

Got any pics??? Gotta have pics...or it ain't real

cheers, jer

[HI WINDING MONZA]

Pretty sure it's an S-10 5 lug and 15". . Cheap tires measure 25" D & 8.5" tread width.

2.73 - .12 for the 2" taller tire = 2.61 rear ratio ( 23 " tire is the stock size) ( plus or minus .06 for every inch of tire size)

Doug in Az

[pcguy]

PC, here is the e-addy of Jim Schaefer. He is a great Go To guy. He is our rear end & gear guru. He can answer all kinds of questions; pinion bearing size, gearing, all of it.

http://jdrace.com

And maybe you have already looked here. http://h-body.org/library/hbodyfaq/hbodyfaq-3.html

Lots of info here, maybe some help.

There are alot of good guys here to help.

I read the original post and when I got to the part about "...[why the]...2.73s" I thought the same as Dick...not finished yet. The guy could have fallen on hard times.

Anyway, good luck on gaining info.

Welcome aboard! Happy to have another member.

Got any pics??? Gotta have pics...or it ain't real

cheers, jer

Tried to contact JD but the website says to use the its forum and I registered, but it requires moderator approval and I haven't heard from them - long weekend I guess.

Here are a couple of photos..........

4.jpg

2.jpg

[pcguy]

Here are a couple more........

9.jpg

6.jpg

[hammerdown7]

Looks like a great catch!

Dick

[megavega]

Thats a nice car to start off with!

[pcguy]

Thought I posted this in this thread earlier and I don't see it. Apologise for any duplicate.........

Some of you have helped with this 75 Vega project I'm working on - appreciate all the help.

Getting close to having this thing ready for the track, at least for a trial run - going to run it with the 2.73's it came with for starters. Have an Eaton posi in the mail with 3.73's.

Anyway, something is bothering me about the B&M shifter neutral safety contact switch - the contact switches (neutral & safety) were absent when I got the car) and the engine starts in any gear. I traced the starter solenoid activation wire (purple & 12ga stranded) to the firewall and I can not locate it under the dash. Removed the driver's seat so I could get under the dash and I even put a tone generator on it - nothing.

What I don't understand is what happens between the key on the column and the wire in the engine bay on the other side of the firewall. That wire is energised when the key is turned to the start position, but there are no 12ga wires going into the column.

Is there some sort of relay under the dash that I need to connect the neutral safety switch to? I don't believe B&M contacts are rated for enough amps to power the starter solenoid, or what am I missing here???

Nick

[v8astregt]

75 was an odd year. I know on my car I had a bunch of extra wires for the seat belt bypass (won't start unless you're seated). I ended up jumping the purple wire under the dash after tracing the system. If your car is still original there will be a block for this interlock/bypass setup. I just removed this and used a spade jumper wire.

As far as the B&M is concerned, I would not use that with the purple wire as it is most likely not rated for those amps, and I wouldn't like to run a high amperage/thick wire through those confines, bends, and near moving parts. Instead use the wire for the factory neutral safety switch. I don't know where it was on a factory auto car, probably on the floor by the shifter. For my factory stick car I just took the clutch neutral safety switch wires, extended them, and ran them to my shifter. Smaller, easier to route wires, and low amperage.