A few upgrades for my '78

pancake

pancake

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A few months back I picked up a 4 bolt vortec block, a set of GMPP fast burn heads, and found an engine shop in Arlington, TX to build a 383. I've had the engine sitting on a pallet in the shop for a few weeks and finally decided to go about the swap.

I pulled out the original L48 yesterday and was surprised as all hell when I saw this:
pressureplate.jpg

Now you'd think that the throw out bearing would be noisy as hell.. but it was quiet. I assure you. I knew that it was on its way out because it felt rough.. but I figured that there would be some screeching when I depressed the pedal..!

Doesn't matter, though... None of those parts are going back in the car.

So I have a questions for you old hats:

1. How much input shaft end play is acceptable on the BW ST10?
 
Enjoy the new power when it's all back together and let us know how impressed you are.
As for the end play, I seem to recall reading in a book a long, long time ago in a galaxy far away something like ".005. But I'm sure someone else will chime in and correct me.
 
Well sonovabitch.. I guess I better crawl under it and pull the numbers and see what it is. To my uninformed eye, I had just assumed that all 4 speed cars post -74 were tagged as Muncies but were the BW ST10. I read that on the internet somewhere.. so it's gotta be true.. :D

The casting number is 8825658. The reprinted build sheet shows the 8YMM4 option.. Four-speed manual transmission.

And my dumb ass ordered the wrong clutch for it.. needed a 10.5"

Damnit. Until today, I did not know that you could get the saginaw 4 speed in the corvette. It was available behind the l48 in '78 and '79.. so it's still probably the original transmission, anyway. I haven't bothered to compare numbers yet.

Ok.. I did some sleuthing and believe I have a saginaw 4 speed in the car based off of the location of the reverse shift lever and the ten spline input.. Mother. Fucker. Oh well, that just further motivates me to put a T56 in there.

I'm glad you guys have eagle eyes and an amazing knowledge of this stuff.
 
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So my understanding of the saginaw 4 speeds is that they were pretty weak. The 383 is supposed to put out in the ballpark of 470 to the flywheel. Am I going to have to baby this thing? If so, I'm probably just going to side step the clutch and let it remove itself.

:hunter:
 
pancake said:
So my understanding of the saginaw 4 speeds is that they were pretty weak. The 383 is supposed to put out in the ballpark of 470 to the flywheel. Am I going to have to baby this thing? If so, I'm probably just going to side step the clutch and let it remove itself.

:hunter:
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:gurney: ummm hummm, and your ASS too, :hissyfit::censored::club:
 
Saginaws are pretty weak indeed. The BW super T10 the Muncies were stronger and you can build them up some but if you are going hammer the car they are not going to last either. Once I built my son his 12 bolt diff the weak link was the trans and he blew up 3 St-10's drag racing them.
 
GTR1999 said:
Saginaws are pretty weak indeed. The BW super T10 the Muncies were stronger and you can build them up some but if you are going hammer the car they are not going to last either. Once I built my son his 12 bolt diff the weak link was the trans and he blew up 3 St-10's drag racing them.
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That's what I thought. My old man worked for a Chevy dealership in PA from '76 to '79 and he said they changed them and did work to them pretty frequently. I'll just have to baby it until I can swing the t56 swap..

Oh well. I guess I'll have to wait until next year to run it at test and tune.
 
Weak or not .... Do you really want to rev 3000 or higher at 65-70 mph ? Converting to 5spd with overdrive was the best thing I've done to my '79
 
I thought it was the opposite, the m22 was slightly weaker then the ST-10... ah well, at least it's not a saginaw; that'd suck if that was in my car :rolleyes:

Problem with the saginaw (other then beside being very weak, and a poor anchor) is when they blow, they tend to take expensive parts, that you wanted to keep, with them.

Any stock manual transmission can be destroyed if you hammer them. OTH, even the weakest transmissions can survive if you learn to drive them. In the early 60s/late 50s my dad raced a 37 Chev. coupe with a 390 Buick (stroked 330). Both the transmission (2 speed chev transmission) and the rear differential were weaker then anything available today - but he ran 9.90s with that combo. IMO being able to break a strong transmission isn't something I'd be proud of... and I know of st-10s running high 7s.
 
pancake said:
Nope, i sure do not want to rev that high. I just did not plan on swapping the trans right now so it will have to wait until next year.
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What gears do you have? Everyone is all hot to trot for the Tremec conversions but I put the Richmond in mine. Found one used for $1100 with the shifter. You'll have to mod the transmission crossmember but that's the biggest change you have to make. I had to use a file and notch the tunnel about 1/4" to clear the shifter in the forward gears. And the last thing was get the correct yoke for the driveshaft. That's as hard as it gets to install one. Everything else just bolts right in. And what I like about it is that it's not an OD transmission. I have a factory 3.08 rear and it will flat get up and go, then I cruise on the freeway at 2400 at 70mph.
Later on, I may go with the Richmond 6 OD transmission if I decided to do any freeway driving at extended extra-legal speeds, but for now I'm really happy with the Richmond box, and I have no doubt it's strong enough to handle pretty much anything I plan on putting in front of it.
 
clutchdust said:
pancake said:
Nope, i sure do not want to rev that high. I just did not plan on swapping the trans right now so it will have to wait until next year.
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What gears do you have? Everyone is all hot to trot for the Tremec conversions but I put the Richmond in mine. Found one used for $1100 with the shifter. You'll have to mod the transmission crossmember but that's the biggest change you have to make. I had to use a file and notch the tunnel about 1/4" to clear the shifter in the forward gears. And the last thing was get the correct yoke for the driveshaft. That's as hard as it gets to install one. Everything else just bolts right in. And what I like about it is that it's not an OD transmission. I have a factory 3.08 rear and it will flat get up and go, then I cruise on the freeway at 2400 at 70mph.
Later on, I may go with the Richmond 6 OD transmission if I decided to do any freeway driving at extended extra-legal speeds, but for now I'm really happy with the Richmond box, and I have no doubt it's strong enough to handle pretty much anything I plan on putting in front of it.
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I have a 4 speed which was in my 455 powered Buick, I have a 6 speed in my 06 GTO. Which is why I'll say these next words. 5 speed is more than enough and 4 speed is the most fun. I get the extra gears for fuel economy, but what I don't get is the "must have" of 5 or 6 speeds when then car doesn't have that narrow of a powerband. My point, figure out what gear ratios you need to match your driving. If you're going to drive on the highway, 3.08 gears are almost as good as 2.73. With the super low gears available on either the St-10, or with the Richmond (where you can choose your gears), not having a high (numeric) rear gear would kill you in the place you never go - the dragstrip - so why build for it... hell, you could put pontons on your car too. 6 speeds really get tiresome, seriously, double overdrive? by definition an overdrive is something you only use on the highway, having a double overdrive actually confuses the issue of which gear to select.

All of that above summed up. Determine your power band, figure where you want to leave the light (rpm), and get a 1st gear matches that, 2nd, 3rd gears are nominally 35 and 45 mph (for the low, comfortable rpm). Find your gear ratio for those speeds. Last, highway gear, 4th, direct drive - your rear gear should match where you want your rpm at 55 mph. Overdrive, if you have it, 65 mph. Simply picking a transmission because it has more shiney babbles errr gears, is just silly.
 
My car has the 3:36 rear end.

I've looked for a used Richmond but have literally never, ever seen one turn up. Whereas I see usd t56's out of lt1 camaros come across the auto parts section of Craigslist in the Fort Worth area all the time. I already plan to make a removable tubular crossmember.

If I were going to buy a 5 speed, I'd go with the tko that has the .82 OD. The reason I'm interested in the t56 is that you get the double overdrive.. I realize that it's just about impossible to have a race car as a cruiser and vice versa.. but a six speed sure lets you get pretty close to that. This car will be driven on the road 99.9% of the time.

Besides.. vettes are fat slobs. If I wanted a real race car to kill the 1/4 mile I'd go find something lighter. The ex has an '11 muskrat gt with the six speed. I am just not bothered by having to shift through a few more gears.. besides, the torque will let you skip shift without issue anyway.
 
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pancake said:
My car has the 3:36 rear end.

I've looked for a used Richmond but have literally never, ever seen one turn up. Whereas I see usd t56's out of lt1 camaros come across the auto parts section of Craigslist in the Fort Worth area all the time. I already plan to make a removable tubular crossmember.

If I were going to buy a 5 speed, I'd go with the tko that has the .82 OD. The reason I'm interested in the t56 is that you get the double overdrive.. I realize that it's just about impossible to have a race car as a cruiser and vice versa.. but a six speed sure lets you get pretty close to that. This car will be driven on the road 99.9% of the time.

Besides.. vettes are fat slobs. If I wanted a real race car to kill the 1/4 mile I'd go find something lighter. The ex has an '11 muskrat gt with the six speed. I am just not bothered by having to shift through a few more gears.. besides, the torque will let you skip shift without issue anyway.
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I think this '72 with 336 rear and used to be a Muncie car saw the drag strip maybe once up north......don't remember the times....could care less, really....it was a club event.....the only time down here was on a autocross course, car FAR more capable than ME, and that was before the rack and brakes, and final suspension mods....did have the C4 wheels on it though....don't remember tire sizes....

driving I95 with a muncie doing 80mph for 850 miles, gets you 4k rpm....

during which it got 24 mpg with the ~stock engine, numbers matching....

trick is, why my drop in MPG?? thinking of going for the 308 rear, got the gearset, need to drop another 10% in RPM with a lockup auto 200 4r in there..?

Bottom line is, I considering a LS engine of lesser CU INches and hopefully better MPG, IF I live long enough....

:bounce:
 
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