:) I have a 79 elky 350/350 stock rear end orig a J code..so that put her in a 267 cu in.. I need to get her into the low 12's/high 1''s with pump gas and not radical in design I want to start with the rear end first. will the 10 bolt 7.50 gears take 400 Hp and hard launches... any suggestions !!!?!?!? thanks Df

No, not for very long it won't! Unless you want to go Big Bucks I'd look for a Grand National or Olds 442/Hurst Olds rear 84-87 complete rearend, its a bolt in swap! But I'm curious as to how your going to turn low 12's high 11's with 400 HP, what magical gizmo have you invented? 13's hmmmmm maybe. I'm building a 500+ HP small block now, and if I can get low 12's I'll be jumpin up and down for joy. Also if you can attain 12's, better see the forum on Roll Cage, I do believe NHRA rules require you to have one if your car is capable of 12.00 ET or less.

I know many Camaro owners with Autos that are running 11s and 12s with their stock 10 bolt. Granted it comes with a posi which you want to upgrade your Elky to for the track. With a manual the 10 bolt would not last very long. A Grand National rear end is not completely a bolt in swap. A new driveshaft is needed. Depending on how you build the DS it can get pricey. I just got a 3.5" aluminum DS 60.5" long for the new tranny setup for my Elky, it cost me $375. I got the 1350 U-joint connections so with the new tranny yoke and rear differential pinion yoke it cost me $575 out the door. It should be able to handle 1000hp. Overkill for my setup but I'll never have to worry about it, especially if I ever turn it into a 388 stroker.

I'm doing mid to low 13s now with my Camaro with 325rwhp. With 400rwhp low 12s or high 11s should be possible. 11s will depend on the loose nut behind the steering wheel. :wink: The one mod that cannot be controlled. Granted I'm using information from Camaros which are a little more aerodynamic but the El Caminos are not that bad in that area. If my Elky ever gets done I'll know a little more about what they can do. The setup I'm putting in we are estimating 300-325rwhp. The track will happen after about 4-5k miles of motor break in.

BTW a cage is not needed until 11.99 or lower ETs. 12s just needs a driveshaft loop and helmet. 13s is just a helmet.

:roll: thank u Mike what kinda goodies R u gunna use to do 500 Hp lot of head work..!?!??! I know a 7 1/2 rear end is not a thang to do. will other axels be a good fit under her. !! David ! :lol:

If you get the May issue of SUPER CHEVY magazine, they built a 383 almost identical to what I'm doing, only I'm using the Edelbrock Performer RPM injection system. I'm also changing over to a Borg Warner Super T-10 tranny. Just purchased a hard to find GM bellhousing for the 11" 168 tooth flywheel for my Elky that I found on E-bay yesterday. There's still one left on Ebay for the 10.5" 153 tooth flywheel if anyone is interested, Buy It Now price is $175. I definately got the better of the two :D . I've been looking for quite awhile for this part, extremely hard to find the 11", the guy even threw in the dust cover and clutch fork. Still looking for a 8.5" Grand National/Olds 442 rearend though , this is a bolt in swap. Thought about going with a 9" F#@d rearend, but they're expensive $2000+, several companies are making them for 5th Gen Elkys, some even make a 12 bolt Chevy, but not much cheaper. I'm pretty confident that the 8.5 will hold up. I don't plan on racing my Elky, just swating an occasional pesky Mustang GT now an then. :twisted:

Mike not to beat a dead horse but are you sure the 8.5 will work with the original driveshaft? I know it has all the same connection points as the 7.5 but I had been told by someone that sells GN parts that the front portion of the axle is longer therefore you would need a shorter driveshaft. I thought about doing an 8.5 down the road but when I was told about needing a new DS I dropped it. Buying one DS was enough, even getting the new one modified I don't think will be that cheap.

Ok guys here it is, if your doing something, anything to your 5th Gen Elky, check out this site http://home.hiwaay.net/~ppatter/links.html

I'll have to go measure my 8.5"this weekend and report back. I feel pretty sure it's a bolt in swap for most (except for me becasuse '78 had English threads on the brake lines).

GM has subbed 8.5's for 7.5's in Impalas etc. since about '81. GM is the KING of standardization unlike Ford so it unlikely they would create more work and inventory than necessary for people building cars on the line by adding another driveshaft. We benifit cause everything fits. :wink:

I rule it a bolt in. No drive shafts mods. For me new wheel cylinders with English threads and convert to English thread wheel studs. Below is a pic of my stock rear end with a 1 foot rule and the cute 8O red 8.5" 4.10 posi I acquired for a net $50. Axle code is 6 TP G 157. All I can translate is that it was built on the 157th day of 1986 at plant G. Gear code is meaningless since they did not come stock with 4.10s.

And in case you are wondering I plan to sand blast and paint it black.


http://elcaminocentral.com/albums/album19/Elc7.jpg
http://elcaminocentral.com/albums/album19/Red8.jpg
http://elcaminocentral.com/albums/album19/side8.jpg

Well just goes to show yet again that I shouldn't listen to people. Too bad I already have everything to rebuild my 7.5 stocker a 8.5 would have been nice.

Axle code is 6 TP G 157. All I can translate is that it was built on the 157th day of 1986 at plant G. Gear code is meaningless since they did not come stock with 4.10s.

Looks like you've got either a T-Type or a GN 8.5" rear. IIRC, the TP was the code for a 3.42 posi rear. Somebody liked the color red.

:mrgreen:

Darn I wish it was a 3.42 ratio. Ideally that's what I was looking for. Right now it definitely takes a little over 4 revolutions of the yoke to move the axle around one revolution. I had a choice to bid on the '79 Malibu this was under or bid the Cutlass 442 with a 3.42 open right next to it. The Cutlass was all there but wrecked a little in the front and went for $450 to be rebuilt. I got the engineless Malibu for $150. This was at the St Louis Police Towing Auction, open to the public with an auction every Thursday. Casual browsers and nosey people aren't welcome. :evil: Make friends with a tow truck driver early so you can get your car out there ASAP.

Moral of the story is to look at everything till you find one.

I got the engineless Malibu for $150. This was at the St Louis Police Towing Auction, open to the public with an auction every Thursday.

Good deal for an 8.5" rear end. I've seen them at swap meets for $850-1000.

:mrgreen: