South African 80 Corvette - good combo?

[Rodney Gold]

Not too many of em here , but I have one and have decided to hop it up. It was originally a l48 and I have recently had it resprayed. Motor was completely redone and I have added Edelbrock performer RPM alloy 64cc heads , Performer RPM manifold , Comp cams 270 cam, Holley 770 street avenger , ceramic coated headers , dual 63 mm exhausts , MSD 6al, Pertronix dizzy. We have 95 octane lead replacement fuel as well as 95 octane unleaded. Im running quite a lot of advance 40 degrees total with no detonation problems. I tried 36 degrees but the car was lazier and less responsive
I have the original 15" rims with 255/60/15s out back and 235/60/15s on the front.
The car has no cat convertors , doesnt have to comply with any emmisions stuff and thus all that has veen deleted along with the Aircon. So its leeetle lighter than stock
The car goes like the clappers above 2500-3000 rpm to a true top speed of 250+ kph. Down low it wont really squeak the tyres but does launch quite well. No drama like my 454 El Camino (actually a Holden ute here in South Africa)
It ran a 13.9 on the dragstrip as is with the stock tyres.
Im getting a Saturday night special torque convertor, 1500-1800 stall and a set of 3.55:1 gears to replace the stock 3.07 (i assume my rear end is 3.07 , seen some references to 80's having a 3.55 rear end but don't thinks thats accurate)
Do you guys thing the TC and the rear end will wake things up a little at the bottom end?
I would be happy with a lowish 13 , albeit the car is not really meant for dragging , I just want a little more guts to go with its looks and to blow away eurotrash hot hatches and riceburners. Top end speed is academic , i dont like taking the car above 220kph (1.5 km/mile) as it's handling isnt that good at high speeds.
The only thing I think i might have done wrong is the cam, as it might be a little overcammed , I tried a 600 carb on the car , but it gave me no better bottom end than the 770 and was a bit strangulated up at the top.
Any comments or help appreciated.

 

[richross]

Hot Dang!

Rod-
I dont think alot of people have replied because it seems you really know your stuff! Sounds like you're doin just fine on your own. All the mods seem to be right on track. Post some pics so we can see your ride. Good luck from over here on our side of the "puddle".
Rich

Not too many of em here , but I have one and have decided to hop it up. It was originally a l48 and I have recently had it resprayed. Motor was completely redone and I have added Edelbrock performer RPM ally 64cc heads , Performer RPM manifold , Comp cams 270 cam, Holley 770 street avenger , ceramic coated headers , dual 63 mm exhausts , MSD 6al, Pertronix dizzy. We have 95 octane lead replacement fuel as well as 95 octane unleaded. Im running quite a lot of advance 40 degrees total with no detonation problems. I tried 36 degrees but the car was lazier and less responsive
I have the original 15" rims with 255/60/15s out back and 235/60/15s on the front.
The car has no cat convertors , doesnt have to comply with any emmisions stuff and thus all that has veen deleted along with the Aircon. So its leeetle lighter than stock
The car goes like the clappers above 2500-3000 rpm to a true top speed of 250+ kph. Down low it wont really squeak the tyres but does launch quite well. No drama like my 454 El Camino (actually a Holden ute here in South Africa)
It ran a 13.9 on the dragstrip as is with the stock tyres.
Im getting a Saturday night special torque convertor, 1500-1800 stall and a set of 3.55:1 gears to replace the stock 3.07 (i assume my rear end is 3.07 , seen some references to 80's having a 3.55 rear end but don't thinks thats accurate)
Do you guys thing the TC and the rear end will wake things up a little at the bottom end?
I would be happy with a lowish 13 , albeit the car is not really meant for dragging , I just want a little more guts to go with its looks and to blow away eurotrash hot hatches and riceburners. Top end speed is academic , i dont like taking the car above 220kph (1.5 km/mile) as it's handling isnt that good at high speeds.
The only thing I think i might have done wrong is the cam, as it might be a little overcammed , I tried a 600 carb on the car , but it gave me no better bottom end than the 770 and was a bit strangulated up at the top.
Any comments or help appreciated.

 

[Rodney Gold]

Here are some pics

 

[XLR8]

I agree with Rich... sounds like you have improvements and upgrades well in hand. I'm afraid I can't offer any suggestions but I wanted to say HI! and comment on your photos - very nice!!

Jane Ann

 

[KANE]

...I have the original 15" rims with 255/60/15s out back and 235/60/15s on the front...

Hi Rodney-

I saw your post earlier and really mulled over your combo. You've set up the engine right!

I think you are looking for balance within the drive line and suspension. So, you may want to move up to a performance tire- either a drag set like M/T or a larger wheel diameter with a better grip.

If you plan to get under the 12s, I'm sure a better tire combo would prove beneficial. Maybe even drag tires that are barely DOT approved. The 255/60/15s don't launch well and they are an old design as for tread.

I have a set of 255/50/17s with an aggressive tread. With my 17' wheels, my '80 launches sooooo much better and the overall handling has improved a lot.

 

[Peer81]

Damn South Afrika, talking about a country were the sun ALWAYS shines!
Nice vette and some nice upgrades. If you want to sell the 3.07 gears just pm of email me Also keep in mind that the diff isn't the strongest link in the car. Some can handle 400hp and others end with 200hp if you dump the clutch.

Well, veel succes! (Dutch is almost the same as south african )

Groeten Peter

 

[Rodney Gold]

Thanks all, glad you like the pics xlr8. Rich , i was in your neck of the woods in Dec a yr ago , wonderful cruise from LA to hawaii and back..... I loved Amerika Sacriledge tho, I hired a Stang convertible on one of the islands for a day , very nice car to drive.
Darkshark , I thought long and hard about the diff ratio vs rims and tyres , was thinking of a 245/40/17 tyre and rim set, however a few problems arose, 1) Availability of rims to fit the vette is real bad here and the cost of the rims and tyres is like $2500 vs the cost of a pinion and ring gear and installation at $500 landed. The current backs arent great , I will admit , but I can get a nice set of 275/50/15's. The current tyres are brand new tho.
I have a set of MT street legal slicks and might just use em if I race. 17"/18" rims would look cooler tho. I doubt I can do under 12's with the car for various reasons the most important of which is our local dragstrip is pretty much a poor imitiation of anything you find in the USA, the startline rubber is ripped to marbles by 4 cyl fwd treaded tyres doing burouts on it, trackbite is kinda used sparingly and the startline and rubber section is like 10meters long as well as the fact that the track is used for all other forms of motorsport. If I could get to 11's , the car wouldnt be really streetable and I go once a month on V8 runs which can encompass 200 mile routes. I'm even worried about the 3.55 gears in that regard. I can get a hold of a set of later model vette rims quite cheap , dunno if they would fit or that I like their design (c4's)??
Peer ,groete van sonnige Zuid Afrika, een van my oumas was van nederlands af. Dunno what I can do about the diff tho , I thought the Dana 44's were quite strong but im probably making 300 hp on the back wheels albeit I was thinking a dose of NOS on the startline might be a possibility , but Im not that convinced about using NOS as it works out expensive for a short burst of power and bearing in mind or track , probably will make me lose traction big time.
Ive had hassles with the u joints and have a set of heavy duty ones on the way here. Ive got a clunk from the diff area too wen i stick it in gear , had the driveshaft checked and it seemed ok , so the diff might be slightly Gemorsed
My next course of action is to bring in a front end and rear end suspension/bushing rebuild kit as the handling is a little vague and the car gets real "floaty" at high speeds. I also need some advice on seats cos the stock ones are in poor condition and the hinges of the drivers one seem messed up , it leans way too far back so i have like a wooden board behind it so im not lying down. Im looking for racing type seats. I dont have pics , but I made a whole new console and bezels for new autometer guages and redid the speedo gauge to white to match the large autometer rev counter I used to replace the original rev counter. Made a whole new housing for it and the speedo. I have a co that uses CnC machines , laser cutters, engravers, digital print and die cutting etc. I have done a lot of my own badges for the car as well as working on a nice aluminium type cladding for my centre console.
Another piece of advice I need is about a shifter, I would love a hurst promatic but dont want to butcher the exisiting shifter console. I have a weight kit on the way to fiddle the governor to try give me shift points at 5800 , but a ratchet shifter wouldnt go amiss. I havent seen one advertised for the vette?

 

[Curtis]

The cam you chose is probably a pretty good match for the heads you have, although it only lifts the valves .470 so you are not seeing the full potential of the heads. They could use more lift, say in the range of .535 or slightly more. You might consider some 1.6 rockers to jack it up a bit. As far as the lifter acceleration rate for that cam, it is considered mild or only slightly more aggressive than OEM stuff. That means you won't get the gobs of torque at low rpms ; thus, Comp recommends a 2000 + stall converter and better rear gears.. going to the 3.55 will help you get the motor to the power zone faster and amplify the torque you now have.. but it will also lower your fuel mileage on the highway. You should feel a good difference from the old setup with a looser converter and the new gears. I am curious about your compression ratio.. I would think you could run at least 10.5 to 1 with those heads. that would also help your bottom end. I believe your timing is maxed out if that is without any vacuum advance. If that includes vacuum, then you might could use more. I run 51 total. (static, mechanical and vacuum) with iron heads at 9.4 to 1 with no problem on 89 octane unleaded. Maybe your balancer has slipped and you don't have all the advance you think you have. There, that is my dollar and a half worth. Good luck.

 

[Rodney Gold]

I was scared of going too radical on the cam cos Ive made that mistake before and basically wanted to limits revs to 6000 , the block is a 2 bolt mains as far as I know and I wasnt really sure it would handle 7000 rpm. I was going for a cam one step higher , but decided otherwise. One of the plans is to stroke the engine to a 383 in the next 12 months or just to get a 400 SB to "make up" the torque.
As to timing , I am not sure that my timing mark is accurate. Advance is without vacuum and Im just going further and further without any pinging etc. Im gonna check TDC and the balancer for slippage.
Im not an expert on compression ratio , but didnt want to get anywhere where I cant use pump gas which does vary here in terms of quality , the motor is bored 30 over and I wasnt sure if the bottom end can handle higher compression so erred on the side of leniency here.
Prior to the mods , the car was a dog re performance , it's a WHOLE lot better now. Mileage is sort of important but not that critical , I dont play golf or do other money sucking hobbies and write fuel costs off to "entertainment" money , I went on a 150 mile run yesterday and got about 5km per litre , thats about 3.2 miles per litre or 14 mpg , which I thought good , was running mostly in the 3000+ range with occasional lead foot episodes.
Im actually having a ton more fun with the vette now than ever , and am even considering using it mainly for daily driving duties - about 10 miles a day
Best thing was last weekend , filled up at a petrol station and a guy in a Ferrari 308 was in front of me , we both pulled out at the same time and paused by a zebra crossing to let 2 hot 20 something chickybabes cross the road , they looked at the ferrari , whose driver was much more handsome than the old ugly bugger I am , and then waltzed over to me and said "Can we drive in your car with you" , did my ego a power of good!!!!!!!!!!

 

[Peer81]

Corvette 1 : Ferrari 0!

Funny to see its easy to read South African!

Maybe you should look into some 700R4 and 200R4 info. With a 3.11 rear gear you gave a good setup with the short 3.06 first gear from a 700R4. I'm not that much into gears but I thought the overall ratio of 10:1 would be perfect(?) And the overdrive will give you lower highway rpm's and lower fuel consumption. Or get a 5 speed for real fun :cool

The 80 to 82 Dana 44's aren't the good diff's they normally refer to. Manual C4's have a Dana 44 (strange it has the same name but oke) but that is the diff to have, the casing is much stronger. But you need to change a lot of things before a C4 Dana 44 will fit. So if someday the diff goes to heaven, look for a older iron C3 diff. If I remember correctly it should bolt up to the 80 bat wing.

Changing the suspension rubbers is always a good idea! Also look at the rag joint at the steering, old ones can give a lot of play. Also look at the bodymounts, mine where like sand cookies after 25 years.

Good luck!

Groeten Peter