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Old 01-13-2013, 07:03 PM
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Project: 1965 Corvair Kelmark V8 - What motor / recipe?

Hello World,

First post ever. Revisiting a project started in the 90s by another, bought by me in 2004, worked on feverishly, then left to sit while raising kids, moving/saving bigger house, etc.

I've got a little bit of a war chest rebuilt and need to finish this project for my soul.

Its a 1965 Corvair Corsa setup for a mid engine Kelmark V8 conversion. Radiator plumbed in the front with copper tubing, disk brakes, 15" wheels, etc. Missing one critical component. The Engine.

Reaching out to the team (long time reader, first time poster) to help with engine selection / build recipe.

Want to build a fun to drive, decent mileage, decent power v8 car that doesnt brake my driveline. I understand the diff and input shaft are weak links. I'm running the hardened, 1" longer aftermarket shaft, and a 66 saginaw. Spider gears in the diff. Even still, what I've read is to keep hp and torque under 300 to be safe. People get away with more I've read but the standard SBC torque is what kills this setup as far as I can tell. The finished car will weigh between 2500-2700lbs.

What I'd like to build is something that will reliably rev to 6-7k, making good power between 2-7,000 rpm happily sacrificing low end torque to keep my driveline alive.

To do this I'm weighing these options (budget for finished motor is <$5k).

1. Get the 350/290 from jegs, run it for a while, see how it does, then move to aftermarket heads and longer duration cam to meet my goals.

2. Get the 350/330 and do as above, hoping with the torque that motor puts out, I'm not replacing my shaft and diff straight away.

3. Get the vortec truck motor (L31), deal with the electric fuel pump issue, but benefit from the better heads and roller cam setup, change out the cam down the road and see how much I can squeeze before I find a weak link.

[www.jegs.com]

All that being said, what do you guys think? Am I on the right track?

what way would you go? I'm not that savvy when it comes to all the SBC variables, but the obvious inputs for you gurus are relatively light car, low end torque is DANGEROUS, want to rev relatively high to drive this car as a mid engine roadster with great handling on windy roads.

Got some money burning a hole in my pocket and dying to get to driver status. Or should I just say screw it, save more money and lose (way) more time and just go LS1 and some other driveline all together. Would love that obviously, but a driver within site if I go Gen 1 SBC, way out in dreamland if I go LS1.


Thanks in advance for the wisdom.

-Mike

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Old 01-13-2013, 08:53 PM
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If you go with a gen 1 engine then consider a 283/302.The 302 has a wow factor and the 283 is not yet rare and can be built using all GM parts that no one wants and make 250 plus HP.take a quick look at the 283 impala thread.
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Old 01-13-2013, 11:08 PM
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One of my childhood dream builds was in fact a mid ship Crown Corvair.Back then the engine of choice was the 327's,but there where 350's swapped in them.

I know you said to exclude the LSx option.But to bring his to current day engines that fit your requirements the 5.3's is almost too prefect to be true.They are cheap to get and you get a engine that responds to a turbo very well and again right within the power curve you want with the power train you have to work with.Winding roads driving with a turbo behind you,yeah life shouldn't be that good.
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Old 01-14-2013, 05:31 PM
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Already have engine mounts welded to subframe for gen 1 v8, and have the kelmark adapter for the gen 1 to corvair diff.

Going with a modern block (LSX or otherwise) would require new adapter and new motor mount locations correct? I feel like the car is so close to drivable should press forward with gen 1, otherwise, its a longer term project and if were to change mount location and adapter, would be inclined to change diff and tranny as well.

Could I find the right bump stick for the 350/290 crate that put the torque down under 300, and still give me ~300+ horseys at 4-6k? Any recommendations?

Thinking 600-650 cfm carb, ram horn manifolds (the engine is in the middle of the car).

-Mike
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Old 01-14-2013, 06:06 PM
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Well its easy to make 400 hp with vortec or other after market heads. If my memory serves me right that is more than enough to shake a corvair to peices. Unless you got major frame and drivline upgrade i would go as stock as possible with a v8. 290 would be plenty if not over kill. The original engine easily could be less than 90 sae hp. 330 sae hp could be as much as 4 times the cars designed output. Too much for stock frame or even boxed up stock stuff.

If you want efi i would consider a 80's vette motor nobody wants them and they make good tq and about 290 hp. Also great mpg with the th700r4. I would buy a corvette donor car swap everything over and sell whats left. Get a roller motor with tpi 88 or 89.

With all the issues with crate motors these days its hard to recommend. I would prefer to rebuild my own engines. A junk yard block that runs and moves can be the best option when the war chest is empty. A great car will wait for a great engine a car that does not move is not a great car.

Now not all crates got the same engine inside. If you are going to spend a few bucks to buy a jegs built motor might as well kick out the rest and buy an all new engine. Built with 100 percent new parts, block and heads. These engines for the most part are considered to be oem reliable.
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Old 01-14-2013, 06:14 PM
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yes, I was thinking about the OEM GM Performance 350/290 from jegs, shortblock is $1900 delivered. I guess the question is, what cam would one of you gurus recommend to move the HP up the RPM line and REDUCE the torque numbers (remember, my driveline breaks at around 300-350ftlbs according to the corvair guys).
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Old 01-14-2013, 06:53 PM
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Quote:
Originally Posted by mikebuongiorno View Post
yes, I was thinking about the OEM GM Performance 350/290 from jegs, shortblock is $1900 delivered. I guess the question is, what cam would one of you gurus recommend to move the HP up the RPM line and REDUCE the torque numbers (remember, my driveline breaks at around 300-350ftlbs according to the corvair guys).
Its still going to make more tq just higher up in the rpm band. A bigger camis not the solution. Stock would be best. Even a smaller oem cam would be better than most aftermarket cams.

Also the 290 is a gm performance parts engines. I think the oem engines are even cheaper. But the 290 is a good shortblock. I would buy a long block to get heads and cam as well.
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Old 01-14-2013, 07:24 PM
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My 1981 corvette 350 near stock when I bought the car,after tuning,made 205 horse power and 279 pounds torque at the wheels.Use a smaller engine
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Old 01-14-2013, 07:27 PM
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sounds like a cool project. Show us some pics! when i was younger i wanted to put a 350 motor up front and out of the hood ( Yah i know out of the trunk). Haha
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Old 01-14-2013, 08:07 PM
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I have built a few over powered cars and this looks like its going to be. Use skinny tires near factory size or a little wider for looks. But make sure they dont hook. Dont buy grippy soft compond tires or it will get enough grip to break something. If it just spins the tires it will be safer for the trans and frame if less fast. A little grip is good just make sure she wont dead hook with all 300lbs of tq.
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Old 01-14-2013, 09:55 PM
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Pics

attached a couple of pics to give you an idea of the project.
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Old 01-15-2013, 04:17 AM
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Quote:
Originally Posted by mikebuongiorno View Post
Already have engine mounts welded to subframe for gen 1 v8, and have the kelmark adapter for the gen 1 to corvair diff.

Going with a modern block (LSX or otherwise) would require new adapter and new motor mount locations correct? I feel like the car is so close to drivable should press forward with gen 1, otherwise, its a longer term project and if were to change mount location and adapter, would be inclined to change diff and tranny as well.

Could I find the right bump stick for the 350/290 crate that put the torque down under 300, and still give me ~300+ horseys at 4-6k? Any recommendations?

Thinking 600-650 cfm carb, ram horn manifolds (the engine is in the middle of the car).

-Mike
Naw Mike.There are conversion engine mounts from first gen to LSx which are a simple bolt on to the first gen's.So that should be no problem.

Is this a stick shift??. I'm not familiar with your V8's conversion's name.
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Old 01-16-2013, 01:57 AM
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great! thanks for that!.

Maybe I will do lsx afterall. Anyone comment on overall dimensions over gen1? as you can see, the box is already built.

-Mike
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Old 01-16-2013, 01:15 PM
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Like 1Gary, I had the Crown catalog and was chompin' at the bit to build one of these. You know how providing for the family has a way of cooling a hot desire though and I never got around to it.

I would build a low compression 350, around 8.5:1, but with a decent set of heads.
I'd want a cam with a wide LSA, maybe something like this Crane cam.....

Great for 305 HO and performance 350 trucks, good mid
and top end torque and HP, axle ratios of 3.73 or numerically higher required, auto or 5-speed manual.
Grind number 2040
Power range 1600-5400 rpm's
Part number 114132
Lifters part number 99277-16
Springs part number 99848-16
Intake/Exhaust duration @ 0.050", 210/216
Advertised duration 270/276
Lobe separation angle 114
Timing events (4), 34, 47, (11)
Valve lift 0.440"/0.454
Intake valve closes at 34 degrees ABDC @0.050" tappet lift
Dynamic compression ratio is 7.5:1 on the KB calc. Should make an easy runner that will operate on any kind of cheap fuel and make good power upstairs to 5400. I'd use a Weiand Street Warrior intake manifold. It matches the operating rpm's of the camshaft.
Holley Performance Products Street Warrior™ Intake Manifold*8120

Last edited by techinspector1; 01-16-2013 at 01:24 PM.
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Old 01-16-2013, 01:16 PM
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Doesn't include the size of LSx's but will give you first gen's to compare against.

Popular American V8 Engine Dimensions

The only other thing to be considered is the LSx's are a one pc rear main and would require a flywheel for the same.Really not a big problem because of LSx's that come with T56's.Good thing is a hydro throw-out bearing which would make hooking it up to a master pretty easy.

The 5.3's can be had from pick and pulls for a range of $300 to $500.Then fashion a junk yard turbo off a import car.I don't think the external size of a LSx is any bigger than the first gen's.
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