We are looking into getting a new high performance engine for our 1975 stingray any suggestions? Or help ?!!!!

 

I'm sure you'll get a lot of opinions - however the engine isn't the only consideration. The trans, rear and suspension need to be considered as well. I believe in '75 they still had cast-iron diffs - what kind of shape is yours in? Does it need to be rebuilt and beefed up to handle more horsepower? I don't know what kind of trans you have but if you're going to up the horsepower you need to make sure your trans is up to it. What about your ignition? Suspension?

My '80 came with a ZZ4 crate motor and Weiand 142 supercharger, headers and a 700R4 4-speed automatic that's been beefed up and a composite monospring. I don't think GM still sells that specific engine but I'm sure they sell units that are similar. It also came with a nice beefy radiator and dual electric fans. The 700R4 seems to be a good match. The weak spot is the stock aluminum differential, which I plan on changing out for an earlier and stronger cast iron unit. It could probably stand a stiffer spring and other traction aids. As is it's plenty quick for me - probably around 425 hp which is probably at the upper limit of what the non-forged powdered metal rods and hypereutectic pistons should be asked to handle, my guess is the 0 - 60 is somewhere between 3 - 4 seconds if I can get the tires to grab.

To support the hopped-up cubic inches you'll of course need some cubic $$.

 

Some good points above. My 77 came with factory stock engine, super T10 4 speed and iron diff with less than great internals and soft output yokes. I've put a fair bit into this over the years.
you wish to put more power to the ground. Not a bad plan as I believe the 75 model year was at the lowest ebb for horse power. But, how is the rest of the drive train and suspension? The car was built for something like 165 HP.
you may wish to budget for upgrades throughout the drivetrain as well as the suspension to make this work. Or, just wait to find the weakest link.
one after another.
Sounds like a lot of flatbed time to me.

 

hi my stingray was my grandfathers and was sitting in his garage for 30 years. It’s now 2020 and I’m looking for better performance and not having to service it a lot. Everything is leaking on the old engine and needs to be replaced

 

How fast do you want to go? Budget? Are you able to do any of the work yourself?

We will be more than happy to help you spend your money.

 

Do a lot of research before you unbolt anything or spend money. All the parts of the whole need to be considered - spend money on parts because you understand why you're spending it and how it fits into your project. It sounds like you're not necessarily a car person, there's a lot of theory to absorb regarding the engine, transmission and rear - obtaining such knowledge is a work-in-progress for myself as well.

I also should have mentioned the U-joints - they're not all created equally. Also, be aware that if your car has higher performance, there's also higher risk and ways to break it and break you. See the video below for a quick demonstration of how things can go wrong. Fortunately there were no other cars around so the idiot didn't have to buy a new car for some other people besides fixing his wrecked 'Vette...and having his insurance jacked sky-high or cancelled - or even worse go to jail because he killed someone. If you want further seminars on avoiding being stupid with a performance car search terms like "street race fail", "burnout fail", etc. - all these clowns who put lots of time and money into a car they didn't know how to control.

This site is a bucket 'o gold for information - a lot of very knowledgeable and helpful people as well as a vast archive of past posts.

 

first off that whole drivetrain was built to handle a 350 hp 350. so don't go replacing everything. replace the valve cover gaskets. there is most of your oil leaking everywhere. get the car timed correctly. 36 degrees at high rpm with vacuum disconnected. get a setback light and set it to 36 degrees. slowly raise rpm's until it stops advancing and turn distributor until timing mark is at 0. TDC. now read timing at idle. and then hook up vacuum and see how much it advances. this was the first year of cat converters. do you have to pass emissions inspection? if not next is exhaust upgrade. the best engine in the world won't make squat for power thru that single exhaust and that VERY FIRST DESIGN cat. you are gonna be much happier with the way it runs. these cars will tell you what to spend money on next. and before you do any of this, it has to stop better than it goes. so brakes.

 

If I was doing a 75 I'd go LS with associated drivetrain.

 

Me personally, I would re-build the engine you already have the way YOU want it. Keeping the original engine in the Corvette will always be a plus. I did this to my 1968 C3 with it's 427. I rebuilt it into a high Compression torque monster that is a whole lot more fun than the stock engine was. My C3 started life as a L71 Corvette and to this day retains the 427.

Just be careful as when you add horsepower there is a point where you need to stop adding power or the Corvette will no longer usable on the highways unless DRY weather is predicted. In the rain it is very hard to let out the clutch and go straight and that makes the car less usable on trips. Don't mis-understand me, the Corvette is a blast to drive and is fun in the hands of someone who knows how to handle a high horsepower engine.

If you keep your Grandfathers Corvette like it was it might be worth more. Here where I live near Washington DC I have seen lots of nice C5 and C5 Z06 Corvettes selling for less than $10k. The nice thing about these cars is they are reliable, powerful and are getting cheaper by the day with the C8 out there now. It is very easy to spend $10k when building a nice engine. The more you know about engines the more you can save by doing it yourself.

Don't rush as it cost more that way. Taking your time and sourcing exactly the parts you want can save you a lot of money. Also remember to save and store all the parts you remove from the Corvette, this way it can be made original again if somebody wanted to. I have boxes and boxes of original parts stored away in sealed bags.

 

Budget to only acquire motor ?

 

if so, budget would be better spent on bushings, u-joints. brake hoses, maybe calipers, maybe valve seals, definitely valve cover gaskets, vacuum advance canister, springs and weights... tires? what is the date code on em? exhaust. you can't throw 4k at a motor until you find out if the motor is the problem. or if it is all the stuff that doesn't come with a motor. and until the exhaust is good enough.

 

I was in a similar position 2 years ago. I had just taken possession of a 1975 C3 that had been purchased new by a much older family member although mine operated more/less fine with no major issues. Even still I wanted a new engine to replace my 165hp L48 the lowest hp unit ever offered in a C3.

I very nearly went with an LS conversion as suggested above. In the end I wanted slightly less of a project so I went with a new ZZ6 350 crate motor from GM. Not inexpensive however it bolted in and says Chevy on it. Made right here in North America (cough Mexico cough).

My engine was basically turn key and works flawlessly. There are about 9000 other options to pick from so best of luck with your decision. As others have suggested you might consider replacing, rebuilding or upgrading each and every other mechanical component of the car.

 

More information would help to make a recommendation.

Do you have the original engine?
Do you have the original transmission? Is/was it a manual transmission or automatic transmission?
What do you plan to do with the car? Is it a driver/cruiser for cruise ins and local shows? Will you want to drag race it? Autocross?

If you have the original engine and transmission, it's almost always easier and less expensive to repair/rebuild with performance parts.

if you don't have the original engine and transmission, I'd shop for an LS swap. Good power, good economy, light weight (get an aluminum block, not a truck cast iron one). There are wiring harnesses available from aftermarket sources to install those engines in "classic cars" which make the swap fairly straightforward.

 

Budget?

 

I should also add that when contemplating where your money is going to go, before the engine your first priority needs to be making sure the car is safe to drive. What kind of shape are the brakes in? If it's been sitting for 30 years, the whole system needs to be looked at - master cylinder, booster, brake lines, calipers - if rust has gotten in the parts needs to be refurbished or replaced. Steering and components? Rag joint? Wheel bearings? Ball joints? If rubber suspension bushings have been sitting for 30 years they're almost surely going to need replacing. What kind of shape are the trailing arm bushings in? All that stuff needs to be solid to be able to align the wheels. Horn? Lights? Windshield wiper?

Then there's things like the windows, door locks. Special tools like a dolly for the doors if you want to take them off and take them apart to work on the door/window mechanisms and then putting the door back in place and getting it correctly aligned. Weather seal around the doors and T-tops.

Btw, have you investigated what kind of shape the "Birdcage" is in? I.e. the steel structure surrounding the passenger compartment - that can be a problem with C3 Corvettes, depending on how much water exposure it's seen. If it was consistently kept out of the rain, it's less likely to be an issue. Look up that term on this site to see endless threads about how to check this - and the frame as well.

When you've assessed everything that needs attention, then see what kind of drivetrain budget you can swing. It can be a heck of a project.