gyalanis

I have a 65 convertible with a fairly stock 327/300. The motor is tired and in need of an overhaul. I would like to add some performance to the motor but not compromise the value of having an otherwise stock motor in the car. I guess my question is, how far can I go with modifications? At what point have I "ruined" the value of the stock motor? Is it enough just to have the the motor block that belongs with the car in the hood?

Any suggestions?

Vetterodder

The single biggest increase in power while retaining a stock appearance would be a better cam. Something like the L79 cam would provide a nice boost without requiring a bunch of other mods to do so. Pocket port the heads. Also, if you haven't already done so, recurve the distributor to bring in the advance sooner.

gyalanis

That's a good suggestion. Have you done this mod before? Do you know what kind of increase in horsepower it will give me?

Vetterodder

I went well beyond those mods on my `65 and gained a bunch of power but there is no way that anyone would mistake the engine for a stock one. With the mods I suggested you could expect a peak power increase of about 15%. Though the distributor recurve won't add any peak power, it's improvement in low and mid range power should be impressive. If you are looking for a more dramatic power improvement, you'll need to rethink the "stock looking" thing.

Donny Brass

I took my 300 hp motor out and built a stock L-79 .030 speedpro forged 11:1 pistons, blueprint L-79 camshaft, 2.02 heads unground on, 049 intake, nothing fancy or expensive

I make about 272 rwhp based on 1/4 times..............

MosportGreen66

There are several ways you could go with this.
1- Keep the original block but put on new heads, intake/carb setup.
2- Buy a new motor, throw it in the car and keep the original parts
and engine to the side.
3- On a smaller note, do a intake/carb setup - (intake, carb, distributor).
4- On a very small note, you could do headers into side pipes.

Kensmith

If you don't want to do any major work to the pistons, crank, block or lower end of the motor, your biggest improvement will be to let the motor breathe better. Call Comp Cams help line (check the internet for numbers). They can help match up a roller cam based on what you need. You will need to port and polish the heads and maybe even increase the valve sizes. Also port match the intake maniflod to match the heads. Make sure the gasket is also matching so no lip between the openings. Add a nice set of roller rockers, I like the Harland Sharp but you may want the Factory look. I think Crane makes stock looking rollers. Make sure you have hardened pushrods and check the valve spring rates as they may need replacing depending on the lift from the new cam. Re-jet your carb, add a nice set of headers and flow through mufflers and maybe even add a double roller timing set. This could increase HP by about 25 to 30%.

NINETNINEVETT

I have a 65 327/300.hp car the only mod is duntov cam and solid lifters runs great sounds awsome with the solid lifters. With the duntov cam which is period correct It sure wont hurt the value any. All numbers that you can see match. This is a great set up. Mike

62fuelie

I would install a L79 cam along with a good 3 angle valve job. I would probably also install a L79 intake and carb, since these are something that can be easily put back stock. I would not try to go to the 11: compression. You can make good power on the flat tops and save a lot of potential hassle. If you want real serious HP, bag the original engine and install a crate 350 or 383.

gyalanis

I like the idea of being able to add that much horsepower. Will these changes change the sound of the engine? I am also thinking that I will add sidepipes to the car. Most importantly...do you have any idea what work like this costs?

gyalanis

do you feel as though you've gained a lot of performance with this mod?

gyalanis

With all of the different options, I am not sure how to go about making a good decision on how much to do. I would like to be able to retain my stock carb, and will probably be adding side pipe exhaust to the car. I guess I'm looking for the best bang for the buck without unnecessarily going overboard...

gyalanis

How does 272 rwhp compare to the stock 300 engine horsepower?

jerrybramlett

What rear end ratio is in your car? Most of the folks posting are talking about power improvements in the 3,000 rpm plus range. If you have a 3.36 rear and spend 99% of your driving time below 3,000 rpm, you might want to scale back your modification plans.

How much do you value a low maintenance engine? Holley carburetors and solid lifters require periodic maintenance. That is just a fact of life.

Do you believe you can get "something for nothing" with a cam swap? If it was possible to improve both low end torque and high end power in sixties 327 Chevy with just a cam swap, all of us would have done it to our cars a long time ago.

There's no substitute for cubic inches. If you really want to feel a difference, install the largest displacement crate engine you can afford with a mild cam. You can save the original engine on a stand for the next owner. And yes, there will be a next owner. Nobody lives forever.

Kensmith

If you add the headers and MagnaFlow type mufflers, yes the sound will change. With a mild to medium cam you can pick up a nice lope. I took a 350 crate motor and did the changes and improved hp from 250 to 420 but I changed heads to Edelbrock RPM 64cc aluminum, Edelbrock RPM airgap intake, large tube headers, and a bunch of other stuff. BIG difference when the motor can breathe. Cam and heads made most of the power. If you don't want to keep the original 327, do a 383 stroker motor.

Donny Brass

here are a few threads to read on the subject

http://forums.corvetteforum.com/show...um_id=4&arch=1

http://forums.corvetteforum.com/show...um_id=4&arch=1

http://forums.corvetteforum.com/show...um_id=4&arch=1

Geek's 65

gyalanis - Go back a couple months in Corvette Fever - near the back of the mag - they had an article on 10 things you could do to your motor and still look stock. Was simple (for those like me with that simple mind) but well written and includes a whole lot of what those here in the forum are talking to. Told you how much you could expect to gain in horsepower (percentage) for each mod. Certain someone here can tell you the exact month. Sorry I am not where my library of Corvette stuff is.

GOSFAST

Recently finished 350/300 HP SB for 1969 restored Camaro. Had to use all original components, to keep factory appearance. Lowered C.R. to 9.2:1, "dusted" ports and bowls, tested with cast-iron exhaust manifolds, and used the factory L82 cam(224/224-.450/.460-114L/S). Came off dyno with 355+HP and 385+Ft.Lbs. Car has been in many shows with no problems, runs in cool weather on 89 octane. I realize yours is 327, but should be fairly similar. It depends on whether or not you want the car 100% original appearing. You actually have the option to build it much bigger (inside) also, still using all OEM parts, in which case I could see near the 380HP/400HP numbers with some serious torque readings and still run on 92/93. Thanks, Gary in N.Y.

wesmigletz

I think you've gotten a lot of good advice here. If you want to use your original engine, I would build a stroker. I've already gone this route with my 59's 283 and am about done with it.

Speed-o-Motive offers a small journal stroker crank. Other crank/rod assemblies are available as well. I would run a six inch rod which will allow you to run a lighter piston, which in turn will let your engine be internally ballanced, which will allow you to run your stock crank damper and flywheel/flexplate. The block will need some clearancing. On the 283 we had to turn the counterweights down as well. From there, I would run a fairly mild cam of choice... L79, LT-1, or what your favorite cam company recommends; be sure the cam matches the rest of your combination. The importance of a free flowing exhaust cannot be understated, be it behind 2.5" ramshorns or small tube headers.

I would have the heads nicely ported, a more thorough job than a quickie pocket port. I would then top it all off with the factory aluminum intake and carb for your model year. You may even be able to squeeze a later Z/28 intake under your hood with a drop base air cleaner. From there, it's just a matter of dialing in your fuel and timing curves.

Having said all that, I would seriously consider storing your engine and selecting a nice GMPP crate engine.

gyalanis

This sounds like a nice option. You are one of several who have recommended storing the original 327. I am having trouble with that entire concept. What is the purpose behind storing that engine vs. modifying it to be a higher performance driver? Is is so that I retain a certain "re-sale" value of the car to a specific buyer? Is it because I can't get real performance out of the engine without totally altering the original character ( inside and out) of the engine? I think my gut somehow tells me that I would like to have all of the car parts in the car and take advantage of them to the fullest extent without totally compromising the "originality" of the corvette. Reality (for me) is that I have a driver which is in very nice condition. I will never make it a show car because I'd like to use it as often as I can when the weather is nice. I will probably add power steering to the car, modify the the exhaust to add side pipes, and add knock off wheels as well to this base model car. There is a part of me though that does not want to change the car so much as to deter the next guys enthusiasm for the way it has been modified as a Corvette and with corvette parts.

That being said, how can I move forward, and at what point is going too far with the engine?

confused.