NassyVette

My 75 isn't numbers matching, and I know it's not a stock 75 engine but I haven't had a chance to dyno yet. So what I'm wondering is why are the 75's rated at 175hp stock. And what can you do to bring up the hp to around 300? Would a heads/cam/emissions removal work? Any other ideas? Lets hear some of em, and why the 75's are so low in hp.

Thanks :seeya

SuperFast80

Exhaust, compression, cam. Bad, bad, bad.

To fix the first one see this: http://www.corvettefaq.com/c3/ganeyexhaust.htm

To fix the next two, REBUILD. :yesnod:

TJRed76

Yellow75,

Mid 70's vettes were tuned down due to the political preasures of the gas crunch and introduction of smog legislation. Your ideas will certainly make a difference.

TJRed76

Jasonty

Your 75's power was lowered just like my 81 which had 190hp stock. I found that the compression ratio was about 8.5:1, and the cam was very mild. A 383 stroker kit, a set of weiand aluminum heads, and a nasty cam solved my problems. ;) I don't know how much HP I'm pushing now, but I'm sure it's over 300. :reddevil It won't cost too much to raise your power far past 175hp. But look at it this way, the 75's look great. :cool: :cheers:

SteveG75

Actually 165 HP for the stock L-48.

Easy to fix though.
1. Better exhaust. Headers with true duals if emmissions allow, or emissions legal headers with a big cat.
2. Swap manifold. Edelbrock 3701 Performer w/ EGR smog legal.
3. Swap cam. The Crane cam I have in the engine right now is legal with CARB.
4. Recurve distributor, adjust carb. May have to readjust at test time to pass but put it back when you get home.

With the mods in my sig, Dyno2000 says 335 HP, 360 ft lbs. I take that with a grain of salt but the old motor is now out and I just have to decide what is going in there now. :smash: :smash:

tnt76vette

See my sig....was a stock 76 L-48, now desk dynos at 275HP with just these mods...... :yesnod: :flag :seeya

SuperFast80

[Modified by SuperFast80, 6:09 PM 1/12/2002]

Captain Morgan

:yesnod: :cheers: :yesnod:

I haven't had mine on a dyno yet but I know the exhaust will make a tremendous difference. That is, if you can change it in your state. If nothing else, at least use a larger, free-flowing cat. If you take the cat off your vette and look at it, you'd be shocked at how restrictive it is. Better yet, here is a pic of what it looks like.



Or you could hypothetically unbolt it, remove metal blocking entrance and exit and then dump out the beads. But that would be illegal so I'm not suggesting that you do that. Just telling you that it's possible. Of course, that causes problems in itself because then you have a huge cave that causes turbulence in the exhaust but it's still better than the stock restrictive cat.

Another choice is to buy a converter "test pipe" (probably have to have it built) and then swap the converter back on when you get emissions tested. This is a decent idea since it's pretty simple to bolt and unbolt your converter. Although this idea would be considered illegal also, so I'm not suggesting that you do it.



[Modified by sharklover, 5:37 PM 1/12/2002]

BubbaJJ

16+ second car stock: geez honda civics do that out of the box. I had the same problem with my 75. Base L48. A Comp Cams 270 H, a set of mild ported SR Torquers, and a Performer RPM got me down to 15.2. I still have to get rid of the stock exaust. The guy that built my engine said that a free flowing dual exaust set up and a shorter set of gears should put it down into the 13s. Oh yeah, I also have a set of 10/1 flat tops. With the 67cc heads it should be right around 9.5/1+-.

corvettemaster

That's what I hate about the late shark generation. Very low power. My '81 stock would have had 190 hp :eek: . My exhaust has been changed and a few other things, and I have around 235 hp now, which still sucks. This summer I am planning to rebuild my engine and do several things the above members have mentioned, such as cam change. I am hoping by time I get done, I'll be right around 350.

Ganey

Steve
You're close. For ex.
Better heads like SR Torquers 2.02/1.60 (w/ 268H) about 335 HP & near 400 TQ.

tnt76vette
You're close. For ex.
Better heads like SR Torquers 2.02/1.60 & exhaust (w/ 260H) about 312 HP & near 400 TQ.

:cheers:

tnt76vette

Ganey, thanx for head recommendation......all things in due time...LOL :seeya Corvettmaster, I like later sharks 'cause they are relatively cheap and soooo easy to "warm up".....my .02 :seeya


[Modified by tnt76vette, 9:36 PM 1/12/2002]

Matt M

here's an option- what I did to my '75




Matt

Vetterodder

Matt, how about some more details? Performance? Any problems? Cost?