Installed true duals (magnaflow with hi flow cats)on my '78 L48,4 speed.
Did I wake anything up or just SOTP?

 

You helped some but you won't see the best gains until you upgrade the air going in too.

Heads and a nice cam package will really liven it up, and combine that with a proper tune up and some timing.

 

Yep, starting for annother $1k you can get that kick in the azz your lookin for. You didn't waste any $$ tho, to get any kind of real power the exhause is a basic building block

 

QUESTION: Did you put headers on too?

Put on an Edelbrock Hi-Rise intake ($225) and a new Performer 600 Carb. ($275). Tri-Y headers ($399). That will REALLY wake the motor up.

 

If you really want to liven that engine up heres the kit for you...

http://store.summitracing.com/partde...8&autoview=sku

You will need headers and a good cooling system with this set up though!

 

And a I forgot to add a 750 DP Holley...

 

Thanks,great info

 

If it sounds faster then it is faster!!!!

 

I always have the t tops off as the open air makes it feel you are going twice as fast as you really are.

 

Sarah said that last night when we went for a drive. I was playing with the throttle a lot, and driving aggressively and she said she thought we were going 90 or something crazy like that and looked over and we were only in the 45-60 range.

It's true you do lose a sense of how fast it's going with all the extra senses finding things to distract them.

 

The neighbors???

GUSTO

 

Yes, some.
http://www.corvettefaq.com/c3/ganeyexhaust.htm

All you need in a carb is 600.
L-48 badly needs more cam.

 

Gee, I'm no expert but that sounds like an awfully big carb for this application.

I remember talking about this topic when we put a ZZ4 in my car nearly 10 years ago now. I was lucky. My husband is a car guy and so we had a few Holley carbs here at the house to experiment with.

We initially went with the 750 Vacuum secondary carb as recommended by GM but also tried some mechanical Double pump carbs.

I'm not expert enough to explain it fully but after a 750 double pump actually DETRACTED from the acceleration performance we tried a 650 double pump carb and found the perfect carb for my car.

In the end the 750 vacuum might have been the best compromise in gas mileage and performance. The 650 accelerated better.

The 750 double pump might very well make more power in the top end flat out on this mild performance street motor but at anything under 5500 RPM it was NOT as good. Both the smaller double pump carb and the vacuum actuated version of the 750 worked better.

Today I'm still running that 650.

My car runs 3.08 gears and an automatic transmission but even so I have a hard time imagining that if a 345HP, 10:1 compression engine can't make use of the extra breathing capacity a stock L48 some-how could.

 

I can't imagine you got much from the true duals...but air out means more air in to some extent - and I'm sure she sounds killer

More air in is the next step. A mild cam upgrade would be my first recommendation, or a bit more agressive cam with heads, intake and carb. Then converter, gears, etc. This is one of those budget things - best to start with what you can afford and what you want from that budget and let that drive your decisions. Otherwise you end up with a) a bunch of mismatched parts or b) a car in parts that sits in the garage