Classic Engine Tech 1967 - 1981 Engine Related

New car 79 Z28, know nothing about carburated engines. Bad tune?

Old Oct 27, 2004 | 09:19 PM
  #1  
ShawnMacAnanny's Avatar
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New car 79 Z28, know nothing about carburated engines. Bad tune?

Ok i just (like 2 hours ago) bought a 1979 Camaro Z28. The top engine of the engine has 2,000 miles on it, and the bottom end has 6,000. I paid 1800 for it. It has a 350 Turbo trans (i think, 3spd) and a 355. Here are the mods.

Performer RPM cam
Holley 750cfm Carburater
Trickflow heads
Perormer RPM intake (i think)
Fuel pump of some sort (can't have a gas cap)
2400rpm stall
3.42 rear gears
Headers of some sort
Blue spark plug wires (not sure what kind of dist.)
ET street rears on weld rims and 4" front on weld rims

.. and i forgot what else. I can check in the daylight, but didn't get the chance tonight.

Problem is is this car seems slow. I have a pretty much stock 1995 Firebird Formula, 5.7L LT1 with an 4L60E (A4) into a stock stall (1500rpm) and 2.73 rear end gears. And the formula seems much faster.

I was told the Camaro i bought needed the carburater tuned. It dynoed 278rwhp, 349rwtq untuned. Shouldnt it be making more power? The cam in it seems pretty rough. I had my dad look at it since i didnt know how to tune a carb, and he said the adjuster screws were backed out so far it looked like they were going to fall out. Any ideas of what i should do?
Old Oct 27, 2004 | 11:07 PM
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Re: New car 79 Z28, know nothing about carburated engines. Bad tune?

throw out that 750 and put a 600 or 650 on it carb is too big to start then go from there
Old Oct 28, 2004 | 11:00 AM
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Re: New car 79 Z28, know nothing about carburated engines. Bad tune?

Originally Posted by spinout
throw out that 750 and put a 600 or 650 on it carb is too big to start then go from there
I agree, you got too much carb and with the adjustments all the wayout, probably too rich. Do you bog down when you take off or smell gas at idle from the exhuast?
Old Oct 28, 2004 | 04:32 PM
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Re: New car 79 Z28, know nothing about carburated engines. Bad tune?

The previous-previous (the one who built it, they're both in my car club) owner assures me that this is the right carb for it. He says it makes all it's power at top end. My dad and I re-adjsuted the screws today. They were 1 1/4 turns out. It idled around 400-500 rpm in gear, now it idles around 800 in gear, 1,000 out of gear. It's also much smoother. As for bogging down, no it doesnt bog down. I do smell exhaust but i have no cats, and i have two exhaust leaks that i can see.
Old Oct 29, 2004 | 01:33 PM
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Re: New car 79 Z28, know nothing about carburated engines. Bad tune?

Your engine combo is not to radical, so 650 should be the most you want on that. Since you've adjusted the mixture, you need to adjust the idle, 1000 is too high not in gear. You should be around 700-800 in gear and 480-520 in gear.

Cats or no cats you shouldn't smell a strong exhaust smell if your properly tuned.

Also is your Holley Mech or Vacuum Secondary?
Old Oct 29, 2004 | 01:39 PM
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Re: New car 79 Z28, know nothing about carburated engines. Bad tune?

I was told today by a guy who does nascar or something like that(he was actually backing a NASCAR out of the trailer and came to see my car), that mine has a vacuum secondary. The cam is small, but i was told i should not go above 500 lift with the Trickflow heads. What new cam would you recomend? Also i have a header leak at the heads and at the exhaust, and the main this in my block seal (the one around the crankshaft) is leaking pretty badley it looks like.
Old Oct 29, 2004 | 03:06 PM
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Re: New car 79 Z28, know nothing about carburated engines. Bad tune?

I Like Comp Cams Extreme energy series. You can go over .500 lift if your studs are screw in, which I think Trick Flow does use screw in. But the biggest under .500 is .480 in the extreme series. Anything over .500 you get that "race car" type real lumpy idle, you'll also need springs to handle the extra lift.
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