79 vette 383 seems slow
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
In terms of importance with your current combination:
1. Ignition timing curve
2. Air-to-fuel ratio (carb tuning)
3. Exhaust and or intake restriction
Depending on the above and your compression ratio, a 383 should benefit with a cam about 5 to 10 degrees longer in duration.
1. Ignition timing curve
2. Air-to-fuel ratio (carb tuning)
3. Exhaust and or intake restriction
Depending on the above and your compression ratio, a 383 should benefit with a cam about 5 to 10 degrees longer in duration.
Instructor
Joined: Jul 2011
Posts: 142
Likes: 1
From: Fort White Florida
How big are the tubes on your headers? I had a 86 Z-28 that I raced with a 383 in it. I had 1 5/8" headers. I talked a head pro about beefing up my heads he said he could rework the heads but the biggest problem was the small tubes on the headers. He recommended a minimum of 1 7/8" but 2" would be the best. Said the 383 engine couldn't breathe with the small tube headers. I put 1 7/8" headers on and gained .5 sec in the quarter mile.
Thread Starter
Instructor
Joined: Nov 2011
Posts: 105
Likes: 0
below is a link to a thread where i posted the build sheets i got for the engine when i bought the car. it has compression data and timing data. this sheet and the data already posted is all i know about the engine
http://forums.corvetteforum.com/c3-t...m-my-79-a.html
http://forums.corvetteforum.com/c3-t...m-my-79-a.html
Last edited by usnfenix; Dec 19, 2011 at 04:41 PM.
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Thread Starter
Instructor
Joined: Nov 2011
Posts: 105
Likes: 0
How big are the tubes on your headers? I had a 86 Z-28 that I raced with a 383 in it. I had 1 5/8" headers. I talked a head pro about beefing up my heads he said he could rework the heads but the biggest problem was the small tubes on the headers. He recommended a minimum of 1 7/8" but 2" would be the best. Said the 383 engine couldn't breathe with the small tube headers. I put 1 7/8" headers on and gained .5 sec in the quarter mile.
Drifting
Joined: Jul 2005
Posts: 1,623
Likes: 30
From: The Netherlands
Let me get this straight:
- When you're at a stand still and then floor it, the car flies.
- When you're cruising and floor it, it also flies.
- When you're cruising and give throttle normally/gradually to increase speed it bogs down and/or picks up slowly.
Correct?
The bogging down, more so in the lower speeds? Or also when cruising at 60 mph?
- When you're at a stand still and then floor it, the car flies.
- When you're cruising and floor it, it also flies.
- When you're cruising and give throttle normally/gradually to increase speed it bogs down and/or picks up slowly.
Correct?
The bogging down, more so in the lower speeds? Or also when cruising at 60 mph?
Thread Starter
Instructor
Joined: Nov 2011
Posts: 105
Likes: 0
Let me get this straight:
- When you're at a stand still and then floor it, the car flies.
- When you're cruising and floor it, it also flies.
- When you're cruising and give throttle normally/gradually to increase speed it bogs down and/or picks up slowly.
Correct?
The bogging down, more so in the lower speeds? Or also when cruising at 60 mph?
- When you're at a stand still and then floor it, the car flies.
- When you're cruising and floor it, it also flies.
- When you're cruising and give throttle normally/gradually to increase speed it bogs down and/or picks up slowly.
Correct?
The bogging down, more so in the lower speeds? Or also when cruising at 60 mph?
so to answer, from any postion, flooring it gives you literally a 2 second burst of hell yeah then boggs down considerably
Last edited by usnfenix; Dec 19, 2011 at 05:01 PM.
Thread Starter
Instructor
Joined: Nov 2011
Posts: 105
Likes: 0
i dont know about the gears but i will say the rear looks like it hasnt been touched since 79, safe to assume stock gear ratio.
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
standing still and floor it, it roars and throws you back but a second later your sitting there like WTF? why didnt that acceleration go anywhere or continue? same thing from a roll. lots of noise but no go im telling you in a dig race id be fearful of pretty much anything. my camaro with only 340rwhp would rape this car.
so to answer, from any postion, flooring it gives you literally a 2 second burst of hell yeah then boggs down considerably
so to answer, from any postion, flooring it gives you literally a 2 second burst of hell yeah then boggs down considerably
Burning Brakes
Joined: Feb 2006
Posts: 1,223
Likes: 5
From: Regina Saskatchewan
I'm no expert but I'm suspicious of that origional torque converter. If its weak it might be slipping. I'd look at replacing it anyway with a quality aftermarket higher stall. 2500 stall fine for the street.
Advanced
Joined: Aug 2007
Posts: 66
Likes: 4
From: Perth, Western Austraila
hi there, I have the same feeling lack of power with my 81, 383, 700r4, 3.54 gears stock size converter 2200 stall,
Sure first gear is great lights up the tires but floor in in drive or leaving in 2nd or 3rd isnt that great . So after all my disspointment i ran it at the track 13.2 @ 103 i've since changed to an air gap manifold and tuning and run 12.5 @ 111 these seem to be pretty decent though my car still feels somewhat docile, I say run it at the track if you can to satisfy yourself, you maybe suprised. Yet I've been in cars that run high 13's that felt quiet scary and alot more powerful on the street. I've just had a custom 9.5" converter built and just about to install it , I hope to post results in near future
Sure first gear is great lights up the tires but floor in in drive or leaving in 2nd or 3rd isnt that great . So after all my disspointment i ran it at the track 13.2 @ 103 i've since changed to an air gap manifold and tuning and run 12.5 @ 111 these seem to be pretty decent though my car still feels somewhat docile, I say run it at the track if you can to satisfy yourself, you maybe suprised. Yet I've been in cars that run high 13's that felt quiet scary and alot more powerful on the street. I've just had a custom 9.5" converter built and just about to install it , I hope to post results in near future
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
Checked your fuel pressure under load?
What pump are you using?
Not a big cam for a 383 meaning its not going to scream up top like your LSx should still run strong though.
What pump are you using?
Not a big cam for a 383 meaning its not going to scream up top like your LSx should still run strong though.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Nothing new here.
#1 Timing curve, Set up according to Barry K's Tech article
#2 Vacuum advance can, Again get the correct can for your setup, Read Barry K's tech article on this.
#3 Make sure your throttle plates are opening fully. This sounds like a no brainer but you would be suprised how many cars I have seen that swapped out the carb and didn't get this right.
#4 A/F ratio. Difficult to get right without an A/F meter but again there is a tech article on this.
Many good builds are done that the owner installs the engine and slaps the distributor and carb back on without making the neccesary adjustments to accomodate the internal engine changes then wonder why they don't get the performance increase they expected.
#1 Timing curve, Set up according to Barry K's Tech article
#2 Vacuum advance can, Again get the correct can for your setup, Read Barry K's tech article on this.
#3 Make sure your throttle plates are opening fully. This sounds like a no brainer but you would be suprised how many cars I have seen that swapped out the carb and didn't get this right.
#4 A/F ratio. Difficult to get right without an A/F meter but again there is a tech article on this.
Many good builds are done that the owner installs the engine and slaps the distributor and carb back on without making the neccesary adjustments to accomodate the internal engine changes then wonder why they don't get the performance increase they expected.
