Bigger secondary jets??
07-04-2013, 12:12 PM
#1
Bigger secondary jets?? Ok I just swapped a proform 650 double pumper onto my 5.3 swapped 81 camaro and it has been running great but when I really try to hammer on it it wants to break up past 5500rpm ever since I raised rev limit to 6000rpm..
I swapped the stock truck cam for a stock ls1 corvette cam bc I had it laying around and all the dyno charts for vettes show them making power upto 5800-6000 rpm so I figured the 6000 rev limit would be good since still a 4 speed manual and would compensate for the drop in rpm when shifting...figured you carb guys would give me some much needed advice...
The carb is out of the box with a little idle tuning that's it here are the specs...
I swapped the stock truck cam for a stock ls1 corvette cam bc I had it laying around and all the dyno charts for vettes show them making power upto 5800-6000 rpm so I figured the 6000 rev limit would be good since still a 4 speed manual and would compensate for the drop in rpm when shifting...figured you carb guys would give me some much needed advice...
The carb is out of the box with a little idle tuning that's it here are the specs...
07-04-2013, 12:35 PM
#2
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Got a wideband? That's the only real time way to see if you need to adjust your fuel. This could be caused by a bunch of different issues ranging from wrong jets to bad plug wires or even bad fuel pressure or a ground. Does it do in in only high load situations like 3rd or 4th but not 1st gear, or all the time?
07-04-2013, 01:51 PM
#3
Ok I just swapped a proform 650 double pumper onto my 5.3 swapped 81 camaro and it has been running great but when I really try to hammer on it it wants to break up past 5500rpm ever since I raised rev limit to 6000rpm..
I swapped the stock truck cam for a stock ls1 corvette cam bc I had it laying around and all the dyno charts for vettes show them making power upto 5800-6000 rpm so I figured the 6000 rev limit would be good since still a 4 speed manual and would compensate for the drop in rpm when shifting...figured you carb guys would give me some much needed advice...
The carb is out of the box with a little idle tuning that's it here are the specs...
I swapped the stock truck cam for a stock ls1 corvette cam bc I had it laying around and all the dyno charts for vettes show them making power upto 5800-6000 rpm so I figured the 6000 rev limit would be good since still a 4 speed manual and would compensate for the drop in rpm when shifting...figured you carb guys would give me some much needed advice...
The carb is out of the box with a little idle tuning that's it here are the specs...
07-04-2013, 02:29 PM
#4
Yeah, you need a wideband to be sure on the carb. Jets look a little fat, I dropped the secondary jets down from 80 stock to 74. But that is with a wide band.
Lots of car mag articles showing truck motors start to experience valve float up around that RPM. Hopefully you upgraded the springs when you did the cam. LS6 springs can be had pretty cheap.
The caution on grounds is a good one. One member on here chased all sorts of problems until he powered the ignition box off a relay to a good +12v supply instead of using the power wire that went to the old HEI distributor.
Lots of car mag articles showing truck motors start to experience valve float up around that RPM. Hopefully you upgraded the springs when you did the cam. LS6 springs can be had pretty cheap.
The caution on grounds is a good one. One member on here chased all sorts of problems until he powered the ignition box off a relay to a good +12v supply instead of using the power wire that went to the old HEI distributor.
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07-04-2013, 10:31 PM
#9
It's just wild because my stock springs on my 98 let me spin to 6k with no problem, oh well it's not like a stock cam making that much more power 500rpm higher than what I'm at...I'm prob better off getting a posi rearend before that, the one wheel peel sucks lol
07-04-2013, 10:37 PM
#10
It may not be valve float, but it sounds like it. Its hard to say for sure. Maybe try another carb or play with it some
07-04-2013, 11:21 PM
#12
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I'd invest in a wideband before spending money on another carb. Also make sure it does it in every gear to rule out drained fuel bowls from a bad fuel pump. Good plug wires?
07-05-2013, 12:40 AM
#14
Ill def recheck everything, but when the limiter was 5500 you could hear it bouncing off the limiter, now it's just plain breaking up but ill check it again with laptop since its easy to do...and yes it breaks up in all gears...ill def have someone check my fuel gauge at carb when I rev it up, I never thought of that..duh!
07-05-2013, 07:12 AM
#16
I did swap out the stock springs on my 5.3 for some low mile take outs but who knows I haven't tested the spring pressure so they could have a million miles I don't know, but as soon as I start working my new engineering job I can finally get some parts to make this car rev to whatever I want lol...
