Low power
09-12-10, 01:02 PM
#1
Junior Member
Thread Starter
Low power
I am having some issues with my 84 GSL-SE. It starts up, idles fine, and sounds good when I rev it without load. The issue is that when I take it out on the road it has very little power. It stutters and bogs a lot at take off unless I rev it up quite a bit and really slip the clutch excessively. Once I get rolling it just seems really low on power, and will not rev past 6500 RPM.
Here is a little info on the car: 1984 GSL-SE with a street port 13b. S2 12a irons, S3 13b housings and rotating assembly. The engine has 85 PSI compression with nice even pulses. It is a fresh rebuild with about 300 miles on it. I have a Weber 48 IDA carburetor with f3 emulsion tubes, 180 mains, 160 a/c, 70f10 idle, 120 idle holder, and 42mm ventures. Full Racing Beat exhaust, Mallory 70 series fuel pump and Mallory FPR set to 3 psi. DLIDFIS using 3 GM HEI ignition modules, 3 MSD blaster 2 coils, cheapo brand new plug wires and NGK BR8EQ14 plugs. Autometer tachometer set to 3ppc (6 cylinder mode) hooked to the (-) on the trailing coil.
All of these mods (aside from the exhaust) are brand new components with this rebuild. In hindsight probably not the best idea to do all that at once!
I believe I have the carburetor tuned pretty well. I do not have a wide band, but my dumb A/F gauge reads the last amber light before the green when I get on it. I am getting about 20MPG with this thing right now. The Tachometer seems to be pretty unstable, at idle it bounces around between 800RPM and 3000RPM but it evens out when the engine is revving up.
I am trying to figure out if the low power is due to an ignition issue or a carburetor tuning problem. Any suggestions on what direction I start digging at?
Here is a little info on the car: 1984 GSL-SE with a street port 13b. S2 12a irons, S3 13b housings and rotating assembly. The engine has 85 PSI compression with nice even pulses. It is a fresh rebuild with about 300 miles on it. I have a Weber 48 IDA carburetor with f3 emulsion tubes, 180 mains, 160 a/c, 70f10 idle, 120 idle holder, and 42mm ventures. Full Racing Beat exhaust, Mallory 70 series fuel pump and Mallory FPR set to 3 psi. DLIDFIS using 3 GM HEI ignition modules, 3 MSD blaster 2 coils, cheapo brand new plug wires and NGK BR8EQ14 plugs. Autometer tachometer set to 3ppc (6 cylinder mode) hooked to the (-) on the trailing coil.
All of these mods (aside from the exhaust) are brand new components with this rebuild. In hindsight probably not the best idea to do all that at once!
I believe I have the carburetor tuned pretty well. I do not have a wide band, but my dumb A/F gauge reads the last amber light before the green when I get on it. I am getting about 20MPG with this thing right now. The Tachometer seems to be pretty unstable, at idle it bounces around between 800RPM and 3000RPM but it evens out when the engine is revving up.
I am trying to figure out if the low power is due to an ignition issue or a carburetor tuning problem. Any suggestions on what direction I start digging at?
09-12-10, 02:09 PM
#2
Junior Member
Thread Starter
Well I caved and bought a timing light. Hooked it up and got some weird results. The timing marks on the pulley are not consistently in the same spot, they bounce back and forth and sometimes are not visible at all. I assume I am picking up interference between the magnetic pickups and the ignition modules. I am going to give some shielded cable a go.
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