Performance options for an LG4? - Page 2 - Carburetors - Third Generation F-Body Message Boards

naf · 09-13-2006, 12:13 PM

14 mpg and poor power indicates that something in the computer controlled system is not working correctly. Probably easiest and least expensive to find the problem and correct it, rather than swapping all new/different parts on top (carb/dist). A properly functioning ccc-qjet system is not going to keep the motor from making power.

Pointless? I average around 23 mpg in my 85 TA. My camaro with a 350 gets around 18-20 mpg with the ccc-qjet (but it's a compromise between better performance and economy).

If you want to fix what you've got, why not start a new thread? If you HAVE to remove it, four bolts and a lineman's pliers.

85t/alover · 09-13-2006, 09:31 PM

i really want to see what i can do with this 305. the previous owners replaced the engine around 15,000 miles ago so fairly new engine. hate the expense of another engine when this one is fine. should i go with three inch exhaust straight back or use 2 1/2? i am used to mustangs and they always use 2 1/2. it seems like three inch would kill torque. maybe i am wrong. thanks for all your help.

85t/alover · 09-13-2006, 09:40 PM

i remember a couple of the many codes the computer was throwing around. (yes i know how to do that. lol) one said the o2 sensor read rich and another said lean at cruising. then another said temp sensor was reading low and high. i replaced that sensor. should i reset the computer if that was the problem or should the check engine light go off by itself? i dont remember all the codes. i am at work and work 24 hour shifts on an ambulance. i will post the other 400 (lol) codes when i get home tomorrow but any info on these would be great.

naf · 09-14-2006, 06:37 AM

Check engine light will go out on it's own when the code is no longer present but will continue to store the code in it's memory until it's reset. Post your other codes and we'll see.

85t/alover · 09-14-2006, 10:10 AM

last night at work i reset the computer. now the only code showing up is a code 34. i thought it meant the map sensor since i notice there was NO vaccum going to it but apparently i was wrong. the other codes that were on there arent there now. i replaced that temp sensor so i wonder if that didnt fix some of the problem. according to haynes repair manual a code 34 for carbs means differential pressure sensor. went to chevy and pontiac and they dont even list one. the only thing they list is mdp manifold differential pressure sensor. and they want 83 bucks for it. i hate to spend that kinda money and not know that that is even what i am looking for. thanks again. i know all these questions must have been asked before but i really appreciate your time.

trumps2000 · 09-14-2006, 11:19 AM

I believe its all refering to the same thing. I often call it a MAP sensor myself, but I think GM's term is the most correct. These cars have barometric pressure sensors located on the passenger side next to the heater core and MAP, VAC, Manifold diff press, whatever you call it, next to the brake booster on driver side.

I would recommend checking yours out first. If there is a hose remove it and check for clogs. Then reinstall it and use a vacuum guage to check for leaks in the hose and sensor. Then with the car idling check the voltage at the connector. You should see ~4-4.5V while Idling I believe. If the Hayes manual doesn't list the pinout I could look it up for you when I get home.

85t/alover · 09-14-2006, 01:15 PM

the vac hose was disconnected from the sensor near the blower on the passenger side of the engine bay. i was under the impression that was the map sensor and the other one was the baro sensor. i did not have a rubber hose to go back on last night at work so i used oxygen tubing. i don't think that is strong enough to handle the pressure but thats all i had last night. it was holding up but still the light was on. so i am guessing the sensor is just bad. i guess i will try and replace it and see what happens. all the other codes it was showing just stopped flashing after i reset the computer. i commute 80 miles one way to work. so it had 80 miles to pop back up but didnt. the car seems to run alright except crappy acceleration. i know the exhaust is worthless. my step dad rebuilt the carb. before he did it smelled horribly like gas. so maybe the com just needed to be reset. also, i do not have a belt going to the emissions pump at the bottom of the engine. is this ok? i was trying to get more power and figured it was sucking it down. thanks again.

naf · 09-14-2006, 03:22 PM

The baro sensor and the map are the same piece, the MAP sensor, on the driver's side firewall, is connected to the carb by a vaccuum line (hard plastic). The baro sensor does not have a vaccuum line connected. The ecm takes a reading of atmospheric pressure from the baro sensor to "normalize" the map sensor readings (adjust for changes in altitude, etc.). The plastic vaccuum line (plastic allows the sensor to read more accurately because it won't flex like rubber vaccuum lines) from the map sensor (near master cylinder) should be run through convoluted tubing with part of the wiring harness, up from behind the dist into the rear of the carb.

85t/alover · 09-14-2006, 03:32 PM

so don't connect a hose to the nipple on the other sensor? the one near the blower motor?

naf · 09-14-2006, 03:36 PM

Don't connect a hose to the nipple on the other sensor, the one near the blower motor. Correct.

85t/alover · 09-14-2006, 07:18 PM

hey where are you at in lexington? i work in west cola at mobilecare. i used to work for lexington county ems. if you are going to be around this weekend i thought we might meet up and if you didn't mind check out my car. let me know. i will be there all weekend.

naf · 09-14-2006, 09:12 PM

I live over near White Knoll Middle School off Kittywake. I'll be around most of this weekend. Where're you going to be at and when? As long as your TA is not black and gold I can probably break free, can't have two of them occupying the same space...end of the world stuff.

85t/alover · 09-15-2006, 05:37 PM

i am in red bank. my grandparents church is white knoll baptist church. and yes my car is gold and black

aww it'll be alright! promise. you can give me a ring on my cell. i am at my g-mas this weekend with my kids. my # is 803-467-5400. call anytime. maybe we can catch up tonight or tomorrow. thanks man. ttyl

Kevin84Z28 · 09-16-2006, 10:03 PM

Quote:

Originally Posted by Fast355

I will add some info to sofakingdom's advice.

A.) If you decide to port the heads, I would pick up a pair of 601s from the wrecking yard. They are like mini 462s in the chamber, have better flowing ports than the 416s stock, and have a 52 cc chamber. That will bring the otherwise stock LG4 from 8.6:1 compression to about 9.2:1. This will add compression and flow, which will increase HP.

B.)The CCQ-Jet is VERY adaptable by changing out mechanical parts and settings. The limiters on the mixture control solenoid can be adjusted to put out the correct air/fuel ratio on the primaries. There are many different primary jet/metering rod combinations from the general. Some cars came with big jets/big rods(V8 4bbls) and some cars cam with smaller jets and smaller rods(V6 2bbl such as the 3.8). Dual Jet metering rods and jets will swap to a Q-Jet. Combine the bigger jets with the smaller rods and viola, more fuel flow on the primaries. Don't worry though as you can set the limiters. The secondary metering rods and jets can be tailored to provide the best WOT power.

C.)If you could find a L-69 chip, they are best for performance and could actually increase the fuel mileage some. Short of a L69 ECM or chip, you might find that boosting the base timing to between 4-6* will add performance and MPG.

A problem I found when using different sized rods on my CCQ-jet was that the Throttle Positioning Sensor would not seat right and was always sending the ECM a signal of 5.0v (wide open) at idle, instead of the proper .05v. It ran O.K. but couldn't get it passed smog and the mileage sucked.

85t/alover · 09-17-2006, 07:40 PM

thanks to everyone. especially naf. you all have been a great help. finally got it running without a check engine light (thanks again naf) and now the search continues for more power.

well, i will be here so just holla whenever.

85t/alover · 09-18-2006, 02:41 PM

alright here goes more questions. on my way home today, i took off suddenly from a stoplight and after it shifted to second gear, with the pedal at wot, it started stalling like it couldn't fire anymore. i let off and it stopped but putting the pedal back down again caused the same reaction. naf, you've seen the car and engine. i take it its not the timing because we set that. could it be the coil or ignition module? wires, plugs, cap, and rotor button have all been replaced. here i am asking for help again.

thanks all.

naf · 09-19-2006, 09:19 AM

Most likely fuel starvation. Any changes to carb/filter/etc. recently?

85t/alover · 09-20-2006, 08:24 AM

naf, i forgot that you said it looked like the fuel line to the pump was leaking. that could very well be the problem. i am thinking about switching to an edelbrock pump anyway. by the way, i lost your number. call me back sometime so i can lock it into my phone. thanks:-)

naf · 09-20-2006, 11:27 AM

You can pull the fuel line off at the carb and check for flow and pressure while it's idling (should idle a minute or so with fuel left in carb). Should put out around 5.5-6.5 psi (with vapor return line clamped) and about a pint of fuel in 30 seconds. I'd hate for you to replace the pump to find out the filter was clogged.

If you have to replace the pump, you can pick one up a AZ or the equivalent for around $15. Save the money towards something that will make a diff.

85t/alover · 09-20-2006, 05:11 PM

cool. i will definately try that. i think i will try just pulling the fuel lines off and putting more teflon tape on them. i think it is leaking a little bit and if it is sucking air then that will definately make a difference. thanks

trumps2000 · 09-20-2006, 05:52 PM

Don't put any Teflon tape on the fuel lines, it won't do anything but make it harder to tighten. I used do that too.

The sealing surface is the 45 degree inverted flare at the end of the tube that mates with the carb's flare. If its leaking I would tighten it a little bit.

naf · 09-20-2006, 05:56 PM

You can check your rubber fuel lines to and from the carb too. Inexpensive to replace.

85t/alover · 09-20-2006, 06:25 PM

well, i gotta work tomorrow so what better time to check that stuff than at work

i will definately check both of those out. thanks again.

phess11 · 09-21-2006, 07:25 AM

Quote:

Originally Posted by sofakingdom

4. If your car has a clutch fan, it uses a good solid 12 HP just to run the fan. An electric fan will give you back those HP. Watch the classifieds on this site for a used fan setup.

That seem a little high. Has anyone actually measured the gain from Clutch to electric fans?

85t/alover · 09-23-2006, 11:09 AM

here we go again. my car just started throwing codes 14 and 15 again. that means the coolant temp sensor is showing low and high readings. how is that possible? plus i just replaced that sensor. what is wrong with this piece of junk? heeeeeeeeeeelllllllllllppppppppppp!!!!!!!

naf · 09-23-2006, 12:10 PM

Loose wiring or bad connector to CTS is likely. The connector gets beat up by the hoses that run right by it. You can short out the two connector leads and "confuse" the ecm into thinking the temp is good. Clear codes, run it a little and see if the trouble light comes on. This would rule out the CTS as it would be disconnected.

Fast355 · 09-23-2006, 10:12 PM

Quote:

Originally Posted by phess11

That seem a little high. Has anyone actually measured the gain from Clutch to electric fans?

I can see the clutch fan taking 10 RWHP off of an engine at 4,500, IF it is engaged. In cooler weather without the airplane effect going on, I doubt that it takes 2-3 HP to turn. 10 RWHP is what it did to my 350 in 105* weather. Took the clutch fan off and made another dyno run (fan-less) and it was 10 RWHP stronger. Before you decide to go electric, let me note that the clutch on my engine is a HD type that engages sooner and more fully and I have a 20" 7 bladed fan from a 454 on it.

85t/alover · 09-24-2006, 08:26 PM

well again, i find out that you are all much smarter than i. i realized that naf was right because the old connector was broken and not making good contact with the sensor. i went to oreilys and bought a kit with a new sensor and the new connector for only 15 bucks. changed the wiring (because i already bought a new sensor) and voila, no more check engine light. by the way, advanced auto did not even have the wiring in their system. next time you need something that az or aa says cant be gotten, try oreilys. pretty good people and parts, even if they do cuss a lot

lol. til the next dumb question.........

naf · 09-25-2006, 06:30 AM

Good deal, been there. PM'd you my cell if you ever need anything.

Mike

ChillPhatCat · 01-26-2007, 08:47 AM

Quote:

Originally Posted by Fast355

I can see the clutch fan taking 10 RWHP off of an engine at 4,500, IF it is engaged. In cooler weather without the airplane effect going on, I doubt that it takes 2-3 HP to turn. 10 RWHP is what it did to my 350 in 105* weather. Took the clutch fan off and made another dyno run (fan-less) and it was 10 RWHP stronger. Before you decide to go electric, let me note that the clutch on my engine is a HD type that engages sooner and more fully and I have a 20" 7 bladed fan from a 454 on it.

I agree, it's hardly worth the effort to change between fans, in general there is no free ride when it comes to necessary engine components and the electric fans will consume almost as much on average by loading up the alternator.

The one big advantage of electrics is being able to run a manual fan switch to help cool off the radiator between drag runs.