86 zz4 swap stalling
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Car: 86 Berlinetta
Engine: Zz4 350
Transmission: 700r4
86 zz4 swap stalling
I recently bought a zz4 350 swapped Berlinetta that’s been having some trouble running and driving. Originally the motor had a q-jet that was swapped for a Holley 0-80508s and msd ignition system. When I bought it I was told it was never tuned for the new carb and that was its main problem, only after making the adjustments it still seems to be having an issue. The car sputters down to a stop after putting it in gear and under load unless I keep the rpm up. It also will stall out at idle on occasion, my first guess was a fueling issue and after putting a pressure gauge on the fuel log it stayed reading zero psi. I redid the fuel lines inside the engine bay as well as a new fuel filter and Holley 12-880 regulator. I put the gauge at the regulator and when priming the system the gauge read 3 psi and dropped down to zero and stayed at zero. At this point I believe I have a fuel pump that needs to be replaced but wanted to get input on any other possible problems and recommendations for parts. Any advice would help, thanks.
#2
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Re: 86 zz4 swap stalling
Sounds like the fuel pump is out, so that's a good place to start.
Next, I'd take the MSD ignition system, toss/sell it, and put an OEM HEI on there. That is another area where you can eliminate gremlins as that motor doesn't need any more than a stock-type ignition set up.
After you've done that give it a once over, check the timing, tune the carburetor, and be on your way. The Holley 750 should play nicely with the ZZ4 once you get it tuned right.
Next, I'd take the MSD ignition system, toss/sell it, and put an OEM HEI on there. That is another area where you can eliminate gremlins as that motor doesn't need any more than a stock-type ignition set up.
After you've done that give it a once over, check the timing, tune the carburetor, and be on your way. The Holley 750 should play nicely with the ZZ4 once you get it tuned right.
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Car: 86 Berlinetta
Engine: Zz4 350
Transmission: 700r4
Re: 86 zz4 swap stalling
Sounds like the fuel pump is out, so that's a good place to start.
Next, I'd take the MSD ignition system, toss/sell it, and put an OEM HEI on there. That is another area where you can eliminate gremlins as that motor doesn't need any more than a stock-type ignition set up.
After you've done that give it a once over, check the timing, tune the carburetor, and be on your way. The Holley 750 should play nicely with the ZZ4 once you get it tuned right.
Next, I'd take the MSD ignition system, toss/sell it, and put an OEM HEI on there. That is another area where you can eliminate gremlins as that motor doesn't need any more than a stock-type ignition set up.
After you've done that give it a once over, check the timing, tune the carburetor, and be on your way. The Holley 750 should play nicely with the ZZ4 once you get it tuned right.
#4
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Re: 86 zz4 swap stalling
Ignition parts you can go one of two ways, you can find a stock-style replacement (i.e. just go to autozone and say you need a whole distributor for an 86 camaro) or go with a large-cap HEI. For large cap HEI parts I recommend AC-Delco, should be easy enough to find. Just remember for that option you're not going to be looking for a distributor for an '86 Camaro. When I'm buying large cap HEI parts I usually narrow the search down to some 1976 model carbureted V8 (like a chevy K20, for example).
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Car: 86 Berlinetta
Engine: Zz4 350
Transmission: 700r4
Re: 86 zz4 swap stalling
Thanks for the help and recommendations, I truly appreciate it. I’ll find a in tank replacement this week and hopefully get it installed soon. I’ll keep tabs on the thread in the meantime and update when I get the parts installed. Again thank you all for the help.
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RedLeader289 (08-22-2023)
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Car: '89 GTA
Engine: ZZ6TPI
Transmission: T56
Axle/Gears: Borg Warner 3.70:1
Re: 86 zz4 swap stalling
I have a large cap HEI takeoff distributor from my ZZ6 crate engine that I would be willing to sell. Brand new, never used, complete with cap/rotor and coil. PM me if interested.
On the fuel pump, it likely only has the mechanical pump on the motor and none in the tank. Some of the L69 305 HO motors had a both low pressure in tank electric pump along with the mechanical pump on the motor. The LG4 low output 305 didn't get the additional in tank pump until 1987. Change the mechanical pump with a stock replacement and change the fuel filter and see what that does before going further.
On the fuel pump, it likely only has the mechanical pump on the motor and none in the tank. Some of the L69 305 HO motors had a both low pressure in tank electric pump along with the mechanical pump on the motor. The LG4 low output 305 didn't get the additional in tank pump until 1987. Change the mechanical pump with a stock replacement and change the fuel filter and see what that does before going further.
Last edited by TransamGTA350; 08-22-2023 at 04:33 PM.
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Re: 86 zz4 swap stalling
I see no mention of the carb setup... Like what jets are in it... Tuning a carb is not just twisting a screw or two... It has to have the right fuel flow for the air and the load. It may be set up too lean... With jets that are too small...
I don't know Holley carbs... I am a qjet man... But I do know that the right internals make all the difference...you have to make changes there and then check performance. A carb is not just a carb.... Read up on metering changes to the carb. All the fuel pump changes in the world will do nothing if the jetting and mix is wrong...
I don't know Holley carbs... I am a qjet man... But I do know that the right internals make all the difference...you have to make changes there and then check performance. A carb is not just a carb.... Read up on metering changes to the carb. All the fuel pump changes in the world will do nothing if the jetting and mix is wrong...
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Car: 86 Berlinetta
Engine: Zz4 350
Transmission: 700r4
Re: 86 zz4 swap stalling
I have a large cap HEI takeoff distributor from my ZZ6 crate engine that I would be willing to sell. Brand new, never used, complete with cap/rotor and coil. PM me if interested.
On the fuel pump, it likely only has the mechanical pump on the motor and none in the tank. Some of the L69 305 HO motors had a both low pressure in tank electric pump along with the mechanical pump on the motor. The LG4 low output 305 didn't get the additional in tank pump until 1987. Change the mechanical pump with a stock replacement and change the fuel filter and see what that does before going further.
On the fuel pump, it likely only has the mechanical pump on the motor and none in the tank. Some of the L69 305 HO motors had a both low pressure in tank electric pump along with the mechanical pump on the motor. The LG4 low output 305 didn't get the additional in tank pump until 1987. Change the mechanical pump with a stock replacement and change the fuel filter and see what that does before going further.
#12
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Car: 86 Berlinetta
Engine: Zz4 350
Transmission: 700r4
Re: 86 zz4 swap stalling
I see no mention of the carb setup... Like what jets are in it... Tuning a carb is not just twisting a screw or two... It has to have the right fuel flow for the air and the load. It may be set up too lean... With jets that are too small...
I don't know Holley carbs... I am a qjet man... But I do know that the right internals make all the difference...you have to make changes there and then check performance. A carb is not just a carb.... Read up on metering changes to the carb. All the fuel pump changes in the world will do nothing if the jetting and mix is wrong...
I don't know Holley carbs... I am a qjet man... But I do know that the right internals make all the difference...you have to make changes there and then check performance. A carb is not just a carb.... Read up on metering changes to the carb. All the fuel pump changes in the world will do nothing if the jetting and mix is wrong...
from my understanding when buying the car, the carb was pulled from the box and put on the engine. This is from the Holley spec sheet. Being new to all of this I don’t know if this looks like it’s good or not.
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Re: 86 zz4 swap stalling
If you tune it and your timing is off. . .you'll have to retune.
If you tune it to work with a dying fuel pump. . .you'll have to retune.
etc.
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Car: '89 GTA
Engine: ZZ6TPI
Transmission: T56
Axle/Gears: Borg Warner 3.70:1
Re: 86 zz4 swap stalling
Your fuel system may be modified from stock.
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