Hey guys whats up? I recently got a 91 z28 for around 2500 bucks. It was a 305 TPI car that waqs converted to a 350. It needed a fuel pump. So anyway, i replaced the fuel pump and the car ran like hell. No low end Tq what so ever, and even the top end was hurting. It didnt feel like a 350 car to me. It had a small hesitation on pull off that would go away after a few feet. It was throwing codes left and right also.

So...after researching a little on here, and going through the car...i saw that they never swapped anything over for a 350....Chip was a 305 chip, injectors, knock sensor...all 305. So i ordered a 16151348 chip (aujp) installed that and did the knock sensor. I havent had a chance to do the injectors yet, but the car runs sooo much better. Still will not smoke the tires from a stop. Does that make sence to you? i figured a 5.7 car would have no problem leaving a little rubber on the ground. The upper rpms feels ok, not 100% great tho. Could timing be the culprit?

Its running hot also, like 220...but i'm not sure the stock gauge is working properly. ....maybe the injectors?? or the timing? just seeing if any of you thirdgen guys knew any other little crap that may make this thing run like a 305....


also the tach does not work.....when you start the car it moves to zero....then it goes all the way over and pegs itself beyond redline....any ideas where the wires are for this?

Thanks again
Ed

 

check the number on the block make sure its a 350. Just being a 350 dont mean its has power. Dish piston and sorry heads can kill a motor. heat up what kind of fan u have? air dam in place?

 

Yes the block does say 5.7....i can look later and post the other numbers to see what it came out off.

the fans are electric stock...
air dam?? shroud?

 

What's your location?

 

OK i found out the car does not have a air dam....i didnt know these were that important. I'll be looking for one of them now.
I live in Near Philly, Pa

Also now its longer cranking time to start. The fuel pump comes on when i turn the key to on...but when u go to start it will crank for like 5 seconds before it starts...sounds like pressure regulator huh?

 

Have you checked your base timing???

 

you should def be able to roll the tires off the line.......my 305 does and it needs a tune-up BAD......

 

Not yet, havent had time. Where is the connector that i have to unplug inorder to check this?

 

Set timing under the following conditions:
Engine idling, all accessories off, no electrical loads, wheels straight.
Normal operating temperature ~75 to 80C
Transmission in neutral/park
Disconnect SET TIMING connector (tan/black wire) located in harness close to distributor (over the top of the A/C unit), but DO NOT disconnect 4 wire connector at distributor. The idle speed should drop, but engine should still be able to idle.

Check the timing with the timing light and adjust - for most cars it should be around 0* base. Modified engines may want to see 2 to 4 BTDC.
Once the adjustment is complete, shut down the engine, reconnect the EST timing connector. Disconnect the battery to clear the error Code 42 the ECM set when it detected the engine running without the EST connector connected.
Re-start engine and drive the car normally to allow the ECM to re-learn engine fueling requirements that were lost when the battery was disconnected.

 

These cars are typically 6 BTDC not 0.

 

wow, that was perfect. Thanks for the explanation. I'll try it tonight and let you guys know whats going on. i hope its retarded....i dont know why else it would be running hot and running like a small CID motor.
I got a air dam from a junk yard for 4 bucks, and it didnt help. A little cooler while driving but when stopped it still creeps up to 220ish....

I'll post later on
Thanks again...
Ed

 

You are stuck at 220 because the computer doesn't tell the other fan to turn on till then. Run a Painless thermal fan harness and get one that grounds at 180. You will be stuck there all day long and I have a bigger motor that is REALLY moded and I stick at whatever temp I want.

Ideally you wanna be at 185-190 all day long. That is when oil is in its prime. Least amount of engine wear and most power. I had a 165 in mine, but the damn car could reach 170 almost ever. So i am swapping the thrmo switch today for a 185 ON, 170 OFF. On a super hot day in traffic in the city, making over 400 HP and all stock cooling components, my car still won't go past 200.

 

I had problems with engine cooling. After getting tired of having to watch the guage all the time I changed the switch that contols when the fan comes on, changed the termostat to a 160 unit, and the biggest improment came after the aluminum radiator was put in.


just my

 

Ok well last night I swapped my 165 thrmo for a 180 and my fan switch that contorls my second fan, made it go from 165 ON, to 185 ON.

Stock EVERYTHING, except wiring and sensors. Drove the car 20 miles to work today, about 70* out. Never got to 185*.

You don't need fancy Al. Rad. or anything like that, just get GOOD working stock stuff.