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Modify 1998 Chevy Vortec 350

I love my Chevy Chevette!
Posts: 1
Joined: 11/13
Posted: 11/10/13 07:39 AM

Not a gear head and this will be my first build. Have a 2 door 4x4 Tahoe with a vortec 350. Want to modify it for more power but keep it where it can be an everyday driver. Suggestions on what to do to the motor.  Is it better to rebuild the one I have which is still running are go with a modified crate motor? Want the power to play a little but also drive it without working on it all the time. Thanks  

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Posts: 122
Joined: 03/13
Posted: 11/11/13 05:03 AM

timing chain... vortecs don't like slack chains..

oil pump.. and screen.. with the screen properly installed and at least tack welded in place.. you don't have to go all the way around..

examining the distributor for wear of the bushings and the distributor drive gear..

warning.. setting the distributor position is CRITICAL.. and requires an advanced scan tool not a generic version.. as there is a test to run to prove the cam sensor in the distributor is within 1/2 a degree or less with the crank.. yep. slack chain is going to give you heck..

vacuum leaks...

you will want to examine the ECT.. engine coolant temp with a SCAN TOOL.. to see if the ECT sensor is sending the proper and accurate signal.. these engines are also programmed to work with a 192/195F thermostat..  if you put a lower temp thermostat in.. you will have rich fuel issues and can melt the cats.. wipe out your MPG..
at AZ stores and others.. they sell an SU102 from duralast and wells.. its the coolant temp sensor and pigtail.. its under 20 bucks for the pair..

you will want to change over to the later style fuel injector spider with the injectors at the ends of the tubes ... far superior design..

read an article on it..

fuel pump grounding and electrical connections. above the tank..

electrical connections at the starter...  at the back of the alternator .. at the underhood fuse box power connection...  at the positive connection next to the radiator on some trucks..

on the negative side..
at the front lower passenger side corner of the block..  take it apart.. wire brush the ring terminals..  reassemble..
the negative battery cable to the body.
the ground strap from the back of the heads to the firewall.

got a digital volt meter... i have a test to check some of these locations..

engine running.. headlights on... digital volt meter set to 20 volts DC..

1. Negative battery post to the Positive battery post.. 14.1 to 14.8 volts is expected.

2. Negative battery post to the engine block... 0.04 volts DC max.

3. Negative battery post to the body... 0.02 volts DC max..

4. engine block to the body. 0.02 volts DC Max..

if you end up with 0.00 on tests 2, 3, 4.. reset meter to 2 volts SCALE and retest..

you can do the same test from the positive battery post to the alternator output stud.. to the underhood fuse box..  to verify those are tight..

why.. i have a friend with a 98 C2500 and a 96 C1500 4x4..  on the 98.. it was eating alternators and batteries..  the tests were too hi.. on 2 3 and 4.. test 4 was 8.5 volts between the engine block and the body..  it was a different truck when i cleaned the grounds up and got them all down to the 4/100 and 2/100 that proved that the connections are tight and the current is flowing just thru the copper wires..

i would avoid removing the blade on the throttle plate.. that blocks part of the flow...  you will end up with a hesitation off idle.. or a flat spot off idle.. as the computer knows how much air will come in for how many degrees of throttle .

the limitation with a fuel injected vortec engine.. is the fuel injectors flow rates.. you are kinda stuck.. there are ways to reprogram the ECM.. but that gets expensive.. you can hurt your fuel economy..

lastly things you should keep an eye on..

distributor cap and rotors..

ignition coils for signs of high voltage leaks... they are cheep.. not that hard to change..  the rivets are easy to cut to reuse the coil bracket..

the wiring coming out the crank sensor.. it comes down off the bottom of the timing cover.. if its not secured.. it can dance in the airflow and fatigue until it breaks leaving you stranded.. and wondering why the truck won't start...

guess what.. there is more..

always carry a spare fuel pump relay...
every once in a while, and a few days before a long trip... with the hood open. engine idling.. reach over and yank the fuel pump relay out..  the ENGINE SHOULD NOT DIE... if it does.. replace the oil pressure sender..  why... the outer 2 wires of the 3 are in parallel with the fuel pump relay.. so the fuel pump gets power from 2 sources..  the fuel pump relays just don't have the ability to carry the entire load of the fuel pump for very long..  the socket terminals get hot and melt..

if you are in the oil system.. have the pan off.. please figure out where the oil pressure relief valves are down in the oil filter adaptors and oil cooler housings.. and replace them.. they are under 8 bucks each..  could be one or two depending on the application..  they look like a TEE bushing..  or a flanged bushing..

keep the oil changed. and you can easily get well over 200,000 miles..

if you really really really want more power.. rather than durability ...

you can drop a carb on a vortec carb intake.. and replace the distributor ... infact..

one could actually change to the 4 barrel intake and install one of the bolt on self tuning throttle bodies..  so you would still have fuel injection but would not be limited by injector flow rates..  you would have the issue of how to control the electronic shift transmission..

or... the hard way.. go to an LS engine..  the 5.3.. the 6.0.. the 6.2 or ....
be careful you don't get a 4.8.. as they are identical to the 5.3 on the outside.. but thats a WHOLE different ball of wax to roll your money into..  

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Posts: 122
Joined: 03/13
Posted: 11/11/13 05:04 AM

sorry.. i did not intend on typing that much.. its a LOT to cover..  and there is some additional info on each of the subjects that should be added.. if you have a question about it..  

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