92 CHEVY 350 TBI

[RobbinsSr]

My son's 92 chevy 1500 with a 350tbi has a bad lifter rattle that come and goes on the front 2 lifters. Oil presure would fluctuated so we put a new oil pump in it and solved the problem. well now 2800 miles on that oil and the rattle comes back. changed the oil and rattle went away. now 50 or so miles latter the oil presure drops to 0 at idle and rattle starts, as soon as you give it some gas the presure comes up and rattle goes away. Any idea of what going on?

 

I have another motor out of my sport mod to put in it. But will the TBI work even with a cam change on a older style block?

 

help please. thank you in advance.

[Alloutpc17]

Cam will work. you only use the short block of course. Make sure to take out the fuel pump rod, since you wont be using the mechanical pump.

[HiTech]

My son's 92 chevy 1500 with a 350tbi has a bad lifter rattle that come and goes on the front 2 lifters. Oil presure would fluctuated so we put a new oil pump in it and solved the problem. well now 2800 miles on that oil and the rattle comes back. changed the oil and rattle went away. now 50 or so miles latter the oil presure drops to 0 at idle and rattle starts, as soon as you give it some gas the presure comes up and rattle goes away. Any idea of what going on?

 

I have another motor out of my sport mod to put in it. But will the TBI work even with a cam change on a older style block?

 

help please. thank you in advance.

possibly cam bearings ..also check thrust clearance on the crank ..

[keith]

It sounds like the entire engine is wore out and loose but it could be many things, excessive clearnace on the rods, mains, cam bearings, leaking oil galley plugs behing the timing chain, a bad lifter, none that you are going to fix without disassembly.

Yes I have ran a flat top 355 shortblock on a stock tbi unti for many years with a used stock vortec roller cam with no tbi mods. I would not run any larger duration or performance cam in the tbi, its more hassle than it is worth trying to gain hp out of a gm tbi.

[jwmbishop]

You are bleeding oil off the bearings excessively from too much clearance worn in. Time for a refresh (bearings, rings, gaskets seals) at the least. When you changed the pump would have been a great time to fish new main bearings in (providing the journals are not scored). My 57 with an '87 305 did that when I bought it (didn't buy it for the engine!). I went to 50w oil and it helped - I was able to drive it short distances (less than 30 minutes run time) with no issues - but once over 185 degrees for any length of time it would rattle again. Eventually the rattle turned into a main bearing knock (idle 12 psi but a steady knock, going away above 1100 rpm) and it got replaced with my built 383...

[RobbinsSr]

It makes since what ya'll are all saying. But agravating because the motor was supose to have been completly rebuilt about 20k 25k ago. But guess I better start saving for a new motor.

[jwmbishop]

It makes since what ya'll are all saying. But agravating because the motor was supose to have been completly rebuilt about 20k 25k ago. But guess I better start saving for a new motor.

 

I feel your pain... and most sellers don't know the difference between rebuilt and repainted junk yard donor.

 

Overhauled, Rebuilt and Remanufactured are three different things.

 

Overhaul is just snaking in new bearings, rings and gaskets usually without complete dissassembly and cleaning. No real corrective work. On a fleet vehicle this is a very economical way to milk many many miles from an engine. On these you will see signs of paint peeling etc where the heads meet the block (and paint on TOP of some gaskets).

 

rebuilt is complete disassembly and cleaning and replacing ONLY the parts that are worn beyond wear tolerance - the crank could be worn .0005 and no work done to it as the bearing clearance yield can be in tolerance yet on the high end which makes bleedoff occur MUCH sooner in the wear life. Although return to service is okay - a rebuilt does NOT (and can not) yield the same number of operating hours as a new or reman would in the same operating parameters... on these you MAY see signs of OEM paint but not always. Gotta be very observant to spot the diff between rebuilt and reman.

 

Remanufacture replaces, without regard to wear, ALL replaceable wear parts - ie crank is replaced or turned to exact clearance by going .010 under stock diameter, usually all new pistons (and rebore .030 or .045 over) rings, valves/springs/guides etc. This is actually the MOST economical approach as $$ is spent on parts rather than labor to inspect and clean small parts. Should be NO signs of ANY left over oem paint. Very rarely are these repainted at all - leaving that for the customer.

 

When buying a used veh claimed rebuilt - I always use a boroscope to explore what was replaced... or simply don't buy for the engine!

 

So far in the past ten years I have bought two trucks with rebuilt "350" - just ignore that big ol 305 cast into the side of the block - On the 57 the seller said it was sluggish because of the 2.76 rear gears - it now smokes em all through the gears going 0-60 in 5.8 WITH THE SAME 2.76 and on the 86 the engine had rods from 3 different engines, two different heads (WAY different runner size 1 head was a 350 the other a small runner 305 - and two of the piston\rod combos were swapped - the oil slingers were NOT oiling the cylinder opposite! lmao). Only bought them because I paid a fair price for the body/interior/suspension with no price consideration to the engine.