HELP What size is my engine?

78Delta88

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May 23, 2022
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Cast date is G140 = July 14 1990, heads are ...193 swirlport TBI, 64 cc, 1.94/1.50, block is ...638 one piece rear seal TBI block, should have roller cam from box Chevy.

What's odd is 350 TBI was in trucks. 305 was in Caprice, unless police fleet vehicle. Yet all of the 350 Police I am aware of, were TPI (Tuned Port Injection) and not TBI. The 350 TPI was same engine in the ambulance units, brought over from the Corvette line. Later on in the "bubble" caprice were LT1. I drove several as an LEO.

Yours has manual FP which was added later. Many of the blocks of this era were machined for manual FP, yet installed the cover plate and with an electric in tank FP. The block most likely will have the cast bosses for the "spider" for the roller lifters. From 86 to 90 was a toss-up if it had roller cam.

Notice on the back of the block, you have the two Oil Pressure sensor/switches. One was for oil gauge on dash, the other (long narrow) unit is the switch to energize the in-tank FP once started.

Notice the accessories are multi V belt system with the AC on the drivers side. This is exactly the way it would have been in a Caprice. It is pre-1991 as the 91 Caprice had the serpentine belt setup. Although some 1990 Caprice had serpentine system.

Basically you have a 350 TBI, factory Dish, 8.6 to 8.8 CR respectively and about .230 lift cam 114 or about LSA. Change to flat tops, 230 to 240 @ .50 and .480 lift and 1 5/8 headers will be nice easy street engine about 9.2:1 and DRC about 7.5 which. Will keep detonation down with pump gas.

Anything more and it's going to max out about 3500 to 4000 with those heads. The block can be worked to 383 but definitely will need better heads.
 
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g0thiac

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Sep 6, 2020
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Cast date is G140 = July 14 1990, heads are ...193 swirlport TBI, 64 cc, 1.94/1.50, block is ...638 one piece rear seal TBI block, should have roller cam from box Chevy.

What's odd is 350 TBI was in trucks. 305 was in Caprice, unless police fleet vehicle. Yet all of the 350 Police I am aware of, were TPI (Tuned Port Injection) and not TBI. The 350 TPI was same engine in the ambulance units, brought over from the Corvette line. Later on in the "bubble" caprice were LT1. I drove several as an LEO.

Yours has manual FP which was added later. Many of the blocks of this era were machined for manual FP, yet installed the cover plate and with an electric in tank FP. The block most likely will have the cast bosses for the "spider" for the roller lifters. From 86 to 90 was a toss-up if it had roller cam.

Notice on the back of the block, you have the two Oil Pressure sensor/switches. One was for oil gauge on dash, the other (long narrow) unit is the switch to energize the in-tank FP once started.

Notice the accessories are multi V belt system with the AC on the drivers side. This is exactly the way it would have been in a Caprice. It is pre-1991 as the 91 Caprice had the serpentine belt setup. Although some 1990 Caprice had serpentine system.

Basically you have a 350 TBI, factory Dish, 8.6 to 8.8 CR respectively and about .230 lift cam 114 or about LSA. Change to flat tops, 230 to 240 @ .50 and .480 lift and 1 5/8 headers will be nice easy street engine about 9.2:1 and DRC about 7.5 which. Will keep detonation down with pump gas.

Anything more and it's going to max out about 3500 to 4000 with those head. The block can be worked to 383 but definitely will need better heads.
It was TBI, for the 9C1 Caprice the LO6 came with that stock and a Y pipe that my mechanic, said that is a real ******* to deal with 🧐😂😂😂
 

64nailhead

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Dec 1, 2014
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Most street motors didn't rev to 6k rpm with a overdrive
C’mon man, everything revs to 6k if the loud pedal is applied to maximum ;)
 
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78Delta88

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Hmmm? Every police unit I came across was TPI and later LT1, but... GM being GM I guess TBI also.
 

SwggMsthh

Not-quite-so-new-guy
Jun 11, 2022
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Alright y’all finally got a chance to further break down the TBI 350 and here are the codes.
 

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86LK

Royal Smart Person
Jul 23, 2018
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Alright y’all finally got a chance to further break down the TBI 350 and here are the codes.

V0725UPK

Engine ID Code Example: V0101CLJ- (V = Plant, 01 = Month, 01 = Day, CLJ = Engine Suffix Code)

V = Flint July 25 UPK

UPK 86 350 165 4B,MT TR (1986, 350,165hp, 4-barrel, , Manual Transmission, Truck)
UPK 90 350 210 MT,TBI TR (1990, 350, 210hp, Manual Transmission, Throttle Body Injection, Truck)
 
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78Delta88

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May 23, 2022
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You have a 350 TBI 638 block from light truck. You will Have to pull oil pan to tell if it's 2 or 4 bolt main. If you have the drain plug in the front of the pan it's a truck block. The side of the block will have 638 or CFD in raised letters. 638 was also used as a crate MR Goodwrench replacement engine.

You will have to pull the intake to see if it's a roller block. If you have the "spider" you have a roller block. If you have the bosses but no spider then yours is non roller cam but the block is preset for a roller cam.

If you have the fuel pump cover plate and is drilled for manual pump or has the pump rod behind the cover you have a TBI light truck or crate replacement.

Your heads look to be 305 TBI Swirl Port heads. Note the two tick marks cast into the end of the head right under the valve cover mounting flange. These are know as Captain Bars, the 350 Swirl port head has one tick mark.

From Hotrod Forum: https://www.hotrodders.com/threads/638-vs-the-880-block.232125/

Still have to be careful of internet comments. I attached the screen shot as noted, plus a couple other places, the 638 is stated as being good base block for making a stroker. However the authors comment about the 880 block as 1995 TBI is dead wrong. The 880 is the Vortec block and would have Vortec heads which are much more preferred over the swirl ports.
 

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