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I invent stupid usernames
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Discussion Starter #1
I found a 1990 Chevy 350 for my 1978 chevy truck and I was wondering what parts are interchangeable between the 1978 engine and the 1990 (pistons, crank, con. rods, cam. Stuff like that).
 

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Wrench Turner
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The 78 engine will have a 2 piece rear seal block.The 90 engine will be a 1 piece rear seal, so the crankshaft & flywheel will be different.If the 90 is from a car, it most likely will have a roller cam/lifter setup vs the flat tappet in the 78.Truck engines still had flat tappet cam until 96, but, no way I would reuse a flat tappet cam.Rods & pistons are interchangeable if the bore size matches up. (Not overbored different sizes).They need to be checked out for sizing/wear before reusing.
 

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I invent stupid usernames
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Discussion Starter #3
The 78 engine will have a 2 piece rear seal block.The 90 engine will be a 1 piece rear seal, so the crankshaft & flywheel will be different.If the 90 is from a car, it most likely will have a roller cam/lifter setup vs the flat tappet in the 78.Truck engines still had flat tappet cam until 96, but, no way I would reuse a flat tappet cam.Rods & pistons are interchangeable if the bore size matches up. (Not overbored different sizes).They need to be checked out for sizing/wear before reusing.
The engine is from a truck so it's flat tappet. I will be using a comp XE256H to fill this area. I have a few more questions though. Does the '90 have a mechanical fuel pump? Can I use my '78 ring gear, flex plate, and torque converter with the different crank? I also will be getting some high flowing '88 fast burn truck heads for it.
 

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Old(s) Fart
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The 1990 truck motor would have been TBI with an electric pump in the tank. I don't know if the block still has a mechanical pump mounting pad or not.
 

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Wrench Turner
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The engine is from a truck so it's flat tappet. I will be using a comp XE256H to fill this area. I have a few more questions though. Does the '90 have a mechanical fuel pump? Can I use my '78 ring gear, flex plate, and torque converter with the different crank? I also will be getting some high flowing '88 fast burn truck heads for it.
I think the 90 model block will still have the fuel pump provision,but,not sure.The mounting pad will be there,but,the hole for the rod may not be machined thru.You will need to look at that.Installing an electric pump is no big deal if not.The flywheel for the older 2 piece seal crank will not work with the newer 1 piece seal.They are balanced differently & have different bolt patterns.
 

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I invent stupid usernames
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Discussion Starter #6
I think the 90 model block will still have the fuel pump provision,but,not sure.The mounting pad will be there,but,the hole for the rod may not be machined thru.You will need to look at that.Installing an electric pump is no big deal if not.The flywheel for the older 2 piece seal crank will not work with the newer 1 piece seal.They are balanced differently & have different bolt patterns.
Will my torque converter bolt up to that new flywheel though?
 

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Will my torque converter bolt up to that new flywheel though?
Yes the old torque converter will bolt to the new one piece seal type flexplate.

The block does not support a mechanical fuel pump the pad is machined but the bolt holes are probably not drilled or tapped and the push rod hole certainly is not machined (drilled and sized with a reamer).

You should look in the engine before buying the cam some truck engines did have a roller cams, barring that the block is most likely provisioned for a roller. A factory style roller is a great imporvement over a flat tappet the whole issue of wiped lobes and tappets is just gone with a roller.

Bogie
 

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I invent stupid usernames
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Discussion Starter #8
Yes the old torque converter will bolt to the new one piece seal type flexplate.

The block does not support a mechanical fuel pump the pad is machined but the bolt holes are probably not drilled or tapped and the push rod hole certainly is not machined (drilled and sized with a reamer).

You should look in the engine before buying the cam some truck engines did have a roller cams, barring that the block is most likely provisioned for a roller. A factory style roller is a great imporvement over a flat tappet the whole issue of wiped lobes and tappets is just gone with a roller.

Bogie
It for sure is flat tappet
 

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I invent stupid usernames
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Discussion Starter #9
I think the 90 model block will still have the fuel pump provision,but,not sure.The mounting pad will be there,but,the hole for the rod may not be machined thru.You will need to look at that.Installing an electric pump is no big deal if not.The flywheel for the older 2 piece seal crank will not work with the newer 1 piece seal.They are balanced differently & have different bolt patterns.
Are all of the bearings interchangeable?
 

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I invent stupid usernames
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Discussion Starter #10
Yes the old torque converter will bolt to the new one piece seal type flexplate.

The block does not support a mechanical fuel pump the pad is machined but the bolt holes are probably not drilled or tapped and the push rod hole certainly is not machined (drilled and sized with a reamer).

You should look in the engine before buying the cam some truck engines did have a roller cams, barring that the block is most likely provisioned for a roller. A factory style roller is a great imporvement over a flat tappet the whole issue of wiped lobes and tappets is just gone with a roller.

Bogie
Are the bearings the same on the two engines?
 

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Are the bearings the same on the two engines?
Yes the crank is the same except for the one piece seal and flywheel/flexplate flange. All bearings on the crank and cam remain the same.

The 92 rods are powdered metal forgings they interchange with the older forged from low carbon steel. The pistons of the 92 are hypereutectic castings, stonger than the earlier cast pistons, they have less skirt extension and run with tighter clearances than the old engine but are other wise interchangable as a set of rods and pistons without rebalancing, the rods are a little heavier and the pistons lighter so you don't want to mix new and old rods and pistons without rebalancing.

The block has shorter lower cylinder wall extensions into the crankcase, this makes these blocks easier to put stroker cranks into. The fuel pump mating surface is machined but mounting holes may or not be drill and tapped, the push rod hole is not machined. These block castings are usually prepared from semi to completely for a roller cam. They most often used a flat tappet cam but if the provisions are there for the spider and the thrust plate it is simple to put a factory type roller into them. The factory cam flat or roller will not have a fuel pump lobe. There are cams both flat and OEM roller tappet that do. There are true roller timing sets for the flat tappet cam and the OEM roller cams. The double row timing set for the roller cam requires some minor grinding of the main oil passage boss that extends into the timing case for clearance.

Bogie
 

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I invent stupid usernames
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Discussion Starter #12
Yes the crank is the same except for the one piece seal and flywheel/flexplate flange. All bearings on the crank and cam remain the same.

The 92 rods are powdered metal forgings they interchange with the older forged from low carbon steel. The pistons of the 92 are hypereutectic castings, stonger than the earlier cast pistons, they have less skirt extension and run with tighter clearances than the old engine but are other wise interchangable as a set of rods and pistons without rebalancing, the rods are a little heavier and the pistons lighter so you don't want to mix new and old rods and pistons without rebalancing.

The block has shorter lower cylinder wall extensions into the crankcase, this makes these blocks easier to put stroker cranks into. The fuel pump mating surface is machined but mounting holes may or not be drill and tapped, the push rod hole is not machined. These block castings are usually prepared from semi to completely for a roller cam. They most often used a flat tappet cam but if the provisions are there for the spider and the thrust plate it is simple to put a factory type roller into them. The factory cam flat or roller will not have a fuel pump lobe. There are cams both flat and OEM roller tappet that do. There are true roller timing sets for the flat tappet cam and the OEM roller cams. The double row timing set for the roller cam requires some minor grinding of the main oil passage boss that extends into the timing case for clearance.

Bogie
Thanks for all the great info. I also got a set of 191 heads (it has 193's on it now) and I was wondering if I could pull 300 hp and 400 lb/ft torque out of them. They're freshly rebuilt with a 3 angle valve job and a planed surface. Also what cc chamber do these have? If you know.
 

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Wrench Turner
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That is debatable. The 191 head is advertised as being 76 cc to create the 8.5:1 compression for the HD L05.However, there are several sources that claim the only difference in the 191 from 193's is that the 191 has 3/8" sodium filled valve stems & exhaust valve rotator along with harder seats & that the chambers are 65 to 67 cc just as the 193's. The compression was lowered using a larger dish piston.Since I've never fooled with a 191 , I can't say with certainty.The safe thing to do would be to cc the chambers. If you do, let us know how it turns out.
 
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