Needing some help here

[desertdeer]

Hey fellas. New guy here and I have a question that I haven't been able to answer by looking through threads. I have a 1985 chev 1/2 ton 4x4 with a 350 that has developed a knock. I am on a real tight budget so a crate motor is out of the question. A friend of mine has a 350 out of a 1991 chev 1/2 ton that he has told me I can have but it has a bad valve. So the plan is to use the 1991 block with the 1985 heads and intake. It has a block off plate for the mechanical fuel pump and I have a summit racing SUM-1102 camshaft that I could put in it.

So tell me guys, is this plan solid? The motor will go in the 85 with a 4 speed manual. Any problems with my flywheel on that motor?

Thanks in advance, I have learned a lot browsing this forum

[Terry Crist]

First, lets figure out what and where the knock is from. Might be able to save you a lot of work.

What does the "knock" sound like? Is it tinny or a solid sound.

Can you tell approximatly where it is knocking from (front of engine, rear of engine, top/bottom)?

Does it knock all of the time or just under acceleration?

How many miles are on it?

Does it run fine other than the knock.

Does it use any oil?

My mom had an El Camino with a SB350. It developed a knock and not knowing much at he time, I just replaced it. I used all of the old sheet metal stuff on the new engine and got it running great.

Then I started inspecting the old engine and found that one of the nylon teeth off of the cam timing gear had come off of the gear and stuck in the timing chain. Thus resulting in the timing chain connecting with the timing chain cover.

Long story short, it could have been a fairly easy fix.

[desertdeer]

I should have said. It is a rod knock. It was my grandpas truck I was given when he passed. I guess in his old age he quit doing maintenance because it was 5k overdue for an oil change and didn't register on the dipstick. I added oil and the lifters stopped chattering but I could hear the knock. It stops knocking when I unplug the plug wire that is #2 from the front on the passenger side of the block.

Knocks on accel and you can hear it at idle with a stethoscope. Its a solid knock sound

[Terry Crist]

If it were me, I would just have the heads re-done on the 91 engine.

While you are at it, re-ring and insert the lower end. Not that much more really and then you know exactly what you have.

Someone else can ring in and let you know about mixing and matching parts if that is the way you would rather go. I don't know much about mixing and matching parts.

[79Betty]

If your 85 has a 2 piece seal you'll need a new flywheel for the 91 bottom end. Heads will bolt on no problemo. If your 85 has a 1 piece you'll not need one.
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[desertdeer]

Thanks guys. I forgot to mention he 91 engine was an automatic. I don't know if that changes anything. I guess I need to weigh the costs of both ways and see if it would be better to redo the heads or play the mix and match game.

What about other clutch components? Will my pressure plate work? What about the pilot bearing, is it in the crank or flywheel on these motors?

[07XCSBZ71]

If you buy pilot bearing and flywheel for an 87, the rest of your components should be good to go. The 91 and 87 both came with a LO5 350,the 87 just came with the SM465 4spd like your 85. If you order parts for a 91, you'll likely get parts for a NV3500 5 spd.

[desertdeer]

You guys are awesome. I appreciate all of the help.

One last thing, is the cam I have (summit racing 1102) gonna work in the 91 block?