I have an LG4 from my 83 berlie that seems to have a wobbly piston, so my bro says. But it knocks around at idle and worse on increasing RPM and is pretty random. Not very safe to drive.

So here is my proposal:

I have a smog-legal 91 RS with an L03 in great shape. I am planning to put the L03 minus the intake and TBI into the 83 Berlinetta.

When I put in the L03 into the berlinetta, I will retain the original intake and Q-jet that came stock on the 83's and place that on the L03 block......

is there any additional work I must do, such as wiring/harness and all that jazz. I figured since all im doing is swapping the blocks basically, that I wouldnt have to do anything but hook it all back up...

This is a perfect opportunity to rebuild the 305 and sell to some S-10 owner. And about this time i can build a 350 or a 383 and plop that in my 91's bay when the time comes.

Both engines are bone-stock.


thanks
-blain

it should be a straight forward swap, you may need to exchange a few sensors and little stuff like that but it should be fairly easy.
you will have to transplant the flexplate with the motor since. the 83 is a two piece seal and the 91 is a one piece seal, you should be better off with the 91 motor because I think it is a roller cam motor from the factory and the 83 is flat-tappet.

what sensors might i need to replace?

from all i can manage to consider.....there arent any...am i missing something?

you may not need to replace any of the sensors just relocate them to the new motor, the sensors on the block are:

knock sensor (in block near oil pan)
fan switch (in passenger side head)
temp gauge sender ( in drivers side head)
oil pressure safety switch (may or may not have)(just above oil filter)
there may be something else but I can't think of anything else off the top of my head. they will show up when you pull the motors to switch them out.

What about the 87-earlier intake you have now on the 91 motor? That could be an issue. I honestly dont know much more except I should bring it up and let someone in the know actually put useful and true info up on it. SOmething about angle of the holes drilled

LO3 heads are about the worst thing out there - certainly of the 3rd gen heads they're the worst.

The LG4 heads, on the other hand, have about the best potential of factory 305 heads. The solution, therefore, would be to take off the LG4 heads, have them reworked; installing 1.94" intake valves and a little porting wouldn't be a bad idea, along with new valve springs.

While you're at it, get a better cam - LO3 cam matches the LO3 heads for performance potential. It is a roller cam, however, which is nice and means you can reuse the factory lifters if they aren't damaged. A Crane roller computer-compatible cam would do you well. Use the LO3 pushrods and '83 LG4-type rockers on the LG4 reworked heads, get a decent exhaust on the thing, and you'll have a very nice package.

Oh, the LO3 has higher compression than an '83 LG4 to boot. And, the '83 LG4 won't have a fan switch (electric fan started in '85).

57 Kid..lol..i learned a bit by your post....but im lost as to what you think i should do...i think

use the LO3 block, crank and such.....place the reworked LG4 heads on the block after some porting with 1.94 intake, perhaps a 1.6 exhaust...new valve springs. Use the LO3 cam and pushrods, reuse the lifters from the LO3 if still in good shape with the LG4-style rockers. You say get a better cam to match the LO3 heads......but using your suggestions....im not using the LO3 heads....i will be using LG4...oh well

Is that what you're saying?

The chambers on the LO3 heads are 56 i think...are the LG4's 64cc? If so, would I want to have them milled down to 56cc to maintain compression?


Say all this is done to the LO3 block....

What would the outcome be if i used the LG4 block, crank and such, rework the LO3 heads, same intake/exhaust, LG4 lifters, new springs, LG4 pushrods, and the LO3 rockers?......basically, reusing all the parts not used on the modified LO3 block/LG4 head combo and making a LG4 block/LO3 head combo and reusing the same parts considering they are in good shape?

sorry if im confusing me and any others in the process. The original plan was to swap engines so that i may smog the '83 and drive it around, and rebuild the LG4 and either place it back in to the '83 or sell it to some S-10'er

I may just yank the LG4 and rebuild it, and install it back in the '83. Then, as THAT is drivable and smoggable.....plant the 91 and plop in a 350.

-blain

You dont want to use the L03 heads at all. They suck. The LG4 heads have about the same potential as iron L98 heads if the same valve size is used. I would use those and port them like five7 suggested unless you are not comfortable doing that kind of work. five7 suggested using the L03 pushrods and LG4 rockers. I would assume he just suggested the L03 pushrods because they are newer, but I am not sure on his reasoning for the LG4 rockers. I thought they were all just stamped steel 1.5 rockers but maybe not.

You will want to use the L03 block because it has a roller cam. As long as they are not damaged you can reuse your stock roller lifters. five7 also meant to get a cam for the L03 block to match the potential of the LG4 heads with the larger valves and possibly some porting. Both sets of heads should have 58cc chabers so you shouldnt have to worry about that.

As far as the LG4 block and L03 head combo it would kind of suck. It has the worse heads, lower compression, and a non roller cam. It would just basically be a transportation motor if that.

Ben

Well, let me try again.

Replace the cam. What I meant by the LO3 cam comment is that it is lame, just as the LO3 heads are lame - replace it with an aftermarket roller lifter performance cam. You can reuse the LO3 roller lifters, and if you do stay with a roller cam, you'll want the LO3 push rods because they are shorter than flat tappet lifter pushrods like the LG4.

The LG4 heads use non-self aligning rockers, so you can't use the LO3 rockers, which are self aligning - I'd go with roller tip rockers like Comp Magnum, although regular replacement stamped steel would be fine.

ahhh, makes sense now.....


im now enlightened, thank you