305 Engine Swap

[Burnzy]

Hey everybody, I've been reading on this forum for a couple months now. It seems like you guys have a great community, and I want to say thank you in advance for any help or insight you guys can give me.

I have a 97 Yukon with a Vortec 350. Unfortunately, the 350 has 137k miles on it and has recently developed a knock. I've done enough self diagnosis to figure out that it is coming from the bottom of the pan and that it isn't a valve tap... So this implies a bent rod?... In any case, I have been avoiding driving it, but had to use it the other day (wife needed her truck).

Now the knock is more like a bang with a high pitched squeel or screech (metal on metal?).

Alright, so the point is that as far as I am concerned my 350 is dead. I was going to buy a 350 vortec long block and do a direct swap. But it turns out my landlord has a 1990 305 that he pulled from a Chevy pickup. The motor only has 80k on it and is apparently in good running condition.

So my question is, will this 305 just "drop" in or will I need to do a lot of modification to make this thing work?

I've been told that the intake would be the concern... but I am also worried about the ECU, motor mounts, and trans hook up... Any insight is greatly appreciated.

BTW, I know a 305 is a sad idea to replace my 350 with, but its a complete motor for $500 and money is tight for me... so if I could make this work, it would be huge.

Thanks again.

 

[lesterl]

used 350s on Craigslist go for as low as $150...... Dont even mess with the 305

 

[Burnzy]

used 350s on Craigslist go for as low as $150...... Dont even mess with the 305

That may be true, but I know I can trust this guy when he says the motor really only has 80k on it and is in good shape. And thats worth the extra $350 to me.

I just found another post that a guy with a 95 tahoe had a swapped in 305 in it. I think 95 was pre-vortec?

In any case, they said the 305 block and the 350 block are the same size and just have different bores... So that answers my quesion about motor mounts. Now I just need to figure out about the intake and the ecu...

Again, any help is appreciated. Thanks

 

[lesterl]

When you put the 305 in, I know as TBI you use the 305 injectors, I suppose the same would be true of the Vortec, the Injectors would be smaller to more closely match the cyl volume......

Problems you will run into is the 90 305 should be a TBI, have flat tappet cam/setup not roller, wont have provisions for the extra crank sensors for the OBD2, the shift points will be programmed for having a 350 and not a 305.

The last 305 truck I drove was an absolute DOG and I would spend more money to replace/ rebuild the 350.......

You can buy a crank kit for around $200 IIRC to rebuild the bottom end on your current vortec.......

http://www.ebay.com/itm/SBC-SCAT-350-CRANKSHAFT-1PC-RMS-9-10526-KIT-/350268640626#vi-content

For that matter, you could stroke that 350...... that could be fun.....

As far as a bent rod, did ya hydrolock it? Knocking would probably just be rod bearings and crankshaft journals toast.... If you wanted it quick and dirty, you could pull the pan, drop the crank, pull the bearings out of the rods (still in the block), drop the new bearings and crank back in with little work to swapping it out......

Either way good luck, I still think staying with what you have would be far eaiser and would end up having far better results.....