Hypothetically speaking, the 91-92 RS LO3 I find isn't running the best...the car will see some strip time, but mostly street. I want it to be reliable as compared to a 170000 mile tired runner. Not looking to take the block out of the car, are there any setbacks, major difficulties associated with an in-car internals replacement? Provided the cylinder walls are in good condition and need no machining, a good hone job would suffice would it not? If I were to take the engine out of the car completely, I know there would be no point in keeping 305 cubes when 350 would be just as easy to drop back in.

I'm just looking to replace with a decent rebuild kit out of summit, and I could get the tear down/rebuild done in a weekend. Considering the car will be my daily driver this would be optimal.

Besides reliablity, down the road I will be adding vortec heads and a fairly aggressive cam similar to the LT4 hot cam, along with the small mods that are a given. Knowing this, I don't want to worry about worn out parts responding to the mods I make. Budgeting is key for this plan since I don't intend to sink all my money into my car, I have other things to concentrate on like music, etc.

All opinions welcome.

 

I would recommend re-thinking it.... you're basing your decision on several faulty premises.

It's an incredible amount of work to try to tear down and reassemble an engine with it in a chassis. Basically, I'd expect it to take at least twice as long to do the work while leaning over fenders and climbing under the car, as compared to standing next to an engine stand.

Plus, the results you get, won't be anywhere near as good as doing it right. It's almost a guaranteed certainty that the block will need boring, after that many miles. And if (since) it does, there's no sense in spending all that money on a 305 core, when a 350 core is only $50 or so. Remember, you're going to have $2000 bare minimum in this by the time you're through; maximize the return on your money, don't be "penny-wise and dollar-foolish", get the most for your money by using a tiny bit of it on cubic inches.

There's no way in Hell that you're going to get a tear-down and rebuild completed in one weekend, even if the motor was already out and you didn't have to put it back in. Especially not if this is your first motor build, and even more especially if you're fighting trying to put it together in the chassis. All it would take, is one little part somewhere along the line to be absent or wrong or defective when you counted on re-using it or more worn that you thought or you lose or damage something; and the "plan" is then shot. Try laying on your back and hoisting a crankshaft up into some constricted place 4" above your face among a whole bunch of parts that can scratch a journal, and I think you'll see just how tough of a goal it is to get it all back together right.

Vortec heads are probably not the best choice for a 305.

All in all, not a good plan. You'd be better off to take out the 305 and throw it away, and just drop a 350 in in its place. That also has the advantage of not disabling the car for any extended period of time, like while things are at the machine shop and so forth.

 

[edit out my Vader reference...] RB is so right...

Mine took a weekend just to simply pull the old motor, swap over the parts from the 305 to the 355 and get the 355 in place and started up... starting at noon on Friday and ending up at midnight on Saturday. That is also w/ 4 guys besides me who have done swaps before, and this being my 4th swap total... the 3 others in other peoples cars...

Exactly. That is what I had to do. I couldn't have the car down for the 2 weeks of machine work needed. So I got everything I needed together, got the machien work done, assembled the shortblock, added the heads and everything else I had available to put on it, and then in that weekend finished up.

It will take mroe than you think it will. Trust me. And no matter what you think your budget is, you will spend more. Count on spending at least another 10% on stuff you didn't think of.

 

Vader is good. He's right and didn't even reply yet!

 

feel the force, vader is working through RB

 

dang its been a long day... I didn't even realize I had typed the wrong person in!!!

 

I failed to mention this will be done in a shop for free, along with a buddy, his Dad (the auto tech teach, IHRA stock class, even if he does race rustangs, plenty of expertise). Shop has all the tools I'll need, including a lift, so no need to lay on my back and bench-press a crankshaft.

The mileage was just an estimate from my first 3rd gen car since it was a turd. Most of the probable subjects I've been making my mind about are around 120k miles. I have seen amazing results from cammed, vortec 305's on this site even, with proper tuning.

But your argument about keeping the car running, while building a 350 shortblock slowly without rushing has convinced me to change my mind. I was steering away from having to find a knock sensor, injectors, an ESC, and a prom most likely because the whole plan was rushed and that seemed like more searching to do.

350 tbi it is, thanks.

 

I think that's a better idea.... build the 350 you really want, instead of doing an incredible amount of work and spending lots of money to half-*** something (as it most certainly would be) that isn't what you really want. Go get your Vortec heads and work them up, find the right injectors, carefully and painstakingly build up a short block that doesn't leak, etc., all at your leisure; then just swap it.

 

That is the dumbest idea ever, to be frank... In car rebuild, lets look at this LOGICALLY, if you tear the heads off the motor, and plan on swapping a crank, that means you'll have to lift the motor to manuver the crank into place, hence, the motor mounts will be off. so once the heads are off, obiously all the accessories are off, leaving only the six bellhousing bolts, the starter, and some very little wiring... Really about 1 hour worth of work. pull out the motor... oh, and possibly the torque converter bolts, if so equipped..

 

If you had looked at it with a little less bias, as well as looked at the other post, the motor mounts would be untouched since the car is on a lift and you can go under the car with ease. Wasn't aware ALL the accessories had to come off, but then again, I've only changed the heads in a carbed drag mustang, obviously some accessories pertaining to this situation (electric water pump, no p/s, etc.).

The main reason the topic of an in-car rebuild even popped into my head is because its done often and quickly in Hondas (yeah yeah I'll stop here). I realize its very different, but it certainly takes out some time if you don't bother getting a separate block.

I don't do "half-***"

 

Whether the car is 200 feet in the air or 6 inches from the ground, your not going to be able to pull the crankshaft out around the crossmember with out lifting the motor for additional clearance, there isn't even enough space to pull the oil pan out. Thats why I went off on a tangent.. virtually every accesory bolts to either head, thats why it made no sense to me

 

Hypothetically speaking, the motor should hypothetically be on a hypothetical engine stand for this hypothetical situation…especially if it will hypothetically be in a shop. Especially as trying to do an in frame is about as fun as getting shot, hypothetically. Well, at least they give you drugs if you get shot… maybe it’s not that much of a toss up.

Hypothetically speaking, summit rebuild kits are just an *** reaming without the k-y jelly. Look elsewhere and for parts….

And finally, make your full plans for this motor ahead of time and just suffer through the poor performance if you can’t afford to get everything at once. And do the research before finalizing the plan. (ex. I’d look to see if you would need any work on those vortecs with that cam, etc.) That way you know ahead of time what it will really cost you.

Other than that, heed RB and you should be fine, but get the in frame out of your mind, it isn't realistic.