Hey everyone, somewhat recently my engine overheated (coolant smells burnt and has brown swirls in it, engine knocking). Planning on pulling it out and rebuilding it, but have never rebuilt anything larger than a carburetor, so any tips or advice would be much appreciated. Also any recommendations on where to get a rebuild kit? Very new to all of this, thanks in advance.

 

Stock rebuild? How many miles on the engine? how far are you thinking you will go. I like rockauto.com BUT if you are getting any machine shop work I would talk to them about parts. That way there is less chance of a miss communication. Also no reason to order parts until you get it a part. You do not know what you need. It may need a CAM it may not. It may need undersize bearings, it may not. It may need oversized rings ect..

How did the oil look? You can not really burn coolant. If you super heat it it only turns to steam. Brown may just be some dirt in there.

Tear down and inspect first. Then you can decide what you are going to do. Assuming this motor is an older one, you can get a surprise in the cylinders. Cylinder wear is a factor of how the car was driven/cared for, how good the factory fit the pistons and the amount of nickel in the block. I have seen motors that where a part for a bad wrist pin or bad bearing and the cylinders are worn so far out of round the new rings can not seal like the ones that where just taken out. If the cylinders are worn more then .005" out of round the block should be bored with new rings/pistons.

If the motor has much more then 80,000 miles it is almost always cheap to just get a remanufactured motor. I have seen many guys try to save money by rebuilding their own motor just to end up with a $2500 machine shop bill and they still had to buy all the special tools and supplies needed to assemble the motor.


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Thanks, oil smelled burnt as well. I want to say the engine is the original one, 350 sbc. Im guessing it has roughly 125k miles on it. Ill pull it apart some time this month and see what it looks like inside.

 

With that kind of miles she is probably going to need a complete rebuild. To do it right you could be close to 5K all in. All that and it will not have a warranty. I know modern engines can just need new rings and bearings a 200,000 miles but back in the day it was not uncommon to see smoke piling out the back of a 70\s car with 100,000 miles on it.

The only reason there is to rebuild a high miles motor like that is if you want a very specific custom engine build. You can buy a new GM engine (assuming they still make them) for a little over 3K that is going to have twice the HP if your engine is original, and it will may come with 3 years / 36,000 miles warranty covered by any GM dealer. Also many guys are upgrading their motors to LSX or 3rd gen motors. I don't see them as much now as I did 4 years ago but you could find good deals on well cared for nice motors that are only being pulled because of an upgrade. If you make a mistake the motor can end up unsalvageable after 2 minutes of running. I have given that news too many times to first time engine builders. I give you this advice after seeing dozens of guys making the mistake of thinking a rebuild will be cheaper then remanufactured. I would guess there is a 1 in 10 chance you will get in and out of that motor without it costing more then a reman and its never as cheap as people hope. What is a good micrometer costing these days? My set cost almost a grand 30 years ago. There is a good deal to be proud of in just swapping a solid motor and doing a few upgrades.

If you read all that and still want to move forward I can help with advice. The only real reason to move forward is to do it as a learning project or something you can knock off a bucket list.

 

Wow, thanks for all the info. I like the idea of buying a reman or a crate motor but I just feel like that's going to be a little out of my price range, still in high school so I have the Mac & Cheese budget. I've been looking for a 350 or other SBC someone pulled because of an LS swap. Also a little different but I assume a LS swap would cost more than just putting in another SBC? I still may rebuild the old one for the experience.

 

In your case I'd look for a good used motor,preferably one you can hear running before it gets pulled for a swap.
Then I'd keep your old motor and gather parts over time as you can afford them for a build.

 

Take a look at sloppy Mechanics website/Youtube channel.

Mat is always going for maximum HP on a budget but a lot of the forums talk about total budget builds. With LS swaps you can spend between $1000 and $30,000. If you have a local you pull it lot and you don't mind starting with a 4.8 your biggest single expense will be the tune. If the motor is near stock you just need the PCM jail broke to avoid the security system and there is even some fixes for that. Almost everything has a budget solution that just takes time and research to work around. The nice part is once your 4.8 is done then moving to a 6.0 is easy. Also the low end easy to find 4.8 still has 125 more HP then your original motor had. In. You should still remove the pan and check out inside of the motor to make sure it was not abused and had basic maintenance. No motor can survive not changing oil and a ton of sludge. If you watch Soppily mechanics go back a few years on the videos. Mat has really been focused on budge all out drag cars in the last couple of years.

The reasons the 3r gen motors AKA LSx engines are so good is. One the precision of the original motors it a better fit, the materials used was controlled better (higher nickel in the block) and the design itself is MUCH stronger. With your 350 the crank hangs below the the engine block with 2 bolts holding the each main bearing cap. The LSx design the crank is inside the block and there are 6 bolt holding the mains. This makes the motor less likely to flex which causes early wear.

 

Once again thanks you guys for all that information. I have been trying to find someone who has LS swapped and wants to get rid of their old SBC however i'm not getting very far there. Any recommendations on places to ask for that? Also regarding the LS swap what kind of accessory drive would I be looking at running? Would the stock one that the LS had new work or would I need to modify/ get an aftermarket drive? (No cowl hood if that helps, just stock engine bay).