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Engine SwapEverything about swapping an engine into your Third Gen.....be it V6, V8, LTX/LSX, crate engine, etc. Pictures, questions, answers, and work logs.
Ok, so last year I purchased a 91 vert bird that had a 305 in it. Blew the 305, and now I have a 350 installed, and almost have it ready for break in. The only thing is that the 350 came out of a K5 Blazer from 1975.
Remembering that there are different variants of the 350, I got bored and decided to see what I got. Found out I have an original LS9 (not the new age LS9, sadly) that only makes 165hp, which doesn't seem far off from the 305 I had.
So, basically, did I screw myself out of a performance car?
What's been done:
.040 bore over
Spectre oil pan
Swap from TBI to 4bbl carb
TSK 3 row aluminum radiator + dual 12v electric fans
Doesn't really matter what the power is, instead, you have the basic 350 foundation to work with. There are infinite ways to make power with a 350 so don't get too hung up on what's in there now. Are you sure the engine is rebuilt to original specs? It may be an LS9 in ID only. Especially if it was rebuilt with upgrades internally (heads, cam, etc). Get it running, enjoy it, and then decide what kind of power you want.
Even at 165hp it will have lots more torque. Like Shifty said though after all these years its probably undergone a rebuild and may even have better stuff in it at this point.
Those old 350s were choked by poor heads (624, 993, 882), a weeeeek cam (929) that was retarded 4° from where it had been when it was originally used back in the 60s in 203s and 327s, barely enough compression to even run at all (8.2 nominal, in the 7s once real-world tolerances are accounted for), restrictive exhausts including the ancient pellet-bed catalytic converters, inadequate spark timing curves, excessively lean carburetor calibration, and possibly (just maybe...) a few other minor factors.
That DOES NOT necessarily mean that just because that motor started out with only 165 HP, that it's STILL making 165 HP. Could be more, might be less.
I'm going to guess you looked up the "stamping codes" on the block. THE BLOCK does not constitute THE MOTOR. You can take THE BLOCK from a wheezy underwhelming L48, zero-deck it, put decent pistons in it, put a solid roller cam in it, bolt 200cc intake runner heads to it, put headers on it, and EASILY get over 500 HP out of THE MOTOR; yet the block will still say "165 HP" right there on its deck. (if it's left after the zero-deck cut) Just like, you can take a 3970010 010/020 block out of a "LT-1" from a "Z/28", put "rebuilder" cast pistons in it, 624 heads, a 929 replica cam, crappy truck exhaust manifolds on it, a junkyard distributor and carb, and so forth; and turn THE BLOCK that "375 HP" monster into something even worse of A MOTOR than a mouse. And like the above, THE BLOCK will still say "375 HP" right there on it.
The odds of this motor still being the exact identical unchanged unmolested original untouched 75 K Blazer motor are quantum-mechanical. (many many zeroes to the right of the decimal point before encountering a non-zero digit) The "codes" aren't going to tell you what has been done to it. Unfortunately, many "rebuilt" motors are EVEN WORSE than they originally came; .020" added deck clearance built into the pistons, for example. Yours may or may not be in that class. You'll never know until you look. But you can be TAKE IT TO THE BANK SURE that whatever you have, it IS NOT the exact MOTOR that the "codes" on THE BLOCK point to.
Concern yourself with THE ACTUAL PARTS AND MACHINE WORK that the MOTOR is built out of, not the "codes" on THE BLOCK. Although, at the level of description you give for this motor, it's hard to really guess what power it might make now. Most of what you said about it is irrelevant to that. Butt who knows, even if you find it underwhelming as-is, it might be a good foundation to make something much better out of, if you go about it right. Details matter ALOT more than stuff like "Spectre oil pan". (although, if that means "krome", be prepared for LOTS of leeeeks over the long term)
So I do know that it was bored .040 over, making it a 357. I have Edelbrock heads on it, as well as a carburetor setup from my mechanic's Corvette he is parting out. I had new pistons installed, but they were bought of someone else who never took them out the box, so I don't really know what type. I'll add a pic. And I upgraded the distributor to an HEI. Oh, and new headers and will be installing straight pipe exhaust off of another Corvette.
Last edited by beetlebaileyx; Sep 28, 2021 at 11:03 AM.
Reason: Pic
Let's hope that what's in your motor now is better than what's laying in that box. Which incidentally isn't stock to begin with, the motor had already been "rebuilt" at least once.
Please keep in mind, this is a site for F bodies. (Camaro/Firebird) Nobody here is impressed about "Corvette" ANYTHING. Nobody cares if your carb was wrapped in fiberglass, cardboard, or sheet metal before you got it. Just because there was fiberglass around it doesn't imbue it with magical properties of any sort. Its actual PART NUMBER, along with a list of any modifications or tuning done to it, will tell us ALOT more than "off a Vette".
Same for an exhaust. You may be assured that ANY exhaust that fit ANY Corvette, will NOT fit one of these cars. Even if it did, it won't necessarily work any better than any other exhaust.
My favorite personal "Vette" parts story comes from the mid 70s, maybe 76 or so, when I was just getting started in this hobby. Like any young dumba$$ might, I answered an ad in the local newspaper's classifieds (remember those? they were sorta like craigslist or nextdoor or letgo, except they came on dead trees) for a set of heads "out of a Vette" according to the ad copy. So, with stars in my eyes, and dreams of romantic racing heritage swimming about in my brain, I drove out to d00d's place in the sticks. He takes me past a BEAUTIFUL 69 427 Vette in his driveway, out to his back 40, where there were a number of decaying 60s Vette parts cars, opens a door on one, reaches into the back, pulls out acoupla castings, and hands me a pair of early 70s 327 sedan 2-bbl smogger heads ... "out of a Vette". I (not so politely) explained about a biological cavity he had where he could store his heads "out of a Vette" for the foreseeable future, and drove back home only slightly poorer (gas was HIGH back then... MUCH higher than today: it was around 70¢ a gallon, when minimum wage was $1.60) but considerably wiser.
The Edelbrock heads are a good sign, as far as they go. They're not "The Fastest" thing out there, but then, that's not what they were meant to be. They're a VERY GOOD street head although not a racing one. A good foundation to build on, as far as that goes. That would depend on what the pistons and cam are, which if you can post the PART NUMBERS off of the boxes, we can maybe identify them, and point you further in the right direction.
HEI (High Energy Ignition) is GM's trade name for their stock ignition systems introduced in 1974. Covers ALOT of ground, from smogger crap in the 70s, on up to fairly modern vehicles. There's ALOT more to getting the most out of one than just slapping it in, no matter if it used to be surrounded by fiberglass or anything else. Both God and The Devil are in the details. Again, we can help you optimize it if you want, but without the details, it's anybody's guess whether what you have is just a junkyard pull out of a 165 HP truck, or what.
Let's hope that what's in your motor now is better than what's laying in that box. Which incidentally isn't stock to begin with, the motor had already been "rebuilt" at least once.
Please keep in mind, this is a site for F bodies. (Camaro/Firebird) Nobody here is impressed about "Corvette" ANYTHING. Nobody cares if your carb was wrapped in fiberglass, cardboard, or sheet metal before you got it. Just because there was fiberglass around it doesn't imbue it with magical properties of any sort. Its actual PART NUMBER, along with a list of any modifications or tuning done to it, will tell us ALOT more than "off a Vette".
Same for an exhaust. You may be assured that ANY exhaust that fit ANY Corvette, will NOT fit one of these cars. Even if it did, it won't necessarily work any better than any other exhaust.
My favorite personal "Vette" parts story comes from the mid 70s, maybe 76 or so, when I was just getting started in this hobby. Like any young dumba$$ might, I answered an ad in the local newspaper's classifieds (remember those? they were sorta like craigslist or nextdoor or letgo, except they came on dead trees) for a set of heads "out of a Vette" according to the ad copy. So, with stars in my eyes, and dreams of romantic racing heritage swimming about in my brain, I drove out to d00d's place in the sticks. He takes me past a BEAUTIFUL 69 427 Vette in his driveway, out to his back 40, where there were a number of decaying 60s Vette parts cars, opens a door on one, reaches into the back, pulls out acoupla castings, and hands me a pair of early 70s 327 sedan 2-bbl smogger heads ... "out of a Vette". I (not so politely) explained about a biological cavity he had where he could store his heads "out of a Vette" for the foreseeable future, and drove back home only slightly poorer (gas was HIGH back then... MUCH higher than today: it was around 70¢ a gallon, when minimum wage was $1.60) but considerably wiser.
The Edelbrock heads are a good sign, as far as they go. They're not "The Fastest" thing out there, but then, that's not what they were meant to be. They're a VERY GOOD street head although not a racing one. A good foundation to build on, as far as that goes. That would depend on what the pistons and cam are, which if you can post the PART NUMBERS off of the boxes, we can maybe identify them, and point you further in the right direction.
HEI (High Energy Ignition) is GM's trade name for their stock ignition systems introduced in 1974. Covers ALOT of ground, from smogger crap in the 70s, on up to fairly modern vehicles. There's ALOT more to getting the most out of one than just slapping it in, no matter if it used to be surrounded by fiberglass or anything else. Both God and The Devil are in the details. Again, we can help you optimize it if you want, but without the details, it's anybody's guess whether what you have is just a junkyard pull out of a 165 HP truck, or what.
LIke I stated, my car is a 1991 Firebird 'vert, which is why I signed up for this forum. And I wasn't trying to impress anyone by saying "Corvette", I was just saying where my parts were coming from so people may have an idea as to what my setup is. Unfortunately, I don't have many part numbers since some parts have come off other vehicles.
Edelbrock heads, any type of flat top pistons and a lil better cam than stock should make for a great street setup. You will not have a 165hp engine that's for sure, it will be light years stronger than your old 305 so I think youre probably good if its put together and tuned in right.
I personally feel that if anyone wants to put a 350 together with up to 450 HP...
You can't go wrong with a new set of Vortec Cylinder-Heads.
If someone wants to make more power normally aspirated...
it is worth the money to purchase a set of AFR Cylinder-Heads that are appropriate for your Engine displacement.
Which incidentally isn't stock to begin with, the motor had already been "rebuilt" at least once.
