Not knowing exactly what engine was in my car has been bugging me for a while, so I decided to check the casting number on my cylinder heads. Keep in mind that I have a 1986 305 TPI engine, meaning my heads number should be 14014416. Well, it turns out that the number stamped onto the heads is actually 14101083 -- which are 350 L98 heads! I initially noticed a discrepancy when my '86 engine had center-bolt valve covers, which didn't debut until 1987. This may also explain why my "305" ran a surprisingly-good 14.6 in the quarter mile. The only explanation that I could come up with was that the engine was replaced under warranty in the late-80s, yet it didn't come up on Carfax when I bought the car. I guess I just need to know whether I have a 305 or a 350 block... I tried to look for the casting numbers but there's no way I'm gonna be able to see the whole way down there. Are there any other ways for me to tell?

EDIT: Didn't Chevy V8's go to the serpentine belt setup in 1988? Mine still uses the V-belt layout. Therefore, this would have to be either a late-'86 350 or an '87 350... assuming that's what I have, of course.

 

Lemme go check to see if there is another way to tell.... brb

 

Ok, I can get to my casting numbers. They are on the drivers side rear of the motor where it bolts to the tranny. You should see either a 5.0LG or a 5.7LG right there. Its right under the rear of the valve cover. With a little prodding and moving of the wire looms and a flashlight I bet you'd be able to see the markings. Good luck.

 

I went to go check the engine and, sure enough, "5.7L" was stamped into the back of the block. This raises new questions... why do I have a 350 when I'm supposed to have a 305, and my VIN number says I have a 305? It couldn't be a warranteed replacement if they stuck a larger engine in there, could it? Might I have one of the "rare" 1986 350 IROCs?

I'm going to see if the guy I bought my car from has the number of the previous owner, who might have the number of the original owner -- hopefully I'll find some stuff out here. Any other thoughts?

EDIT: And another thing... the IROC 350s came with Borg-Warner rear axles (3.27). The 1986 305 automatic came with a 2.73 rear axle. After checking my RPO sheet, I've come across this: "AXLE REAR, 3.23 RATIO." Was a 3.23 rear axle available as an option for '86?

 

I own a 86' IROC, and it has 3.23 in the rear.

Wow, 5.7, that's an awesome find, you lucky bastard!

 

What's the history on your car? How many previous owners? It's very easy to replace a long block.

 

The Carfax history said nothing of any accidents, etc... I'm the fourth owner of the vehicle. I can tell that the front end of my car has been repainted (even before my accident), so maybe the car was in an accident and had the engine replaced without reporting it to insurance. Still, it's confusing why a 305 would be replaced with a 350 if the car was in a wreck.

 

IT'S NOT AN ORIGINAL 350.

There were only about 50 of them produced and not EPA certified.
So, someone swapped the motor out. I don't see carfax ever telling anyone of an engine swap. I know when I did mine I didn't report swapping engines.

 

Interesting. Speaking of the EPA, would having a 350 make it harder to pass if the garage is checking for 305 emissions?

 

No, everything looks the same. And I don't know of any emission laws in states that check the block # to verify the engine.

 

If there were three owners previously, then it's very likely that one of them swapped in a 350 and heads for more power. Everyone is doing it.

 

California. I actually had some guy check the numbers on my block and he refused to smog it, because it was newer than my car.

 

That's a good point. If anyone were to swap engines, it would most likely have been the second owner. The first owner was some lady who only drove it on the highway, and the guy I bought it from still thought it was a 305. The second owner put the car in car shows, so I guess it's possible. I'm going to make a few calls today and see if I can find out the truth. The weird thing is, if you swapped in a 350 and sold the car, why would you tell people that it's only a 305? Very curious.

 

They only do that for the shady looking charactors...

 

lol. Yeah really, he must have worn his Jegs hatand Summit sweatpants to the place.

 

That California BS is the only reason why I apent money rebuilding a 305, so at least the original block would be in the car... I think they checked its casting # but I'm not sure...

But if course I'm about as shady-looking as they come. They checked everything in my car, down to the part #s on sensors; they traced every vacuum line, checked the timing with a light, etc.

It's not an orignal 350 I'm sure. There are so few, it would be all but impossible for someone to have either one of them and not know it. I'd be inclined to agree with the warranty suggestion, the belt setup they would have transferred from the old engine to the new one, so it would logically still have the 86 setup not the later one.

 

Actually it depends on the person doing the smog. We had been going in that station for years and the guy as it turns out was just a jerk. Maybe he just didnt wanna smog my car. I took it to another place and it passed the sniffer test with flying colors.

 

I decided to check the engine's timing, as well... it turned out that it was at 10° BTDC! There seem to be two logical explanations for that: either (1) when I got my coil, cap, and rotor put in the garage bumped the timing up, or (2) the guy who owned the car beforehand had it there. I thought about retarding the timing back to the stock 6°, but I figured "what the heck?" and increased the timing a little bit more, to the tune of 12-13° BTDC. I took the car out before and noticed that it seemed to run a little "smoother"... is that possible if I advanced the timing? Also, I didn't notice anything that sounded out-of-the-ordinary.