What is the easiest way to identify either engine type. Just bought a 79 and the VIN calls for a 305, but the guy said there was a rebuilt 350 in there. The engine code has been stripped off so any help would be great.

If there are no casting numbers on the block I don't think you can tell without pulling a head and measuring the bore.

Yeah, its a 350, just trust me http://www.nastyz28.com/ubb/wink.gif Ohh, the engine numbers were stripped off to save weight, but I swear its a 350!

He's lying or a complete idiot.

The engine CASTING numbers will be on the rear of the block behind the drivers side (left) cylinder head. You'll probably need a flashlight to see them, but they are pretty big. Go to www.mortec.com (http://www.mortec.com) to see what you end up with. Good luck, I'm hoping for a 350 but it sounds bad so far.

The numbers that he says were stripped off were probably the VIN numbers located on the right front of the block. These are generally wiped out when a block gets decked. Theres no "normal" machining process that will remove the CASTING numbers from the rear of the block.

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11.74/118mph, thats all..

most 305's ive saw say 5.0L beside the casting numbers on driver side behind the head

<font face="Arial,Verdana" size="2">Originally posted by daves 76 rs:
most 305's ive saw say 5.0L beside the casting numbers on driver side behind the head</font>

Wow, I Didnt noticed that on any 305 blocks Ive had. But yea look on the back of the block behind the driver head. Those number most ceratinly better be there or somthing is fishy. Then youll have to waste some water and a gasket to find out the engine bore (if you really want to find out)

even if the casting numbers are ground off.. there is a possibility the pad numbers stamped on the front pad might be still there.. the pad is right behind the alternator

Newer generations of small-blox have the metric equiv cast in next to the tranny on top of block. My '87 4-bolt 350 says 5.7L there. The '79 305 that came in it didn't have that. Also, the stamped numbers on the water pump pad behind the altenator prolly did get wiped out if the block was decked really deep.

[This message has been edited by 79supergasdriver (edited June 30, 2005).]

I could be wrong on this, but I thought 305's had a small or thinner harmonic balancer...

i really won't have time to dig around for those numbers till after the holiday, but I did take a quick look and found some numbers on top of the block (not the firing order), but haven't looked them up yet. it also has a two valve carb, so things aren't looking so good for the 350....

Remember on the 305 heads that there is an extra hole where the exhaust bolts on, just on one end. Not sure if the balancer is thinner or not. Some day soon I'll have an extra 305.
The 406 will be here soon.

The balancer doesn't matter I've seen 305's with the big one and 350's with the small one. And all the later heads have the extra exhaust bolt holes. Only real way to tell is the casting numbers or pull the head. Or at least the valve cover and see what heads you have most people would never put a 350 head on a 305. It would kill the compression badly. Jeff

Just Thinking on this one,dont GM put the valve centrelines closer together on the 305 heads,so if you measured them on a known 350 head,then measured them on yours if they were closer then it would indicate a 305?Does anyone else agree with this?

<font face="Arial,Verdana" size="2">Originally posted by chevyjeff:
...most people would never put a 350 head on a 305. It would kill the compression badly. Jeff</font>

There could be 305 heads on a 350. It is a common (and cheap) way to raise compression. So, heads won't be a definitive test for a 350 either.

My early 80s 305 Targetmaster engine has "305" cast into the side of the block near the front of the engine, IIRC.

Just curious but when replacing a 305 with a 350 is the exhaust bolt pattern the same on the heads?

<font face="Arial,Verdana" size="2">Originally posted by Simpo58:
Just curious but when replacing a 305 with a 350 is the exhaust bolt pattern the same on the heads?</font>

Yup, they match and headers/manifolds will interchange.

You have to watch out sometimes. I put a 350 in my dads Monte SS & the stock 305 manifolds would not bolt up-the last bolt hole on the passengers side manifold was spaced further out. I believe the 350 has 882 heads. Whatever they were, they did not have the extra bolthole. Ended up spending a mint on some Edelbrock headers just to get it all to work.

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11.74/118mph, thats all..

<font face="Arial,Verdana" size="2">Originally posted by Quick Nick:
You have to watch out sometimes. I put a 350 in my dads Monte SS & the stock 305 manifolds would not bolt up-the last bolt hole on the passengers side manifold was spaced further out. I believe the 350 has 882 heads. Whatever they were, they did not have the extra bolthole. Ended up spending a mint on some Edelbrock headers just to get it all to work.

</font>

Most mid 80-90's 305 exhaust manifolds were the "over the ports" type. They also used the extra bolt hole found on most 305 & 350 heads manufactured in the mid80's to 90's. You could not use a mid 80's+ "extra bolt" manifold on an older set of heads. usually buying a set of 350 manifolds, and having the exhaust shop make a minor modification did the trick.

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