Im Looking To Drop A 350 Into My Iroc, I Found One For Sale But I Want To FInd Out Exactly What It Came Out Of Before I Do So. Im Having Trouble Decoding This One So Hopefully You Guys Can Help. This Is All The Numbers The Guy Gave Me To Go By So Bear With me.

Block Casting Number: 3914678
Block Id Number: V0510yw
Heads Casting Number: 3927186

Any Help Would Be Appreciated!!!

 

Block
3914678 1968 350CID 295HP 2 bolt mains Chevy II/Camaro

Heads
3927186 1968-69 302/350 2.02 1.6 63cc

Only listing I can find for the YW suffix code is
1966 327, 185 HP, truck

Engines that is listed for sale is a mid to late 1960's SBC with a 4" bore with restrictive heads that have no accessory bolt holes and large valves. If it runs and is complete, it's worth at the most $300 since it has no real potential other than a stock replacement engine or if someone needs to build a period car and needs casting numbers for that era. If the engine doesn't run, it's work $100 for core value.

 

So Really The Only Good Part Of It Is The Heads, Not Really A Very Big Upgrade If It Only Has 185Hp

 

Not really. 50 years ago they may have been a good performance head since good aftermarket performance parts were limited and expensive but with a huge amount of aftermarket performance parts available now and very affordable, old parts like that are just paperweights. You can buy a cast iron performance heads with the same size valves that will out perform those old heads right out of the box. Brand new heads with new valves, guides, hardened seats, bigger springs, screw in studs, accessory bolt holes, better castings etc at very reasonable prices. Even aluminum heads are affordable compared to 30-50 years ago.

The 185 hp was the rating given to it based on the compression ratio, cam grind heads etc. Those old ratings were also without accessories. Many GM 350's were never rated over 250hp even through the 80's. Most were under 200hp.

Like I said, it's only good if you're building a period car with proper casting numbers. There are much better engine options to pick from. Inexpensive or even free doesn't mean it's a good deal. You could have a better engine buying a stock replacement engine from your local parts supplier and doing a simple cam swap.

 

Here's what I come up with

3914678 1968 302/327/350 2 bolt main block

V= Flint engine plant
05 = 5th mo. (May)
10 = 10th day of mo.
YW = Is not correct for this block. Only SBC YW suffix code comes up as a '66 327 truck engine as alky mention.. The block casting is later than the suffix stamp so that's not right and can't be it. The other YW codes come back as a 427 bbc and 400 and 455 pont. engine.

With sbc stamp numbers it's real easy for one letter to look like another. I bet you it's really a YU or YV suffix code.
Both of those are 1968 327, 220 HP truck engines, which goes with the '68 block casting number

Heads Casting Number: 3927186 is 1968/69 302 / 327 and 1970-72 350.. 2.02"/1.60" valves. Camel hump heads, 64cc chamber, 160cc intake ports. with acc. holes in end of heads. Flow about 187 cfm intake, 135 cfm exhaust stock.. So not real great

Now on the block, keep in mind that's factory. It's a large journal 327, so a 350 crank will fit right in it, as well as 350 pistons..

So with out opening it up and seeing whats inside you really can't be sure what it is, but it left the factory as a 1968 327.

Oh BTW. Most factory 350's and even 400's were dogs when it came to power.
1971 and older engines was rated gross HP, while 72 and newer is net rating. Gross HP was a BS number that you will only get on an engine dyno, dyno exhaust, no belts, acc. drive, air filter, etc.
Net is at the crank still but with factory style exhaust, all belts, pumps, fiters, etc.

Look at a 71 350 rated at 270 HP, no changes to that engine for '72 but HP went down to 200. Which is what it really made in 71 a s well.

So all those 300, 330, 350, 370 HP engines of the 60's and early 70's was not really that much.

Then during the mid 70's to early 80's all the emissions, EPA guidelines, etc had the engines down to a pathic 140, 150, 170 HP. A few of the corvettes in that time frame pushed out 220 HP.

It wasnt untill '85 or so that the power started coming back up with the TPI engines.

 

If your looking for a great stock engine to swap in then look at the 96-02 L31 350 vortec truck engine. It's a gen 1 sb.

Roller cam, great heads, stock 255 HP.

Swap intake, cam, and exhaust and you have a 350 HP or more engine