How can you tell just by looking at it? I have a 1981 4 speed and I know they came with 305's but the previous owner said it has a 350. Just want to make sure. The dipstick is on the drivers side and there is no readable numbers on the engine I can see with it installed.

Thats not the original engine. It should be a passenger side dipstick.

On the block behind the distributor there should be a casting number. If you get that number - you can identify the block.

Look for the last three digits especially. A factory 81 Z28 block will have a casting number ending in 207, but is a passenger side dipstick. You have a drivers side dipstick which is an older engine.

Should be a 350 though right?

I have a '72 or 3 350, the dipstick is on the drivers side.

You can also try looking on the pad on the block behind the alternator for a code. If theres one there you should be able to decipher your motors ci's and what car it came in originally.

That's how I found out.

[This message has been edited by sikzdrivr (edited January 06, 2005).]

[This message has been edited by sikzdrivr (edited January 06, 2005).]

You can also find the block casting number - it is behind the drivers side head on the bellhousing flange. You will probably have to scrape off a bunch of crud and use a flashlight to see it, but it can be read with the engine in the car. The last three numbers of the casting number will usually ID the block for you.
If you are lucky and they swapped in a newer engine, GM switched to putting GM5.0 or GM5.7 back there sometime in the mid 80's. Makes ID easy

I will try to see something later. So they visibally look the same? There's nothing other than numbers to distinguish the two?

Look for the three digit engine suffix code on the block pad just behind the alternator and let us knw what you find. Thats the best way to be sure of what you have.

John
79Z28

If the car was an 1981 built in Canada or destined for export to Canada, it would have had a 350 not a 305, not that it matters in your case cause the engine been swapped.

My 81Z was built in the US & shipped to Canada, it's a 350 with the 3.42 1st geared ST-10.

No, just looking at the engines theres no true way of telling.

From 1955 through the 80's every small block looks very close to each other

some of the older ones had a smaller damper, diff color paint, etc but all that can be changed around, swapped from engine to engine.

The 400 is about the only SB you can look at and tell by looking what it is (due to 3 frost plugs on the side, all other SB's only have 2)

You need to get the numbers.. Casting and sufix

Sufix is on the pad in front of the pass' side cyl. head

Casting is on the driver's side rear, above where the trans bolts up.

Sufix code is stampped into the metal, Casting # is rasised numbers

You will need some WD-40, carb cleaner, etc and a stiff small brush. Spray the pad with your cleaner, then scrub with brush, wipe with rag, then you should see the numbers.

Post numbers here, or look on the front page of this site under number decoding or on www.mortec.com (http://www.mortec.com) to see what the numbers means

O.K. after scraping some paint I found this on the pad behinf the alternator.
K02 01 CKD

The drivers head number is 3973487
According to that site (cool site) it was from a 72 Z28 with 75 cc heads. Is this good?

<font face="Arial,Verdana" size="2">Originally posted by gregh:
If the car was an 1981 built in Canada or destined for export to Canada</font>

All f-bodies up to 1993 model year were built at either Norwood, Ohio or Van Nuys, CA. All 1993 to '02 were built at St. Therese (Montreal) Quebec.

1980-81 Z28's exported to the Great White North (beauty, eh http://www.nastyz28.com/ubb/smile.gif ) could get the 350/4-speed combo and did not have the computer controlled Q-Jet.

<font face="Arial,Verdana" size="2">Originally posted by night rider:
The 400 is about the only SB you can look at and tell by looking what it is (due to 3 frost plugs on the side, all other SB's only have 2)
</font>

Not all 400's have 3 frost plugs on the side. Some only have 2.



------------------
'Silver Bullet' 1977 Z-28 413" SB
11.73 @ 115.10 and dropping...
Old Vortec combo:
12.15 @ 110.52
1989 GTA L98
Daily driver

<font face="Arial,Verdana" size="2">Originally posted by Z28 4 speed:
The drivers head number is 3973487
According to that site (cool site) it was from a 72 Z28 with 75 cc heads. Is this good?</font>

Yes! The 487 is a real good head for being made at the beginning of the smog era. They were used on the high performance 350 engines.

CKD can be any of these...

1972 350 tur hydro trans 175 HP 4bbl F A B X body

1973 350 tur hydro, Calif L48 200HP 4bbl. A B F X body

1974 350 T350 NB2 4bbl. A B F X body

1977 CKD 350 a/t, high altitude L vin L48 180 HP 4bbl Vette


The heads...

3973487....71-72...350..........used on 71-72 350 LT1, 75cc

Could be 1.94"/1.50" or 2.02"/1.60" valves

Those heads flows pretty good for when they was made. Only thing is the high camber CC, you may need to have them milled to lower the CC and build more compression

Thanks, at least I have a 350. Now it's mated up to my stock 4 speed and not an auto. I know the heads were machined by the previous owner but don't know much else about them? How much horespower do you think I am running now? Lunati Cam (no specs)bored .030 over, ported heads, 650 carb, torquer II intake, electric fan, headers, no cats, 2.5" exhaust, msd dist. and Mallory hi-fire coil.

[This message has been edited by Z28 4 speed (edited January 07, 2005).]

Maybe mid 300's. Without the cam specs it's a shot in the dark. But "IF" someone went to the trouble of matching a cam with the rest of the setup, I'd say mid 300's or just a hair less.

the 305 costs about 300.00 more to rebuild?
(is this a trick question?)