Help decode Chevy 350 block numbers

[CharlesInCharge]

Looking at an 1966 Chevy C30 that has had a new engine put in it. Seller is vague and uncertain what block is in it, as it predated his possession. He has said from the beginning it's a 350, and it appears to be the case. I want to be more certain. I'm needing to decode it to see if this is something I want to pursue. Looking at various sites, my head is dizzy from the numerous ways Chevy stamped and coded engines!

We do believe it's a 350, and it has had Wix filter on it part number 51069 and currently has Microguard with same part number, which corresponds to a old 350 engine of MANY of years of manufacture.

Engine block has two sets:
10127CIX.
13R459516 (I think this might be a partial VIN, but that's a guess on my part.)

Any Experts here want to take a stab at this?

 

[Chris142]

Really need the casting numbers off the rear of the block. Can you post some pics of what you have? Are the valve cover Bolts around the outside or down the center? What insignia is on the front of the heads?

That oil filter will fit any 262,267,327,302,307,350 or 400 built 1968 model year or newer

 

[clinebarger]

There will be a casting number on the Left bellhousing pad....Right behind the Left/Driver side cylinder head.

All '68 & up SBC's can use the same spin on filter......They did use different length filters depending on the application & '88-'99 4wd SBC's had a unique adaptor & smaller filter to clear the front drive shaft.

 

[CharlesInCharge]

I don't have any pictures right now unfortunately. I only got a text with the numbers. He said these were the 2 sets of numbers on the block. Surely someone knows how to decode these?

 

[Chris142]

If that code is "CTX" it's a 400. I don't think there is a "CIX".

 

[clinebarger]

And if it is a 400, That's not exactly a good thing in my opinion.

You can usually identify a 400 by the 3 Freeze Plugs on the side of the block vs 2 on all other small blocks.

 

[CharlesInCharge]

Maybe CLX - I think 1973 350?
This is frustrating.

 

[oldhp]

The WIX filter 51069 would also fit 307, 327, 350 engines. Which numbers are cast (raised up?) and which are stamped. Where are numbers at on the block?

 

[JeffKeryk]

Not sure, but CIX does not sound correct.
The CLX is a 1973 350 2bbl 145 hp. Used with Full Size, Automatic

Engine ID Code Example: V0101CLJ - (V = Plant, 01 = Month, 01 = Day, CLJ = Engine Suffix Code)
Another example: T0830CTY - (T = Tonawanda, 08 = August, 30 = 30th day, CTY = 1970 396 Camaro, 375 hp, 11.0:1, TH400)

Engine Plant Code​

Code	Engine Plant
F	Flint (Motor)
H	Hydramatic
K	St. Catherines, Ontario (McKinnon Industries Canada)
M	GM of Mexico
S	Saginaw Service
T	Tonawanda
V	Flint (Engine)

 

[CharlesInCharge]

Not sure, but CIX does not sound correct.
The CLX is a 1973 350 2bbl 145 hp. Used with Full Size, Automatic

Engine ID Code Example: V0101CLJ - (V = Plant, 01 = Month, 01 = Day, CLJ = Engine Suffix Code)
Another example: T0830CTY - (T = Tonawanda, 08 = August, 30 = 30th day, CTY = 1970 396 Camaro, 375 hp, 11.0:1, TH400)

Engine Plant Code​

Code	Engine Plant
F	Flint (Motor)
H	Hydramatic
K	St. Catherines, Ontario (McKinnon Industries Canada)
M	GM of Mexico
S	Saginaw Service
T	Tonawanda
V	Flint (Engine)

Thanks, I had read that site too. If it's an anemic 145hp, I don't want it. This is why it's critical for me to figure out which 350 ci this is, whether it's powerful enough for the application. It would crawl at 145hp.

 

[JeffKeryk]

Thanks, I had read that site too. If it's an anemic 145hp, I don't want it. This is why it's critical for me to figure out which 350 ci this is, whether it's powerful enough for the application. It would crawl at 145hp.

How it was built at the factory and what it is now are likely 2 different things. I doubt there are very many early Chevy small blocks (or big blocks) that are original at this point.

 

[methusaleh]

All that I can add that hasn’t been said is that the dipstick was moved from driver’s side to passenger side beginning in MY1979 as far as I know.

And I know the headers for a 350 versus 454 (not sure about 400) have the ports spaced out evenly on the 454, compared to the middle two being close to each other on a 350. Hard for this old man to explain using words— you’d know it if you saw it.

 

[Rob_Roy]

How it was built at the factory and what it is now are likely 2 different things. I doubt there are very many early Chevy small blocks (or big blocks) that are original at this point.

x2. The cylinder heads and rotating assembly are more important than what the block came out of.

Thanks, I had read that site too. If it's an anemic 145hp, I don't want it. This is why it's critical for me to figure out which 350 ci this is, whether it's powerful enough for the application. It would crawl at 145hp.

Short of knowing more details about the engine, about all you can do is drive the truck and see if the power meets your expectations.

 

[Chris142]

x2. The cylinder heads and rotating assembly are more important than what the block came out of.

That's why I asked for the head i.d. on the front

 

[Snagglefoot]

Thanks, I had read that site too. If it's an anemic 145hp, I don't want it. This is why it's critical for me to figure out which 350 ci this is, whether it's powerful enough for the application. It would crawl at 145hp.

Anemia can be solved quite easily on SB Chevies with a new set of heads, intake manifold, 4bbl carb and a hotter cam!

 

[CharlesInCharge]

Anemia can be solved quite easily on SB Chevies with a new set of heads, intake manifold, 4bbl carb and a hotter cam!

Good to know. What, generally, would be the process to bring an anemic 1970s era GM 350 up to more potent powerhouse numbers. For instance, instead of 1/2 HP per piston, push it up to 1 HP per piston.

 

[Rob_Roy]

Good to know. What, generally, would be the process to bring an anemic 1970s era GM 350 up to more potent powerhouse numbers. For instance, instead of 1/2 HP per piston, push it up to 1 HP per piston.

https://www.motortrend.com/how-to/46320-gm-350-crate-engine-build/
https://www.motortrend.com/how-to/46326-gm-350-crate-engine-build-ii/
https://www.motortrend.com/how-to/46359-gm-350-crate-engine-build-iii/
https://www.motortrend.com/how-to/46364-gm-350-crate-engine-build-iv/
https://www.motortrend.com/how-to/46370-gm-350-crate-engine-build-v/

 

[JeffKeryk]

Good to know. What, generally, would be the process to bring an anemic 1970s era GM 350 up to more potent powerhouse numbers. For instance, instead of 1/2 HP per piston, push it up to 1 HP per piston.

Buy a crate engine and install it. You will get a balanced, proven build based on your needs.

 

[ARCOgraphite]

Good to know. What, generally, would be the process to bring an anemic 1970s era GM 350 up to more potent powerhouse numbers. For instance, instead of 1/2 HP per piston, push it up to 1 HP per piston.

You don't want 1 hp/cu-in that in the truck, you want a nice torquey motor. My clients always wanted to overcam their engines and I talk them out of it and they thanked me for it. Mild cam ( under 210 deg duration) and a small 4bbl with good heads factory iron heads and moderate compression - you are all set. That may likely be 250-275 HP. need a nice Delco L82 vette curve HEI distributor. May not clear the firewall without a massage.

 

[The_Eric]

You don't want 1 hp/cu-in that in the truck, you want a nice torquey motor. My clients always wanted to overcam their engines and I talk them out of it and they thanked me for it. Mild cam ( under 210 deg duration) and a small 4bbl with good heads factory iron heads and moderate compression - you are all set. That may likely be 250-275 HP. need a nice Delco L82 vette curve HEI distributor. May not clear the firewall without a massage.

Fortunately with modern tech, you can have 300hp AND good usable torque