Engine code deciphering help please

[blongdon]

I have hunted high and low and I can't find any indication an "MH" prefix was used on a small block Chevy anywhere. I believe the engine is a 327. It's in my 1967 K10. In case the photo is too small the code is MH15353. Any info is appreciated.

[geezer#99]

You'll need to do some more scrapping. Should be more stampings on that pad with a suffix code.
That code is for a mexican built block. Generally the truck motors didn't have that code with the part of the vin.
You'll need to get the casting code off the bellhousing flange.
Search here.
http://www.nastyz28.com/sbchevy/sblock.html

And here.
http://www.mortec.com/

[blongdon]

Thanks for the response. I will do some digging on those sites. I scraped the whole tab clean and that is the only number on it. ....strange.

[mechanicalman]

Originally Posted by blongdon

I have hunted high and low and I can't find any indication an "MH" prefix was used on a small block Chevy anywhere. I believe the engine is a 327. It's in my 1967 K10. In case the photo is too small the code is MH15353. Any info is appreciated.

You probably have a replacement 350 engine, that might explain the lack of code numbers that would indicate what vehicle it should match up to and the black paint with no trace of orange under it that can be seen in the picture.

The 67 should have a PCV valve grommet behind the intake manifold and have a pad for a canister style oil filter, although most have been converted to spin-on with an adaptor. If you have had the filter off you would have seen a full width adaptor as opposed to the small adaptor the later blocks have.

If you have a 327 you probably have a smaller balancer like in the middle, if a 350 you probably have a larger balancer like on bottom.

[GASoline71]

Does the engine say "HENCHO EN MEXICO" along the top of the bellhousing flange on the back of the engine?

Gary

[cla511]

On a non-replacement there is a 2-3 letter suffix that tell you what it is. A lot of the replacement motors don't have this. You need the block casting from the driver side bell housing.

[blongdon]

Thanks for the helpful responses. I guess I will go after the number on the bell housing. I was hoping to not have to chase it as it buried in there and covered in years of grime.

The motor does appear to have the larger harmonic balancer Mechanicalman mentioned so I am guessing it is a 350. I also notice it has a screw on Fram PH13 filter on it which I believe also points to a 350. The PVC tube is connected to the Carb rather than the manifold. I am now 100% sure it isn't a '67 327. Just need to do enough cleaning to find out what it is.

Funny how the guy who used to own it had no clue what it was. How do you get parts and such? I just can't imaging not knowing but I guess ignorance can be bliss.

[GASoline71]

PCV moved from the rear of the engine to the passenger side valve cover around 1968 or 1969. The both attached to the back of the carb.

All the external parts will swap from almost any SBC to almost any SBC. As long as you have the original bracketry and such on the front of the engine and a short water pump. Everything will be just fine.

If someone swapped in a replacement engine or a later model 350 replacement with a long water pump, they probably used a later model alternator bracket that put the alternator on the passenger side. The original location for the alternator on ALL '67 to '72 Chevy/GMC trucks is on the drivers side.

Gary

[blongdon]

Thanks for the feedback Gary. Here are a couple pics of the motor. The Alternator is on the driver side using the long ugly bracket. I am going to get the pressure washer and some degreaser after it this weekend to get a look at the numbers on the bell housing as was also suggested. Sounds like as long as I know "about" what I have it will be fine from a parts perspective.

[GASoline71]

For replacement parts, anything external on the engine for a 1967 truck should work. It does have a short water pump on it too. So water pump, alternator, power steering pump, belts, hoses, etc.

However, I have never seen that big mess of hoses coming off the top of the water pump to the manifold. That must be something a prior owner did to help with cooling or water flow of some sort. There are lots of cats on here that are way smarter than me when it comes to these trucks, so maybe they can chime in on that.

Gary

[DANTIP]

Originally Posted by GASoline71

Does the engine say "HENCHO EN MEXICO" along the top of the bellhousing flange on the back of the engine?

Gary

I agree with looking for the "HENCHO EN MEXICO". The "M" looks like the plant code which would be Mexico. Interesting!

[ray_mcavoy]

Originally Posted by GASoline71

However, I have never seen that big mess of hoses coming off the top of the water pump to the manifold. That must be something a prior owner did to help with cooling or water flow of some sort. There are lots of cats on here that are way smarter than me when it comes to these trucks, so maybe they can chime in on that.

That's actually a factory bypass hose setup that was used on 1967 & earlier truck 327's.

Pick-up trucks & Suburbans used a single bypass hose as shown in blongdon's picture. While the medium duty trucks used two bypass hoses going into a Tee fitting on the top of the water pump. Both use the same adapter plate under the thermostat housing. Here's a pic of the medium duty setup in a 1966 C-60

[mechanicalman]

Originally Posted by blongdon

Thanks for the feedback Gary. Here are a couple pics of the motor. The Alternator is on the driver side using the long ugly bracket. I am going to get the pressure washer and some degreaser after it this weekend to get a look at the numbers on the bell housing as was also suggested. Sounds like as long as I know "about" what I have it will be fine from a parts perspective.

OK from this picture you have later model heads with accessory bolt holes, and later valve covers.

Seeing the bypass hose, now it's more important to know if it's a later block and the casting number on the bell housing flange driver's side is really important.

Reason is, you have a non-a/c truck, and the heater hose does not have a control valve as it's not supposed to with no a/c. That is 1 circuit bypassing the thermostat.

You have a factory thermostat bypass hose coming off the spacer under the thermostat housing, that's a 2nd circuit bypassing the thermostat.

If you have a later model block, and we know you have later model heads, that's a 3rd circuit bypassing the thermostat. I expect the water pump has been replaced at some time and has the proper by-pass port as shown in the picture below on the passenger side of the mounting flange (to your R side of picture), but verify this before installing an aftermarket a/c and heater water control valve.

You only need one circuit bypassing the thermostat, 3 is too much coolant not getting circulated through the radiator and a recipe for engine overheating.

IF you DO have a later block, remove the bypass adaptor and hose from under the thermostat, unless it has a "two way thermostat" that closes the bypass when the thermostat opens. If it has that it's the best by-pass, then you would want to plug the one on the water pump with a cup plug or allen head pipe plug.

What say you, SS Tim?

[geezer#99]

I'm totally shocked mechanicalman!!
You didn't even mention his heater hoses are installed wrong.
For shame!! For shame!! LOL!!

[mechanicalman]

Originally Posted by geezer#99

I'm totally shocked mechanicalman!!
You didn't even mention his heater hoses are installed wrong.
For shame!! For shame!! LOL!!

I'm hanging my head in shame!

[geezer#99]

I suppose we should mention it's intake to bottom of core. Top of core to water pump or sometimes rad.