[Firedup6975]

I have a 78 Trans AM that has an XH block code. I was able to search it could be a full size 69 or 70 Pontiac 400 but from what? What cars would have had that engine code. The car is automatic. Any way this could have been in a newer Trans Am?

[ponchjoe]

Grand Prixs, not sure what else

[Poncho Dave]

Need to know if you’re car came with the standard l78 400 or the w72. The standard 400 would have been a 557 block, stamped YA, if it was a w72 car, the block would have been a 988 xx block stamped X7.

[ponyakr]

According to the Wallace engine ID, an XH code engine could be one of several 400's OR a '78-'79 301. So, does that mean that according to the date code/casting number, you know that it came in either a '69 or '70 model ?

http://www.wallaceracing.com/enginesearch4.htm

The XH code was used on 5 different 400 blocks. So, what's the block casting number and date code ?

[ponchjoe]

Originally Posted by ponchjoe

Grand Prixs, not sure what else

Let me clarify, 69-70 GPs with #62 heads.

[ponyakr]

Originally Posted by ponchjoe

Let me clarify, 69-70 GPs with #62 heads.

According to the Wallace info, only a '69 would have had the #62 heads.

The '70's would have had #13 heads and a different casting number block.

If the Wallace info is incorrect, I have no idea.

Just always heard/read that the #62 heads were used in '69, #13 heads were used in '70, and the '70 blocks had 5 motor mount bolt holes on each side, whereas the '69 blocks had only 2 holes on each side. So, the block should be very easy to ID.

[goatless]

What is the head code? Easier to see that than date code/casting number.
Might give us an indication if it's a 301 or 400.
What letter in the 5th position of the VIN?

[Firedup6975]

Originally Posted by Poncho Dave

Need to know if you’re car came with the standard l78 400 or the w72. The standard 400 would have been a 557 block, stamped YA, if it was a w72 car, the block would have been a 988 xx block stamped X7.

I just got this car 2 weeks ago, from a dealer, sight un seen., through recommendations of others. The car belonged to his friend who had it a week, and he bought it from another guy. So the Dealer I got it from don’t know anything about the motor or engine or anything that was done to it. We looked at the block and got that code. I looked it up on Trans Am Specialities site and that is the info that was there. The spark plugs are the smaller ones, so we’re thinking it might be from something 72 or newer? Is there a date code on the heads anywhere that can give info? We know it’s a Pontiac 400 just don’t know what Pontiac and year.

[Firedup6975]

Originally Posted by goatless

What is the head code? Easier to see that than date code/casting number.
Might give us an indication if it's a 301 or 400.
What letter in the 5th position of the VIN?

That would be a K.

[Firedup6975]

I just want to know what engine they put in it from what car and year. It’s a clone, so I already knew it wasn’t the original engine in the car.

[77 Canamman]

A source indicated that there was a 180hp 400 in 1977 that used that code.

[goatless]

Originally Posted by Firedup6975

I just want to know what engine they put in it from what car and year. It’s a clone, so I already knew it wasn’t the original engine in the car.

Ok, was thinking since XH was available in '78 that it might have been original. The K code for engine rules that out, since that was the 403.

If you can see the head code, usually a 2 or 3 digit and or letter combo cast onto the center exhaust ports that will give us a clue as to what you might have. The date code and casting number for the block are back near the distributor, and harder to see.

[johnta1]

If you're wanting to know what the engine is, it doesn't matter what the heads are or date on them?

You need the date code on the engine and the block casting code also.

The 67-69 are not probably the engine unless you can see some engine adapters.

The 77-78 301's would be easy to tell the difference from the 400 also.

On the engine is also a partial VIN and with that you can figure out a lot from it, model year, plant the car came from and with PHS on it, everything known to man about the engine.

[Firedup6975]

Maybe I should explain it this way...... this car is a 78 clone. It was born a 79 403 thus the K in the vin. Someone swapped engines years ago with this one and I just want to know what it came out of with the XH code that also was a Pontiac 400. As I said it has the smaller spark plug wires, which kinda tells me it's from a newer car? Just thought someone might have this motor in a Pontiac they have and could tell me what they have.

[goatless]

I understand all of that. The XH code was used on many different applications through the years.
If you look back near the base of the distributor, you can the casting number and casting date for the block which will pinpoint what it is. The head code will tell us if it was swapped in as a complete motor. Also, it'll give you a pretty good idea of what the compression ratio is, which is something I'd want to know if it were my car.
Also, as John pointed out, the partial VIN on the front of the block will give you info as well.

If we don't have any of this info, we'd just be guessing what it is.

[ponyakr]

Casting number is on a pad below the rear end of the passenger side head.

Date code is usually a 4 digit code near the dist hole.

[Firedup6975]

Originally Posted by goatless

I understand all of that. The XH code was used on many different applications through the years.
If you look back near the base of the distributor, you can the casting number and casting date for the block which will pinpoint what it is. The head code will tell us if it was swapped in as a complete motor. Also, it'll give you a pretty good idea of what the compression ratio is, which is something I'd want to know if it were my car.
Also, as John pointed out, the partial VIN on the front of the block will give you info as well.

If we don't have any of this info, we'd just be guessing what it is.

Ahhhh ok I get it. Will have to look at that.

[Firedup6975]

Originally Posted by ponyakr

Casting number is on a pad below the rear end of the passenger side head.

Date code is usually a 4 digit code near the dist hole.

Ok thanks!

[77 TRASHCAN]

Originally Posted by Firedup6975

Ok thanks!

You can stick your cel phone back there and snap a bunch of pictures, sometimes it works.

All 301's had engine oil dipstick behind drivers side head....

['ol Pinion head]

A '69 400 coded XH would require motor mount adapting to fit in a 2nd Gen subframe. A '70 uasge XH 400 block would not, both are very common 400 coded blocks as tons of GrandPrixs were equipped with '69 & 70 400 XH engines.

Ray Charles could spot a 301 Pontiac, though he'd have to do some feeling around. Since the two letter engine ID code is visible, does the block surface where the head attaches, does the block surface set down real low compared to the top of the timing cover? 301 heads have an 01 as the cast identifier. A small oil filter will also screw sideways into a 301 or 265 block towards the lower passenger rear side, versus using a bolt on alum oil filter adaptor that points a much fatter diameter oil filter up & down.

All normally aspirated 301 4bbl engines had a big THICK alum spacer that was sandwiched between the minimal intake manifold & the Quadrajet carburetor. This thick alum spacer was part of the EGR system. There are no aftermarket intakes for a 301, so the near two inch thick spacer would be visible under the maze of vac hoses, PVC hose, etc.