Cylinder head Questions

[anders]

So I have seen 3 heads on my D24t's that have the stamping "D24T" on the front driver side where the power steering bracket bolts to. Now is this a stamp from a re-builder? I have two 1982 blocks with cylinder heads stamped with this and the Kibbles-n-bits engine that was a 1984.

[v8volvo]

The engine type stamp was there on both D24's and D24T's through roughly mid-1984. All 1983 D24T's have it, I have seen some '84's with it and some without, and from 1985 on there was no stamping.

I assume Volvo put the stampings there themselves, since D24 and D24T are not VW engine codes and as such I doubt that VW would have stamped them for Volvo.

[Jason]

Yup, my original engine in my '84 had it, my new engine that I rebuilt out of the 85 did not.

Jason

[anders]

Now would the stamping be from 84 and older block date or car manufacture date? All the blocks I have seen were 1 year older then the cars they are in. My 84 block that had the stamped head was from a 1985 740.

[v8volvo]

Don't know about that. I assume the engine manufacture date is the relevant factor. Almost every component in the car will tend to have a manufacture date sometime in the year previous to the model year of the vehicle...

Maybe they quit stamping in the beginning of 1984 and it took MY84 and part of MY85 to use up the stamped motors. Who knows. I kind of like the "D24T" stamping being there...

[anders]

Okay here is another question- I'm trying to find out whats different about the D24 vs D24T heads. What I do know is the casting codes are 072 for D24 heads and 075 for D24t heads.

So that leads me to believe there's something different about the castings... Is it possible that the D24T heads have a larger Pre-chamber then the D24 heads?

[ngoma]

Isn't it a different alloy?

[anders]

It might be a different alloy. I was thinking it would make more sense if they installed larger chambers in the T heads. I have read that's the difference on the 1.6 NA vs T heads.
I will try to measure pre-chambers tonight, I think there's 30mm and 32mm?

[anders]

So it's just the opposite of what I thought. I checked 4 turbo heads and they had per chambers measuring 30mm. I checked 3 NA heads and they had chambers measuring at 32mm. So it would seem to me that if someone was going to build a performance motor with high boost levels they would want a NA head for the larger combustion chamber and slightly lower CR. Here are some pics comparing the two chambers.

[anders]

Another picture comparing the two.