Early Vs Late 7M Blocks

[Mikael_7m]

Same boat as me mate, my car is an 04/89 Aus-spec GTE with a late block & 6M crank... More of the weird '89 model obscurities I guess

Haha makes me feel a bit better I guess.
hey you're also in the progress of a rebuild

 

[eraezer]

Is there any reason to hunt down a "heavy" block instead of the "light" one? Or can they handle about the same power/torque?

I'm about to pick up an engine, but I don't know if it's a "heavy" or "light" one and at this price it's pretty hard not to pick it up...

 

[IJ.]

By now most of the light blocks will have the infamous deck cracks, not to mention even thinner cylinders from errosion of the water jackets from jackasses NOT running coolant.....

Up to you but I wouldn't build a performance 7M on a light block these days.

 

[eraezer]

Ok, I see, then I have to check this before I drive the 300 km one way to get it.

 

[IJ.]

Get a pic of the Ribs on the side of the block....

 

[eraezer]

I will, but for that price I might get it anyway so that I have a spare head and many other parts.

 

[IJ.]

Don't forget to hardness test the head when you get it.

 

[4U2QUIK]

mmmmmmmm...... I've got my own opinion on that. The material the head is made of becomes non-homogenous from the heat leaving the upper layers soft while leaving the inner layers still in their original state.
I've hardness tested a head that was supposed to be junk (annealed) before and after machining and discovered the latter statement to be true. The heads seems to get a case "softness" in some situations.

 

[IJ.]

I've found most to be T1>T0 on the exhaust side and for me that's Junk....

Carved up an early head I had here and it was t0 right through hence my suggestion to test it at least before dropping coin on a rework.
(but having said that people are going to do what they're going to do and on reading your post I'm betting the majority will use that as justification for not even checking)

 

[4U2QUIK]

nice. I didn't go that far lol, The point I was trying to get at is that you should check, just don't throw out a head before taking a cut on it to find out if it's just annealed on the outside, or annealed throughout.


btw, the table on your mill looks super clean!!!

 

[Jimbo]

IJ in your description you called the 87 a light block but in the pictures you labeled it as a heavy block.. or am I looking at it wrong?

 

[IJ.]

IJ in your description you called the 87 a light block but in the pictures you labeled it as a heavy block.. or am I looking at it wrong?

Link the pic in question please.

 

[Jimbo]

Block differences are in the pics below click them to enlarge I've written what to look for on em, the light block is an 87T the Heavy is my New 93T from Toyota.

Heavy
[thumb]http://ij.supramania.com/blocks00.jpg[/thumb]

 

[IJ.]

Now I'm confused, that pic IS the Heavy block as labelled.
(note extra ribs on it's side)

 

[Jimbo]

Yes, the pic is labeled right, extra ribs=heavy.
But the heavy block in the pic is also the 87 one, isn't it?

the light block is an 87T the Heavy is my New 93T from Toyota.

In your first post I think you accidentally called the 87 light.
Or am I the one thats confused?

 

[IJ.]

87t=light
93t=heavy

Heavy block pictured IS my 93t brand new block from Toyota..

 

[Jimbo]

Ok it was me then. I was confused I always thought the 87 was heavier then later they tried to cut material costs by slimming it down a little. Sorry!! :biglaugh:
Thanks for clearing it up.
Feel free to delete anything I've said.

 

[IJ.]

LOL no probs, they actually made them heavier/thicker/stronger, oddly it started with the GE blocks before the GTE's though, possible explanation was the Group A engines were all cherry picked GE blocks without Squirters so sort of makes sense.

M engines are quite an old design that was expanded many times over the years, almost all the legacy mounts are still on the very last of the 92 GTE's i.e. Where the Cam Cover vent goes into the block was the Distributor mount from the earlier engine, Mechanical fuel pump boss is still on the block as is the Cam to operate it on the AUX shaft.

 

[survyor2]

Maybe I missed it, but whats the weight difference between the early and late model blocks only? I should have weighed mine as I have an early model block in my 1990 and a late model block in the shed (cracked). I opted for a good condition early block for my rebuild and its hold up strong. I just wonder how much weight I'm saving with that choice.

Dennis

 

[IJ.]

Maybe I missed it, but whats the weight difference between the early and late model blocks only? I should have weighed mine as I have an early model block in my 1990 and a late model block in the shed (cracked). I opted for a good condition early block for my rebuild and its hold up strong. I just wonder how much weight I'm saving with that choice.

Dennis

No idea on actual "weight" to the Eye Toyota have added +2mm EVERYWHERE so I'm "guessing" it would have to be 15>20 lbs.

The newer blocks are much more stout from a performance perspective but as always this is a double edged sword, mine had a lot of core shift compared to my early blocks, what happens here is the Inner surfaces of the block are offset in relation to the outside surfaces so you will have a thick and thin wall in the cylinders BUT (there's always a but) Even with Core shift the thin side "should" still be thicker than a 18 year old Thin block that's cast on centre so would still be preferable especially if you're going past 84mm bores.