Early Vs Late 7M Blocks

[IJ.]

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]

Light
[thumb]http://ij.supramania.com/blocks01.jpg[/thumb]

Heavy
[thumb]http://ij.supramania.com/blocks02.jpg[/thumb]

Light
[thumb]http://ij.supramania.com/blocks03.jpg[/thumb]

Crank differences.

6m
[thumb]http://ij.supramania.com/crank01.jpg[/thumb]

7M
[thumb]http://ij.supramania.com/crank02.jpg[/thumb]

#16 Head
[thumb]http://ij.supramania.com/head9a.jpg[/thumb]

 

[Nick M]

How about the 12 or so castings for the head?

 

[87M-GTE]

Ian, your a BEAST
Cool thread btw.

Sam

 

[IJ.]

How about the 12 or so castings for the head?

Only have pics for a couple of different one's Nick, my last head was a "#16" and the really early ones were unnumbered so there are a least 17 revisions.

Ian, your a BEAST
Cool thread btw.

Sam

Figured it'd be a good thing to sticky while it was on my mind

 

[87M-GTE]

Only have pics for a couple of different one's Nick, my last head was a "#16" and the really early ones were unnumbered so there are a least 17 revisions.

A sticky regarding the cyl head differences would be cool too.
Also the casting number info and what not..

Great job Ian!

Sam

 

[IJ.]

Main differences are the Intake dividers Sam, most of the other changes are running changes not performance based.

Would need to flow both types to understand if one is better than the other but I suspect the runner change is more an emissions thing.

 

[Nick M]

Only have pics for a couple of different one's Nick, my last head was a "#16" and the really early ones were unnumbered so there are a least 17 revisions.

I was only joking about posting all the heads. I have seen a few castings here and there posted. Like the divided runner and open. One of them was a number 9, but I couldn't tell you which.

 

[whitemike]

Is this looking like the 'wider rail' ?

---------- Post added at 02:13 PM ---------- Previous post was at 02:09 PM ----------

So It's only got extra ribs on ONE side? I was confused looking @ these two pics..

Extra ribs:

No extra:

Safe to say I have the later block? It came with a 6m crank in it but I suppose the guy I bought it from could have done that.

 

[IJ.]

I was only joking about posting all the heads. I have seen a few castings here and there posted. Like the divided runner and open. One of them was a number 9, but I couldn't tell you which.

Ahhh thought you were being serious due to the lack of a !

Is this looking like the 'wider rail' ?


[/COLOR]So It's only got extra ribs on ONE side? I was confused looking @ these two pics..

Extra ribs:

No extra:


Safe to say I have the later block? It came with a 6m crank in it but I suppose the guy I bought it from could have done that.

Yes that's a Late block, the only differences are as noted in my pics in post #1, they were all taken on the same night as I had both blocks on stands just before assembly so we were able to examine them carefully.

 

[Heavy D]

nice thread keep it up, i remember some corolla motors are like that, like the 4afe, and the 7afe, 7a has more ribs, good motors to make a GE out of it

 

[Beefy_Heafy]

very cool. and the motors equipped with 6m crank have a higher red line than the 7m crank ones yes? Its like 6500rpm vs 6250rpm isn't it? I decided since i was balancing internals that the 6m crank would be better since it weighs less.

 

[IJ.]

very cool. and the motors equipped with 6m crank have a higher red line than the 7m crank ones yes? Its like 6500rpm vs 6250rpm isn't it? I decided since i was balancing internals that the 6m crank would be better since it weighs less.

Not sure what the actual hard cut is on both ECU's but either crank is happy to spin to the higher limit, I ran both cranks in the same engine within a 2 week period with the crank being the only change, both were prepped identically and the 7M was smoother across the range until 7500+ where it was hard to pick any difference.

My "solution" was to lighten a 7M to just under the 6M's weight while retaining the I-6's inherent balance.

[thumb]http://ij.supramania.com/crank03.jpg[/thumb]

 

[Jeff Lange]

ECU's changed at the same time as the crank, there was no weird crossover as far as I am aware.

Jeff

 

[Beefy_Heafy]

Damn IJ that sounds like a much better idea than what I have done. I had the option to use either crank since i trashed my original one before the first rebuild but went for 6m due to my knowledge at the time telling me it was the better option. Since balancing, the engine is ultra smooth anyway so it would be a very anal decision for me to swap out cranks at this stage. My 6m crank was nitrided to so it would be a shame to waste that. Ive heard people say it a lot but dont know the exact meaning of the term "prepped" as in prepared. What does that involve?

Oh and my post above with the red lines was referring to the actual point at which the red line starts on the taco. I have no idea where the ecu cuts are at, haven't really attempted to hit mine yet

 

[IJ.]

Prepped ie: identical Main, Rod Journals and Thrust dimensions, Balance, Heat treating, Niteriding so getting each crank 100% interchangable.
(clerical error resulted in me having both cranks ready at the same time)

 

[Beefy_Heafy]

Lol @ clerical error. But makes for excellent controlled experiment
So now i'm wondering if both the 6m crank and 7m crank are balanced identically on a machine how come the 7m is still smoother in application? Does it have something to do with the combustion stroke vs counter weighted and non counter weighted throws. or just more even placement of counterweights

 

[IJ.]

The 6M has a couple of longer counterweights to cover the MIA ones, while this "works" it's not ideal, look at a Jz crank and you will see it's 7M heritage.

 

[Beefy_Heafy]

Yeah It looks the same except "chunkier" very cool. Now I want a 7m crank! Dammit IJ, teaching me through my own lack of experience

 

[JDMMA70]

Im starting to think Late 88's came with the late blocks. My 88 (June 88) has the Late style block and the original head casting was a #12 ive got a #14 on it right now.

 

[4U2QUIK]

I've seen both blocks in 89's. but not in an 88 that was original.
Weird thing is, I have a head off of a 92 cressida, and it's a 7.