need opinions on switching to E31

[deadflo]

There is a rebuilt E31 on ebay that strikes my fancy for a couple reasons.

A) I have a 1/71 build date car, that I BELEIVE would have come with the E-31,it currently has an E-88.

I am leaking coolant at the head gasket to the outside of the block.

My thought is since the gasket will need replacing, I could put an original head back on. I need input on a few things.

First, there is much divergence of opinion on the net as to when the e-31's were phased out. Would my car have had one? (it is the original block in the car).I beleive Carl B knows the answer to this one.

There seems to be the same variety of opinions on the nature of the E-88, in terms of the valve sizes. Wading through the info I seem to discern the 72 and 73 still had the small valves, the 74 E-88 the larger valves?

I'm wondering this because I have no idea if my current head has the larger or smaller valves.

But I'm assuming I have the small valves currently, so going to the e-31 should not be a step down in performance. (despite the increased compression of the e-31).

What downside could be lurking in using this E-31? The seller says it not been milled, so should give compression that can handle pump gas.

I noticed in the MSA catalog that they listed the E-31 head gasket as not available! Would the gasket for an E-88 work?

OK the other deal is the seller of the head. UR Gellis, who I Know has been mentioned on our site before, when he had his eback feedback hidden. It seems he is now letting us take a look at it and it seems ok. There are a few negative comments, but I emailed some folks he sold heads to in the past, and i have gotten a couple of good recomendations from them.

Feel free to weigh in on this, and confuse me further!

[zguitar71]

The E-88 with big valves will not work on the 240 block, the valves will hit the cylinder walls. My 7-71 had an e-31. I see no reason not to go with the 31, the compression will go up a bit and on a 240 block it is still well below the need for anything other than pump gass. If it is not milled there could be some warpage, you might have to get it milled for the head to work. If it is rebuilt then it should have been milled for flatness, it is part of the process.

[Arne]

My 4/71 had an E31, but my 7/71 has an E88. So probably somewhere in the middle of July, 1971 was when they were phased out.

[Zs-ondabrain]

The E-88 with big valves will not work on the 240 block, the valves will hit the cylinder walls. My 7-71 had an e-31. I see no reason not to go with the 31, the compression will go up a bit and on a 240 block it is still well below the need for anything other than pump gass. If it is not milled there could be some warpage, you might have to get it milled for the head to work. If it is rebuilt then it should have been milled for flatness, it is part of the process.

Weird. I have a 8/70' 240Z stock block with an E-88 head on it and it works flaylessly.

Who told you that the E-88 won't work on a 240Z. As far I as I know, the E-88 head is what comes on the 73' 240Z.

I'm confused.

[nwcubsman]

As Arne mentioned, the E-88 started in '71 and was used through '73 at least. It is the 280Z heads that had the bigger valves. The E-31 simply ran a higher compression ratio.

My concerrn would be with what is lurking inside the oil galleries inside the head. Since you don't know who rebuilt the head, they could have media blasted it to make it look pretty and some gunk is still in there. Rusch Motorpsorts, who specializes in porting Z heads says great pains must be taken to clean the of chips once it has been machined. That doesn't even count shot blasting.

[Arne]

Dave, the latest E88 head that came on the 260Z with the larger valves won't fit on a stock bore L24 block. The cylinders need to have a notch for valve clearance added. An E88 that came on an L24 (with the same valve sizes as the E31) obviously is fine.

I've seen references to at least 4 separate versions of the E88 head. Very early ones had a chamber very similar to the E31. The bulk of the '72 E88s had a small chamber but it was quite different in shape than the E31. The E88 on the '73 240Z had a larger chamber and lower compression. Lastly, the E88 on the 260Z was similar to the large chamber head, but with larger exhaust valves. That last version is the only one that won't fit on a stock bore L24. But I believe that almost any overbore is OK, even .020" over gives enough clearance for the larger valves.

[superfunk]

I have one of the ealier E-88 style heads on my L24 that is similar to the E-31. It seems to have had the bigger valves put in it. I assume that my block has been bored because it runs fine.

[deadflo]

Ok, so it IS likely my 1/71 car came with the E-31. Thanks for the confirmation folks, i thought that was the case. Again, i have contacted some other people who bought heads from UR Gellis on ebay and two have responded with good reports. Anyone else dealt with this seller?

[jmark]

See this thread.

http://www.classiczcars.com/forums/showthread.php?t=21502&highlight=UR+Gellis

[MAX]

My 73 240Z came with the E88 head. Due to a problem with this head I had it replaced with an E31 with the larger valves. The guy who sold me the E31 head didn't inform me that the larger valves would be a problem on the stock L24 motor. And being a novice at the time I didn't know of the potential problem....

Well, I ended up having to tear my motor down and bore out the cylinders and have a relief cut out of the upper edge of the cylinders. This was due to the larger valves coming into contact with the upper edge of the cylinder walls.

But after doing all that the engine now runs great with those mods....

[tbird481]

I own a 1/71 series-1 Z as well. It originally had an E-31 that formed a crack and had to be replaced. Not knowing any better, I purchased a complete (cam/valves/etc) rebuilt E-88 and immediately noticed a drop in performance. Could have been the cam (I was running the stock E-31 cam as well).