[Son of Magni]

Well, I searched the archives and couldn't find anything on the E88 so...
'72 L24 w/orig. E88 head
According to the owners manual (and Chiltons) stock CR is 8.8, the FSM gives it at 9.0. Let's assume the FSM is correct. I want to increase CR to somewhere between 10.0 and 10.5 along with installing a new cam; .460 lift, 270/280 duration. Questions are:
1. How much to shave off (I'm guessing about .050)?
2. With a stock head gasket will there be any problems with clearance (flat top pistons)?
3. Is there any reason to shim up the cam towers?
4. How high can you take CR and get good performance from 93 octane fuel?
Thanks in advance, SoM

 

[john cross]

Just a side note, but what is the designator for the stock head that was used in 73, and how much compression was lost?

 

[Son of Magni]

John

That would be still an E88 head but with a slightly different chamber, 8.5/1 compression I think. On the '72 there's a distinct notch near the plug in the intake side. On the '73 there's still a little notch but not nearly as distinct. I have both heads side by side right now, I'll see if I can get pictures to show the difference.

I've heard that there's another early E88 with an E31 chamber but as far as I can tell it's just rumor. No one can tell me how to ID it. My manufacture date is 11/71 so there's a chance I have one if it really exists...
SoM

 

[Son of Magni]

Two different E88 heads

Ok, I've never done links on a post here so if they don't work, paste them into your browser address bar to see the pics.

This is the chamber from my E88, manufacture date 11/71 ('72 model year).
http://www.sonofthor.com/images/E88-1.jpg

This is from an older E88 that was on a 240z with flattops (must be a '73 right?).
http://www.sonofthor.com/images/E88-2.jpg

Note the notch is much less radical on the later head. Sorry I couldn't clean them up any better but it's pretty cold out there...
SoM

 

[T4240Z]

I had .080 cut off an L26 E88 and put it on a L26 block. I did not shim the towers either. The result of not shimming it is it retards the timing. This will give you more top end while sacrificing a little down below. You can advance it with the factory gear though. It ran on 88 octane leaded (this was 10 yrs ago) and never knocked. I port matched the int & ex.,unshrouded the valves, put a 2 1/14" exhaust on and 72 SU's. It wasn't turbo fast but was alot faster than stock. If you do get a little rattle back the timing off a few degrees, no biggie, but I didn't have any problems. One more thing If you plan on the cam I would do the springs too. The cam you mention will move your peak up more and old stockers will float around 7000 rpm if not sooner. You can run stockers but you'll be loosing power up top.
Clifton

 

[Mack]

Your biggest concern is is the timing T4 mentioned. You should be fine on 93oc up to 10.5:1, but beware of cheap gas. Get it from a good station(not Racetrack or other water stations.). The cam you mentioned is an MSA right? Go ahead and buy the kit, it'll save you money and you need new rockers with a new cam anyway. If you use a non-compressable gasket you can calculate your CR mathematically before you do anything provided you know the combustion chambers dimensions.