ZCar Forum banner
Status
Not open for further replies.
1 - 9 of 9 Posts

·
Registered
Joined
·
996 Posts
Discussion Starter · #1 ·
What year could i find an l 28 block with dished pistons. its called a f 54 but i need dished pistons. I have herd the flattop pistons will produce 10:8 compression on a e 31 head. i want a low compression setup. what would be the best year?
thanks
matt
 

·
Registered
Joined
·
625 Posts
Re: which year L28 block for a e-31head with low c

> What year could i find an l 28 block with
> dished pistons. its called a f 54 but i need
> dished pistons. I have herd the flattop
> pistons will produce 10:8 compression on a e
> 31 head. i want a low compression setup.
> what would be the best year?
> thanks
> matt
I believe 75 through early 80 model used dished pistons. >Later ,norm
 

·
Registered
Joined
·
399 Posts
Re: which year L28 block for a e-31head with low c

> I believe 75 through early 80 model used
> dished pistons. >Later ,norm
Norm is correct. By the way, the 81-83 block is the F54, and you are right, it has flat top pistons
 

·
Registered
Joined
·
107,695 Posts
Why use this setup for low compression?

Matt,

Why do you want to mate an e31 with an L28 and try to get low compression? High compression is optimal in N/A engines, and thats why the e31 is desirable. If you're going to use an aftermaket turbo setup (and thats the reason for the low compression), don't use the e31. Go with something else. The e31 is really only good for making a HIGH compression engine.
 

·
Registered
Joined
·
996 Posts
Discussion Starter · #5 ·
Re: Why use this setup for low compression?

> Matt,

> Why do you want to mate an e31 with an L28
> and try to get low compression? High
> compression is optimal in N/A engines, and
> thats why the e31 is desirable. If you're
> going to use an aftermaket turbo setup (and
> thats the reason for the low compression),
> don't use the e31. Go with something else.
> The e31 is really only good for making a
> HIGH compression engine.
well if i mate a L28 flattop block with the E31 head if will give me 10:8 compression and thats too high for 93 pump gas. Could i make it work without it pinging?
matt
 

·
Registered
Joined
·
1,129 Posts
Re: Why use this setup for low compression?

> well if i mate a L28 flattop block with the
> E31 head if will give me 10:8 compression
> and thats too high for 93 pump gas. Could i
> make it work without it pinging?
> matt
I run that exact setup, except my block was decked and my head was milled and it runs fine on 92 octane. The high compression gives it an awesome sound though!
 

·
Registered
Joined
·
482 Posts
Block Decked and Head milled with E31??? WOW!

> I run that exact setup, except my block was
> decked and my head was milled and it runs
> fine on 92 octane. The high compression
> gives it an awesome sound though!

What is your C.R.?? It must be almost 12:1 or more! What timing are you running? Aftermarket ignition?? I'm curious as to how you're doing it.
 

·
Registered
Joined
·
1,129 Posts
Re: Block Decked and Head milled with E31??? WOW!

> What is your C.R.?? It must be almost 12:1
> or more! What timing are you running?
> Aftermarket ignition?? I'm curious as to how
> you're doing it.
I never checked my comp. ratio before building, but How To Modify Your Nissan OHC says that this setup, bored, decked and milled will produce 11.25-11.5 comp. ratio. My block was decked only .008 and my head milled .010. I run a '77 L28 block with .040 over flatops and a ported and polished E31 head with the 280 valves installed. The first time I started the engine, I forgot to check the timing(it was too advanced), 4 cracked pistons later, I began my second engine with 4 new pistons. This time I retarded the timing a whole bunch on startup and used trick 110 octane race gas to break in the first 100 miles. That got too expensive, so I started using octane booster with 92. Still would ping a little under heavy load below 3K. Above 3K rpm's no detonation. I slowly started running less and less octane booster over the next 3,000 miles, and now I only run 92 with no detonation, except when it's over 95 degrees during the summer. It seemed like the engine slowly got used to lower octane over time. Oh, I also run stock type distributor through an MSD ignition and big .065 gap on my plugs, LOTS OF SPARK! This is all with 44mm Mikuni's, 6-1 header, and cam with .495 lift and 290 degrees duration. If you have any questions, just ask.
Chris
 

·
Registered
Joined
·
1,158 Posts
Re: Block Decked and Head milled with E31??? WOW!

I'm getting ready to pull my head to try to diagnose it's failure (think I blew it - quit on the highway after a loud tapping sound & lost power altogether - please see previous post on ENGINE REBUILD-MAJOR OR MINOR) & the more I follow this forum the more I learn about my Z. It's a '77 with an L28 like yours without all the modifications. Only had it a few weeks & assumed the octane level should be as high as I could get - 94. Should I have been using a higher octane? I'm wondering if the timing was retarded - I should have had the timing checked prior to driving daily but exactly how did you know you cracked pistons? I want to make sure I'm doing the right thing when I begin tearing down - my plan is to pull the manifolds & do an in-car repair following Tom Monroe's book on OHC rebuilds.
Any information is greatly appreciated. I've always loved Z's but didn't realize how much loving care was required. Live & learn.I
 
1 - 9 of 9 Posts
Status
Not open for further replies.
Top