Spark Plug, Compression, Gearing, and Power Feedback

[240260280]

Your timing is now 12 to 32 , you can try 16 to 36 to get more pep once you sorted out the chain.

Most Z's like 35 to 38 max timing.

[Patcon]

Is it possible the timing has already jumped a tooth?

[Zed Head]

Could be the E88 head has been shaved but the cam towers not shimmed.  Seems weird that somebody would bore an engine, with all of the expense of, at least, new bearings and pistons and rings, then put worn out parts on it.  Scrapes on the valve cover is a lot of loose, isn't it?

The notch and groove will give a clue about if it's jumped a tooth.

On the bright side - there's potential for more power once you get the parts right.

[gundee]

On 2/1/2018 at 7:32 PM, Hardway said:

Compression: #1 150, #2 151, #3 150, #4 151, #5 151, #6 150  I think this looks really good!

The FSM states for a N42 L28 with dished pistons, the compression is 164 to 178 psi.

A bit low but all still very even so just fine to drive if you do not want to pull apart for now. I see no issue.

I would look elsewhere for any problems.

[moelk]

Questions: Are you sure the engine is bored at all, or could it be just a stock block with dished pistons?

I have a bored N42 block + 1 mm flattop pistons and the late 240/260 E88 head. With bigger valves and a Schneider stage3 cam and triple 45s.

I have my ignition timing at 16-17 at idle and it's shows 34-35 at 3000 rpms.

Try to set the timing higher but listen for pinging.

 

 

[Diseazd]

Without smog equipment, my cars are happier running 17 degrees advance at idle (1000 rpm). The 73 E88 head isn’t your best choice for a performance head (large chambers, small cam and a small intake valve.......low compression).....does the N42 block run dished pistons? If so, that means even lower C/R.  Also, you could check your air fuel ratio on your triple setup. As far as the chain marks, you could go to the number 3 timing hole on your cam sprocket and see if that compensates for a tired chain, or better still install a new chain. Never easy when you don’t know what a previous owner did to the engine.

Edited February 5, 2018 by Diseazd

[madkaw]

I’d try notch 3 on the cam sprocket. Take some slack out and advance your cam timing to get the intake valve closed earlier and get back some compression. If the chain is that loose your losing power

[siteunseen]

Glad to know you're okay Steve.  @madkaw

 

[Hardway]

I don't think moving the chain over is something I feel comfortable with.  Given that the chain has so much slack, as shown in the video in my build thread, I don't feel more power is worth chasing until the primary components of the engine are right.  When I pull the engine to do the chain replacement I am going to pull the head at the same time to look at the block and pistons.  At that point I may drop the head off with my machine guy and have him install a stage-2 or stage-3 cam and install a ceramic coated header as well.  That way I can really take advantage of the triples on the car.

Build thread -> http://www.classiczcars.com/topic/58524-hardways-red-rocket-1972-240z-build-thread/

[madkaw]

46 minutes ago, siteunseen said:

Glad to know you're okay Steve.  @madkaw

 

Did I miss something ?

[Diseazd]

1 hour ago, Hardway said:

I don't think moving the chain over is something I feel comfortable with.  Given that the chain has so much slack, as shown in the video in my build thread, I don't feel more power is worth chasing until the primary components of the engine are right.  When I pull the engine to do the chain replacement I am going to pull the head at the same time to look at the block and pistons.  At that point I may drop the head off with my machine guy and have him install a stage-2 or stage-3 cam and install a ceramic coated header as well.  That way I can really take advantage of the triples on the car.

Build thread -> http://www.classiczcars.com/topic/58524-hardways-red-rocket-1972-240z-build-thread/

If you are going to pull the head, go back with a better head IMO, and flat tops if they are dished. Don't go Stage II, have Isky grind you a Stage III.....you won't be sorry.

[Zed Head]

He just wanted know if he should change his spark plugs, now he's about to rebuild his engine.

I'd do a little more detective work.  Still not clear what's actually in there.  Could be that it's a perfectly fine engine, and parts, but the chain tensioner popped out.  Might just need to remove the front cover and make it right.

You can see the pistons through the spark plug holes and tell if they're flat or dished.  You can see the chain tensioner from the top if you get your eye in the right place and have a bright light.  The notch and groove still work even with a loose chain, to tell if cam timing is right.  They measure what's happening on the tight side, while the loose side flops around.  You can check the top of the head for machine marks to see if it's been shaved.  Although it won't tell you about the bottom.  But it's a clue.

On the other hand, the unknowns are a good reason to take things apart.  But you might find a simple problem that didn't need a teardown.   Seems like a full throttle in to the fog adventure at this point.