Dave W 1971/240Z rebuild

[grannyknot]

13 hours ago, madkaw said:

If those are original seats I wouldn’t skip that step . I doubt they are steel . You’ll really have some dings if one of those let loose . 

Right😒 soft bronze valve seats with unleaded gas, not a good combination.  I forgot about those, so since the seats and valves have to be replaced anyway then we might as well go for the larger L28 valves and let this E31 head breath properly. Thanks for catching that @madkaw

Off the top of my head I can't remember if installing the larger valves will affect the compression ratio, anyone?

I believe the E31 head is already at 9.5:1 now and I don't want to go much higher than that.  Damn, I spent several hrs yesterday reinstalling the valves, springs and cam yesterday and now I have to take it apart again, but better me than the machinist, I work a lot cheaper than he does😁

Dave, I will get a firm quote from him before I go ahead.

[madkaw]

34 minutes ago, grannyknot said:

Right😒 soft bronze valve seats with unleaded gas, not a good combination.  I forgot about those, so since the seats and valves have to be replaced anyway then we might as well go for the larger L28 valves and let this E31 head breath properly. Thanks for catching that @madkaw

Off the top of my head I can't remember if installing the larger valves will affect the compression ratio, anyone?

I believe the E31 head is already at 9.5:1 now and I don't want to go much higher than that.  Damn, I spent several hrs yesterday reinstalling the valves, springs and cam yesterday and now I have to take it apart again, but better me than the machinist, I work a lot cheaper than he does😁

Dave, I will get a firm quote from him before I go ahead.

Upgrade valve size is no brainer if you already have to replace the seats and yes it might raise CR slightly . To mitigate that you could unshroud the valve areas which would help it breathe and slightly enlarge the combustion chamber. 

BUT - you will have to clearance the cylinder bores unless you have over sized the pistons. There is a chance the larger valve will catch the edge of the bore . There are plenty of threads addressing this . This will also decrease CR - but with added benefit of better breathing . 
 

I do have tons of used 35mm exhaust valves if you want to run Nissan stuff . They all in good shape and I would about give them away . They all came out of Maxima engines so maybe less abused than Z stuff . 
 

Not trying to increase your work - but the seats MUST be addressed or all your work will be in vain. 

[davewormald]

This is what I love about this forum. Experts helping experts. None of the usual online nonsense. The car and I are feeling well looked after. Thanks guys!

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[siteunseen]

I'm almost positive when I had my E-31 updated my machinist was able to use seats for a Dodge Hemi motor, they measured out the same size. Just an FYI little tid-bit. 

[grannyknot]

8 hours ago, madkaw said:

Upgrade valve size is no brainer if you already have to replace the seats and yes it might raise CR slightly . To mitigate that you could unshroud the valve areas which would help it breathe and slightly enlarge the combustion chamber. 

BUT - you will have to clearance the cylinder bores unless you have over sized the pistons. There is a chance the larger valve will catch the edge of the bore . There are plenty of threads addressing this . This will also decrease CR - but with added benefit of better breathing . 
 

I do have tons of used 35mm exhaust valves if you want to run Nissan stuff . They all in good shape and I would about give them away . They all came out of Maxima engines so maybe less abused than Z stuff . 
 

Not trying to increase your work - but the seats MUST be addressed or all your work will be in vain. 

Thanks, yes I will take 6 of your exhaust valves and the same of intake valves if you have them.

I'm trying to send you a PM with my address but it doesn't seem to working, did that function change while I wasn't looking?

 

Those detonation marks have lots of room from the fire ring.

Just a few shots of the block assembly, 3rd pic down is the #6 piston going back in, next to it is the knuckle cutter, also know as a ring compressor.

I hated throwing all the duplicated SU parts in to the plating bucket but I had to or it would cost twice as much, here's my map to sort them out afterwards. Plating is going in on Monday.

[madkaw]

2 hours ago, grannyknot said:

Thanks, yes I will take 6 of your exhaust valves and the same of intake valves if you have them.

I'm trying to send you a PM with my address but it doesn't seem to working, did that function change while I wasn't looking?

 

Those detonation marks have lots of room from the fire ring.

Just a few shots of the block assembly, 3rd pic down is the #6 piston going back in, next to it is the knuckle cutter, also know as a ring compressor.

I hated throwing all the duplicated SU parts in to the plating bucket but I had to or it would cost twice as much, here's my map to sort them out afterwards. Plating is going in on Monday.

Yes - you have tons of room away from the detonation holes . I would unshroud those chambers . That engine will breathe much better and it’s easy to do . 
1” drum sander with 80 grit is about ideal. You can use that on the chambers and on the block to clearance everything.

Just email me and we will work out a deal on the valves 
 

 

Sfinnerty1018@gmail.com

Edited July 22, 2023 by madkaw

[grannyknot]

Now this isn't anywhere near a proper port n polish but I thought I would smooth out the combustion chamber since the seats are coming out anyway, opened up the exhaust runners a bit so at least the ports match better. Still have to grind down the fresh air pipes in the manifold.  Also clearenced the cylinder walls for the new intake valves.

This car surprises me again and again how pristine most of the parts are, once you get the crud and minor rust off.

[davewormald]

Looks like there are owls in my cylinder head. What did you use to clean off the fender supports (or whatever they're called)? I spent hours cleaning the dealer undercoating off the insides of the wheel wells. The metal underneath most of it was beautiful, but it was quite a job. I used everything I could think of, including kerosene, wire wheels, a heat gun and scraper, sandpaper, a grinder, etc.

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[madkaw]

While you’re at it 🙂 - take your dremel tool with the biggest drum sander you have and clearance those areas I highlighted . Installing the larger exhaust valves will have a harder time breathing with the shrouding of the chamber . Etch a line from the HG and sand a nice radius to allow them valves to breathe . The engine will appreciate it . 

[grannyknot]

On 7/23/2023 at 8:10 PM, davewormald said:

Looks like there are owls in my cylinder head. What did you use to clean off the fender supports (or whatever they're called)? I spent hours cleaning the dealer undercoating off the insides of the wheel wells. The metal underneath most of it was beautiful, but it was quite a job. I used everything I could think of, including kerosene, wire wheels, a heat gun and scraper, sandpaper, a grinder, etc.
Sent from my SM-S908W using Tapatalk
 

24hrs in a pan of Lye (sodium hydroxide) then a heat gun and a putty knife.  I call them mud guards as that's all they are really doing. 

[grannyknot]

It's always a good day when the plating comes back, makes all those hrs at the wire wheel worth it.

 

[Patcon]

What is your system for figuring out where it all goes? I really struggle with that.