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Captain Obvious

F54/P79 Swap Project

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12 hours ago, Jeff G 78 said:

it sounds like you have a very good grasp of the tension, timing, and chain position as it glides over the guides and tensioner block.  

I slotted the slack side guide holes much more than stock so that I could move them closer to the chain and get the slack right. 

Thanks Jeff, my confidence in the plan grows. What you did to your head is pretty much what I was planning to do with mine. I was thinking I would go .040 off rather than .050, and that should make my timing chain tensioning mods just that little bit easier than yours.

And I don't know if you read this part of the previous pages, but I've already verified that I can chuck the cam gear up in my lathe and I have enough swing to index it to the side and bore out the original dowel pin holes for the eccentric bushings. So I'm confident that I've got the valve timing issue under control.

In case you missed that part... Cam gear on the lathe. Indicated to a fraction of a thousandth on the original hole. I didn't cut anything yet, but I'm confident I can when I need to:
P1150123.JPG

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7 minutes ago, Captain Obvious said:

...and I have enough swing to index it to the side and bore out the original dowel pin holes for the eccentric bushings. So I'm confident that I've got the valve timing issue under control.

In case you missed that part... Cam gear on the lathe. Indicated to a fraction of a thousandth on the original hole. I didn't cut anything yet, but I'm confident I can when I need to:
 

When I modified my gear for the eccentric bushings, I leterally just used my drill press and punched the #2 hole the right size.  There is almost no meat left on the inboard side of the hole, but it does fit.  One thing I forgot to mention was that I had to cut a piece of 3/8" stock and use it as a plug once the eccentric was in place.  The cam gear is about 1/2" thick and the eccentric bushings as well as the cam dowel are only about 1/4", so the bushing could walk off the end of the dowel with the bolt and washer in place.  The plug keeps the eccentric bushing in place once you set your timing.

From what I recall, I ended up with about 9.5:1 CR.  I don't have my calc sheet handly.  You will see a bit less with 0.040" cut off, but it should still make good power.  The guides were super easy to modify with a small burr and a file.  I wouldn't be afraid of taking 0.050".  I spent almost nothing building that engine.  The hot tanking of all engine parts, measuring everything, crank polishing, head milling and valve job was $500.  I bought a quality made in USA timing set, new oil pump, new bearings, rings, and gaskets and then had my stock flywheel lightened by about 10 lbs.  The whole build was about $1,200.  I use a distributor from an '82 ZX which has a lot of advance, but it has no issues with 93 pump gas.  I already had the cam (Web Racing #91) and the header was given to me by a friend.  It was beat up and needed some work.  I added an O2 bung so I can keep an eye on the AFR.

With a bigger budget, I'd opt for the Kameari tensioner and cam gear, but those two components cost the same as the rest of my build. I did add a BHJ damper and Kameari bolt kit this time around after failing my stock damper and chewing up a bunch of parts in the process.

What are you doing for fuel delivery?  My SU's with SM needles do a good job.  I had to ditch the stock fuel rail though for racing.  It created terrible vapor lock on the track.  

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Thanks much.  There's lots of other stuff I need, but it's not the kind of things I can lean on vou for. Bigger stuff like gasket set, rings, head bolts...

You have a pair of piston ring pliers or a ring gap grinder? I don't have that stuff and I'll probably only ever use them this once.

And I'd love to fight over another lunch bill.  My house is your house!

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11 hours ago, Jeff G 78 said:

The cam gear is about 1/2" thick and the eccentric bushings as well as the cam dowel are only about 1/4", so the bushing could walk off the end of the dowel with the bolt and washer in place. 

From what I recall, I ended up with about 9.5:1 CR.  I don't have my calc sheet handly.  You will see a bit less with 0.040" cut off, but it should still make good power.  The guides were super easy to modify with a small burr and a file.  I wouldn't be afraid of taking 0.050". 

Yeah, I could just use the drill press, but the lathe would be more accurate. On the lathe I can index the part to be spot on and it also doesn't mind the interrupted cut so much if you cut through the wall into the center hole. I can also size the hole so the bushing is a slight press fit into the hole. I'm not quantized to drill bit sizes.

And that's a great piece of warning about the bushings being thinner than the gear. What I can do on the lathe is mount the gear back side out and bore from that side. I can control the depth of the bore so it doesn't go all the way through the gear. That way I can leave a shoulder in there to keep the bushing from possibly walking out. Easy peasy, but I didn't know that until you brought it up!

For fuel delivery, at this current point the plan is to redress it back up with the stock fuel injection. I suspect I'll have to tune the system a little, but I'm hoping that will work. I've heard that the stock system doesn't adapt well to modifications, and I guess I'll be able to confirm or deny that accusation. That's the current plan.

If that fails, I'll throw on a pair of flat top carbs or maybe an aftermarket EFI system.

Your 9.5 compression ratio sounds pretty much in line with my calculations. I came up with about 9.3 at .040 off.

Thanks so much for the info, I appreciate the details!

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8 hours ago, Captain Obvious said:

I can also size the hole so the bushing is a slight press fit into the hole. I'm not quantized to drill bit sizes.

And that's a great piece of warning about the bushings being thinner than the gear. What I can do on the lathe is mount the gear back side out and bore from that side. I can control the depth of the bore so it doesn't go all the way through the gear. That way I can leave a shoulder in there to keep the bushing from possibly walking out.

I would suggest NOT doing that.  The bushing actually needs to be easy to slide in and out from the front so you can swap different sizes in and out as well as rotate them a bit as needed to get the hole in the right orientation for assembly onto the dowel.  The eccentric bushings work great, but they are easiest to install after the gear is on.  You pick a bushing that you think will be right and then slide it into the large gear hole and over the dowel at the same time while you rotate the cam into the right position to line everything up. The offset is very small in some cases and it is almost improssible to line up exactly if you try to make it a tight fit in the gear.  It also has to be installed from the front as you will need to swap them in and out to get the cam degreed in.  As I found, the cam will be a degree or so off on either the intake or the exhaust.  Unlike a dual cam, you have to work with what you have.  I'm not sure why mine was like that, but I'm guessing it's normal.  I never tried to degree a stock cam to see if it is a tad off too.  Are you running the stock cam?  If not, you will get frustrated very quickly if you attempt to use the stock FI system.  I tried numerous times to use this same cam with FI in a different L28 and it sucked.  The stock EFI hates low vacuum which is what you will get with any mild duration cam.  It made no power and idled like crap.  No amount of tuning will change the L-Jet's need for vacuum.  That's when I gave up and put the cam on a shelf for 10 years until I built this motor with SU's.  My 10:1 street Z still runs the stock cam and EFI for this reason.  This motor at 9.5:1 is way better.

Good luck and feel free to throw ideas at me.  I'm happy to share my good and bad experiences.

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Thanks for the additional insights Jeff. About the eccentric bushing... My plan is to put the stock cam back to the stock valve timing using the original timing marks. For the bushings, I'll come up with a simple fixture to press the bushing into place (off the car) and locate the holes for me. So the difficulty of turning the bushings once installed won't be an issue. In the end, even though I'll have the ability to change the bushings to mess with the timing, I wasn't planning to do so. The only reason I was going to use the bushings was to account for the timing change incurred as a result of cutting the head. But once I get it set back to the stock timing, I wasn't planning to mess with it (ever?) again.

The plan is to pick a bushing while I have the front timing cover off and hopefully be done with it. Pulling the gear off to change bushings shouldn't be a big deal.

And at this point I'm planning to put the stock cam back in and run the stock EFI, so it sounds like your street Z. When you say that this 9:5 motor is better than your 10:1 street Z motor.. . Why is that? Just raw power?

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11 hours ago, Captain Obvious said:

Thanks much.  There's lots of other stuff I need, but it's not the kind of things I can lean on vou for. Bigger stuff like gasket set, rings, head bolts...

You have a pair of piston ring pliers or a ring gap grinder? I don't have that stuff and I'll probably only ever use them this once.

And I'd love to fight over another lunch bill.  My house is your house!

Yup. PR pliers, ring grinder and piston installing ring clamp thing. I'll also send the anaerobic sealant for the main side bearings.

 

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Sounds like a plan.  That should be similar to my street engine.  That engine does run well, though my race engine pulls harder and has a broad powerband.  It pulls hard to 7,000RPM.  It's a little hard to quantify since the race car isn't street legal, they are hard to directly compare to each other.  I think the light flywheel helps as well.

The only time you'd have to change the eccentric if you stick with the stock cam is to adjust for chain stretch.  That will not happen anytime soon though.

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I'm just looking for a little more than stock while still being pretty much stock. Sounds like exactly what you did with your street motor.

I don't know if you had seen my whole broken camshaft debacle with the motor that's currently in my 77, but as part of that whole fix, I found and repaired a whole bunch of previous owner caused problems inside that motor and it's now running way better than it ever did as long as I owned it. For me, that upgrade step was just getting that motor "back to what it should be producing" and I found that increase noticeable. It's amazing what happens when you have all six cylinders actually contributing to the power output.

So my threshold for success on this F54/P79 build is "noticeably better than a properly working (but worn) stock N42/N47 combo". Should be pretty easy to achieve.

While I have you here... You pulled out the plugs in the oil galleys and talked about flash in there that you cleaned out. Any additional info about that? Any pics? I've not pulled the plugs and I wasn't planning to do so unless I had a compelling reason. Did you pull the plugs on the head as well?

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32 minutes ago, 240260280 said:

Yup. PR pliers, ring grinder and piston installing ring clamp thing. I'll also send the anaerobic sealant for the main side bearings.

Awesome!! There are three of us working on these motors at the same time and I know none of us have that stuff.   @GGRIII  @Av8ferg

I should post my parts list and tool needs...

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You are also getting 2 Clevite Rod Bolt Condoms.  Let me know if you need a formal ring land cleaning tool?  It is a bit clunky. I prefer using the old rings (and my ultrasonic cleaner)

 

Engine Builders Unite!

care package.jpg

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CO's motor should make it to my garage on Wednesday.  Since I have his hoist he will finally be able to get to the bottom end!  Since I have a 260 my exhaust is set up for square exhaust ports.  I'm thinking about using an E88 head and sticking the bigger valves in it or using a P90 head depending on what I can find.  That means I would have a P79 head laying around - if I can find an E88 or P90.  As part of the 280zx strip I also have an extra 5spd and diff.  CO will have first dibs but at the end of the build I will be clearing out the garage of extra stuff :).

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CO, great thread but 1/2 off it is going straight over my head. I’ll need some babysitting on the whole drilling of the cam sprocket that I failed to understand.
I was going to pull my oil galleys and tap and put in brass hex nuts back in. Seems fairly straight forward and the NPT Hex Plugs are on Zcardepot. Why are you not considering it? I guess I see it as an opportunity to make sure it’s all the funk will get cleaned out when it goes to the hot tank.

https://zcardepot.com/products/pipe-plug-npt-1-4-3-8-oil-passage


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My 2 cents. Not sure why all the offset drilling/ bushing stuff . I’m betting the stock timing could be achievable with just advancing the sprocket , or at least be close enough. That gives you 8 degrees in hole 3. My 2.4 was shaved .050 and ran 8 degrees valve timing advance . You could always go another tooth for more . 

Worst case scenario is your rpm  power band would be somewhat off from stock.

 

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madkaw, Yes, All the discussion about the drilling and offset bushing stuff is premature.

Don't know yet if it'll be necessary, but I was just confirming that I can do it if I have to. Stock stretch holes may be good enough, but I have the means to achieve finer degrees of accuracy if necessary.

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11 hours ago, Av8ferg said:

I’ll need some babysitting on the whole drilling of the cam sprocket that I failed to understand.
I was going to pull my oil galleys and tap and put in brass hex nuts back in.

Don't worry about the cam gear stuff going over your head. I'll draw you some pics next time we get together. We got you covered.

About the oil galley plugs... It's just one more thing that if I didn't have to mess with, I was hoping to leave it be. I am a little worried about the hot tank not being able to thoroughly get to that area if I don't pull them though. Maybe I should just pull them. I think I'll wait until my motor is on a stand over at GGR's shop.

We're gonna have two of them sitting next to eachother as they're being built. Would be extra cool to have three of them in a row you know......   :cool:

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Thanks, if I end up driving up there for work next month I’m going to bring the head a block. But it only gives us 2.5 days and I will be flying from 8am to 6pm. So it might be tough unless your will do do it while I’m working?


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Thanks!! I'll let you know when that stuff gets here.

My motor and my stand are going to GGR's tomorrow. If I remember, I'll try to get pics of the two motors side-by-side.

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