Complete Misfire on Three Cylinders

[siteunseen]

I saw this Zed when I was figuring out if I had an A. (sorry but I don't)

http://xenonzcar.com/s30/cams.html

[jonathanrussell]

And...when finding a cam...unless you want to fiddle with lash pads and geometry, you will want to find an uncut original cam with original base circle. This all assumes your cam is the original base circle and your lash pads are original.

Is your cylinder head an N47?

 

[jonathanrussell]

@Captain ObviousI have an A cam that I think was from an N47. I acquired it by itself without a head at some point though. It has oil holes in the lobes. Lobes are clean as are bearing surfaces. 2nd lobe from sprocket measures appx 1.585 which is the same as a low mileage n42 A cam I have on a head that I know has never been rebuilt, nor cam cut. So, if your cam is uncut and you have original lash pads, should slide right in...assuming you are able to sort out the cam tower mounting mess.

If you would like to have this cam, message me with your address and I will ship it to you.

See two photos.

 

 

Edited July 9, 2019 by jonathanrussell
add photos

[Captain Obvious]

7 hours ago, jonathanrussell said:

I have an A cam that I think was from an N47. 2nd lobe from sprocket measures appx 1.585

If you would like to have this cam, message me with your address and I will ship it to you.

Wowsers!! Yes, that's exactly what I have now. Both pieces. Haha!!

I measured my lobes at 1.585, so the same as what you have there. I'd love to have it! Thank you so much for the offer!!

PM on it's way!   

Edited July 10, 2019 by Captain Obvious

[Captain Obvious]

I'm not sure if my PO had my head planed as part of the "work" he did to the engine. I took a quick look through the FSM and I didn't find a spec for the overall thickness of the head when new. Is that number known?

I measured my head thickness at 4.255 in (108 mm)*.

Anyone know if that's factory original thickness, or if it's had material removed?

* I didn't clean the head well before that measurement, so I could be off a couple thousandths.

[jonathanrussell]

I have a new in box, never been built E88 head...so it is perfectly clean. When I measure with my digital caliper, it reads 4.247. So, if you are getting a bit of a higher reading...due to cleanliness....I would say you have an uncut head.

On page 55 of the Honsowetz book, he says 4.218 which is incorrect. I hand wrote in the book 4.248...which I probably found researching online. So, I would say my measurement is close. I may have been pressing a bit hard for the measurement. On further research, apparently I have the 1st edition of the How to Modify book. I see something that says the 2nd edition shows 4.248.

FYI, I measured my "new" head again and 4.248 seems more correct- pressing too hard to get 4.247.

Edited July 10, 2019 by jonathanrussell
added Honsowetz info

[Captain Obvious]

So with the incredibly generous help from @jonathanrussell, I've got a replacement cam on the way. Since they are both factory grinds, I'm hoping his cam is a drop-in.... errr.... slide-in replacement for what I have now. So with his help, I'm not out of the woods, but I should be a lot closer to the tree-line than I was before.

This people here on this forum are fantastic!     

[Captain Obvious]

11 hours ago, jonathanrussell said:

I have a new in box, never been built E88 head...so it is perfectly clean. When I measure with my digital caliper, it reads 4.247. So, if you are getting a bit of a higher reading...due to cleanliness....I would say you have an uncut head.

I will get a better measurement on the head thickness once I get things cleaned up. But even though I took just a quick check, I don't think I've got eight thousandths of grime on my head. There might be a little error in my 4.255 measurement, but just a couple thousandths. Plus or minus two thousandths maybe? Probably not eight.

So either they made the N47 head thicker than the E88, or I'm thinking your E88 has been cut.

Anyway, when I get things cleaned up a little more, I'll take a more reliable reading.

[jonathanrussell]

Someone correct me but...my recollection is that all L6 heads, well certainly in my mind the ones used with S30 cars have the same thickness measurement....uncut.

Also, I have found it pretty difficult to get to this number without a perfectly clean head. 70 thou doesn't sound that unrealistic on a less than clean head.

Edited July 10, 2019 by jonathanrussell

[Zed Head]

Everything I've seen suggests 108 mm as the number.  Metric, of course.  From a manufacturing perspective I don't think t's a high accuracy, precise dimension.  Valve lash adjustment can take up quite a bit of error/range.  Might be that a half mm either way was acceptable during manufacturing.,

[Captain Obvious]

Well I don't have an explanation for why your E88 is different than my N47, but I do stand by my numbers.

I cleaned off the measuring surfaces and even broke out the big guns. More accurate than the springy calipers for things like this. I don't know the last time this ol' girl saw the light of day, but she's still got it where it counts:

Installed the correct anvil, checked her against the measurement standard rod, and then rechecked the head. I get the same thing I got before. About 4.254 inches or about 108 mm.

So I don't know if they changed the head thickness over the years, or if yours has been cut.

[Captain Obvious]

23 minutes ago, Zed Head said:

From a manufacturing perspective I don't think t's a high accuracy, precise dimension. 

Even though functionally it's not critical, It would be highly un-Japanese to not control that dimension from the factory. These things are running down the assembly line and IMHO it would be extremely unlikely that they were not all peas in a pod to within a thousandth or so.