'77 CJ360T (Café SOS) - Calling it Done (for now...)

Re: '77 CJ360T (Café SOS) - Head and Valve Work in Progress - Expensive Mistake

crazypj said:
If you 'do' dyno, make sure they connect up the EGA, you need to know what fuel is doing
Hopefully, you should be getting around 42~45bhp with the mods you've done
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That's kind of the range I was thinking/hoping-for as well. What would you expect to see at the rear wheel? I haven't been able to find any info on drive train losses for 360s. I'm guessing around 10-15%?
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work in Progress - Expensive Mistake

Those are rear wheel numbers.
My pretty much stock 378cc motors were getting over 35 at wheel before I got carbs sorted, power was dropping because F/A ratio was way too rich (10:1 instead of 13:1)
It's probably in the 38bhp range now.
Better cam and bigger valves should be worth a couple BHP
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work in Progress - Expensive Mistake

F/A ratio was way too rich (10:1 instead of 13:1)
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PJ I hope you mean A/F not F/A ratio ;D ;D
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work in Progress - Expensive Mistake

Doh, yep, A/F 9.8:1
F/A 10:1 would be just a bit too rich too run ;D
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work in Progress - Expensive Mistake

crazypj said:
Doh, yep, A/F 9.8:1
F/A 10:1 would be just a bit too rich too run ;D
Click to expand...

tumblr_lkjsv3ULrW1qb4i6t.png


lol
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work in Progress - Expensive Mistake

Spent a great afternoon with my dad talking engines and performance mods. We had a look over the head and he's going to try to track down a pro to look it over and see what, if anything else needs to be done. All the work (including the 3-angle grind) to get the +1mm valves working is still on the shopping list, but port work may not be handled at this stage.

We're also considering taking a bit of metal from the base of the head to bump up compression. I need to get the domes of the pistons measured up so I know how much of the combustion chamber they occupy. Currently, the combustion chambers are measuring out at 26cc and if those pistons aren't taking a good chunk of that, then compression isn't quite as high as we'd like. Furthermore, there is about .040" of squish clearance along the edge of the piston at (what I think is) TDC. First order of business will be to verify TDC for real and then double-check that squish area. As I mentioned, some metal may come off the head and so we need to know with how much room we have to work.

In the mean time, upholstery is still in progress. The Mrs wants to handle it, so my task is to help her be as motivated as possible. She and I have different ideas on time frames. ;)

Also, I'm taking this opportunity to remove a little bit of weight (in the form of casting marks) from my rocker arms (video linked below).

Finally, I've decided to set a new goal for this project. It's not enough just to hit the ton. I want to do it in style. My dad and I are looking to get this thing to break 100 mph in the 1/4 mile. With an 18 tooth front sprocket, I should be able to hit 101.4 mph in 4th gear at 10,000 RPM.

http://youtu.be/V4bRo3JcW2w
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work in Progress - Expensive Mistake

You can take 0.020" off head without any problems
Probably need to check clearance at edge and possibly re-machine angle to match piston.
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work in Progress - Expensive Mistake

OK... I've finally got a definitive list of the work being done to the head:

> Head Milled .020
> Guides removed & replaced.
> 3-angle valve job.
> Head cleaned
> New valves vacuum-checked to verify seal
> Guides set up .001 tighter to reflect bronze guides

With any luck, the machinist will be done before the end of the week and the engine can be reassembled and specced out again. We'll need to recheck clearances between the pistons and valves and also check to see if the cam needs to be degreed. With any luck (as pj was saying), .020" off the head won't make a difference.

I've also decided to throw in the towel on the upholstery. Unfortunately, the machine the Mrs is using just isn't up to the task of something as thick as several layers of vinyl. I happened to meet up with a fairly local guy who does it for a living and said he'd help me out for a pretty cheap price. So I just need to find some time to run the stuff over to him...

In the meantime, I've finished up removing the casting marks from the rocker arms and it's a shame they have to go into the rocker arm cover. I think they look pretty decent. Even more importantly, there's almost 5 grams shaved off of each one.
 

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Re: '77 CJ360T (Café SOS) - Head and Valve Work in Progress - Expensive Mistake

Shiny ;D
I don't go that far
Removing weight from the ends is the important bits, the center is just to allow faster oil drain and slight possibility of cracking.
You may need to degree cam, if you were using stock it doesn't need it.
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work Complete

The head is back from the machinist and reassembled. I leak checked the ports with some acetone and I've also found TDC on my bike. I'm pleased to say that the factory got it right. Tonight, I plan to get the head back on the engine and get everything torqued down so I can check clearances and ensure the .020" that came off the head hasn't changed the cam timing too much.

Here's some pics of the work done:
576572_10150790678890159_734955158_11584196_1704638458_n.jpg

Three angle grind and the combustion chambers have been matched in volume

580720_10150790678970159_734955158_11584197_1828415449_n.jpg

New (shorter?) bronze valve guides installed. No pics, but on the inside of the ports (particularly the intake side) these barely clear the port wall.

536806_10150790679025159_734955158_11584198_1031556551_n.jpg

New valve on the right, old on the left.

562717_10150790679080159_734955158_11584199_1389950168_n.jpg

Just a shot of how things look with the valves resting in place.
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work in Progress - Expensive Mistake

I would do two things.
First, the stock ports are a bit large so don't open them up, just make them wider around valve guide plus reduce guide boss
second, put a 30degree back cut on those valves
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work Complete

We already looked at a backcut on the valves, but any more and it will take the margin out of spec. :(

I'll take a look at the ports though for sure. There's a lot of casting marks that can still be cleaned up.
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work Complete

30 degree cut goes on top of face, nowhere near margin
you can see Honda did it stock (oop's, it's just the dark edge, not back cut.)
Yamaha did it stock from about 1969, I'll find pic
Couldn't find a pic of Yamaha valve so just took one and uploaded it ;D
XS650valve.jpg
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work Complete

Hmmm... not sure I'm understanding. A backcut on the valves were something that was specifically mentioned to the machinist and he told us it was a "no go".

My limited understanding is that a backcut is just removing metal from the fillet to help with flow and reduce weight? Is the idea to keep this removal closer to the stem and away from the margin?
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work Complete

It helps low lift flow
I think your machinist was thinking of 'trenching' which is completely different and weakens valve
The margin is the 'flat' piece around the maximum diameter of head, I usually polish/radius the edge a few thou, although it can cause low rpm flow reversion on intakes
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work Complete

OK... I've emailed for a quote for the backcutting of the valves to my local machinist. The problem is, I don't really trust this guy. He's done good work for me before, but his assistant flat out lied to my face and made up a bunch of BS. Hopefully the price is right...
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work Complete

It takes about 20 seconds if they have a valve re-facer
You can do it by hand on a grinding wheel although it's obviously not as accurate (I've done hundreds without problems though)
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work Complete

Good luck this time round! You deserve it :)
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work Complete

Erskine said:
Good luck this time round! You deserve it :)
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I hope so, man, I hope so. I do honestly believe that most folks get what they deserve, so hopefully I deserve to have one cracking 360. Of course, that also means I deserved to have it fucked up by my own impatience and ignorance as well... lol

Just hoping the weekend gets here pretty soon. I'm really chomping at the bit to get it reassembled and running again.
 
Re: '77 CJ360T (Café SOS) - Head and Valve Work Complete

Purdy :)
 
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