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Which means "Evil Twin". Lets see your projects where you change boring into fun or create the fun from scratch.
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PostPosted: Wed Apr 01, 2020 6:31 am 
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looks like they need to be deeper and a little bigger as well. You should mock it up with the most radical cam timing that leads to the closest piston to valve issue and clearance for that and then you will be fine with whatever you do. Don't need to be fighting this kind of stuff again. Start up and tune up, that is what you need now.

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PostPosted: Wed Apr 01, 2020 8:09 am 
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FoaTech wrote:
I have a jig, do I need to send it to you?


I was laying in bed this morning thinking about what I needed to make to hold the pistons...borrowing is sure a lot easier :)

I looked back though old posts and the best I can tell I never check the piston clearance. I cast the chamber (just found the fake stub cylinder I used but didn't recall what it was until I saw the pics), sent it to JE, trusted their work completely and installed the pistons.....which was clearly stupid. Not sure how JE got it so wrong but shame on me for not checking it

I spent lot of time with the simulations picking valve timing thinking its a pain in the butt to mess with on the engine so even though I KNOW I will be leaving HP on the table by not messing with it on the engine....I just don't believe I'll ever mess with it on the engine and the timing is set. Even on the engine I wouldn't be moving it more than a few degrees.....the simulator says its a mid-range vs peak power thing with a get here by giving there compromise and I was looking for the spot that made the least difference when I settled on my final numbers. If you drop the DM key in the box I'll see what kind of clearance changes I might want to account for with any reasonable timings I might ever want to try even though as I said I know me pretty well and will most likely never mess with it.....at least not until everything else on the whole car is done and I find myself bored.

My plan is measure the marks on all the pistons and go from there. Most car places say .080" intake/.100 exhaust on depth but motorcycle places are more like .050/.080 and these are motorcycle valves so I guess anywhere in between the 2 sets of numbers is good...probably go towards .050+ actually as the valve most have defected making the marks. Then I guess about .040-.050 radially and that will be good. Looks like all my new found compression after I had to face the heads when repairing the chamber is gone :(


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PostPosted: Wed Apr 01, 2020 8:20 am 
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FoaTech wrote:
I have a jig, do I need to send it to you?


It looks like it needs a long wrist pin...do I need to make one in preparation or do you have 1 with it?


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PostPosted: Wed Apr 01, 2020 8:35 am 
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I've never used a piston vice, but I always thought you used them with two wrist pins... and just didn't over tighten the clamp.

Summit has one as well: https://www.summitracing.com/parts/pow-pow351090

With a pent-roof chamber you shouldn't need compound angles, though.
Also, that price probably reflects a few items on your Lana to-do list as well.

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PostPosted: Wed Apr 01, 2020 9:01 am 
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Yeah....I'm not buying a $1000 piston vise :o

My plan was to just make a set of aluminum piston jaws for the vise I have which is shit or maybe use this as an excuse to finally buy a curt vise knock-off and make the jaws for that. That will hold the piston square and repeatable then kick the head to the valve angle and get on with it.

I'm sure 2 wrist pins works....its the just don't tighten too mush that scares me and 20-30 minutes on the lathe to make a single long pin eliminates the concern.....the peace of mind just seems worth the effort

I really need a better vise.....

https://www.amazon.com/Milling-Machine- ... p_pl_dp_15


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PostPosted: Wed Apr 01, 2020 9:03 am 
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mk e wrote:
FoaTech wrote:
I have a jig, do I need to send it to you?


It looks like it needs a long wrist pin...do I need to make one in preparation or do you have 1 with it?


Just two wrist pins like Dark said.

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PostPosted: Wed Apr 01, 2020 9:24 am 
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FoaTech wrote:
mk e wrote:

It looks like it needs a long wrist pin...do I need to make one in preparation or do you have 1 with it?


Just two wrist pins like Dark said.


Really? ......that scares me so I'm thinking I'm making a single long pin. Oh, mcmaster has 1ft long ground 20mm +0/-.012 steel for $11.55. Ordered. I'll sent it to you when I sent the vise back :)


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PostPosted: Wed Apr 01, 2020 9:29 am 
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mk e wrote:
FoaTech wrote:

Just two wrist pins like Dark said.


Really? ......that scares me so I'm thinking I'm making a single long pin. Oh, mcmaster has 1ft long ground 20mm +0/-.012 steel for $11.55. Ordered. I'll sent it to you when I sent the vise back :)


The kind of operator who cuts valve reliefs is the kind of operator who's probably sensible about tightening the vice and can take small cuts. Is that not you, Mark? :P :lol:


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PostPosted: Wed Apr 01, 2020 9:38 am 
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TheDarkSideOfWill wrote:
The kind of operator who cuts valve reliefs is the kind of operator who's probably sensible about tightening the vice and can take small cuts. Is that not you, Mark? :P :lol:


I once filled 3 55 gallon drums with steel chips in 1 shift by mounting 2 cutters each cutting an inch per side which let me rip 4" per pass off the OD of a 3ft billet (5" per pass stalled the 50HP lathe and blew the fusses) and have been know to reach for a sawzall when things don't fit....so generally no, I'm not very gentle in my approach to things :lol:


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PostPosted: Wed Apr 01, 2020 6:27 pm 
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Pulled a valve out of its bag, into the mill collect....runout.

new valve, no run out....well 2 tenths.

1st back in different answer....more runout....hold it in different places and get different answers

New valve....wait, same thing....choke all the way up its prefect, move a couple inches up the stem and its got 4 thou....the stem is not straight on the brand new valve.

I pulled a second used valve out and its much better overall than the new one. but a little more runoff when I choke up all the way.

These are 5mm wet noodle stems so a little runout is probably okish...but.....I need to find some specs.


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