The Jalopy Journal
Discussion in 'The Hokey Ass Message Board' started by 27troadster, Mar 19, 2013.
Why limit yourself like that?? Get an old Bridgeport and dive in!!
Found your thread last night, subscribed, couldn't get the post in before the battery quit (posting from my phone).
So I'll try again.
Firstly, thank you for your service.
Sorry to hear you are havng to move, and it's impeding your project.
I look forward to progress when you can, and appreciate your posts so far.
It looks like quite a bit of the stuff I see on the salt.
If you are concerned about the tappet to valve interface, you could turn the plunger in the hydraulc tappet upside down and machine a reciever in that for a small motorcycle lash cap (about as big around as a baby asprin).
You would need a tool to raise the valve while the tappet was on the base circle of the cam, and some sort of relief notch to lift the lash cap out through, but that shouldn't be a problem for someone that carves their own cylinder head.
Oh yeah, I meant to ask, how do you intend to keep the tappet from rotating in the bore?
If the spacing is close, I suppose you could use the factory dog bones, if you have the room.
Great project! I love this stuff!
I assume you will mill water passages between the 2 head halves?
As for roller lifters, Harley lifters, until the early/mid 80's were about a .731 diameter, if I remember right. You could always just add a sleeve to what you have, and use those.
We have done all of the mods you are currently doing, to my Caddy flathead. If we can be of any help, please PM. me.
damn, just what we need is another Lockhart or Miller stinking up the place....
From the look of things the Navy, and our country, are fortunate to have you on board. Where ever you are bound, whatever you will be doing I wish you clear sailing.
On the ignition, you might look up previous dual plug designs and get info on putting a firing delay on the second plug. It has been beneficial on several engine designs.
Pertronix makes a modern setup for it.
On the cam design, to get the lift rate you want with a roller cam, you will have to have a profile with an inverted flank. It is a good thing you are planning to machine the cam by CNC methods because while it can be done on a conventional cam grinder, it involves MUCH modification to the grinder.
Thanks for the suggestion on the lash cap idea. The fact that the hemispherical relief for the push rod in the top of the lifter plunger will not work with the flat end of the valve is a detail that I haven't worked out yet. I like your idea, I hadn't thought to invert the plunger, it should be flat on the bottom if I remember correctly...hmm maybe I can just flip the plunger over and keep the lifters hydraulic and put the plunger 1/2 way down it's travel with the length of the vlv stem. I was leaning toward putting the stock lifter, with handy adjuster built in, inside the SBC lifter, unfortunately the OD of the stock lifter is about .010 larger than the I.D. of the SBC lifter. But some machine work would take care of that, provided the lifters are not hardened.
Rotation in the bore - factory type dog bones, either stock or custom.
Very nice to see something created
38FATTIE - I've seen your Cad project in the past, Awesome stuff your doing there!
Yes - water jacket machined between the head halves.
Motorcycle lifters - I did some research on that a while back because of their small diameters, however, all the ones I found had a large ~1" roller on the bottom. there is only 3/8 - 1/2" between the nose of the cam and the bottom of the lifter bore so not enough room for the large motorcycle roller. Are there other types out there that may work better, ie. ~.750 bore with ~.750 roller?
Pete1 - thanks for the info on the delayed spark and Pertronix. You are correct on the cam. So the basic idea for the project is to have fun building a cam from scratch, not ultimate HP (if that where the case I'd break out a Summit and the credit card), that said, why not run the wildest, baddest cam that can possibly be stuffed into a flathead and not eat itself in the first 1000 miles!! So yes, inverted flanks, which, as you pointed out, requires a non-conventional grinding wheel. I'll use a 1-2" roller with a grinding belt in order to achieve the inverted flank. I plan to build a dedicated cam grinder for this purpose. Seen some great ideas from the guys building miniature V-8's. I will also be dwelling the valve at the top of its lift as long as possible. Both the inverted flank and the dwelling require the use of much, much heftier vlv springs, but since I don't have to worry about rockers and push rods, this shouldn't be a problem.
As soon as I get some free time, I'll start a thread on the cam portion of the project. I've written a computer program for designing cams, it's ~90% done, I need to figure out how to share that with all of you guys. It's pretty cool to play with different cam pattern's and see how that affects vlv spring rates, etc....Anyways....thanks for the ideas.
Subscribed, can't wait to see more.
I seem to recall a smaller cup and sprin seat are already there, if you could get the check valve and spring to work, you might be able to maintain hydraulic adjust, biggest PITA there will be not maring the surface of the plunger (as they are already fitted that tight.
I believe they are hardened, but I'm not sure.
As long as we are dreaming it up how about crank trigger ignition with 2 sensors firing 2 banks of coils? All common junkyard parts.
The Harley lifters are .730 bore, .855 wheels. Would they work? Can you 'slot" the bottom of your lifter bores for the wheels? It wouls also then act as an alignment guide for the lifter.
You could use the Harley bodies, and Chevy .750 roller wheels .Aftermarket ( Morel, Crane, etc) rollers for Chevy had some .842 bodies with .750 wheels.
Quote["So yes, inverted flanks, which, as you pointed out, requires a non-conventional grinding wheel. I'll use a 1-2" roller with a grinding belt in order to achieve the inverted flank. I plan to build a dedicated cam grinder for this purpose. Seen some great ideas from the guys building miniature V-8's."]Quote
You are on the right track there.(1 inch) That is what I did to grind the Allison hydro cams.
When you get to it, Buddy has a friend that might help you with some ideas on the lifters.
Quote["why not run the wildest, baddest cam that can possibly be stuffed into a flathead and not eat itself in the first 1000 miles?"]Quote
I am quite sure you know the answer to that. It has to do with cake......
A short duration cam with an extremely high rate of lift will give you about equal top end hp to a long duration cam with a much slower rate of lift.(area under the cam curve) The one with the high rate and short duration will be much more drivable but will obviously wear out sooner due to the spring pressure required to control it. The long duration one will have a very rough idle and poor performance at low rpm's.
The long duration cam will be easy to duplicate in a roller design.
The short duration, high rate of lift design will be very difficult to achieve and keep it together in a roller design.
It boils down to the fact that there is just not enough room in the present cam tunnel for a cam design that will "do it all".
If there was you could go to a desmodromic design and have all the cake.
I don't suppose we could get links to the threads that gave you your ideas about grinding cams?
I would love to read more bout inverse radius, I remember hearing about that in the late '80s somewhere.
Subscribed. Will be following this with interest.
Due to all the interest generated in the portion of this project that entails building a cam shaft I started a new thread titled "Homemade Camshaft Project"
NEXXUSIAN, I answered your above questions in that thread.
Here are some shots I took of a two piece head in the pits at Bonneville last year. I know nothing about it. The guys were really busy so I didn't get a chance to talk to anyone.
Getting back to the camshaft for a minute... you could hard face it with Hypereutectic welding rod the way Isky did back in the fifties. Then you could use stock lifters.
As he described it, they would grind a groove in each cam and fill it in by arc welding with a special rod. This gave a super hard wear surface where the lifter contacted the cam. Then they would regrind the cam.
From the Isky web site:
[FONT=verdana,helvetica][FONT=arial,helvetica,sans-serif][FONT=verdana,helvetical,sans-serif][FONT=arial,helvetica,sans-serif][FONT=verdana,helvetical,sans-serif][FONT=arial,helvetica,sans-serif][FONT=verdana,helvetical,sans-serif][FONT=arial,helvetica,sans-serif][FONT=verdana,helvetical,sans-serif][FONT=arial,helvetica,sans-serif][FONT=verdana,helvetical,sans-serif][FONT=arial,helvetica,sans-serif][FONT=verdana,helvetical,sans-serif][FONT=arial,helvetica,sans-serif][FONT=verdana,helvetical,sans-serif][FONT=arial,helvetica,sans-serif][FONT=verdana,helvetical,sans-serif]HAROFACE OVERLAY: A process originated by Ed Iskenderian to apply a tungstencarbide, chrome-nickel alloy to the outer surface of the cam lobe. These combined alloys provide an extra-durable surface for the tremendous spring pressures and high rpm of today's all-out competition engines. Camshafts that have been hardfaced are for maximum competition only, and cannot be used on the street.
There may be some other alloy that can be used on the street, I don't know why a cam will stand up in competition but not for street use.
Haha! Those are my heads. The details are in the build thread for my blown Cadillac flathead '38 Chevy-The FlatCad.
That's cool. That car sounds so good. I couldn't remember what car the head went with. I get overwhelmed out there.
or you could look into salt bath nitride which puts a surface hardness of about 90 rc with about .010 penetration.Crane currently offers this as a upgrade when you purchase their cams.We use it quite abit in our business were materials have to ride on each other through many cycles.This is a heat treat process and has very little if any distorsion so I can be done when the component is complete.Look up salt bath or gas nitride theres lots of information on it.
This is awesome. I thought of milling my own head for my A but couldn't figure out how to do the water jacket.
Maybe I missed it, but the jacket is in the top half right?
In all the ones I've seen and owned, the jackets were in the top and bottom halves.
38Flattie, How thick is the head above the combustion chamber?
I was going to leave .500" overtop the quench area and .300" over the vlvs with a rib in the top half that will add support to this thinner area.
(7.5:1 comp and 6 pounds boost)
What do you think?
Thanks for the pics.
Kipp, Awesome tech thread. As one sailor to another fair winds and following seas if you are heading out on deployment.
How does that compare to gas infusion nitride for hardness and depth?
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