Small V8

[dvbydt]

Hi, new on this forum and have just read this fantastic thread. I probably missed it, but did you dismiss the possibility of making the crank like the Rover V8 (a Buick design) with two conrods per crank pin? It should be easier to machine especially if you have a big bore 4 jaw chuck which will accept the offsets.

Ian

 

[stevehuckss396]

Hi, new on this forum and have just read this fantastic thread. I probably missed it, but did you dismiss the possibility of making the crank like the Rover V8 (a Buick design) with two conrods per crank pin? It should be easier to machine especially if you have a big bore 4 jaw chuck which will accept the offsets.

Ian

Working with a 9X20 with a 3/4 bore. There are 4 crank arms (pins) with 2 per layed out 90 degrees apart. Nothing is easy but it is all I have at the moment. I still have 2 more ideas for the crank but I have tied myself up with the heads. I am going to continue with the heads until i hit a wall or finish them and then revisit the crankshaft.

Welcome to the forum Ian. There is alot of talent and wisdom here. Great bunch of people!!

 

[Lakc]

First the seats. When I cut the seats I set the compound to 45 degrees. I always make the valves after, and cut the angle on the valve having never moved the compound slide. This way I know that the angles are exactly the same. If I were to grind the valve I cant be sure the angles are exact using 2 machines.

Full size practice is 1/2 to 1 degree of difference to get a skinny contact patch with high seat pressures. They all lap in together eventually.

The hole was reamed to .250 and all the cages were .2503 - .2508. When I press from the top I make them .001 - .0015 over size but they press hard for such a tiny piece. These slide in much easier.

Thanks! I never trust myself enough to design any press fits. This upcoming build of mine will be the first with cages for that matter, so this has been very informative.

 

[LongRat]

Very useful information, thanks Steve.
I have a very small high speed spindle that could be mounted on the compound (I also have a 9x20). I always fancied the idea of grinding the valves with that, with the compound still set at the angle used to make the valve seats as you did.
Do you notice the sliding fit of the valve stem in the guide changes (tighter) after the cages are pressed into the head?

 

[stevehuckss396]

Do you notice the sliding fit of the valve stem in the guide changes (tighter) after the cages are pressed into the head?

Don't know. I make the valves after the cages are in so I dont know how they fit before.

 

[stevehuckss396]

I made 10 more blanks today so I have a total of 18 made so far. They take a few minutes because when I turn them the stem gets small and they get a bit of a taper. I just use some sand paper to polish the taper out. If I have the weekend off I might get them finished up.

 

[jpeter]

Hey, I've been following your posts about your crank follies. I too had lots of problems making a satisfactory crank of v8 length. After a few failed attempts I fell on the following procedure:
I used round bar, 4140 I think. I centerdrilled the ends for the four throws like you did. Next I clamped the blank to the mill table laying it in a slot for alignment and support. I then used an end mill to remove most of the excess material. After completion I'd turn the blank 90 degrees and repeat the process until I had a complete crank but with square journals not to much oversize. I next placed it in the lathe and turned the throws in the four throw centers. Faced the inside of each throw at this time too. I use 5 main bearings so i knew it was very important to get the mains collinear so I turned them last. Before turning I placed spacers between the throws so I could put some squeeze on the mains with out collapsing the thing, clamped it between centers and turned the mains to size; trued up the outside too. This procedure worked so well for me I'd not change a thing. One V8 crank; about 8 hours.

My first attempts were much like yours with the square bar. The extended deep interupped cuts wrecked my lathe, tools, took vast amounts of time and was ruining my hearing from the chatter and ruined my disposition.

 

[jpeter]

Got some valves to make? Got CNC? Check this link to see how I made a few. I know I could have stylized them with reduced shanks and such but it was just a start and early on. Later on I fancied them up.
[ame]http://www.youtube.com/watch?v=47tx15FgLQ8[/ame]

 

[stevehuckss396]

Got some valves to make? Got CNC? Check this link to see how I made a few. I know I could have stylized them with reduced shanks and such but it was just a start and early on. Later on I fancied them up.
http://www.youtube.com/watch?v=47tx15FgLQ8

How did you get the taper out of the stem. My stems are only .093 and .850 long so it is unavoidable unless I put a center in the tail stock. Of course that would have to be cut off and it just seems easier to polish a bit of taper out.

 

[Lakc]

How did you get the taper out of the stem. My stems are only .093 and .850 long so it is unavoidable unless I put a center in the tail stock. Of course that would have to be cut off and it just seems easier to polish a bit of taper out.

Lots of rake on a very sharp bit and tiny cuts. Otherwise, if you dont mind wasting the material, you can always make it long enough to use a center.

 

[jpeter]

Your point about the small stem is noted. My stem is 1/8 dia..
Regarding taper: Notice the first pass is pretty deep and the second pass is a finish cut. Notice too the cutter is working pretty nicely. I can't fool you guys, there is some taper but in the area that slides in the guide the size is less than a thou under. If you haven't yet seen my v8 its on youtube. Search for jpeterjpeter.
There's lots of different way to install valves and the bucket idea is the current fashion but in my engines, v8 included, I generally press in brass guides reamed for the valve stem. Its a pretty light press cuz the spring holds everything together. I make the stem undersized by a thou or so. I cut seats directly in the aluminum using a home made cutter which has a guide machined on the end. I control the depth of the cutter with the mill cuz without control the seat cutter tends to hog in in spots. I lap the valves in then with baking soda, spinning them with an electric drill or Dremel on slow. I test the results by bolting the head to a plate, gasket included, and blow air, from my mouth, in the chamber through a modified sparkplug; small tube required here. A bubble every 5 seconds is my limit for leakage.

Hey Steve, sorry for hogging up your thread. Seems I always have to pitch in my 2 cents. Your project is looking mighty fine. I see you don't live too far from me. Some day I'm gonna drop in on you and check out your stuff. Did I notice there's a club that meets out in McComb county somewhere?

 

[dvbydt]

So, I did miss something, put it down to old age. The marking on your crank blank looked like you were trying to do one journal per conrod.
Jpeter has given you a method that obviously works and I am very impressed by his skill level. Doing this between centers is not something I would find easy, even though I have been earning my living as a machinist all my working life.
Pity you are the other side of the pond, you would be welcome to use my 12 x 36. The bore on the big 4 jaw is 2 1/4 ins. and you could rough plunge each journal before moving the blank out to do the next, then finish size between centers.
This is a brilliant project and I look forward to future posts. (Camshaft?)

Ian

 

[stevehuckss396]

I see you don't live too far from me. Some day I'm gonna drop in on you and check out your stuff. Did I notice there's a club that meets out in McComb county somewhere?

What city do you live in?


Yes there is. Here is a bit of info

Metro Detroit Metalworking Club
2nd Wednesday of the month
Macomb Community Collage
South Campus (12 & Hayes)
North Lobby of “S” Building
7:00 PM

 

[stevehuckss396]

This is a brilliant project and I look forward to future posts. (Camshaft?)

The cam will be alot easier than the crankshaft. .070 lift, 280/280

 

[jpeter]

Steve, I live in Kingston. Its up VanDyke a few miles north of
Marlette, then a little west. From my place its about 65 miles to Lakeside mall.

How many attend? What goes on at a meeting? Whats the cost?

 

[stevehuckss396]

Steve, I live in Kingston. Its up VanDyke a few miles north of
Marlette, then a little west. From my place its about 65 miles to Lakeside mall.

How many attend? What goes on at a meeting? Whats the cost?

There are about 15 regulars. the meetings are very casual. There is sometimes a program like once there was a rep from loc-tite and every fall there is a swap meet in the parking lot. September meeting a fellow came from Ohio to talk about casting aluminum. There is a guy lined up to talk about heat treating but i'm not sure when. Even when nothing is going on, It's still a good place to go to talk about all things metal but the guys are into wood, guns, model railroad, ect.

 

[stevehuckss396]

Hello All!

I am now up to 32 valve blanks when I ran out of 1/4 inch drill rod. I will get a piece tomorrow after work and hopefully get the last 8 done so I can get on with cutting the slots and valve angles into the blanks.

 

[stevehuckss396]

Hello all!

All 40 of the valve blanks are completed. They take forever but it will someday be worth it.

To cut the slots I used my ER11 collets. I was able to put the valves in backward and slot the stem for the E-clips. I have an insert holder and a .020 slotting tool. Makes it easy to have a nice sharp tool because I stink at grinding tool bits.

Then I made a few test pieces. I chose not to reduce the size of the stem at the head so I could hold the valve real close for rigidity. I took a light cut accross the face. I want the valves flush in the head and the hole for the valve cage is .250 so I reduced the OD of the valve down to .245.

Then I cut the valve angle into the back surface.

So now you all know what I'll be doing tomorrow!!

 

[1hand]

Wow thats some tiny stuff your workn with there. Looks like they turned out very nice.


How many times you chase them parts across the floor..... :big:

Matt

 

[kcmillin]

I just put an ER collet chuck and collets on the Must Buy list. That would have been nice when I made my valves. But I only had to make 16, well 17 if you count the one that was eaten by the swarf pile.

They look real nice BTW, have fun lapping those puppies in.

Kel

P.S.

Anybody know why the spell checker doesn't like the word collet?

That IS how it's spelled, Right?