| Author |
 Topic Search  Topic Options
|
SteveC(NS) 
Orange Level
Joined: 12 Oct 2009
Location: Nova Scotia
Points: 663
|
 Post Options
 Thanks(0)
 Quote  Reply
 Topic: Steve's CA Knock
Posted: 22 Jan 2012 at 10:41am |
Just thought I'd start my own thread on the above instead of further cluttering Stewart's I started the tear down and got some plastigauge but before going further I decided to check some measurements to permit a calculation of my compression ratio. So I took off the head. It's a 3.4375" bore. I CCed the head at 70cc (4.2716 cu.in.) and I sorta guesstimated the bore space above the piston including the gasket to be 4cc (.245 cu.in.) and the swept volume is 532.124cc (32.4722 cu.in.). I got 8.287 to 1 compression. I then checked the piston top to block top and got about .032". I wondered if my overbore pistons were higher compression too. Today I pulled a piston they're M&W "add power" pistons and compared it's height to a 3.375" piston I had and to my amazement it measured about 0.060" BELOW the stock piston. The only reason I could think of for the lower height was to compensate for the increased swept volume of the overbore and subsequent increase in compression that would result. But heck if they were "more power" pistons they woulda been even more at a higher compression. I'd appreciate anyones thoughts and possibly corrections of the 8.25 to 1 compression figure that my figuring produced. So I'm now doubting my comp. ratio calcs. I'll redo my calculations and check back. Steve
|
 |
|
Sponsored Links
|
|
|
GregLawlerMinn
Orange Level
Joined: 11 Sep 2009
Location: Lawler, Mn
Points: 1226
|
Post Options
Thanks(0)
Quote Reply
Posted: 22 Jan 2012 at 10:59am |
Steve Sent you a pm; my new Clevite stock pistons are "0.325 below the deck at TDC. I believe compression is determined by the distance between the wrist pin and the top of the piston. A longer dimension should have more compression than the shorter dimension.
|
|
What this country needs is more unemployed politicians-and lawyers.
Currently have: 1 D14 and a D15S2.
With new owners: 2Bs,9CAs,1WD,2 D12s,5D14s,3D15S2s, 2D17SIVs,D17D,1D19D;1 Unstyled WC
|
|
Brian Jasper co. Ia
Orange Level
Joined: 11 Sep 2009
Location: Prairie City Ia
Points: 10508
|
Post Options
Thanks(0)
Quote Reply
Posted: 22 Jan 2012 at 11:02am |
|
8.25:1 would help make a pretty strong CA. Seems like original CR is in the 6.25:1 area?
|
|
"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford
|
|
SteveC(NS)
Orange Level
Joined: 12 Oct 2009
Location: Nova Scotia
Points: 663
|
Post Options
Thanks(0)
Quote Reply
Posted: 22 Jan 2012 at 11:11am |
OK folks, I've re-done my calculations and I get 6.41 to 1 as the CR which sounds more reasonable. The lower height of the M&W 3.4375" pistons must be calculated to keep the stock 6.5-1 CR. I'll continue checking for my knock and pondering how to increase the CR before re-assembly. More to follow.
|
|
SteveC(NS)
Orange Level
Joined: 12 Oct 2009
Location: Nova Scotia
Points: 663
|
Post Options
Thanks(0)
Quote Reply
Posted: 22 Jan 2012 at 12:14pm |
If the M&W "add power" pistons were the same height, from the wrist pin, the compression ratio would have increased to 7.324-1 just on the swept volume increase. Too bad, I'd have liked that. I can't really measure the volume of the combustion chamber in a head milled, say .100" without actually doing it but I estimate the volume might decrease by,say, half the diameter of the bore or .464 cu.ins. If I subtract .464 cu. ins. from the chamber size my 6.41-1 goes up to 6.86-1 hardly worth the effort. If i could machine the block I could get more but I'd have to pull the liners and then rebore the block for their lips.
|
|
Dick L
Orange Level
Joined: 12 Sep 2009
Location: Edon Ohio
Points: 5087
|
Post Options
Thanks(0)
Quote Reply
Posted: 22 Jan 2012 at 4:18pm |
I would get taller pistons before I lowered the deck. Most pistons for that engine are flush with the deck as in this picture.
|
|
SteveC(NS)
Orange Level
Joined: 12 Oct 2009
Location: Nova Scotia
Points: 663
|
Post Options
Thanks(0)
Quote Reply
Posted: 22 Jan 2012 at 5:57pm |
Thanks Dick, Does anyone know where I could get taller 3.4375" Pistons? But then I could also get the crank stroked to bring my M&Ws up to the top of the block. Speaking of M&W pistons, I'd love to hear any more information about them. I'll run the "even with the top of the block" numbers tomorrow when I'm a little sharper. At my age I start the day dull and it isn't long before I'm BLUNT. Thanks all, for your thoughts and keep'em comin'. Steve
Edited by SteveC(NS) - 22 Jan 2012 at 5:59pm
|
|
SteveC(NS)
Orange Level
Joined: 12 Oct 2009
Location: Nova Scotia
Points: 663
|
Post Options
Thanks(0)
Quote Reply
Posted: 10 Apr 2012 at 3:24pm |
Just a little progress(?) note. After successfully milling my CA head 0.100" I decided to change the crank before reassembly ( I just happened to have a couple of reground cranks with bearing inserts).
That done, pan back on I was ready to put the milled head on it and in so doing I discovered that the long head bolts had to be shortened to compensate for the 100 thou removed from the thread. That done I checked the short head bolts and found their tapped holes in the block to be fine, no need to shorten them.
Dick L (et al) have you ever come accross the need to shorten the head bolts after milling a head?
I know this project seems to be dragging out but NOTHING gets done in a timely manner here.
|
|
StewartMD
Orange Level
Joined: 10 Dec 2009
Location: Emmitsburg, MD
Points: 314
|
Post Options
Thanks(0)
Quote Reply
Posted: 11 Apr 2012 at 9:04am |
Steve,
I know what you say about getting things done in a timely fashion. I tore apart my CA engine back in January, and just last night I finished putting the head, rocker arms, valve cover, and exhaust manifold back on. But now I am putting a wide front on it. I'm sure it will be quite some time until I get finished. With field work and mowing the lawn, etc, it's hard to find enough time. Glad to hear that you are making some progress.
|
|
8030, 8010, 220, 185, 160, D-17, WD, Unstyled WC, CA, G, 20-35, Gleaner E
|
|
SteveC(NS)
Orange Level
Joined: 12 Oct 2009
Location: Nova Scotia
Points: 663
|
Post Options
Thanks(0)
Quote Reply
Posted: 11 Apr 2012 at 4:48pm |
Stewart, glad to hear from someone else with too many irons in the fire.
It just seems to me that when I worked 40+ hrs. a week I got more done at home than now that I'm retired.
Anybody else ever have to shorten head bolts after milling the head?
|
|
BrettPhillips
Orange Level
Joined: 11 Sep 2009
Location: Strasburg, VA
Points: 808
|
Post Options
Thanks(0)
Quote Reply
Posted: 11 Apr 2012 at 8:25pm |
|
You might want to check into shortening your pushrods as well. I've had trouble in the past with binding rocker arms after milling a head. Of course that was on a JD, but the same geometrical laws still apply I think.
|
|
Dave (Mid-MI)
Orange Level
Joined: 12 Sep 2009
Location: Hemlock, MI
Points: 566
|
Post Options
Thanks(0)
Quote Reply
Posted: 11 Apr 2012 at 8:54pm |
|
M & W pistons for the A-C models B, C, and CA were piston set SP-5. That number should be on the piston somewhere. They are 3-7/16" bore, and have 6.4 to 1 compression ratio versus the stock 6.2 to 1. M & W claimed observed belt horsepower of 29.7 versus the stock 25.9. dave
|
|
SteveC(NS)
Orange Level
Joined: 12 Oct 2009
Location: Nova Scotia
Points: 663
|
Post Options
Thanks(0)
Quote Reply
Posted: 12 Apr 2012 at 9:15am |
Way-ta-go Dave, Now you come forth with M&W piston info, now that they're back in the block and the pan is on etc.
I guess I should have written down any and all of the numbers and identification.
Still, I can't figure how they could provide higher compression than the stock 3.375" pistons that came up higher in the bore??
Kinda tricky shortening the pushrods too.
Maybe a shim under the the rocker brackets?
|
|
GregLawlerMinn
Orange Level
Joined: 11 Sep 2009
Location: Lawler, Mn
Points: 1226
|
Post Options
Thanks(0)
Quote Reply
Posted: 12 Apr 2012 at 9:25am |
Steve You can use gr8 washers under the long head bolts to eliminate shortening them. I have "shimmed" rocker arm supports using machine washers (long story about why I needed to do this, suffice it to say that the old timers were very ingenious on keeping these machines running) with good results.
|
|
What this country needs is more unemployed politicians-and lawyers.
Currently have: 1 D14 and a D15S2.
With new owners: 2Bs,9CAs,1WD,2 D12s,5D14s,3D15S2s, 2D17SIVs,D17D,1D19D;1 Unstyled WC
|
|
BrettPhillips
Orange Level
Joined: 11 Sep 2009
Location: Strasburg, VA
Points: 808
|
Post Options
Thanks(0)
Quote Reply
Posted: 12 Apr 2012 at 2:39pm |
|
The trouble with shimming rocker stands is that then you end up having trouble getting the valve cover to seal. Sometimes you end up with two gaskets.
|
|
SteveC(NS)
Orange Level
Joined: 12 Oct 2009
Location: Nova Scotia
Points: 663
|
Post Options
Thanks(0)
Quote Reply
Posted: 13 Apr 2012 at 8:03pm |
Thanks Greg & Bret. I've already shortened the long head bolts on the lathe and re- torqued them (one by one) when I get to cold gapping of the valves I'll see if I need to take any other measures. I'll keep you informed ( at my normal rocket pace). Thanks for the response. Steve
|
|
