Chamber size for large log on weekend driver? 50cc?

I would go with the adjustable rocker arms. The 1.6 rockers would help mid & top end. If your wallet is fat 1.65 rockers are available that use the rocker shaft oiling. You will need pushrods with a cup to mate with the adjusters.
The best is the Yella-Terra 1.65 full roller rocker arms, but you need to use the V8 lifters cause the oiling is via the pushrods. If you go that route you need to install a screw in plug in the left rear of the block to block the oil to the rocker arms. Otherwise you will have an oil leak in that area cause the headgasket cannot hold the oil pressure.
Going with a higher rocker ratio will not change the cam specs on the seat. However at .050" the duration will increase as well as the rate of lift & total lift.
 
I just ran the numbers on Comps 260H and there's a discrepancy with their listed specs. 260/260 advertised duration with 110 deg lobe seperation and a 106 degree centerline equals Intake Open: 24 BTDC, Exhaust Open: 64 BBDC: Intake Closed: 56 ABDC, Exhaust Closed: 16
ATDC. Overlap = 40, ground in advance = 4 degrees. Not open 22 BTDC/62 BBDC and closed 57 ABDC/17 ATDC????

I haven't seen a cam that I looked at that the number's didn't jibe with the Pat Kelly program I'm using.

If you say 107 centerline, the closing angle would be correct and the ground in advance reduced to 3. But the opening still off by a degree, 108 vice versa and the ground in advance reduced to 2. I'm surprised this has never come up. Hard to know where you are at when the #'s don't work out.

Running the last numbers/assumptions in bobcat's last post, but assuming 260/260 110/106 at the calculated event timing above, I come up with:

@ .030" deck clearance,

quench=.074"
displacement=202.7579"3
SCR=8.907
DCR=7.623
dynamic stroke=2.6185"

@ .019" deck clearance,

quench=.063"
SCR=9.133
DCR=7.813

Which is pretty different...
 
wsa111, unfortunately the wallet is not fat right now, so the 1.65's aren't going to happen. Do I need the 1.5/1.6 adjustables? Or can the hydraulic lifters compensate from going from 52cc to 48cc?
 
Howdy Back Nick and All:

FYI- it's not the ccs that will make the difference on whether or not non-adjustable or adjustable rockers are needed to make a discreet contact with the valve tips. The FoMoCo shop manual indicates that the hydraulic lifters have a range of .125" + or -, which is alot of leeway. In other words any variance from factory dimensions should be considered. For example, if you were to mill a stock factory head .025", you'd be will within the factory lifter spec. So add up and subtract all the machining and parts variances from factory specs and you will have a clearer picture of what is possible.

And, an added and real value of adjustable rocker arms is in maximizing the effectiveness of the cam.

IF you can't afford adjustable rockers right now, assemble with the non-adjustable rockers and watch the rocker arms contact the valve tips. Ideally, you'd like to see the rocker tip move fore and aft from the center of the valve tip.

Using the cc comparison, 52 to 48 ccs is a difference of 4 ccs or approximately a .020" mill cut on the head. This may not be a exact as you would like, but it is a good estimate. And, if that is the only dimension variance the hydraulic lifters can compensate.

The stock deck height, the distance from the top of the piston to the top of the block, on a factory 200 is typically right near .025". Did you measure yours? Deck height and head gasket thickness make up deck clearance. I saw the head gasket compressed thickness of .035", or .010" more than a stock steel shim head gasket. I did not see the deck height listed. Did I miss it? IF the block was decked as part of the rebuild, that would add to the math.

Keep it coming.

Adios, David
 
The block was not decked, so should be stock.. Unfortunately I don't have a gauge that's very accurate measuring a distance that small, but it came out as 1/32 with my cheap one. So .025 or .030 sounds about right.

As for the gasket, I got a NOS steel shim that I'll be using.

Should be getting the head back from the shop this week, so I figure at this point whatever the C/R is, is what it is. I can't imagine I would feel a huge difference between 1/4 of a point or so anyway. Especially for a weekend driver.

While things are apart I'm also taking the opportunity to switch out to an aluminum radiator and a 6 blade fan to keep temps lower when I'm stuck in traffic on hot summer days... so might be a few weeks before I have everything back together again. I'll post back when she's running again... thanks for everyone's help!
 
Make sure that gasket is a 200-250 and not a 170...They are being passed off as 200-250. when they are really 170s ..to small :(
 
UR link sez 'truck' so I'd assume it's a 240/300?
(altho that's a misnomer 4 me - like PrezClinton sez: "define" truck).
8^0
What's the application?
Compression thickness?
Boar diamiter?
Material?
:eek:
 
If you have the gasket in your hands let us know what it is?...It looks like a 200-250 but a composition not a thin steel embossed steel shim.
How thick is it?
 
Yup, I opened it this morning and checked... composite. I should have read more into it before I bought it, I just assumed they were still using steel in that time frame. If it's indeed only .035 though, that's still really good I think - I was using a Victor before which was .044 and that was the thinnest I could find at the time.
 
The ford part number is correct for the small 6 regardless of what the seller advertised as. I bought the same part from a different seller and is installed and working. Bore is 3.81" and thickness is 0.035".

My only advice is to use some centering studs when you install. I put some rubber nipples on the end of my studs prior to instal to avoid buggering the head surface. TEST FIT THE COVERED BOLT THROUGH THE CHANNEL before trying to install. You don't want to find out that the rubber is too wide to fit through the stud channel through the head. That head is heavy when you're leaned over and especially so when you're flying solo. Mine was snug and worked perfectly. These old gaskets aren't going to be as forgiving of you trying to slide things around...
 
Bought fiberglass fenders from a major mail order...Box marked right, was Chevy not Ford ... :banghead: The supplier just put some thing in the box to get paid and then went out of business :eek: I was in high school, it was delivered when I was at school, young and dumb.
 
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