Intake  Lobe lift .291, .448 valve lift

                      .020 open at 19 deg BTDC

                      .050 open at 3 1/2 deg BTDC

                      .050 closed at 44 ABDC

                      .020 closed at 62 ABDC

Exhaust Lobe lift .294, .453 valve lift

                      .020 open at 72 BBDC

                      .050 open at 52 BBDC

                      .050 closed at 0 TDC

                      .020 closed at 21 ATDC

I figured .050 duration to be 228 deg. but not sure that is right.  Measurements were repeatable, and done with stock timing set.  Dial indicator extension was placed on top of lifters. 

The only marking on the cam that may make sense is "Full" on the front, which must have been an old reference to Full Race camshaft.  I think this was left over from the 60's.

Is there a measurement I can do to help determine what the lash setting should be?

Mike

Exhaust duration of 232,centerline of 116 and an overlap of 3.5

Has an advance of 2.9 *

Looks like a blower cam to me or damn close

It"l twist up to 6K or so easily.

I would use the safe lash of .019

Oldmics

Thanks a lot for the help Oldmics.  I put some toothpicks on the degree wheel and can tell how you got the duration, centerline, and 3.5 deg. overlap.  But how did you figure lobe separation and get an estimate of advance?  Also as I look at the toothpicks, it shows a large overlap between Exhaust opening and intake closing, approx. 95 degrees.

It is hard to believe, but true, that this cam was installed in an engine with 7:1 CR .

Edit Note:  Another measurement I did was at .001 open/close.  Thought it would give an idea of advertised duration.  I didnt write it down because it didnt make sense, as duration was well over 360 degrees ????

Seriously,someone much smarter than myself many years ago gave me an old DOS program that runs these types of specs.

You can also manually enter the offered parameters into the Preformance Trends "Cam Doctor" software (if you own it) and get the answers.

I do have the math around here somewher on how to do it but I have been using the software methods for soo long now as its just faster and easier.

Oldmics

Oldmics

John, this probably is a dumb question, but what is meant by "If .020 is close to operating clearance"?  It sounds like you dont think the figures add up, and I agree a 261/273 duration cam is a surprise.  Maybe this evening I can do the measurements again.

Intake lobe lift .291

          .020 ope at 19 BTDC

           .050 open 3.5 BTDC

           .050 closed 45 ABDC

           .020 closed 63 ABDC

Exhaust lobe lift .294

            .020 open 69.5 BBDC

            .050 open 49.5 BBDC

            .050 closed .5 BTDC

            .020 closed 27 ATDC 

262/276 cam.  Weird.

.050 Durations are almost the same.  228.5 and 229 .                                                                                    

What I'm trying to say is that maybe he intake lash should be around .016 and the exhaust around .020, giving a duration of around 272, which wouldn't be all that unusual.  Crane used to grind cams with "odd" durations, I think the one I'm running now has an intake advertised duration of 292 and exhaust 302.

I get 228.5 for intake and 230 on exhaust for duration.

The intake centerline moves to 110.8, exhaust centerline 114.5

Lobe spread of 112.6, Advance of 1.9*, and an overlap of 4 *

My concern is about the exhaust closing BTDC (.5) That doesnt sound right and will obviously screw up all the figures.It should be an ATDC measurement.Perhaps an error in spec placement nomenclature?

Are you sure that you are measuring the correct lobes?

The cam is setup front to back as E5-E1-I5-I1. Are you sure you are on the correct lobes?

Forgive me for asking but the basics have to be correct before going deeper.

Respectfully,Oldmics

I've been working on number one cylinder, with the front lifter being ex. and second intake.   No problem here with questioning the method, as it is clear my cam understanding can be improved, and actually has been helped with this exercise and you and John's input.  The .050 closing was definitely at 1/2 BTDC.  I was carefully bumping over the crank and the wheel indicator wouldnt quite make it to 0. 

In the next few days will check at least #2-4 cylinder lobes to help rule out methodology error and premature lobe wear.  Visual inspection didnt show any wear, but then the eyesight used to be better.

Mike

Are you using the right hand side of the block (passenger side) for #1 cylinder?

And then using the most forward lifter bore on the right side as E-1 ?

Then the second lifter bore on the right side as I-1?

I am not clear on how you are counting back the lifter bores.

Oldmics

Is it possible that the crank has been missground, somehow throwing everything off, beginning with the TDC location?  Before removing pistons I visually noted a large discrepancy in piston to deck clearance between #1 and a piston on the other side (dont remember which) .  Checked number one and it was .045.  Didnt check the other that I had noticed on the opposite bank, but believe it was .010 or less.  Figured the issue was different rod lengths from rod resizing, and that I would try and sort it all out later.  However when I put this current piston rod assembly (different than when originally taken down) into #1, clearance was still .045.  Crank has been ground quite a few times, as it is now .050 under on rods and .040 on mains, so even with journals being in good shape this will be the blocks last go round.  Block is .080 OS.  Numbered markings on rods had no correlation to their location as found.  I think only one rod piston assembly was in the proper hole according to its number, and that must have been someone's dumb luck.

I chose this block to check the cam only for convenience.