PUZZLER!!! My new motors a dog! what did I miss?

[nm9stheham]

I think the centerline method is most accurate. When you did that, and got consistent results, that said you had it pretty good. Now, if it runs less doggy, it'll be a bit surprising. You have retarded the cam about 2 degrees, and it will tend to have less torque with the cam more retarded/less advances.

BTW, how did you index your wheel measurements to TDC? I can't see how you did that. Looking at your first degree wheel picture, with the pointer at a few degrees BTDC (which I assume is intake opening at .050" lifter lift), it look likes the cam sprocket dot is not quite where I would expect; I would expcet it to be to the left of the vertical centerline. But it is hard to see in that small pix, so is probably an error in my viewing.

Understood on the 'stop and think' thing! Not yet sure where to head next.....going to re-read the original complaint.

BTW, I just worked up your static CR. looks to be in the low to mid 9 range, so that should be good. Is that what you expected? But the cylinder pressures sure seem very low for that SCR. I got 140 psi for my /6 rebuild with .050" head shave and very mild cam! Something seems wrong with the pressure....hence the cam timing questions. Trying to think what could be holding the valves open a bit too much; did you use the Lunati lifters?

 

[mbaird]

just did recheck from scratch and all comes out at 107.25 so I should be good.

i used Lunati lifters...

low cylinder psi was due to wrong valve timing.

yes mid 9s is what I expected for CR.

time to button it up and hope it runs like it should.....

 

[AJ/FormS]

I have that same wheel!
The centerline is a calculated number halfway between the endpoints of the 050 specs. As such it sits on the top of the lobe where it dwells for several degrees, moving very little. I cannot see using that point to establish an accurate installed centerline. The 050 open dwell point only lasts for fraction of what the centerline dwells at, and so is much more accurate. If you also find that the 050 closing point is per the card, then you are spot on.
You could actually use many different before and after heights, equidistant from the centerline and far enough to not be caught on the slowing ramps.But since the cam manufacturwe supplies the 050 points, a guy might as well use 'em.
Having said that, The calculated installed centerline, as compared to the theoretical centerline; what we normally refer to as 4* advanced or 6* or straight-up, or whatever, is just as dead-nuts accurate.
EDIT But I repeat this is a calculated theoretical point.

I was very glad to see that you were so close.

 

[nm9stheham]

low cylinder psi was due to wrong valve timing.

Confused.... retarding the timing should further lower cylinder pressure. But, heck run it and see what it does.

 

[Cudafever]

When you get it back together, find out what the stock carb jets, and needles are, and PUT THEM BACK IN that Carb! From the factory, the carb is jetted a little on the RICH side.

That cam should get you good gas mileage, you say it drinks the fuel! Stock jetting should work GOOD for your combo.

Is it possible that all three carb were not jetted properly to begin with?

I'm not sure the spark plugs are tell you what you thing they are.

You said your eye's were burning, aka "WAY TO RICH" !!!

If you are running a vac advance, remove it, and plug it, for now.

My last thought is that you said it runs like a NOISE /6......LIfter noise? like a lifter is not pumping up? Or pushrod is to long, holding valve open slightly...................

Did you check the lifter pre load when you put the motor together. aka how far the push rod push down into the lifter bore?
If the heads have been shaved previously, your stock push rods my be two Long.

 

[nm9stheham]

Well, he got Smith Bros pushrods, so presumably they were measured for the new Hughes rockers, but perhaps the preload is adjusted too deep in the lifters. If the lifters were holding the valves open, I would expect it to break up a bit; they won't likely hold all valves open evenly. OP, is this what is happening when it quits above 4500 RPM?

 

[Inertia]

I had Midas phone and ask if I could do a timing chain on a truck they were working on.. Long story short... Truck came in on hook,, I checked the T/chain with the split overlap at TDC method, and it was good,, so phoned and asked what was going on.. they said they put exhaust on it, it died half way across their lot.. We checked for spark etc,, then I had one of my guys crawl under and sawsall off the muffler,, got in ,, turned key,, and drove it back to Midas, told 'em it needed another muffler that wasn't plugged..

At post 37 I mentioned unhooking headers,, cuz it was all new (unknown)exhaust ,, so when you get it running, please consider seeing if exhaust is coming out both pipes,, and have someone stand behind while revving,, scrutinizing exhaust flow.. consider a run with open headers,, jmo

hope it helps,, "puzzler's" right

 

[AJ/FormS]

Well I keep hearing about checking split overlap on non symmetrical cams being a problem. So I thought a few words on that would be helpful.I'm not trying to be a smart-a$$, but rather, helpful.
I have a Hughes HE3037AL cam in my 360. The specs are 230/237 @050, and 276/286 advertised. It is a 110cam installed at 104. If you map this out, you will see that the intake opening point is at 32* BTDC, and the exhaust closing point is at 29* ATDC. As you can see there is a 3* (32 - 29)spread.So when using the split-overlap quick check the equal point would be just half that amount from TDC or 1.5 degrees . Keep in mind that a 10* spread in the durations is fairly large and most street cams like this will have less spread being closer to 5-8 degrees.
Now let's look at a typical symmetrical cam of 230/230, and 280/280adv.Again a 110 cam installed at 106* or 4* advanced.This cam maps out to show the Intake opening at 34* BTDC and the exhaust closing at 26* ATDC. That puts the spread at 8*, and the centerpoint(split-overlap) at 4* away from TDC
What this shows is that it's actually worse to check the split overlap point on a symmetrical cam than the
other, assuming the symmetrical cam is not straight-up.
But in both cases the split falls within 5* of TDC
Now let's look at retarding the cams. the asymmetrical cam at 3* retard, will put the split-overlap at 5.5 degrees from TDC, while the symmetrical cam will have split-overlap at 3* from TDC. So in this case, the symmetrical cam comes in tighter.
And that takes us back to post #61, where I said if you are within 4 or 5 degrees cam timing won't cause this kind of problem. I guess I should have said 4 or 5.5 degrees.....
In any case once your cam is in, and you know where split overlap is, subsequent checks could use the split- overlap method.
I guess we'll see...........

At one time, I had the 292/509 cam in that engine. I was so disappointed in that cam I moved it all around, trying to get some street manners out of it. The moving around of the cam caused no issues from 6 advanced to 4 retarded.That was a symmetrical cam, so the split overlap would have moved from 3* before to 2* after.IMO, that was not a very good street cam. It made a lot of power up top, but had nothing in the basement.But it sure sounded fast! I put 4.30s, and a GV on it to make it work, on the street,with an M/T.
The power was all up top, and I imagine it would have been a great race cam.

 

[KnuckleDuster]

Midas got stumped by a clogged muffler?
Too funny!
..and a little sad.

 

[Inertia]

And that takes us back to post #61, where I said if you are within 4 or 5 degrees cam timing won't cause this kind of problem. I guess I should have said 4 or 5.5 degrees.....
In any case once your cam is in, and you know where split overlap is, subsequent checks could use the split- overlap method.
I guess we'll see...........

My Mentor taught me that method waaayy back,, he explained that jumping a single tooth on the cam gear was (IIRC) 6*, and the crank'd be 12*(?), so allowing for a worn chain,, as said ,, more than 6* needs attention regardless of whether it's causing a "noticed" problem.. It's a quick easy check to eliminate the T/C as a prob..

cheers..

 

[AJ/FormS]

I've put teener chains on, one tooth out on purpose, to compensate for worn chains. Sometimes you do what you gotta do, when family comes first.Boy I'm glad I'm not that broke anymore!

 

[tarvin890]

the install was looked correct and when I checked the alignment using the method Lunati recomended it was spot on. But it was 2.5 off when I checked using the centerline method.
1st time I moved it I went wrong way....2nd time brought it to my 107 installed. It actually made me feel better to see that the math came out the same just + and - of true centerline both times.

I have built and degreed several engines over the years but when they are 10 yrs apart from each other you have to stop and think each time.

HA !!!! my degree wheel say direct connection !! Thats how long its been since I first got it! ( some members might not even recognize the name..lol

the guy in that other thread said the same thing... built a many..... this one got him....he straightened the marks and waaalaaaa....

 

[Inertia]

I've put teener chains on, one tooth out on purpose, to compensate for worn chains. Sometimes you do what you gotta do, when family comes first.Boy I'm glad I'm not that broke anymore!

You likely had tremendous top,, or bottom end.. lol

 

[mbaird]

AJ.... your saying use the split centerline method..but on .050 after opening not before closing....
right?
the cam did not come out to Lunatis specs @.050 when I was done. Their spec was 2 BTDC...
it came out to -.5 to TDC after setting using centerline method.

 

[70aarcuda]

gee whiz...the intake opening on the card is based on the intake opening not the spit difference between the intake opening and something else....

if you got .5 ATDC and the cam card says it is suppose to be 2 BTDC.....was does that tell you?
the intake is opening late....

 

[mbaird]

gee whiz...the intake opening on the card is based on the intake opening not the spit difference between the intake opening and something else....

if you got .5 ATDC and the cam card says it is suppose to be 2 BTDC.....was does that tell you?
the intake is opening late....

you are catching on...

 

[67Dart273]

gee whiz...the intake opening on the card is based on the intake opening not the spit difference between the intake opening and something else....

if you got .5 ATDC and the cam card says it is suppose to be 2 BTDC.....was does that tell you?
the intake is opening late....

you are catching on...

OK, but you didn't move it that far this time you tore it down did you? I'm lost again.................

 

[nm9stheham]

By any chance did you check the exhaust center line, just as confirming info? It ought to be at 116 BTDC, using the same method. (And BTW, I re-read and saw where you got the TDC set with a piston stop.)

Do you have the actual measured crank angles at .050" intake lifter lift for ICL that you can share? (Just to re-check the math......)

 

[mbaird]

I did not check the exhaust....probably should.
This mild build should not be so complex!

67dart...Im not sure what you are asking.

 

[AJ/FormS]

AJ.... your saying use the split centerline method..but on .050 after opening not before closing....
right?
the cam did not come out to Lunatis specs @.050 when I was done. Their spec was 2 BTDC...
it came out to -.5 to TDC after setting using centerline method.

I don't know what exactly you are asking here.
But no, I don't use a centerline method, except as a calculation from the .050 opening and closing points. Those .050 numbers are what matters and what the card supplies.
The centerline is just a calculation, and a shorthand way of referencing the other points, without listing them.
And saying that you installed X amount of degrees advanced is an even shorter way of listing all the points. For instance; if you told me you installed a 230*/110 cam +4*, I can generate all the closing/opening points for you.I can do the math and spit out the numbers.They are 9/41 on the intake and 49/1 on the exhaust. I think I said that wrong. Not just I, but anyone with a wee bit of experience, can generate the numbers.
Or say you had a 218/224 cam on 110, in at +4. the numbers would be 3/35 and 47/-2.( the minus being a failure to close in the usual ATDC but in fact closing BTDC)

Being 2.5 degrees late, to me is nothing. It might move the torque peak up 100rpm, or something, with that cam. Certainly your a$$ dyno wont know the difference.LOL She's gonna have a strong bottom end as is, with that 262 cam! Or rather should have. Like I think I mentioned in an earlier post, I would get a second opinion on the cylinder pressure. And if the second gauge also reads low, for me I would be going straight to a leakdown test. I'd be wanting to know either where the pressure is going, or if it's not being lost, then it would be on to checking split overlap, on the assumption that it was never being created in the first place.These are quick checks that lead to answers, or further checks. You just skipped ahead a bit, that's all.
Soon we will see. I too, like nm9, wouldn't mind seeing the numbers.

 

[AJ/FormS]

You likely had tremendous top,, or bottom end.. lol

Naw, what I got was a restored to normal cam timing and thus a stock worn out teener with a few more good miles in her.

 

[nm9stheham]

I did not check the exhaust....probably should.
This mild build should not be so complex!

LOL, I know! But I am very good with math and measurements and still have fooled myself on this. The cam specs are referenced to 3 or 4 different things, and ATDC vs BTDC on the wheel can be counter intuitive. Easy to be fooled if you do not do it regularly.

And as said..... 2-3 degrees one way or another is not going to do this. The low cylinder pressures don't make sense for your SCR and cam (at least it does not seem right to me), but would explain the dogginess. A retarded cam would do that, but the other ideas AJ just offered seem wise to explore.

 

[AJ/FormS]

Yeah using a degree wheel for the first time; for me was very frustrating, for the exact reasons nm9 mentioned. I still occasionally sorta get fooled, but somehow a red flag goes up in the sub-conscious part of my brain which says "WHAT?, that can't be right". And then it's a do-over. If the heads are off, I always check the split overlap as a back-up. Like 4 seconds with a straightedge, can save hours of redos.
I can tell you one thing tho; on some H/P motorcycles, split-overlap don't mean squat.

 

[mbaird]

ok... so Lunati say that the cam should be at 2 degrees before top dead @.050 (intake)

thats exactly where it was when I originally checked it after getting engine from machine shop....
but it ran like a dog. a smooth dog but a dog.... and jetting didnt seem to change anything....plugs were always white. engine would pull to around 4500....

so I reinstalled using centerline method (.050 before and after max lift ÷ 2) to 107.25 (cam card says 108 for installed centerline = 4 degrees advance) but that puts the cam around 0 (TDC) @ .050 after BTC
that measurement

 

[nm9stheham]

I would not be too concerned on that; if you get the dial indicator axis just a little off of the exact axis of the lifter, then the indicator will read a bit low and you will have to turn the crank a bit more CW to get the indicator to read .050", and the intake opening will look a bit late (retarded). That is why I feel the ICL method is better; you take numbers at .050" lifter lift on the dial indicator, and even if it is actually .052" lift at the lifter due to indicator misalignment, then that will fall out with the math of the ICL method.

MMMMM......Something written above bothers me..... " .050" before and after max lift ÷ 2 ". That is not the way I do or understand ICL; I check crank angles at .050" lift from zero lifter lift, measured at the lifter, both right after opening and just before closing. If the cam lobe is perfectly symmetrical, then if would not matter but I am not sure measuring .050" below max lift will be symmetrical due to cam profiles and controlling the valvetrain deceleration from opening and acceleration towards closing around the peak. The cam specs, including the ICL numbers, are based upon .050" lift from zero lift at the lifter, not referenced to max lift.

Plus I can't remember if you can just average the results as you have done. I need to dig out the formulas again.... supper calls first. EDIT: Yes, it looks like that method works fine for ICL as long as the intake closing is measured on a scale of 0-360 on the wheel. (I.e., typical intake closing will be 200+ degrees for a perf. cam.)