I'm aware of that, good info though. I'm offering a solution to the inconclusive premise regarding extra ratio on the exhaust side.
The dynamic compression with this cam in at 109* on the intake seems a little high for 93 octane pump gas. Using your 10:1 static compression and a good quench of .035" yields 8.5:1. 8.5:1 is about the maximum practical dynamic compression you want to use with 93 octane fuel. The fuel, quench, engine temperature, air intake temperature and chamber need to optimal to resist detonation at that dynamic compression on 93 octane (aluminum heads would not hurt either). Dropping the static compression to 9.75:1 would yield 8.25:1 dynamic compression with the cam in at 109* on the intake. That would allow a little room for one of the factors above to be less then optimal and still use maximum ignition timing without detonation. Beyond the dynamic compression, running the engine and cam through Dyno 2003 with the cam and a good flowing set of Nailhead heads with a 1.94" intake valve proves interesting. The cam manager uses both the seat to seat (advertised) duration, @ .050" duration and valve lifts to auto calculate the lifter acceleration. Using the 1.9:1 lift figures, the cam rated a 3.6. This registers between mild and medium on the 1-6 scale for lifter acceleration. Again, indicating no need for a lifter bore girdle. The heads flow numbers used are for a known set of ported Nailheads with a 1.94" intake valve. They outflow a known set of Gessler Nailheads by a good margin on the intake (smaller valve) and a little at each lift on the exhaust. The dyno simulation above uses the cam in at 109* on the intake, .040" over 401 bore and stroke, 1.9:1 rockers, 10:1 static compression, the above ported head flow, exhaust manifolds, dual plane intake and 1000 cfm carb. Even though it is a simulation, as Joe can attest, it has been used to make the closest guess to actual dyno numbers on this site and others more then once. It is generally accurate with good information inputs, but not smart enough to know what can not be done. The above simulation only changes the rocker arm ratio to 1.6:1 and then it is superimposed over the first simulation with 1.9:1 rockers. The larger ratio (dimond marker) appears to make HP and TQ gains earlier in the rpm band, but gives them up later. Cheryl Sent from my iPhone using Tapatalk
^^^^ I would have expected the opposite..... the 1.9 rocker ratio = bigger (effective) cam = more top end gains and a loss at lower rpm's. I'm confused by your results.
great post:TU::TU:. the only thing i can see is with a small hyd. cam and the nailhead motor the peak numbers will come in at 300-500 rpms less then the chart.
Walt, I think when holding the duration's and centerlines constant, more lift by itself adds more air at lower RPM, but in turn reaches the limit of the available air through the heads manifold and carburetor earlier. Like swapping a larger bore displacement under the the same heads and valve train. Then it makes sense that the trade off for having more power lower in the RPM range by capturing more of the available air sooner would cause a lower rpm limit to power. I think the limits projected are a function of the carb and intake. I would bet if I opened those up some with the 1.9:1 rocker program, there would be far more power up top. Cheryl
Joe, there is no advance ground into his cam according to the card. It has a is a 109* L/S with the intake at 109*. The normal 3*-5* of advance ground into this cam would move the power curve 300-500 RPMs sooner. But, that would also raise the dynamic compression even higher by closing the intake sooner. Cheryl
11-5-16 WOW, Thank you everyone for the feedback! I will have to agree with ya Tom- I've kicked the Girdle idea around lately as one last insurance policy to keep from potentially tanking the engine at all costs, along with whats left of my bank account!!! That thought alone, with a bit of ambition, is what drove the idea of adapting the TA Girldle, or other means to brace the Lifter Bores. That being said, I've been VERY busy lately but had a moment or two this evening to stare into the Lifter Galley, and installation of ANY of the girdles I mentioned doesn't even seem possible. I'm sorry to have wasted internet space with the ambitious idea. Like I said, I was trying to insure the 'Nail to the 'nth degree! Just doesn't seem needed per you guys input, and now having taken a second glance at the block, it seems undoable! NO real space to mount that girdle, OR the Pontiac blocks under the bores AT ALL. Wouldve been cool though, and if it were feasible, id have done it! Thank you, Gsgtx! I think i'll be pleased w this CAM. I can't express enough HOW LONG I dwelled on lobe selection. I know for a fact that I read EVERY SEARCHABLE CAM POST on this website, at least twice!!! Practicality, low end torque, and drivability were my MAIN considerations upon selecting those Custom Comp XFI Lobes. I ran that same simulator multiple times, and printed off a dozen PLUS "test runs" with the different cam lobes, all installed at different degrees of advance (3A, 2A, 1A, 0A and a couple Degrees R as well) MORE advance seemed promising, and it made Tq numbers I was happy with (on the computer anyway) 497 Ft lbs at 3000RPM, installed 0 Degrees Advanced aka "Straight Up", with projected porting numbers, etc.. But practicality and the real world will be the deciding factors AKA : Too Much advance w Too Much Compression as mentioned... All that being said, I have the 9 Way Adjustable True Roller cam, but am still undecided as far as what Degree Im gonna install the cam, and where to start with those damn Beehive springs... Im interested in reading what responses come along next! Thank you all.
This is usually true with induction limited combos. They pull harder all the way through, then once it's tapped out, it's tapped out. This was the main reason people started spreading LSA and retarding the cam position...to reduce the rest of the curve a bit and extend past the peak a few hundred rpm, esp. when porting isn't allowed or the limits have been reached. Mild circle track deals do this when they can use more gear...the extra ratio makes up for the torque loss the entire curve and the few hundred R's simply hang on longer.
Great thread. Was wondering what was the best combo on them sheets? Was any of them done with long tube headers? Also what was the flow numbers you used.
The Flow Numbers I used were I'm sure, from Greg Gessler. As well as I remember, thats the numbers I used.. Those numbers and the program are all on my old Windows machine. I wish that Engine Dyno software was MAC compatible!!! In short, my old Windows box is junk, and I don't feel like suffering through the boot-up to open the simulator. The numbers I was personally most pleased with, and what someone else considers best are two different things. I went with the conservative duration, with higher lift for a more street able 5000lb tank. There certainly were combos that provided higher, NOT SIGNIFICANTLY HIGHER, but higher torque and HP, but much higher in the RPM band. Im building an over-kill cruiser, so a smaller duration cam, yet with higher lift fit the bill. Along with Toms Rockers, i don't see why Id wish for another Cam... LOW RPM TORQUE is whats gonna make my tank enjoyable, in my opinion. Higher RPM combos, as mentioned, will obviously offer more. There is no feasible way for me to upload those sheets. 12 Cams, with 6-7 different degrees of install/simulation. MY CHOICE is the "Closest to the 091 1959 CAM" Duration wise AND the LSA, but with more lift. I doubt this helps, but hey.. COMPS website/ catalog is printable and it was FUN to pick out lobes, punch them in the SIM and see what pleases you most. Real world output is another story. I can't wait to see!
If it's still up, you can use the Comp website by finding a similar bore/stroke but more common platform for cam choices. Bore isn't as important as stroke (piston speed and position). Pick a head (w/ valve size) that limits HP amount and work from there. Watch the trend rather than the final #. Both peaks and torque below the peak. Wallace racing has better than sim formulas to use if you have good head #'s (CSA with flow to get velocity #'s) You can find the practical limitations and cross check the validity of your sims. Or...step up to Pipemax.
UPDATE 11-19-16 Starting to assemble the short-block, guys. I have put together a nice set of Dial Bore Gages, along w my Mics to triple check everything as I assemble. Going smoothly as time permits. However... Not too happy with what I found upon removing Moly Grease off one of my Main Bearings. Somewhere along the way, during mockup of the 4 corners for decking most likely, it appears a piece of debris was caught between my crank and the #5 Main Bearing, then spun over... Upon discussing the situation with Tom, and the possibility of repairing the bearing in some fashion... I doubt ill be using it regardless. Too much time and $ invested thus far to use anything that isn't absolutely perfect. Pictures attached for the heck of it. SO.. Does anyone have a source for a NICE set of .010 UNDER Main Bearings? I CANNOT find a set of Johnson / Michigan / Clevite 77 or other NICE, QUALITY Bearings and need some help sourcing them! Dont we all, it seems!?The ones I have are Rebuilders Choice which was all I could find roughly a year ago, and appear to be a BI-METAL, Aluminum layer bearing. ( 4039M ) What I HAVE found online is a readily available Federal Mogul / SEALED POWER Bearing. Upon reading the bearing description, it seems to be a TRI-METAL Bearing. CP Prefix denotes Tri-Metal ( 4265M10 ) http://www.northernautoparts.com/part/fm-4265m10 http://www.federalmogulmp.com/en-US/Technical/Documents/Bearing Selection Guidelines.pdf Is the Sealed Power worth a shot vs another set of Rebuilders Choice, or even worse (in my eyes) Egge? Unless someone is kind enough to offer up an old set of .010 Under Mains from a Known-Good Name Brand, looks like I'll be getting one of the aforementioned replacement bearing sets. Whats your take? Sealed Power Tri-Metal? Rebuilders Choice Bi-Metal? Or the unlikely chance that theres a NICE set out there w my name on it?! haha.. As always, thank you for ALL input! And keep checking back as I update with Pictures!
I'd be concerned about the fore/aft scratches from what appears to be your bore gauge. All too often the spring tension is too great for bearing use, if that's what that is. If your crank came back from grinding clean looking, it still needs a good scrubbing and air blow down the oil holes. Was the moly grease on the bearings intentional? That shouldn't be put on bearings. [Sometimes a stiff bore gauge can simply be set up to have barely enough travel to move the needle. Also...many 'name brand' bearings have had pn's moved to overseas production facilities. Various issues have surfaced over the years. NOS USA made are still the best. ]
I know some of the Fore and After marks appear to be scratches, BUT most of those actually are just marks left behind from my fingernail, even if they aren't quite as visible as the actual scratches. The bearing material is just so soft, even fingernails leave behind a tracer mark. There are SOME fore and aft scratches too though, yes. Haven't even set up my Gage for the bearing ID though, so thats not it.. Heading back to the shop now to verify my Main Housing bores are correct with the new gages. You wouldn't know where I could snag a set of those NOS, USA made ones, do ya?
The only ones I have are std. I guess I was confused on the fingernail scratches. For as many bearings as I handle, I've never seen that.
Rats. The search continues. My phone takes EXTREMELY detailed pictures and makes the linear scratches looks pretty bad as well. Regardless, its more than likely going to wind up being a pretty, expensive paper weight...
Upon further measuring tonight with the little bit of free time I have, I'm not too happy with my Main Housing Bores or Clearance. ONLY HAVE MEASURED #1 SO FAR Specs are SUPPOSED to be 2.6870 - 2.6880 for the Housing. Mine is 2.6892- A bit big, and also irregular/oval. X measurement is .0022 larger than what I Zerod' my Gage to (2.6870 which is what I was told I had) X Measurement 2.6892 Y is .0002 smaller than 2.6870. Y Measurment is 2.6868 When will this end...? I wish I had these tools before I messed with ANY SHOPS! Main oil Clearance is .0028 as well (on #1 thus far) Was shooting for a bit tighter. NOT done measuring. Just reporting back. SO... To tighten that up, and to be a bit more concise with these unfortunate ramblings- I GUESS ILL BE LOOKING FOR DECENT .020 UNDER MAIN BEARINGS!!! I have NO problem doing the Mains/Crank over to get this perfect. Its just a long hard road getting there... Damnit, the more ya know...
I guess before you get angry with yet another shop, lets chill for a bit and take a look at what you can do on your end... Forgive me for being overly basic here, I have a tough time accepting that the new purchaser of these precision tools is really seeing everything the same as the people that do this day in and day out. I'm aware of the incompetence out there and do not automatically defend from the shop's perspective. I'm approaching this from the perspective that the assembler (you) are responsible for the project, and must eliminate yourself from this equation of failures. Why would you take a chance on the clearances ending up a random # by NOT asking the crank grinder to hit a dimension AFTER your mains have been worked on AND the bearings have been measured? Crank grinding should be the last thing done, regardless of your 'production schedule'. That's kind of a huge no-no these days with bearings made in different countries, to different specs at times, with coatings changing the dimensions....and the fact that you are using parts that are 50 years out of production. Sorry, but you asked for that one. Are your tools recently calibrated? Not talking about the piece of paper that comes with them. Your numbers 'could' be meaningless at this point. (Still aware of the out of round condition, hold off on that for now) Which way is X and Y oriented? Is there any chance of dirt, grit, a burr, misalignment, or the mains not being fully torqued or torqued to a different spec? What does the crosshatch or machining look like? (I forget) Was this align bored or honed? Is it possible that you dropped a cap? Looking at your 'fingernail marks' on the bearings begs the question... What was the agreed upon work or description of specs? Could you bring it to them and have them demonstrate it's satisfactory condition? If they show you that you have made a mistake, are you going to lay some money down to pay for their time? Some places are using very nice gauging, they can be $800 a pc for bore mics, not cheap indicators. Please know that precision measuring takes a certain amount of training and experience. Production shops have people that go around all day and assist the machine operators with their measuring. The workers measure thousands of things weekly and still need some help and problem solving. A hobbyist's (measuring 20 things a year) results should be completely ignored at this point [no offense, I don't know you or what you do]. There are plenty of solutions before bashing this place and running off to another one. I have to ask...if you are really good with precision machinery, and are aware of incompetent shops in your area and at the same time NOT afraid to spend the $$ to do it right or for as many times as it takes to get it right, then; ***Why aren't you paying the best to do just that only once and spend the shipping costs, rather than going through what you know for a fact is going to be frustrating and time wasting adventure??*** Precision manufacturers heavily utilize the techniques, procedures, and vast engineering resources to eliminate chance of time and profit wasting practices...so I am asking that you approach your findings with a humble attitude and try to calmly work with your shop to resolve this.
The Crank grinding- I was saying I think its best at this point to have the crank re-ground for the .020 Under Bearings- Didn't say I was grinding the crank first, as I dont even have bearings to grind for. Typing things out can lead to this confusion, I know. I have worked in a machine shop before- 5.5 years. Learned a lot, and saw a lot. Not claiming to be the worlds leading machinist, but I can accurately use my precision tools and it isn't my first time using them. My Micrometers are Mitutoyo- all calibrated and Certified. Standard Dial Gage Co. Dial Bore Gage. again- Calibrated and Certified. KNOWN GOOD. As I said, I WISH I had my set of bore gages BEFORE I dealt with any shops- period. I hit hard times a few years ago, and the shop I was working for shut down, and had to sell ALL of the tools I wouldn't be using day in and day out- including my Sunnen Dial Bore gage kit. I am not claiming to know it all, or have had my hands on every set of unique anomalies- But I am fully capable of keeping a room 70 degrees, Being conscious of how the heat of ones hand has the ability to change measurements, keeping things CLEAN, and carefully taking measurements as I assemble things, ESPECIALLY things as simple as seeing right off the bat that the Housing is out of round, and my Oil Clearance is larger than specified. Trying to hit all the bases you touched. Y is typically always oriented "UP", as in the vertical diameter. X is typically horizontal- "side to side" Main Caps, Bearings, saddles in the block... ALL were and ARE surgically clean. Even stuck the heads on to insure all movement thats going to happen is viewable, measurable, and recordable. Its beyond frustrating that I now have the tools to check what I have- and once again paid for, and upon inspection- it just isn't there. Remaining calm, and continuing to measure what I can today with what time I have. Gathering numbers, and formulating a plan of where to go from here... Thank you 8ad-f85 for taking the time to reply- even if it puts me in a questionable position publicly. Im trying to remain as transparent as possible, to hopefully yield the best results and keep this blog as honest-to-the-situation-at-hand as possible, even if it aint painting the prettiest picture. Its real. Its where I'm at. And you're right- Its hard to find competence locally NO MATTER how hard you try to hold yourself accountable with the knowledge of HOW IT SHOULD BE, ultimately, I'm NOT the one running the machines. Just playing "Lie Detector" with some very nice tools of my own. I MAY be hitting the road to Connecticut sooner or later. We'll see what the next few weeks unfold. Measurements first... Ill report back, PROBABLY with an uploaded build sheet next time for those who are interested. Thank you all.
