Kevin Shasteen

Keep in mind all of our Z's came from the factory WITHOUT A/C. The A/C systems that some cars have were either "Port of Entry" or "Dealer Installed" systems. Most were "ARA" systems. If they could add it to your car; so can you. It is just a matter of locating all those parts. Go to your nearest Barnes & Nobles or Hastings Book Store & buy this book: "How to Air Condition Your Car" by Timothy Remus and Jack Chisenhall; published by MBI with a copywrite date 1993. Good book and also address the issues of converting from R-12 to the new (yuk) stuff, R-134A. And yes, many people, more resourseful than I have swapped A/C systems from one car into another car. As Lone said, the engine components are a breeze; its the under dash stuff that tends to be clear as mud and twice as confusing at times. However, it is not impossible if you know what to look for and where to get your parts. If I were you I would, not only buy the book, but look for a parts Z that has the A/C hardware. Obtain that hardware and you are half way there. Also obtain a Factory Z Service Manual. Most Nissan Dealers will have your Manual on CD. The hardest part is "Just Doing It". Good luck, sounds like an adventure. Kevin, (Yea,Still an Inliner)

I also agree that you should not sell it; I sold my first "mule/parts Z" and an excellant used Hi/Perf. SBC (very strong runner) simply because I could not find factory AC/Heating parts for the car; as used Z's with working AC/Heating units are getting hard to find. I decided I didnt want to spend a ton on a sporty car if I could not have a working AC/Heating system. I then turned my attention to an older Cutlass I no longer have. I spent a ton of time and money on the Cutlass only to realize how HEAVY the Cutlass was and that it lacked that "real" performance that a V8Z with a much better power/weight ratio would have given me. Well, shortly thereafter, I discovered the aftermarket company that sells a good system for the Z; a few on this board are using this system. Anyway; along story simply to say I wish I would not have sold that engine. I like the Z I have now but now I dont have the resources I once had which would allow me to have made the swap; oh well, spilt mile-not gonna cry about it. Dont let it go just yet. Instead of wasting time on what could have been I chose to learn as much as I could about the "Engine" in general; not just SBC's. I am glad I did as I have learned a lot. Get you some auto math books; believe me, those will keep you busy. Sorry to hear about your injury (whatever it may have been); any disableing injury is one injury too many. Hope you get better.....and DONT SELL THE Z! As an ex-insurance adjuster who has handled my share of BI claims; you think now that time is passing slowly, but, if you can find something that will "OCCUPY" your time, [Time] will pass quicker than you think. Locate as many auto math, aerodynamic books you can and learn their techniques. Also, from reading the posts on this board, write down what parts you would like, so that your list is a complete lists and not a partial list. When your injury has healed you will be far ahead of most of us slobs who spend a lot of our time chasing our tails; dont get down on yourself/keep your chin up & time will pass. Good Luck Kevin, (Yea,Still an Inliner)

Also late to chime in; but it looks great. Just a few questions tho. On your date with your wife/did you get to second base? What about the looks from other people; my car's bone stock w/faded paint & people are always giving me that second look (like is that a british car or german car; wrong on both accounts) so I'm sure everyone & their mother was eyeing your car...nice going! One last statement....DONT EVER SELL IT; NOT EVEN TO PAY FOR THE KID'S COLLEGE TUITION! Kevin, (Yea,Still an Inliner)

Lone, Looks like my 78 & your 72 actually do have something in common after all. My Z also houses the original spare. You know (regarding the original air in tires) you should replace the bad air with new air every now & then/or the tire(s) might rot from the inside out Kevin, (Yea,Still an Inliner)

Glad to hear it Mike; I knew a smaller duration cam would help. after fine tuning your carb & prior to installing 3.90 rear gears, be sure to solve for your "Lack of Traction" problem 'first & foremost'. Once you solve your traction issues then you can look at your gearing needs. A more appropriate Dynamic Compression & less Overlap both have extreme positive effects on low rpm power; good vacuum makes all the difference in the world-glad to hear things are looking better! Questions: 1) What does your engine idle at now? 2) Is the Weiand manifold a dual or single plane manifold? Kevin, (Yea,Still an Inliner)

Hey; you laugh, but a "Real" conspiracy between the two parties exists (which are we-the right or the left?); and we can call it Z-Gate! I've already written my congressman requesting to be on the oversight committee; that wouldnt be considered a conflict of interest-would it? I want..no, I 'DEMAND' ANSWERS! This is undermining American Soverignty-what has the world come too; anyway? Kevin, (Yea,Still an Inliner)

I have not used the Performance Trends Engine Analyzer but have heard good things about it; definately a little more expensive. About DD2000 or Drag2000; they are cheap and I dont look at their outputs as "the Gospel". What I look for are trends. In other words; what are the outputs when I have these compenents as opposed to changing the data by one point/or one unit of data. Such as changing the camshaft's duration by one point at a time & noticing the effects of when/how & where the hp/torque is altered. Everything you (we rodders) do to modify our car will be based on our experience as we approach our projects. The more experienced you are, the higher level of difficulty our modifications will be also. So everything is relative. Use it as a learning tool; and when you have surpassed what it has to offer-then purchase the more expensive software. Kevin, (Yea,Still an Inliner)

Typical BMEP (Brake Mean Effective Pressure) for typical NA engines are: 1) 130-145 for a typical street engine 2) 165-185 for a high perf.engine 3) 185-210 for an all out racing engine Keep in mind; your psi will/may increase drastically once you go back to a supercharger. Could the noise you're hearing be "Pinging" or "Detonation" from abrupted airflow/velocity and or an improper timing, all due to the supercharger having been removed(?). You may want to take everything apart & mic the entire engine and internals; just so you know what you have. Then make the needed decisions for addt'l hardware. You definately will need to first know what you have before you can possibly know what it is you need; baby steps....slowly and caustously. Kevin, (Yea,Still an Inliner)

Mike, For starters, DD2000 is probably about 20-35 hp/torque to high-it usually is. But this doesnt mean we should throw out the baby with the bathwater..(where did that saying come from anyway?). There is something amiss that your engine builder has done (that we are not aware of) in relation to somthing that Edelbrock didnt do in their dyno test engine, something-somewhere, that has skewed our outcome compared to Comp.Cam's outcome. Your Performance gains will improve when you first solve your traction issues. Also, a cam with lower duration and a 112 LSA will also improve your Street Performance at lower rpm's as your torque curve wont come on so fast: which has a tendancy to break the tires loose/good or bad tires it doesnt matter. If nothing else, a cam with slightly lower duration and slightly lower lift will drastically improve your low rpm power. If you want extra torque in the true "Low" rpm's (2500-3800rpm) then you will need a cam in the 260, 265 duration arena. Once you surpass the 270 Duation-your peak #'s are going to be reached on the upper rpm range; period/what can I say(?). As Duration is increased so to will the rate at which peak hp/torque be reached also. This higher Peak Power/Rpm (as you know) comes at the sacrifice of low rpm power. You still need to address the "Lack of Traction" first; then and only then will you truly know what your engine is or is not capable of. If you are running high 13's and that is with excessive wheel spin/then there is no telling what gains can be had once you eliminate that wheel spin; instead of more rear gearing-how about less gearing to eliminate so much torque at the rear wheels. This will offer more launching ability w/out wheel spin, and that translates into an improved 1/4 mile times. Keep us apprised of how things turn out. Kevin, (Yea,Still an Inliner)

If they truely are sinking that loooooow; then they definately are bottom feeders. Why do poeple have to be so pathological at times, are they so insecure in their little worlds they cant allow someone else to have an [idea] or opinion of their own? Sad, sad, sad indeed. Eh; we're better off w/out'em. Kevin, (Yea,Still an Inliner who never opens email from someone I dont know/or recognize)

Mike, DD2000 says/Drum Roll Please: RPM's..HP...Tq 2000..145..380 2500..188..395 3000..233..407 3500..286..429 4000..338..443 4500..384..448 5000..418..439 5500..435..415 6000..437..382 6500..420..339 7000..395..296 7500..366..256 Mike, in your other post"Cam/Intake Changes" you mentioned "Lack of Traction"....what did you mean by that-were you referring to "Wheel Spin"? If you had lack of traction w/your current intake & cam-you may need to address the lack of traction issue prior to making any cam/intake changes. Just something to think about. Kevin, (Yea,Still an Inliner)

Davy, Are you forgetting the 4th or was it the 5th commandment of the Hot Rodder's Ten Commandments: "Thou Shalt Not Covet another Rodders Intake Manifold" shame, shame, shame on you! Kevin, (Yea,Still an Inliner)

Dome's, Oooh(?) Dont think I'll be able to help you; unless you can call the mfg/vendor selling them & ask for the cc's for your .040 overbore...then we will be able to play w/the numbers. Till then, the only way of knowing is by cc'ing them w/one in the bore; the ole fashion way. So sorry. Kevin, (Yea,Still an Inliner)

Gearhead240z, Does your 400SBC have the 400's crankshaft also or has it been destroked: what is your crank's stroke? Also what pistons do you currently have or are thinking about? Any Valve Reliefs and if so how many and what are their cc's, Dish cc's or Dome cc's? I may be out of town the latter part of this week; I'll try to keep tabs to respond to your answer here-so bear w/me if I dont respond immediately after your answer. Just wanted to let you know if I dont respond immediately that I'm not ignoring you. Kevin, (Yea,Still an Inliner)

Gearhead240Z, I'ld be more than happy to crunch any numbers that I am capable of crunching. I've seen your other thread about DD2000 on the Chevy Forum requesting info on your set up...I'll be asking any questions on that thread: KO?(OK?) Mike, When you say "You could not even get it to hook up" and are displeased in that you only ran 13's; are your referring to "Lack of Traction"? If you have lack of traction-then the engine is not your problem; traction is your problem! A 383 is going to have even more low rpm torque-AKA: Less Traction if you dont first solve your traction problems that you currently are experiencing now. Puzzled; give us more description of what you mean by "Lack of Traction". Kevin, (Yea,Still an Inliner)

Mike, The #6089 Edelbrock heads IMHO are not the problem, in that they are considered to be in the upper-mid range as far as a [sTREET] cylinder head is concerned. But, again IMHO, your cylinder heads react to a problem you already have; in that they are too small for the Camshaft, Single Plane Intake Manifold and possibly Carb that you have chosen. Providing that the carb is improperly tuned, then it may be exaggerating the effect of the "High Duration/Single Intake Manifold, by dumping too much fuel at low rpms (if we assume it isnt properly tuned to begin with). The notes I've collected on the #6089 heads indicate the airflow #'s, taken at 28" H2O, to be: Lift...Int/Exh .100...67/58 .200...130/108 .300...183/144 .400...226/169 .500...229/175 .600...232/182 Now if you were to look at the airflow #'s of other cylinder heads-such as the Airflow 190 & 195, Trick Flow G2 (190 CC Intakes) you will notice that their airflow #'s within your .500-.600" lift area are going to only be about 20-25cfm difference(?). Not that big of a change; so what gives then? The difference will be the fact that your overlap (the Lobe Separation Angle) is also effecting the slumbering Airflow Velocity at low rpms. The LSA effects Low Rpm Airflow because it is the overlap that determines the amount of Reversion at low lift...smack dab in the middle of your Cam's OVERLAP is where your camshaft will find itself at low lift. So Overlap has an equal important role in determining Airflow Velocity Characteristics "AT LOW RPMS" as will your Dynamic Compression has which is determined by the IVC event. Once the rpm's pick up then the Velocity of the Airflow also picks up and LSA has no real effect anymore; now Duration is the key indicator of your peak power at higher rpm's and not the overlap. Overlap will still have an effect on the range of your peak power but once Airflow increases/Velocity Increases-and Overlap no longer will have the final say-Duration will have the final say. Other articles I've read indicate that Edelbrocks Cylinder Heads dont have as good of "Swirl" numbers as the newer designed Alluminum Heads. This will also exacerbate the slumbering Airflow Velocity at low rpms, especially if the parts are mismatched. I'm betting if you go with a properly tuned carb, dual plain manifold, and cam with a smaller duration that includes a 112 LSA; your engine will act like an entirely different engine. BTW: In Lingenfelters book he states that when looking at cams if you find a cam w/exact spec's whereby the only difference is the Duration-he suggests to take the cam with the smaller duration as it will allow better cylinder pressures while still breathing in the same amount of air. Lastly, when looking at GM's cams-be aware they have interesting ways of measureing their Asvertised Duration. So their .050" will give you an at .050" measurement, but it wont give you the Lobe Intensity. Remember Lobe Intensity will tell you if the lobe ramp is a passive ramp or an aggressive ramp. I dont have any info on the ZZ4 cam. I do know that most of GM's perf.cam's have ramps similar to the old muscle car cams: Excessive Duration -vs- Moderate Lift with a 114, 115 or 116 LSA. Their roller cams follow this w/the exception to having a higher lift. If I were you; I'ld concentrate on a dual plain manifold, the first ZZ4 cam (Pete likes that rumpity rump sound of Reversion ) and a smaller or properly tuned carb...I'm betting that will get you where you want to be for a street performing engine. Lastly; when looking at the Duration spec, remember that the higher the Duration is on a cam-usually the higher the rpm will be that your engine comes on to Peak Power. You've already said you dont like the 3500rpm onward Peak Power and that you'ld like a cam whereby you have low rpm power also-dont get to crazy with high duration cams or you might find yourself making the exact same mistake of slumbering Airflow at low rpms: "Caveat Emptor-Let the Buyer Beware". Hope all this wasnt too long & helpful in some manner. Kevin, (Yea,Still an Inliner)

BAlford, What the other guys are trying to say is that this engine is most likely a perfectly good engine. The problem you currently are experiencing in the way of "The Lack of Power" is due to a supercharged and turbocharged engine's having to compensate for the extra "Pressure" and maximum increase in Airflow due to "Boost". Because of that increase in boost once pressure rises; the initial Static Compression Ratio is low w/out boost msut be in the neighborhood of a 7.5:1 as Grumpy stated earlier, and the cam of choice for such a set up would leave you with the 5.5:1 or 6:1 Dynamic Compression Ratio as a result once the Intake Valve Closed on the Combustion Stroke. These Comp.Ratios in and of themselves equal "Low Performance (actually; NO PERFORMANCE) up until the supercharger or turbocharger spools up to its maximum boost; then the ENGINE COMES ALIVE LIKE A BEAST WITH A BAD ATTITUDE. So, now that you own the car and as you said ealier-the supercharger has been removed; what you are left with is a tame kitty cat that has forgotten how to purr; w/out the supercharger your engine is a mild mannered Clark Kent and the whole time you want a Superman. You cant remove the supercharger & expect a Superman level of performance w/out the appropriate Static Comp. and Dynamic Comp. You get the proper Comp's from the appropriate relationships between the components that make up your engine: pistons, cylinder head chambers & ports, Bore x Stroke w/the proper choice of a camshaft. What I'm sensing from your posts is that you are equating "Non-Performance" with a "Delapidated Engine". When in reality, your enigne is not dead, it is only sleeping as a result from the supercharger having been removed. If the engine doesnt smoke, in all likelihood, it is a perfectly good engine. You just have to decide if you want to put another supercharger back on it; "To bring it back to life" or rebuild the engine w/a higher Static Comp.Ratio to mach a higher Dynamic Comp.Ratio for a Normally Aspirated Engine. If I were you (and I'm not) I would call the previous owner & find out all I could about the pistons-Dish cc's, Cylinder Heads-Port Volumes and their Chamber Volume cc's, the crankshaft-cast or steel(?) and what were the cam spec's. You would also want to know if the engine block had been specially prepped in any way. If the engine were prepped properly, chances are you have a very nice engine built for durability, which would be very much worth keeping and not scrapping. Bottem line, do you want it to remain supercharged or are you wanting a Normally Aspirated engine. Either way, you probably have a very capable engine already sitting between the fram rails of your Z, its only a matter of [KNOWING] how the engine was prepped, what tolerances it was built to and what you plan on doing with it from here on out. Call the previous owner and obtain as many spec's as you can. If the previous owner had an engine builder build the engine then you will want to contact that builder and ask the very same questions. Kevin, (Yea,Still an Inliner)

Mike, Have you called Edelbrock yet to find out which Cylinder Heads do you have? Surely Edelbrock has some part# in a readable place whereby you can simply look at them and tell which cylinder heads you have; yes/no? Completely assuming here, I'm betting that your 750 double pumper may also be a part of the problem. Completely assuming here, it may be dumping to much fuel at low rpms; causing enough of a stumble that it impedes the power build up process up till the airflow speeds up which you have said-is around the 3500 rpm range. This is just an assumption though. This extra fuel adds to your single plane intake manifold's phenomena of slower Velocity within the Airflow characteristics making things doubly (is that even a word?) as bad; again, right up until Velocity speeds up-which for your engine appears to be at the 3500rpm range. About the ZZ4 cam; I dont have any spec's on that cam so without knowing anything I'ld be afraid to venture a guess. Kevin, (Yea,Still an Inliner)

Mike, Just had a thought; How well is your 750 double pumper tuned? If is not properly tuned, you could be dumping too much fuel at too low of an rpm. This could be "flooding" your engine, till the air velocity in the heads pick up(?). Have you pulled any spark plugs lately & checked their colors/conditions? When you call Edelbrock, try to not only get their flow #'s in .100 increments up to .600; but also get their Intake Port measurements where the air first enters the cylinder heads Length"xWidth" just adjacent to where the push rod's travel through the head. Also, if they have the info available, try to get the port valve's throat cross diameter, this area is exactly at the point where the air hits the valve stem guide just before it hits the top side of the valve; as this area bottle necks. These two measurements will determine "Velocity" of a cyl.head at any one specific "RPM". BTW: Unless you know the driver of that 5.0 personally-dont simply accept what he claims he has in his engine; many rodders will lie thru their teeth just to get in you head, knowing the whole time they have more mod's than what they are leading on. Having said that, I think if you are going to a lower gear ratio, then you will want more than a 3.90 as that would only net you 300rpm's more than what you currently have. Consider something a little larger and your engine will really come alive. Let us know what Edelbrock tells you. Kevin, (Yea,Still an Inliner)

Piece of mind will go a long long way; you definately did the right thing. So many busted top rings? What in the world did the previous owner do/or not do correctly? Atleast now you car rest at nights knowing your internals are happy now; happy engines make for happy owners. Kevin, (Yea,Still an Inliner)

Dont forget about the Lobe Intensity of a cam. The comp.cam you are currently running has a 52* lobe intensity compared to the cam card on the Crane which indicates a 35* lobe intensity. Crane's card also indicates the valve spring "Open Seat" pressure of 330lb/psi compared to your Comp.Cam's requiring their 290lb/psi and slightly different installed height/open seat height's compared to the Crane's cam card. Indicating that the Crane cam has a slightly more agressive lobe which will require [slightly] that much more pressure on the valve. Crane measures their seat to seat events at .004" while Comp.Cam's measures theirs at .006; Like Grumpy said-close enough to compare these apples to oranges. If you are not going to put in lower differential gears then I would not entertain a camshaft w/duration close to what you already have; IMHO, I'ld consider a duration in the Advertised 270 range: But then again-I'm not really good at spending other people's money. Just something to think about. Any chance you might call Edelbrock and ask their tech lines what their port volumes are for your cyl.heads? Dont ya just hate all these variables; oh yea/would you like paper or plastic with that new camshaft? Kevin, (Yea,Still an Inliner)

Labrat, I would have to say your method to your madness is all fine and dandy; providing you knew what the measurements were prior to the initial build up of your engine. If you did not actually take those exact same measurements prior to their initial install-then everything from here on out is only "Assumptions" not substantiated in any fact and we all know what [assuming] will get us. Still, if you want to know cylinder wear; then take your in cylinder North/South/East/West measurements at the top of the stroke, mid stroke and bottom of the stroke w/in the cylinder. Then take those same measurements on each piston and compare them to the measurements of their proper cyl's. Then and only then will you know what or how your cylinder has worn in the few thousand miles. BTW: why are you tearing down the engine after only a few thousand miles? Kevin, (Yea,Still an Inliner)

DD2000 or Drag2000 simulators are pretty much identical where as just about the only difference being that Drag2000 requires data on the actual car. What someone would need is just about as much info as you can offer: 1)Displacement 2)Compression of your choice/needs 3)Fuel type (racing or pump) 4)Cylinder Head Chamber Volume 5)Intake/Exh.Valve Diameter 6)Street Ports/Racing Ports or Stock Cyl.Heads 7)Street Exh.Manifolds/Mild Headers/Racing Headers 8)Turbo/Supercharger or Normally Aspirated 9)If Turbo/Superchrg. then what boost/intercooler 10)If turbo/superchrg. then what efficiency of turbo/superchrg & intercooler 11)Camshaft of choice; spec's can be "Seat to Seat" or "@.050" Spec's". Now you know why a cam's tech line will ask so many questions; everything effects the airflow of the engine which is relative to the intention of the car's purpose. Kevin, (Yea,Still an Inliner)

Mike, If your pistons are true Flat-Tops, .023" Crushed Head Gasket, 64cc Cyl.Head Chamber Volume and your block has the usual .022" Piston to Block Deck Height for a 3.48" Stroke/5.703" Rod SBC: then your SCR should be 10.75:1 This would give a DCR for various Comp.Cams Roller Cams: 1) XR258HR = IVC 55* = 9.17:1 DCR 2) XR264HR = IVC 58* = 9.0:1 DCR 3) XR270HR = IVC 61* = 8.87:1 DCR 4) XR276HR = IVC 64* = 8.61:1 DCR 5) XR282HR = IVC 67* = 8.4:1 DCR 6) XR288HR = IVC 70* = 8.2:1 DCR Still; none of this takes into consideration the Veloicty. Your Intake Manifold's restrictive or non-restrictive characteristics will have an effect, but when considering component modifications: such as an intake manifold, keep in mind that their profiles should match your Cyl.Head Port Volumes ability to flow in relation to the intention of the engine. Every engine has its "Optimum" component needs. If you slap a dual plane manifold on your current engine, then you are in essence "Suffocating" your Heavy Hitting Street Engine. This will then be less of an efficient engine. So when considering your camshaft and or intake manifold: keep in mind that what you may actually need is a cylinder head w/smaller ports, smaller cam, dual plain intake. There is a [fine] very fine line between "Throttling" an engine -vs- "Suffocating" an egnine. Remember, it's a Total Pkg, as no one particular component makes an engine. You currently have a nice engine; when you go to a smaller cam you will be diminishing its peak rpm power and this wont automatically make your low rpm power return if the Velocity of the airflow is still lumbering at low rpms due to the Cyl,Head Ports being too large for a street engine. Just something to think about. Anyway; let us know how it turns out. I always enjoy crunchen #'s. Since I dont have a V8 of my own; I have to live out my V8Z aspirations thru you guys. Kevin, (Yea,Still an Inliner)

Mike, Before going any further; it is important to know that my first calculations were based on a pretty big assumption. That assumption was that you: 1) Actually Have 10:1 SCR 2) AND.., that SCR or DCR alone determines your Performance (SCR=Static Compr.Ratio & DCR=Dynamic Compr.Ratio) The reality is: What if You Dont Truely Have 10.1 SCR? Junk in eauals junk out. Furthermore, When we calculate Compressions we are dealing with only one of the three essential elements: Volume, when we should be considering all three elements, which are: 1) Velocity: Speed of the Air 2) Volume: Port & Chamber Configuration (Size) 3) Density: Moisture Content of the Air Obviously we cant control Density. Velocity is a control issue if we knew the Intake Port's Measurements where the air initially enters the Cylinder Head as well as the cross sectional "diameter" of the port just where the air begins to approach the intake valve: but we dont know these measurents w/out measuring them, so we move on to Volume. For this exercise in futility, Volume is about all we can measure, & before we can acurately do this we need to know for certain what your SCR really is. Things we do know: 1) 355cu.in's = Total Displacement of engine 2) Cyl.Heads have 64cc chambers 3) .036-.041" Head Gasket crushed thickness 4) 1.2cc's Crevice Volume of a SBC Piston 5) Current Cam's Profile & Future Cam's Profile What I dont know: 1) Piston to Block Deck Clearance 2) Piston Dome/Dish cc's *NOTE: I'm assuming a typical SBC Piston to Block Deck Clearance of .022" The variable here that is within our control that I dont know is your piston: what Dish/Dome cc's does your piston have? I went to the KB-Perf.Piston site & looked at the 350 SBC pistons. The only one I found remotely close was a piston that gave 10.2:1; with your .030" overbore that would put the piston close to your [alleged] 10:1 SCR. This piston alwo has a 7cc dish; so let us play w/this number to determine SCR & DCR w/your current cam & future cam. BTW, correct me on your dish cc's of your piston if I'm wrong & we'll start over from scratch & do it all again w/the correct #'s. 727.17cc's Cyl.Displacement .041" Crushed Gasket Thickness and .022" Deck Clearance coupled w/a 64cc Head Chamber, 1.2cc Crevice cc's and 7cc dish: = 85.37cc Total Chamber cc's 727.17cc + 85.37cc / 85.37cc = 9.51:1 SCR Using the above, you dont have a 10:1 SCR; if I've "ASSUMED" correctly, for the second time, then you actually only have 9.5:1 SCR. Using this we can now determine what your true DCR is with your current cam. Using the Slider Crank Mech. to determine Piston Location in a cylinder for a 3.48 stroke 5.703 Con.Rod engine we know that your current cam's 70* IVC (Intake Valve Closing) leaves .740 cylinder volume above the piston after the IVC. 727.17 x .740% = 538.11 538.11 + 85.37 / 85.37 = 7.30:1 DCR In my previous post my assuming you had a 10:1 SCR gave us a 7.9:1 DCR; we now see where assuming gets us. If this second attempt at assuming is correct; then you actually only have a 7.3:1 DCR and that is why your engine is so sluggish at low rpm's. Now, using this second set of "Assumed #'s" let us consider your latest cam of choice, the #12-423-8. Comp.Cam's list this cam as the XR276-10 which gives a Seat Duration of 276/282, lift .502/.510 w/1.5 rockers and a 110 LSA. This cam allows the IVC @ 64* ABDC. This leaves the Cyl.Volume above the piston of .782% after the IVC. Now determine your DCR with that number, like so: 727.17 x .782% = 568.65cc 568.65cc + 85.37cc / 85.37cc = 7.66:1 DCR As far as DCR's go; this isnt going to get you that much better of a low rpm idle nor will it add to your low rpm power: it will be improved but it wont be great. If you want low rpm power-then you need to get closer to the 8:1 DCR. Yea, I know this is going to be a compromise but that is how the ole engine works. When you subjugate longer duration for lessor duration-then you get sluggish low rpm power: JUST NO WAY AROUND IT. If a cam change is what you truely want as opposed to swapping differential gears, then you need to be looking for the 264 Roller or the 270 Roller. The 264 Roller would give you an exact 8.0:1 DCR where as the 270 Roller would give you an 7.8:1 DCR; which may be borderline for your expectations. Again, all this is speculative without knowing what the Velocity will be as I dont know your port's entry measurements nor do I know your port's valve throat measurements. Another option would be similar cam profiles from another mfg'er but with a 112 LSA. Comp.Cam's have concentrated truely on the performance enthusiast in that they believe the 106 Intake Centerline to be the optimum for airflow Velocity in filling the cylinders (actual intake centerline 106 w/exhayust centerline of 114; 106+114 = 220/2 = 110LSA) keeping in mind the lobes are 4*'s advanced. Where as other cam grinders will often give other LSA's of 112 up to 116 for their perf.cams Comp.Cam's prefers to concentrate on a 110 LSA which allows the engine to rev up quicker to its Peak Power range. Hope this helped; aint all this SCR & DCR stuff just too too cool? Kevin, (Yea,Still an Inliner)