pparaska

Mike, I agree on the weight and gearing (3.70s, Tremec ratios, 26 inch tire) helping things and that the 268 Extreme solid being so close to the 270 Magnum solid. The latter is really mild - very sligth lope at 800 rpm. I think the 274 Extreme solid (flat) tappet cam will be perfect, even though some of the general and new rules of thumb shown above point to it being "too big" for my motor/car. I did run all three cams mentioned above through Desktop Dyno on my motor. The difference between the XS268S-10 Extreme solid flat and the CS270S-10 Magnum solid flat I have now in the engine was very minor. Just a tad more high rpm torque and power(above 5500) - maybe 10 ft-lbs. The XS274S-10 Extreme flat on the other hand gave up about 10 ft lbs at 2000 rpm but hit about the same torque peak (3500-4000 I believe), but the top end increased hp by like 30 hp. The hp peak moved up about 4-500 hp. It had a slightly (< 5 ft lb) lower torque peak, but the torque band was flatter and longer and therefore higher in the 5000+ range. I think this cam would be ideal for my uses. I realize that computers can't match real life, but this is exactly the kind of thing simulations like Desktop dyno are good for - comparing combinations against each other. I really doubt the 400 ft lb peak that it shows for the 270 Magnum solid cam I have - I bet it'll be lower. My heads are 461 double hump castings, with 2.02/1.60s. Only thing done to them was they were port matched to the intake gasket. With the bigger cam, I think I'll need to upgrade the springs, as the ones on there (Lunatis, close to the spring that Comp recommends for the smaller 268 and 270 cam) don't have the pressure at .500" lift that Comp recommends for the larger 274 Extreme Solid flat cam. I may just wait and drive the cam I have if it checks out o.k. (I expect it will). I agree that the heads are more of a limiting factor now than the cam to making mid to high rpm torque and power. That upgrade will have to wait until the next salary plus-up and pending wifely approval . It'll be a while on that last one . Cheers,

Cool! Great to hear it's out there on the street bringing down the Honduhs. [ July 26, 2001: Message edited by: pparaska ]

An old hotrodder buddy of mine used to have a 69 Z/28 with the 302. He actually didn't like how it drove around town as the motor made little torque down low. Sure was a blast up high though! One of the things I didn't like about the stock Z was the need to rev to make torque. That's the whole reason I went to a V8 anyway. Personally, I'd go no lower than a 327. They rev quick, and have a sweet disposition. Torque down low is good as well. That extra 1/4" of stroke over the 283/302 is worth something. Your point about will it have enough torque and power when your done spending the same money on a larger motor is dear to my heart. Making more torque and power is easier with more stroke and cubes.

Right. I was looking at the factor only, not the factor-1. The spreadsheet was using 8.5-1 for me and I got the same numbers you did for the compressions. I don't understand why this method says a 9.7:1 (it really is that - I measured it) 327 only needs a cam of less than 218@0.050 cam. That would be a stump puller. Come to think of it I had an RV cam in 327 that was just like that. Ran out of steam at 5000 rpm - no thanks. but it had incredible throttle response and low end for such a small motor. [ July 25, 2001: Message edited by: pparaska ] [ July 25, 2001: Message edited by: pparaska ]

Kevin, thanks for running those numbers. But I thought the pump gas constant was 8.5, not 7.5? That's what my spreadsheet and notes from before say. Anyway, using this method, even if I went to the smallest cam (12-674-4 or XS256S-10): Valve Timing At 0.015 Open Close Intake 22 54 Exhaust 65 17 These Specs Are For The Cam Installed At 106 Intake CL Intake Exhaust Duration At 0.05 218 224 Lobe Lift 0.31 0.318 Lobe Separation 110 (from their web site) my motor still would need a compression ratio of 9.9:1 to work out with this method of cam selection. That's an incredibly mild cam. I don't know how much I trust that cam selection method now. Ain't no way I'm putting a 218/224 @ 0.050" cam in my motor. I've got a 224/224 solid Magnum cam in there now and it's mild. Terry, the old road race grinds were pretty radical on valve springs. I've had the old 327/350 cam - man that thing was dead until about 3000 rpm in my 327 10:1 motor I had years ago. But it ran like stink up top! Even pulled on a bud's GT500 Shelby from a 15mph roll until about 90 mph. Surprised the heck out of both of us (I had this motor in a 70.5 Camaro with a stock converter TH400 and 3.08 gears - bad combo.) All I read about cams these days says that the old grinds had too much high acclereation to get decent duration, causing lots of valvetrain problems. Maybe Ford just had it right on your cam and no one else at GM could figure this out. Duntov was pretty sharp though!

O.K., I've probably had the most varied experience here on this, except maybe James Thagard or Scottie. I had 240 stubs and 280ZX Turbo companion flanges on with the CVs. The only bit of bind I got was actually related to the severe angle one or both of the CVs had to deal with on the left side at full suspension droop (last 1/2" of droop travel only). Still, I was uncomfortable with this, as if I ever went over a rise enough to fully unload the rear suspension, the binding would have occurred. Also, this was probably exaggerated by me raising the rear of the diff about 1/2". Now I have Jim's 2 pc adapter for the regular 240-280Z companion flange. This part or Scotties is needed if the 280Z stubs are used, as the 280ZX Turbo companion flange only fits the 280ZX and 240Z stubs. I have no binding issues with this setup, but there is very little margin from what I can tell. Anyway, I believe the 240 and 280 stubs are the same lengths. The 240 stub has been known to fail in racing (ask a few racers), and I think it was at the friction weld between the flange and the axle. Scottie, is there a reason for the depth of you adapter? It seems that the thread engagement could be less on the 6 bolts, although I don't always feel comfortable with the threaded portion of bolts being put in shear. But heck, you've proven the design is pretty damned tough! I was just wondering if your part could be made even 1/4" shorter to give some margin for the CV shaft length. It seems some cars have binding with CV shaft installs and others don't (ask Greg Kring, he had this problem).

Yeah, I thought that was interesting too - government engineer doing NASCAR R&D at work? Cool. Best work related thing I ever got into was checking out the use of composite materials that Rousch Engineering (actually a small company they had bought out) was doing to quiet some desiel engines that Cummins was building for the US Navy. Awesome computer modelling that took all the noise from the moving parts taking up clearance and running the motor in the computer. Actually had audio as an output. Damn thing was loud, even without the combustion noise figured in. Anyway, we got a quick tour of Rousch Racing's shop and machine shop. Saw some neat stuff, to include a spare Merlin V-16 in the back of the shop for Jim's P-51 Mustang that he bought because he wanted to learn how to fly . Must me nice! The race shop had a dozen or more old pristine Cobras, Shelbys, etc. sitting under covers over on one side of the shop. We got to talk to the race car engineers about the road race cars they were working on. What a boon-doggle that trip turned out to be! That was my only trip to Detroit, and I never imagined I was going to get that treat!

Ross, I think that nipple on the end of the CV shaft may be the reason for the length of Jim's adapter, maybe Scottie's too.

I am still on the fence, but I will call back and hopefully get someone else. Remember that you need to subtract 6 to 8 degrees from the 0.050" duration numbers of a solid lifter cam to make it comparable to hyd. lifter cam. 1) The comp cam guy even noted that the solid lifter cam will give more torque down low than a hyd, so it will help. 2) The other thing to remember is that the Extreme cams have a typically higher 0.050" duration to say a Magnum grinds, due to the accelerated ramps. These two reasons are why I think this cam may actually be more streetable than you might think. Much of the "225@0.050" rule of thumb is based on typical slower ramp profiles with hydr. lifters. Another thing to note is that the recommended rpm range for the hydraulic version (XE274H) of this cam in the Comp Cams catalog http://www.compcams.com/catalog/056_057.html is 1800-6000. Those ranges are usually for a 350 engine, so the 327 range would be several hundred rpm higher. I'm slowly becoming convinced this XS274S cam may not be too unstreetable after all. The Extreme grinds have better low rpm torque than a typical grind (of the same 0.050" duration), from everything I've read and heard about them.

Mike, thanks. Unfortunately no installed pics. I'll be visiting the old service station I used to work at in college (saturday mechanic, I was ) to do a full under car phot shoot as SOON as it's on the road. Whenever THAT happens .

Fire, as awesome as that paint looks in pics, it's not up to the standards of the painter and he's redoing it free. Thanks, I love it to, from 10 feet . The color absolutely glows now after the wetsanding and compounding - it really brightened up after that. The roll bar was the S&W kit, modded. The hoop had a section taken out of the middle and rewelded with an internal pipe in it. That was done to get it to fit between the wheelwells.

dual 2.25s or 2.5's to a single 3" should be fine, I'd think.

The number of bolts to keep checking IS an issue. Jim found a few loose now and then, even with Lock-tite. Also, some have had trouble with the the other conversion, using the 240 stub axles and the 280ZX Turbo companion flanges that make this a bolt in swap (besides the dust and oil seal mods). On some cars, the CV shaftss bind because they are compressed too far. Each car seems to be different.

I did exactly what scca Mike said. Summit and Jegs sell them too, made by Hooker, similar price I believe. There are few mandrel benders in exhaust shops, and I agree all the exhaust shops do is use pre bent pipe pieces and straight lengths to build mandrel bent custom systems. It's not really hard, just time consuming, especially if you are laying on the floor under the car . I have pics of mine on my site under "Exhaust". [ July 25, 2001: Message edited by: pparaska ]

Agreed. For what you will pay for a new Camaro radiator (the smaller one is the one that fits), you'd be way ahead of the game with a Griffin 19x24", even the 1" tube model, if not the 1.25" tube one.

Just got off the phone with Comp Cams tech line. I had chosen the XS268S-10 230°/236°@0.050" .488"/.501" lift 110° lobe sep cam. It' an Extreme Energy solid flat tappet lifter cam. I didn't tell the Comp Cams tech that I was looking at that grind though. I described my car (engine specs: 327 cu.in., compression 9.7:1, Holley Contender high rise dual plane, 750 vac sec.) 5spd, 3.7:1 gears, 26" tire, 2700 lbs. and street performance use. The guy came back and suggested the Xtreme solid flat tappet cam ONE SIZE LARGER: XS274S-10 236°/240°@0.050" .501"/.510" lift I was shocked, thinking that I'd hit the largest suggest cam for my use and the larger one would be too much for the street. I asked if it would it be o.k. around town or too peaky, and he thought it would be fine. He said it'd probably have a useable power band from 2200-6200. Pretty much what I'm looking for. And it ought to work well at 70 mph in 5th gear in my car (2270rpm with a 3.70:1 r&p, 0.68:1 overdrive ratio, and a 26" tall tire (255/45-17) ). What do you guys think? I'm looking for a visceral feel to the car, a nice lope in other words, and don't want to give up ALL the low end, but Desktop dyno shows my current cam (a 224@0.050" solid lifter Magnum grind) having near 400 lbft at 2500 rpm. So if I give up a bit of that, I think it will still be a strong performer around town, plus give me some more top end and the low end lope that I want just for effect. Feedback appreciated! [ July 25, 2001: Message edited by: pparaska ]

Funny Ross and Mike are saying that about the expensive L6 head work vs V8. I used to be around a local shop that's long since closed (Datson Pitstop, Upper Marlboro MD) where the owner was an ex professional crew member/mechanic for one of the big 70s Datsun race teams. This guy knew more about Zs than anyone I've ever met since. Anyway, he had a customers car he was building up with no money spared. LOTS of money in the engine and porting, etc. But next to that car was the shop owner's project car - a 240Z that he was converting with a Scarab kit (this was the mid-late 80's). Funny that his choice after many years of tweaking and building hi-po 240Zs was a V8 conversion. Bang for the buck, he used to say...

Scottie, if you get to 11 sets, let me know as my current engine troubles are making money tight and I'd want to back out. But if you need my set to get 10, I'm not going to hold things up for everyone and just keep my order in there in that case.

Dan, I did some research on this and the result was that I hooked the top heater hose on the firewall to the intake manifold and the lower one to the water pump. I'm 99% sure this is the correct way to hook it up. Interesting to see other's responses.

quote: Originally posted by SPL311: On gearing - I have a friend that builds V8 Zs. In the last auto trans he built, he put in a short first gear. He uses it to get him just rolling then hits 2nd. His times dropped. This keep him from spinning too much - get forward momentem going, then to full power. Phil Hmm. The 3.27:1 first in my Tremec TR-3550 is super short with 3.7:1 ring and pinion and even 26" tires. I will try that launch method (some day when I drive it some year ). Thanks.

One article I've read ("Cam Comparo", August 1999 Car Craft, by Marlan Davis) that say that a roller really isn't worth it torque and hp band wise on a SBC until you get into grinds above 240-250 degrees @0.050". Sure, there was some improvement from a solid flat tappet to a solid roller (14 ft lbs more in the 3500-5200 range, 8 ft lbs in the 5300-7000 range), but for the quoted increase of three times the cost, Marlan said he'd stick with a flat tappet unless the block already had hyd. roller tappets. And this was for a 350 that put out 469hp@7000 with a flat tappet cam (Comp Cams 294S) and 477 hp at 6400 (still making 453@7100). This is an old single pattern roller, so a newer design would be better. The hydraulic roller XR294HR-10 Extreme Energy cam made 491@6200, plummeting afterwards due to the heavy lifters and valve float. With stiffer springs than Comp recommends on the street due to longevity, the engine was able to rev higher and make a few more ponies. Interestingly, Marlan said that the solid cam in a computer simulation produced better E.T.s due to increase low end torque that the solid roller had. Comp Cam's take on this (Billy Godbold) was that the solid cams exhibit "artificial initial acceleration", even with the valve lash factored in. It snaps off the base circle faster. Marlan winds up saying he prefers te solid flat tappet over the hydraulic flat tappet because it better maintains the powerband upstairs. I'd love to see this test redone with all Comp Cams Extreme cams, since all four variations (hyd and solid flat, and hyd and solid roller) are available now. I bet that solid flat tappet Extreme cam would be damned nice. When/if I upgrade cams, I'll forgo the small hp and torque increase the solid roller gives and stick with the flat tappet, since I'll be using even smaller cams than they tested. BTW, I'd think a 225@0.050 cam in a 383 would be small. Lots of torque, but it could go with a larger one with little loss of response, I'd wager. [ July 20, 2001: Message edited by: pparaska ]

Guys, the problem with the AWD Talon's/Eclipses is the drivetrain is fragile at elevated power and traction levels, and expensive to rebuild/replace. I don't do much Internet stuff with the Eclipse, but the place to start looking is http:///www.dsm.org BTW, the Getrag setup in the Stealth is not without it's problems either. Jamie, the best bang for your buck is a releif type manual boost controller. $50-$60 bucks - check dsm.org for links.

Agreed Mike, this is also why is so expensive to get good bodywork done on an entire car! My next project car will either have a great body and paint when I buy it or I'll learn how to do this myself! Too much money in body and paint in my case that could have been put in the motor, etc.! Scott, hang in there bud. Do it RIGHT and you'll love the results. Those last steps of blocking, guide coating, blocking, (repeat), paint, and then wet sanding is what makes it go from not so hot looking to killer! If it stops raining soon today, I'll be going to pick mine up from the paint shop.

Cool! Take it for a ride yet? Congrats on the birth of your new loved one

For an idea of how close the bolt patterns are, look at the two piece bolt-on adapter that Jim Biondo designed (on my Z now): The 4 large holes in the adapter are holes there to clear the bolt heads of the companion flange to flat plate outer adapter shown here: The rest of the info for this swap is at: http://members.home.net/pparaska/280ZCVHalfshaftConversion.htm if anyone is interested. [ July 17, 2001: Message edited by: pparaska ]