jakeshoe

I haven't seen any issues with the custom ground cams from Comp, and their shelf grinds are usually relatively close (within tolerance of +/- 2*, which is acceptable) anytime I have ever had anything out of spec it has been no more than 3* and the 1* could easily be error on my part or equipment or slop in a timing chain. The custom grinds seem to hold a bit tighter tolerance though. I assume they are grinding these on machines doing them obviously one at time, where the shelf cams are being ground in lots of several dozen or hundred at a time, and the machine may not be perfectly reset between each cam. Wear on the grinding wheel, camshaft not true on machine centers, wear on the master lobe profile, etc. I'm not here to bash Comp Cams, I don't use their cams due to some very poor customer service I experienced but that doesn't necessarily mean their products are bad on the whole. I like their Pro-Magnum roller rockers and use some of their valvesprings. I can get an equivalent product at lesser cost and with MUCH better service. I also don't typically need much help selecting a profile so their tech lines are not of much use to me, although it is fun to pick a profile, do some research using other similar combos, Engine Analyzer, and then call Comp and see what kind of answer they come up with.

Mike, The problem seems to be isolated to the Endure-X lifters. I've heard good things and have a few acquaintances who have run the "Super Roller" line without any issues that I know of. Obviously there are some people who can tear up an anvlil with a ruber mallet, but the frequency of the failures is pretty suspect IMO. They have updated the design in the last couple of years but my understanding from other machinists who have milled the lifteds down to see how the oiling works, is that they do not oil the pin as the two I suggested do. That said, I absolutely agree with Grumpy on you avoiding a solid roller for your combo. It just isn't worth the expense or trouble. My personal Z project has a solid flat tappet cam in a 400 based SBC with Trick Flow heads, 11.25- compression, Air Gap style intake, etc. My combo will see ~7000 rpm shifts. You just really don't need the additonal 30-40 HP you MIGHT gain from a solid roller over the solid flat tappet in a package weighing less than 3000 lbs. A stout 383 combo like Grumpy is suggesting would easily run 10's in the 1/4 mile in a Z car if it would hookup. I helped with a 383 combo in a full weight 75 Camaro. Very basic combo, 383 with flattop pistons, Comp 292H hydro flat cam, AFR 195 heads, Victor Jr Intake, 750 holley, Hooker Super Comp 1.75 headers. That combo, keep in mind thats a hydraulic cam, not even the latest tech stuff, would run 6.90s in the 1/8th mile with a 150 shot of N2O. That's a 3700 lb car. Deduct 1000 lbs of weight, and according to the 100 lbs lighter= .1 second 1/4 mile ET improvement, that's a very fast Z car... A rough estimate of ET for 1/8th to 1/4 mile is( 1/8 mile ET x 1.56 = 1/4 mile ET) You could even run the 355 and it would be quick. The key to making an engine work well is usually the heads, spend your money here. AFR has their new line coming out, the Eliminator series and they are touting some very impressive numbers, independant flow tests and dyno results. I'm not a huge fan of hydraulic rollers. However your combo would work fine with a hydraulic roller. IMO there is a narrow range of benefit to using the hyd roller cam. A bit of tech for you, and some disagree with this but you can do some research and verify it. A flat tappet cam has a faster initial opening rate than a roller. This happens because the flat cams ramp can traverse to the edge of the lifter and then begin to lift the lifter. It can stay right on the edge but not past (otherwise the lifter will "dig" into the cam lobe). All the new lobe designs like the Comp "Xtreme" line are designed to push the envelope and accelerate the lifter as fast as possible. They are able to do this now because of better equipment and technology. However I think it is part of the reason we are seeing more cam failures on flat tappet apps. A larger diameter lifter can be accelerated faster.. However a roller lifter's initial rate of acceleration must be slower or the cam lobe will try to push the lifter sideways in it's bore. The roller cam however will surpass the velocity of the flat tappet (and by a far amount in the right application). So in most cases the reason to run the roller is for more "area under the curve". This means the valve will open faster, lift higher, and stay open longer before quickly closing. What this all comes down to in practical application is that on a mild street motor the flat tappet cam may actually outperform the roller because it has better low lift valve actuation. My opinion based on looking at many cam lobe profiles is that the roller doesn't really gain any advantage until your cam duration gets to the 230-235*@.050 range. If you look at a hyd flat tappet and hyd roller profile in the 210-220 range, the roller will usually have a slightly longer seat duration for a given .050 duration, and the duration at .0200" lift (about half lift, the motor sees this lift twice, peak lift only once) and peak lift will not be remarkably improved if at all. However when you start to look at the 230'ish range, the seat and .050 duration becomes more similar and the .200 duration is bigger on the roller. A 383 combo with a hyd roller will need a cam in this range if not slightly bigger. But I think that a hydraulic flat tappet will work almost as well for you, probably vey little power gain for the additional expense. A solid flat tappet would also work well, and if you run quality roller rockers, pushrods, it will only need lashing every few months depending on driving style.

http://www.chevelles.com/forums/showthread.php?t=24840&highlight=endure-x http://www.chevelles.com/forums/showthread.php?t=108696&highlight=endure-x Couple of quick links.

Does anyone see an issue with my above post? Some seem to think I have a "chip on my shoulder" due to this post. I'm relating some valuable information based on my experiences as a machinist and engine builder with hundreds of builds, but much of this information is also from other machinists and racers I have spoken to whom I trust for accurate information. If I only knew of one or two failures of the Endure-X lifters I wouldn't even bring it up, however their reputation isn't isolated.

The Comp Endure-x lifters are knownd as "Explodex" in racing circles. They do not hold up, and they do not have true pin oiling like the Crower or Isky's. Check on Team Chevelle at http://www.chevelles.com in the performance section or on Drag Race Results, or about any other forum where people who race and see what the opinions are of the Comp Endure-X lifters. I've heard of quite a few people racing with good luck with the regular Comp lifters but the Endure-X line seems to be aimed at the street roller market with lighter valvespring pressures (because of the junk cast core cams). Do your research...

Don't tell that to the 427 in my Chevelle...

Crower has much better tech support than Comp, and Quality control. I personally use a small cam grinder in Tacoma, Washington for 80% of the stuff I do. Delta Camshaft http://www.deltacam.com There website isn't fancy, they cater to local racers and engine remanufacturers/machine shops. I often use there reground camshafts in my own personal motors, I have used probably 100-200 of their camshafts ( I used to street/strip and racing build engines in the Tacoma area) without issue. They can grind a cam from quite a few different profiles, and they use Comp Cams masters for alot of their stuff. That is, if you call wanting a SBC hyd flat camshaft with a 280* adv duration and ~230*@.050", you will get a cam ground using the same master lobe (it is attached to the cam grinding machine to grind the lobe to a specific profile) as the one Comp Cams uses for their 280H Magnum cam. They also have pretty good prices on quality lifters, springs, pushrods, etc.. They stock alot of Comp stuff too. I usually talk to Scott.

Can anyone scan me the specific pages for the hood latch. I have the JTR brackets, but don't remember all the measurements, etc. Car runs and drives but I need to get the hood latching to drive it. jakeshoe@yahoo.com TIA

Other than the fact these were used on a N2O motor I would think they are all a mismatch for a 383+ cube motor with a cam in the 240'ish duration range. 250* @.050 in a 400 cube motor is a street/strip cam and would peak before 6500 rpm, not in the 7000-8000 rpm range. This range would be better served with a Edel RPM style, Stealth, or Holley 300-36 dual plane. I'm curious about your experiences with the Hurricane, as several of my machinists and/or racer friends who have dyno'd these back to back had better results than the Edel Victor series (even mildly ported). Very similar experiences with the Air Gap knockoff style. Mostly contributed to probable larger runner sizes and better port shape at the flange. What were the exact motor specs and back to back results. Can you scan the dyno sheets? Jake

With some "clearancing". Not much difference in the TH400 and 350 bellhousings, but the TH350 will hit.

North of you near Sanger. Thanks!

My JTR manual is MIA and no luck finding it for the last week. I just need to know for sure what hood latch I need to rob at the wreckin gyard, and what all.. I just need the portion that bolts to the hood on a 280ZX right, and I cut down the spring... Just need a couple of final tidbits to make the Z roadworthy and can't find my book.

Got the trans installed today, crossmember re-installed, and the rear diff/driveline all secured. The rear diff actually sits higher than the trans, so actually the angles don't look nearly as bad as I initially thought. Just opposite of what I'm used to looking at. Now I just need to have an exhaust installed, and get it tagged/inspected.

I made some brace plates to spread the load on the floor from 6x6" steel 1/8" thick metal. Should really help as far as that goes. MY main concern is not so much the mounting as just the geometry. It seems way off to me. The trans is angled upward. I'll have to get under it with an angle finder and check all the geometry but it seems it would be WAY off just looking at it visually.

V80z, You have to adjust the inner set screw so that the lash is slightly loose with the outer nut being finger tight, then you tighten the outer nut (and the set screw equally simultaneously) to set the lash and lock it. You cannot just tighten the set screw once the lash is right, it will not stay set. It takes a few rockers to get the feel for it, but once you do it this way, you won't have anymore issues. Use a go/ no-go method with the feeler gauge to ensure you have the correct lash.

Yah, It's plenty stout enough, the floorboards will give out before the crossmember does. It doesn't seem to fit real good or give the correct driveline angles. My car is a early styel 260, so I'm wondering if the crossmember is more oriented to the 280 cars...

I'm playing the trans swap game again in the Z car. I have yet to really drive it, but long story short, I pulled the initially installed TH350 out to rob the converter for another project. I then installed a 200-4R in the Z, but I got a serious offer on the 2004-R, so I sold it, and now am re-installing the Th350. I really do not like the way the JTR crossmember fits, and it appears to elevate the transmission too high causing odd driveline angles. I would have to space the crossmember down from the car to get a more idea driveline angle. I'll probably just fab up a different crossmember after looking at it tonight. I need to actually measure the driveline angles but I can look at it visually and tell the engine and trans are tilted upwards in the rear instead of downwards or even level as they should be. Any other experiences?

I don't believe the combo is mismatched. The cam specs are in line for a stout 350-383 combo with 10.4-1 compression. The heads are better than what many have used. I know of a combo that is running a very similar setup that is pushing a 1st Gen Camaro to LOW 11's. The dual plane intake and that cam will work well together, both will peak before 7000 rpm even in the 355. The Edel air Gap is good to 7K, and makes more torque across the board than a Victor series does. I don't really see anything mismatched about the combo, it porbably just needs tuning. The FIRST thing to check is the timing. This type of combo will want timing, it will want 25+* at idle, and probably 34-36 on top, if he has it setup with the proper WOT timing, it is probably a bit lazy on bottom and throttle response will suffer, especially with a tight converter. A Z car can use a tighter converter, as the car is so light that a stout motor will get it moving anyway, they can also use a looser converter because they are so light the converter may not flash to it's "rated" stall anyway. For a mostly street car, I would always err to a slightly too tight converter. I wouldn't change any parts, I would start with the easy stuff and look at all the tuning aspects.

Second gear starts with a TH350 are indicative of a governor problem. You likely have a worn governor/bore or stuck governor weights. Worn bore and gov is common. If you remove the governor the lands should mic .800", no less and be smooth.

Deja, Looks like you're on track. Yes the Accel is probably the same part even... either should work, I have used and am familiar with the Crane so that is what I use as an example.

Ya, it is a lot of numb ers and steps mixed up. Let me try to summarize it. Determine ideal idle timing, determine amount of built in distributor mechanical advance, determine vacuum advance amount, adjust distributor setting for best total timing without vacuum advance, then adjust vacuum advance for ideal idle timing setting.

Probably not in your case, You have a relatively small amount of mechanical advance, this usually works better for a performance oriented engine. OEMs went to very low initial timing to reduce hydrocarbon emissions at idle (retarded timing creates hotter exhaust temps, thereby burning the charge further as it exits the exhaust and contacts somewhat more oxygen rich air), this makes an engine not idle as well as it could. What you will see on many combos is that a guy is running a fairly decent combo, it could be anything but we'll say it's a 355 SBC, with a properly matched aftermarket intake, heads, cam of around 230* of duration at .050, 9.5-10-1 compression, headers, decent exhaust, etc. This combo will not idle very well at all at 4* or even 8* of intial timing, it can be MADE to idle decently by cranking the idle speed screw to open the throttle plates. This causes the idle transition slots in the carb to be over-exposed and creates an off idle stumble. The real solution is to advance the timing. You set the idle timing on a performance combo (emissions not a consideration) for max idle speed and vacuum. The first time you do this you will realize that most of these combos will idle best (and have best throttle response) at WELL over 20* of initial. I have seen some combos that would idle great at over 50* of intial... So the above combo we'll say really seemed to idle best at 26* of initial. We'll assume it has a decent chamber design and flattops, so would need a maximum of 36* of total timing. This means that you would want a distributor that only has 10* of mechanical advance. If you were using a stock HEI (even with aftermarket weights) it would usually create 20+* of mech advance. We'll use 20* for this example. With 26* of intial, adding in 20* of advance you now have 46* total timing. Too much for WOT, it is almost guaranteed to cause detonation. So you can either limit the mechanical advance (very frustrating for most people without a distributor machine), install an aftermarket distributor, or run with overly slow initial timing and the poor idle, lack of vacuum, and driveability problems it creates. OR you can cheat... You can use the vacuum advance to create "initial timing" greater than what the distributor will allow. We know that at WOT we lose almost all vacuum, so the vacuum advance is no longer in play at WOT. If you hook the vacuum advance to manifold vacuum, it will pull in quite a bit (sometimes too much) timing at idle. Vacuum advance usually adds an additional ~20* of timing. So if you have the initial at 8* and add that 20*, then now you are very near your best idle timing of 26* on the combo I am using. Let me tell you how I set up a distributor on a fresh combo to simplify it. This is using a stock type points or HEI and maintaining a vacuum advance function. Get out the dialback timing light, get the motor running and a "rough tune" for cam break-in if necessary, etc. Get all the idle mixture screws set to attain a good idle. Just tune it well enough to run and idle as smooth as possible with no vacuum hooked up. Get engine idling, set the timing for maximum idle speed, re-adjust idle speed as necessary to compensate for added timing. Your aim should be the least amount of idle speed screw. Now if it seems to idle best at 32*, I back it off about 2*, so record 30* as being the best idle. Now rev the motor to bring in full mechanical advance. Record the difference. We have the distributor set at 30*, at 3000+ rpm it achieves max advance at 54*, so we have 24* of mechanical advance. Most typical SBC combos will like 34-38* of total, the Vortec headed or similar combos will often not like anything over 32*. We'll set this combo for 36* total as an initial setting. So obviously we have way too much mechanical. We now hook up the vacuum, record how much vacuum advance we have. If we had 30* initial and plug in the vacuum and it jumps to 50* we have 20*, you may want to rev it up a bit and watch for any additional advance with vacuum increase above idle. So the combo as it stands has 24* of mechanical advance, 20* of vacuum advance. With the vacuum plugged in we can back the distributor back down 20* to the 30* idle setting. It should be idling at 30* with the vacuum connected to manifold vacuum. This gives us an actual initial timing of 6*, idle timing of the ideal 30*, and total timing of 30* at WOT (which leaves us a bit slow). What you will need to do is use a Crane adjustable vacuum advance to limit the vacuum advance. We could pull 6* of vacuum advance out leaving only 14*, this will allow us to pull the actual initial up to 12*, leaving the total at 36* and the idle at 30*. This also keeps us from having over-advanced timing at cruise. Its really not as complicated as it sounds... Its a pretty easy process once you do it once. The Crane kit is about 20-25 bucks. It workes pretty well, only potential drawback is that in some cases if vacuum drops off alot on gear change with an auto trans, you will get a stumble or engine will die. Usually combos that this is an issue will work very well with locked out timing. Hopefully this will help you.