Ordered 4.30 gears today. They should be here tomorrow. I should be able to get them in on Thursday. That should perk things up.
What are you running for rear suspension? And are you running slicks or DOT tires? Your 60's are pretty erratic, and deeper gears might make that worse. Don't take this the wrong way, because I don't know how serious you are about going rounds VS just going out to the track, making passes, and having a good time. BUT, If you're serious about going rounds, I'd get the car to the point where it 60's consistently...VERY consistently. Even if it doesn't necessarily translate to the quickest ET. If you don't get that down, the car will never be consistent enough to repeat and go rounds. Now, if that's not really your thing...and it isn't for everyone, then disregard what I just said and keep having a blast lol.
60s wont be consistent until you do every thing else consistent but I know you are just learning your car, the gears will help get your 60 down but at the big end you will probably be hurting because you will be out of the hp/tq range. You engine will be screaming when you cross the stripe but I guess we will have to wait and see. At any rate you know that you can reach your goal of 12 and a little under
I'm running stock rear leafs, Caltracs, 28"x9" slicks, spool. The inconsistent 60' times were because I staged it differently and launched it differently on each run trying to find out where the sweet spot with this converter. And, it appears that it likes to be stalled against the brakes. There's another TnT this saturday. I'll learn more then. I'm in this to go rounds. If I wanted to just go faster I'd install a nitrous kit.
I'm going through the lights at 5700 with the 3.89 gears. By my math I should be going through the lights with the 4.30 gear at 6250. My cam rpm range goes to 6500 so I should be good there. My torque peak rpm is 5500 so I need to run the engine to 6500. In addition, I had the shift light set at 5700. I will move that to 6000. More time in lower gears should bring my rpm in the lights down a bit. I haven't been using all the power this engine can make because I had stock roller lifters in it and it valve floated at 6200. It appears now to make power all the way to 6500. Last year I had the rev limited set at 6200 and I was bumping it through the lights. I had to decide on either 4.11 or 4.30 gears. I went big. Saturday will tell me if I made the right decision.
Shouldn't we also keep in mind this is a moderate compression 302. In that case you'll almost always want to be a few hundred rpm past peak for best et. I would suggest you fool about with slight overrev shifting into 3rd gear too. This often helps et when dealing with lower torque output motors like 302's mated behind c4 factory gearing. The 4.30 gear will make shift timing that much harder to control but this little motor will love the extra torque multiplication in its high rpm sweet spot. I also believe that decently sized cam.. for 302 cid.. will rev further than you may realize and i wouldn't shift much before about 6,800. Cant see not feeling out the cams topend either.. might even touch 7,000. The lifters will easily take it now too. Don't forget about collector tuning. Things might change for the better since it rpm's better with the new lifters now.. but you may still trim more et by way of higher torque multiplication coming off the still too low stall speed converter. Also don't be surpised if the new gears negatively affect stall speed to some small degree. Faster rpm rise and quicker acceleration rate should more than make up for it though.
I didnt notice you were running a 28" slick that helps a lot, I was only running a 26" slick. I've never really ran mine all out because of not having a roll bar and they only let me get away with 11.40s once before they tell me no more so I just short shift and keep the rpms under 6,500. Seems like the stall speed on converters is never as high as they rate it I had mine custom built to my cars specs and am sadly disappointed with it but I did tell them it was a street strip car so they probably kept it lower for street driving and heating up but I can only hold it the light until about 2,200 before it pushes through anyhow, if I could launch at 3,000 it would be wicked
Greg, I think you and I are in agreement. I will set the rev limiter to 6500 because that's what both AFR and Comp Cams guys told me would be the rpm limit with the heads/springs/ lifters. The combination of more available rpm, lower gear, and great air this time of the year should lower my ETs some more. Yellow75, you are running more engine than I am with the 347. Your torque peak is, just guessing, around 4500 which would be a 1000 rpm lower than mine. What cam are you running?
lol.. tech line guys.. gotta love em'. Not trying to get you to break or wear this bullet out before you're completely ready for that new 347.. and while I can't rightly say about the current combo's spring spec's, IIRC maybe 150'ish seat/high 300's open?.. still plenty sufficient for shorter lighter 8mm valves, I will lay cash those 185cc heads and lifters will EEAASSSIIILLLLYYYY run WELL past peak hp on 302 cubic inches. True on 350 cubic inches and even truer on only 302. If you can't tell by the dyno graph(your extremely narrow 1,000 rpm spread between torque and HP peaks still confuses me), which generally should have been run past peak to build a proper graph shape, it's a pretty simple test really. IF she's still pulling hard and seemingly wants a few more hundred rpm beyond that 6,500 rpm rev limit?.. the c4's current converter and factory gearing WILL pay you back with lower et's. Could also just use that little extra bit of overrev power potential for days when the air is bad too. Set the rev limiter to 6,700 or 6,800 rpm and stay down deeper in your index. Here's a smaller AFR 165 headed, smaller cammed(220/240.. wider exhaust duration splits generally help carry power further past peak), smaller dual plane manifold 302 combo. This car runs consistent 12.10's and rev's to 7,000+ on every run. I see dozens of similar combo's every year too. Bread and butter type stuff and no way in hell your powerband suddenly drops over a cliff well before 7,000 rpm. Your XE282 roller grind is extremely popular with fairly warmed over street motors.. Ford's and Chevy's. It will rev past peak just fine on a smaller motor like this. If you're going to all the trouble of making another reverse collector cone.. try to stay below 2-1/4" choke size. Myself?.. I'd be starting at 2-1/8" on such a small CID motor. Also worth wrapping the headers on this car if you ever have them out again too. This allows less heated air to get up into the induction but the other benefit is the hotter exhaust gas flow expands to better fit the 1-5/8" primaries cross section. In essence the primary pipe thinks the motor is bigger and flowing more exhaust mass than it actually is which further increases velocity and improves scavenging. Hotter exhaust flow mass also has less flow resistance as it snakes its way through the primary bends. This improves peak torque by a few more ft/lbs but more importantly fattens and widens up both sides of that peak(reduced pumping losses and better scavenging) to give greater average power. Unless you have a 6,000 stall speed to keep you running right near this engines peak power.. this car/most cars equipped with auto trans will run faster as you spread the torque and hp peaks further apart. Higher average power output through the run = lower et's without as much need for peak overrev and is usually easier on parts in the long run. sorry for the rambling, I seem to be running from my chores this morning. Much rather talk engines than work on the ever growing honey-do list. lol
Greg, as always thanks for your insight and help. Yesterday wasn't a disaster, but it was close. I only ran it twice before loading it on the trailer and bringing it back home. Where to start? Ran 12.05/111 and 12.009/112. With the 4.30 gears I can't hold it in the lights with the brakes past 2000. The engine will not rev past 6200 (6000 on the tach). Completely spits sputters and runs like crap. So, first run I set the shift light to 6000 on the tach and the engine fell on its face before I could complete the shift for both the 1-2 shift and the 2-3 shift and went to crap just as I went through the traps. The second run I set the shift light to 5700 and 1-2 and 2-3 shifts went fine, but I ran out of rpm about 100 feet before the traps. Lessons learned: 1. the lower gears lower the stall on the torque converter. 2. new lifters did not solve the rpm limit/valve float problem. Back to the drawing boards.
I'm pretty sure I mentioned the gear would tighten the converter.....I'm not sure what's up with your setup but my stock roller lifters will go 6800. I'D almost look at the ignition system for the miss.
I did wonder about the brakes holding that shorter gear. Probably didn't mention it because my posts already run long enough as it is. Lol You're constructive learning mentality is right on target. As frustrating as it surely is when a plan full of hard work and cash doesn't come together, now we have new superior parts and more data to work with. My couple quick off the top questions to help me get my mind around the issue. 1. Did you or the engine builder ever degree this camshaft during mock up or assembly? And funny as it sounds to ask(do this stuff long enough and you realize shit happens to everyone and some even more than others).. did you or engine builder ever confirm grind #'s stamped on the cam itself? 2. Have you confirmed balancer is at 0 during true tdc? 3. What was the lifter preload adjustment procedure? 4. Oil pressure at idle and wot? Oil type/weight currently in the crankcase? 5. Rather involved question.. but what are the complete carb spec's? 6. AFR gauge? Preferably wideband. 7. What do the plugs look like? 7. What pistons and rings? Ring style and thickness? 8. How are you evacuating crankcase pressure? Pvc valve/breather.. dual valve cover breathers? I'll leave it at that for now.
Ps. I lied.. couple more questions. 9. Have you ever confirmed timing lead stays consistent at high rpm? 10. Any signs of ionization or spark tracking in the dist cap? Properly vented cap?
Greasemonkey, yes you did mention the stall, so it was no surprise. Greg, all valid questions. I will be going through everything in the next few days. One of the first things I'm going to do is plumb a fuel pressure gauge that I can see in the car to confirm I'm not running out of fuel at 6000. I don't think so because it did the same on the dyno. Yes, the cam was degreed, spring pressure set, new balancer, 0 confirmed. Oil pressure is about 50 at idle and 70 at rpm. Running Valvoline VR-1, 10w-30. Valve adjustment is zero lash plus 1/4 turn. Standard size moly rings on stock flat top forged pistons. Don't have an AFR gauge. It was confirmed on the dyno with the original 750 vacuum secondary Holley. The current carb is a QF 650 double pumper. I'll have to dig out the spec sheet to see exactly what jets, bleeds, etc it has in it. Plugs look good. Double valve cover vent caps. No PCV. Not sure what you mean at #9. The distributor is locked. I will check the cap again. Looked good the last time I checked it. Cap is an MSD and vented.
The fifty questions was to eliminate the more remote and obscure possibilities right off the bat. IF.. the rings were unseating due to excessive crankcase pressure those scenarios typically cause the motor to lose rev's nose over or flattens the power peak up top.. not break up. Plus the breathers would likely push some oil and the oil would probably stink of fuel in no time flat. Was worth a couple minutes of mentioning anyways. With only mid to high 30's of ignition lead it seems highly doubtful that the rotor phasing would be very far off but it is still something to confirm during the basic process of elimination. Clean caps/contacts are good to see but sometimes race motors don't see enough run time to create tell-tale spark tracked witness marks. #9.. locked timing or not, had to do with the possibility of erratic spark timing occurring at higher revs. Very few people rev and hold 5,000-6,000 rpm for a few seconds to confirm steady timing numbers and you would be very surprised at how many have at least some minor issues going on. I have seen 20+ degree erratic timing sweeps(incorrect rotor phasing is a biggie here) and also witnessed firsthand the effects of defective MSD boxes causing erratic timing(google it.. you'll probably see many P'd off consumers). Be sure that the MSD box is well grounded and the motor has a good chassis ground strap too. Product quality hasn't drastically improved with all the outsourcing being done these days, so defective parts still happens on occasion. Also worth noting that IF the distributor was originally equipped with a functional vac advance pot its advance mechanism should also be pinned tight as this has caused MANY to chase their tails around. Many distributors already have the kit included but many fail to install it as they get lost, sidetracked, or move away from vac assisted advance along the tuning process. Eliminate that variable altogether by locking the vac advance mechanism. Should be a very quick and easy A-B test. Not to imply this is even remotely related to this issue, but IMO 1/4 turn preload is good for regular or stock lifters and you should definately rethink that number with reduced travel lifters. 1/8 turn is more than suifficient and they will rpm a little better. 1/8 turn is about .015" plunger compression and should last you a good long while, especially race-only.. maybe goes the whole season without readjustement, so long as the cam and valvetrain is wearing normally. Also allows less valve standoff IF plunger metering becomes taxed(not likely as these lifters can EASILY go upwards of 7,500 rpm) or the valve spring control becomes marginal. Remember that an extra 1/8 turn more than needed equates to that plunger preload(depending on stud size.. around .015") being multiplied by the actual rocker ratio at the valve.. meaning around .025" more valve standoff if something starts going south with valve control. Bigger springs have bigger heavier retainers and more spring mass which can more quickly turn into spring surge. Which as you probably know bounces the valve around and makes seating tougher precisely when and for how long it's normally supposed to be seated according to the cams lobe spec's. Aside from fuel pressure related issues I would be inclined to think you are severely leaning out on the top end. Even with marginal fuel pressure it seems unlikely this little motor would run both bowls dry by the time second gear comes into the picture. A quick and dirty test is to raise the float levels to 1/2 or 3/4 up the glass and do a quick first gear pull. This immediately covers/enriches all the metering blocks available emulsion orifices with more raw/larger droplets of fuel. Same can be said for inserting very fine copper wires into the HSB(be sure to tightly triple wrap that wire around the vent tubes and tape, bread/zip tie it in place). HSB tuning is THE first place I'd start right after checking on the ignition and locking out the vac advance mechanism. If it likes more fuel/revs even slightly higher before breaking up?.. then you will easily see and know the need for more fuel. Surely post up the carb's spec's but I couldn't really imagine this little motors cam and induction needing much less than about 74/76 or 74/78 main jets with middle of the road HS bleed sizing, maybe somewhere up around 30.
