Yards, your car damn near broke mine and Palomas neck when it was running in those first ten minutes, its scary how quick your boat is. Didn't you mention you were running a spacer when you dynoed it? I hope you figure out what it is and can get it running like that all the time, best of luck. I also hope my ported aluminum intake opens my boat up a little. :grin:
**UPDATE** Just wanted to give an update. I wish it ran all the time like it does before it is fully warmed up!! When still relatively cold it revs effortlessly to over 5500 and pulls every inch of the way. After a full throttle blast and complete warm up it just stops pulling and struggles to get over 5000 RPM. All the following made no difference: New MSD box New MSD distributor/cap/rotor/wires gapped plugs to .030 timing back to 28* (to avoid detonation - on dyno it liked 30* best) jetting 88/98 (on the dyno a box stock Holley 830 was jetted 84/84 with 2 power valves) fuel pressure 6.5 lbs at idle and 5.75 lbs at WOT Last on the list is to run open shorty headers and see how it behaves. I'm thinking on buying new collectors and welding 3" pipe on them just to get the exhaust down under the car.
Have you taken vacuum readings at wot when it runs hard, the wot after its fully warm? If not, please try it and report your findings. Is your oil hot while your doing this? I'd hate to see you hurt the engine.
Good idea. I'll tape the vacuum gauge on the windshield right next to the fuel pressure gauge. My neighbors are going to have me commited. But now I'm curious about the vacuum thing... The water is at 160* (I have a 160 thermostat in it and it won't get over 160). The oil isn't HOT, but it is at least circulating. And when it "warms up" and stops pulling, it is by no means "hot" . Not in this weather. I suppose I can try swapping in a 180* thermostat and see what happens. Anyone ever see a transmission cause this kind of thing?
fuel - air - spark ...and eliminate the independanet variables one at a time from the dyno session. That, and not accepting false values from invalid readings. where the fluid temps recorded from the dyno run ? you've pretty much eliminated spark, so Fuel - what kind if gauge are you using ? how is it plumbed ? Do the readings change cold run to hot run ? try boosting the pressure up 1 lb in half lb increment. Also - this is not the carb you dyno's with - correct ? can you borrow that carb ? air - in: are you running the holy hood ? tried without air cleaner ? same spacer as dyno runs ? .....out: difference from dyno is now running shorty's as compared to dyno w/ long tubes ? .....vacuum - very good suggestion to get readings hot run/cold run. take a passenger along and let them take the readings
That's one thing I was wondering, if perhaps the trans is involved somehow? Maybe like the fluid gets up to temp and causes internal slippage somehow? But I don't know; if slipping the rpms should keep rising, just less power/forward motion. But for some reason a trans issue keeps popping into my mind.
Yards, this is one for the books. When we talk just about every day about this it always ends with "Well, let me go try (fill in the blank), but I pretty much know that isn't it". And unfortunately that's held true so far. If it's any consolation, when you do finally figure this out I'm sure it'll help others going forward. So, on the dyno it exhibited none of these conditions and pulled like it does now when "cold". What's different from the dyno: -Cooling system: You're running a 160 deg stat and it's cool outside and your gage is reading 160 +/-. The dyno had it's own cooling system. -Fuel delivery: Dyno had it's own system going to the carb vs. your modified stock electric pump system. Fuel pressure at WOT is consistent, but is there is a possibility of heating the fuel somewhere where a line runs too close to engine/header? -Transmission vs dyno: Is it really possible for a trans to hold back a 455 after it warms up and not demonstrate any other signs of imminent grenading? You did say the 1-2 shift cold is different in feel than the 1-2 when warm. How would you describe that? -Headers: You're using shorties on the car, but MT's on the dyno? There's a thread on here recently about headers primary tube dia. and hidden HP (with aluminum heads) but no RPM issues. -Rest of exhaust: Yes, the Riv exhaust is long, but you have 2 1/2" all the way back with Walker mufflers. And it works just fine when cold, so unless something is moving inside the mufflers when warm and creating a huge restriction. The dyno was open headers? -Ignition: On the dyno you used the dyno operators ignition system. Was that just the MSD box? Or different ditributor too? In the car different distributors, different MSD boxes, different wires, different coils, smaller plug gap, resistance on your wires in the car fine when checked, ignition system isolated from rest of harness via MSD box (with exception of 12v source to tell it to turn on). All made no difference. -Accessories: None on at dyno, all connected in car. -Air cleaner: None on dyno, open element in car (with no hood) What else? Questions: You have an AFR in your car- is it reading different cold and running to 5500 vs. when it's acting up? Are you sure it ran long enough on the dyno to get into the "problem area" you're seeing in the car? Spacer on the dyno, no spacer on the car? How long from dead cold to when it starts to lay over? How long does the car have to be off in order to pull to 5500 again? Is it fairly consistent for the above two question? If so, what if you iced down the intake? (yes, I know you told me it isn't getting that hot) If you start the car and let it idle for an amount of time where you're into "layover-mode", is that in fact what happens when you drive it WOT? Is the electrical system voltage the same when running to 5500 vs. laying over? Just offering up some ideas for adding to the knowledge base along with trying to summarize dyno differences and actions you've taken to attempt to rule those differences out.
Thanks Rob, I recieved the solid lifters the other day, we put them in the dyno box to test with when I see this problem again. JW
Since even when I had the last engine in the car, I always said that the 1-2 shift felt horrible when it was laying over. When it is cold the RPMs snap up to 5500 and the 1-2 shift happens immediately when I move the shifter. When it is "laying over - or, it just stops pulling) the 1 - 2 shift seems lazy. If you re-read my post, somewhere in here I mention that the engine sounds like it is revving to the moon just to get to 5000. I've hooked a vacuum gauge to it and will drive it in a few minutes. The fuel pressure readings are the same hot or cold. We began the dyno session with this QuickFuel 850 and then put the stock Holley 830 on it to see if it would rev over 5000. It never did with the B4B, but with this carb abd the SP1 it would rev. We ran out of time to swap my carb back on, so yes, it is an unknown variable, but the engine ran the same with it as the 830 when bolted on the B4B. We can extrapolate that it would run the same on the SP1, but that is an educated guess. If I can borrow a carb I will. But I already have a street/strip trans and converter lined up and ready to go in. I expect to get that done one night this week. Unless the vacuum readings surprise me, which I don't think will happen. More later.
On the dyno we used their MSD box with my distributor. Which is why I wasn't surprised that a distributor swap made no difference. Could my voltage be dropping? I suppose, but only over 5000 RPM? It doesn't seem likely. I don't have an ASR on my car now. The dyno uses warm water so the operating temps were in play from the 1st pull. It is an auto meter fuel pressure gauge plumbed into the "supplied" fitting on the Aeromotive pressure regulator. Pressure is steady. 1/2 tank gas.
If you recall, it took Transmission Specialties 4 attempts and 3 different trannies to get me this one. At least it has kept 3rd gear, something the other ones never did.
At cold and hot idle I have 13-14" of vacuum. It goes to zero at WOT, both hot and cold. Here is what happens next: swap tranny and converter... see what happens. if it is fixed I'll swap my converter in and see if it noses over. If the trans is the problem then it gets thoroughly checked out and rebuilt. If it is the converter the same thing with that. If it still noses over when warmed up with new trans and converter then the car is for sale.
Yards before you drop trans run the headers open.Years ago they had double wall pipes i know you don't have them but it would do the same thing.Choke the motor, with your luck maybe you have some wierd thing with a pipe or muffer.
