Don't ever rule out anything until you find the probem. Again, a wideband 02 sensor would be invaluable IMO. Sometimes fuel pressure seems to be good, but that is only as good as where you are measuring from. Some fuel lines get restricted (ie are big on the outside, small on the inside) between the carb and gauge tap.
What are you running for cylinder heads? if they are factory castings, did you have hardened seats installed? MY first 430 build involved a typical 3angle valve job with shimming the springs. anyway after 8k the motor was lasy, 6 out of the 8 exhaust valves sunk- pounded the seats way back. obviously that changed the installed height and the car ran like ass. ofcourse they probably were not sealing that well either. but back to the smoker- i suppose if the car developed a vacuum leak the idle characteristics would also change. however its such a simple test, with pretty much no wrenching invloved, or alot of time, or alot of money. hell I have a smoker on my tool truck if you wanna take a ride to erie. I can "demo" it for you...
All hardened seats installed when he redid the heads. I have just over 15" of vacuum at idle. Sounds like a lot if I were to have a vacuum leak. I will check the valve stem heights.
Joe, Not to hijack but could you tell me about the smoker and the simple test? Maybe over in my "I'm ready to give up thread".
Just a thought - make sure that none of your fuel lines run near your exhaust piping. We had a situation a few years ago where gasoline was boiling inside the fuel lines (engine was a 455 but installed in a non-Buick body which had different fuel line arrangement). Symptoms were the same - ran great when cold but had big problems when hot. -Bob C.
Thanks Bob. All lines run cool. I don't think it has anything to do with "warming up", but instead after I run WOT once or twice. I'm thinking lifter collapse or something. The lifters don't get any louder after a run, so I'm stumped. It is going to the dyno next week. We'll run it with the current TA cam, then swap to a custom Scott Brown grind and run it again for comparison. We'll see. I have a feeling we'll see the numbers fall with each run we make with the current setup.
Following up from Bob's post - is your fuel pump in-tank, or in the front or rear of the car? Having the fuel pump up front if the gas is 'boiling' in the line, means you are trying to suck vapors. That's what was happening to our 455. Adding a tiny fuel pump in the rear as a 'booster' completely solved the problem. The fuel line ran pretty close to an exhaust pipe, about a fists's width away, and wasn't hot to the touch until the exhaust system got good an hot (think towing a camper uphill). We found the problem after I installed a clear glass fuel filter and we realized there was barely any fuel going through it when things were hot and problematic! Hope you find your problem! I like the 20w50 idea to help rule out lifters. Have you tried different lifters?
On the front of the wiper blades are these arrow-head like barbs that spring open after sliding through the slots on the wiper arm. Make sure the barbs are fully extended and not stuck in a partially closed position :TU:
And the horns have proper clearance...This can cause a lean condition if not monitored...:laugh: I feel for you Yards...
i remember reading that someone that had an 8 sec. camaro that the motor would pull like an animal on the dyno but fell on it's face in the car. turned out to be a bad ground cable. did you do a voltage drop test on the ground side of things? also never rule anything out w/out varifying everything. i would check the fuel press. again with a known good gaugeeven if it is a snap on one or something and you have to wrap bubble wrap around the lens and then tape it to your windshield. good luck.
Yards did do a voltage drop test and everything looked fine. He did do an oil change today for 20/50 and it consistently falls on its face at 5,000 RPM- but that's a full 1,000 RPM higher than what was happening before, so it definitely seems like a valvetrain issue when the oil heats up. I know he's running Chevy lifters, which are supposed to be pretty bullet proof, but defects do happen. He also talked to Greg Gessler today and I think he was going to do some valve tip height measurements (as was mentioned earlier- by Jim Weise?). At least he's finally onto something. I'm sure he'll add more whenever he logs in....
I've run the "fast ramp" cams such as the Pop Mechanics cam and run into the "crash" problem. That was at 5400 rpm though. I don't know how your problem would be related to "crash" at such a low rpm especially since it didn't do it originally. The way I got around it was to run the Comp Pro Magnum lifters. I set them at barely 1/8 turn preload which is under .010". Ran right up to 5700 rpm no problen then. I would say that the 1.6 rocker arms aggravated the problem some. I'm sure you could try the same thing with normal lifters to see if it helps. They are meant to actually run near zero preload but I wanted to keep them quiet which they were. They are great lifters because they don't "pump down" when you park it so there is no noise at startup. They pump up hard so they run almost like a solid. I've also run the KB701/TA1125 dual springs on all kinds of cams and never had any problems with them as long as they are intact. I'm talking about 10's of thousands of street miles with lots of racing in between. I have had a few break, mostly inners, and then you'll know because the engine will feel like it has a rev limiter on it at a certain rpm. The more broken ones you have the worse it will feel and the bigger the cam the lower the rpm will be that it kicks in at. Years ago with a KB MK3 cam I didn't realise I had 6 broken inners and the car would just hit a wall at 5200 rpm. That wasn't good because I ran 4.10's out back and I was pretty far from the finish line when it would hit in 3rd. It was barely noticable in first, more so in second, and just plain bad in 3rd. I believe it was that way because in the lower gears you buzz through them much faster than in 3rd when it is accelerating much slower.
I didn't do an actual "voltage drop test" on the ground, but at the battery and the coil they were both 14.5. Same with the voltage going to the MSD box... 14.5. The car pulled a lot easier to 5000 with the 20/50 oil in it today, but still fell over. I'm swapping cams and lifters. I'm istalling a Scott Brown custom grind. It is a fast ramp on the intake side (which I just found out about anb hour ago) bit Scott assures me there will be no problems with it.
The car pulled a lot easier to 5000 with the 20/50 oil in it today, but still fell over. I'm swapping cams and lifters. I'm istalling a Scott Brown custom grind. It is a fast ramp on the intake side (which I just found out about anb hour ago) bit Scott assures me there will be no problems with it. Whoa, whoa, whoa..... Finally, after this long, you do something that changes it.. let's put away the box of parts to throw at it, and figure out what's wrong here.. It's not the cam, I have run your cam to 6000 rpm more times than you can shake a stick at.. I would be willing to bet, regardless of what you were told, the valve tip heights in those heads are way high.. measure them.. It's as simple as airing up a cylinder, removing the valvesprings, and measuring from the tip of the valve to the spring seat with a veneer caliper (use the end, vertically).. I will give you a pick if you don't get what I am saying here.. "Fix the problem, don't make it worst by guessing" Gene Krantz- Apollo 13 flight director JW
Jim, This cam, if bought today from TA, is ground on a 114* Lobe Center. My copy of this cam is ground on a 116* Lobe Center. I remember you saying you wanted on a 114, but Mike ground it on a 116. I believe this could be the very 1st it copy of this grind. Could that contribute to the inability to rev?
