Yes i have the 80570 except the power valve is the 6.5 now. It is the factory HO cam. The secondaries are closed as far as they can go without sticking. They are locked closed right now for troubleshooting. The transfer slot is about .030 exposed at about 700 rpm. These are the reasons I was thinking I might have multiple leaks under the manifold. The wires are new. I used them because I had them. I have a set of moroso spiral cores now and they will be on the car in a few minuets. Are the FR wires spiral core ? I have heard they last forever. I also have a procomp gm style distributer that is going in with them. That should tell me if if it's an ignition issue. My carb guy comment was misleading , and kind of a joke. This is my carb guy...
What gaskets did you use ? And how did you torque it ? If you only made one pass on the torque values then you need to go back and retorque it multiple times till the gaskets are fully compressed and you get solid clicks on all the bolts at the same setting.
I used a 4 hole gasket that came with the Mr gasket heat shield between the carb and the 4 hole shield and an open gasket between the shield and the manifold. The open gasket is a Holley. I re torqued the carb. This time with the torque wrench. It was at less than min torque but 70 inch pounds all around didn't change anything. I'll torque it again when I go back out there. The procomp dist is in . I'm ready to start it and set the timing. I got distracted by some spaghetti.
The manifold gaskets were another thing that I used because I had them. They were unbranded but I thought they looked like good gaskets. I've been suspecting them ever since. I did go round and round on the manifold with the torque wrench until I was sure all the bolts stayed at spec and again after about an hour of run time. I re torqued them again after I did the carb a few hours ago and they were all still above minimum torque. My new ignition system also produced no improvement.
Ok, usually you'd have coolant leaks if the gaskets were bad or the fitment was off instead of vacuum leaks, but you never know.
It is a used manifold. It looked almost new . It was bolted onto something but i don't think it ever had gas through it. That doesn't mean it wasn't angle milled. If / when I take it off that will be the first thing i check. I'm running out of ideas.
I'm going to post this for consideration. A few years back prior to installing a Weiand Stealth intake on my 302 I was running a `60s vintage Cobra intake. I had decided to change to a Performer RPM intake although both intakes are very close in design. I went to Summit Racing which is just a few miles from my house and purchased a new Performer RPM came home installed it and ended up with a very rough running engine. Retorqued everything, still no good. I then reinstalled the Cobra intake. The engine ran fine. I took the RPM back to Summit and got another. Foolish me, I installed the second RPM without checking straightness of the head mating surfaces. My engine ran rough. I removed the second RPM and checked the mating surfaces with a metal straight edge. Sure enough they were not machined level. Took the second RPM back to Summit and made them aware of my findings. I then purchased the Weiand Stealth and installed it, no problems. Assuming the first RPM had the same issue as the second, what is the likelihood of getting two poorly machined intakes in a row? Perhaps jbrich you have a poorly machined RPM intake.
Several years ago I purchased a set of Performer aluminum cylinder heads, when they arrived one head had a scratch that ran from one chamber to the adjacent chamber. Long story short, the forth set still had the scratch but barely noticeable. It would seem that there quality control at times is lacking to say the least.
Hmm... I have other manifolds. I am thinking about closing all the intake valves and smoke testing the manifold that way. I can't find where anyone has done that but it sounds logical to me. Is there a better way to test this ?
I agree although a bad sealing intake valve could complicate things. Doing a vacuum test might be better ? But then again a poor seal on any of the valves would show up there too.
I've leak down tested each cylinder. I can't find the results right now but they were all well within tolerance. I've never heard of a vacuum test. How is that done ?
At this point I wouldn't be too concerned with cylinder to cylinder leakdown tolerances, although that could be a clear indicator of a re-rung motor that hasn't sealed the rings up yet. What to be looking for.. more like listening for.. are the tell tale signs of specific leakage paths past valves, guides or rings. This is generally THE baseline test to confirm everything else from there on should become the true focal point. The vac pump test is usually done loose to confirm water and valve job/seals are all good but you can buy or fabricate a o-ringed or gasketed plate to use a basic hand vac pump. I'll warn you know though.. your hand is gonna get crazy tired evacuating a larger air volume like an intake port. lol And if the valve is even slightly unsealed(daylight showing) you'll never begin to build enough depression to help pull it shut and build vacuum on the gauge. Been there done that.. doesn't always work like you want. Leakdown test should easily find an unsealed valve with its higher frequency hiss. Shop needs to be dead silent and mechanics stethoscope helps quite a bit too. Seem's like we're missing something simple or the troubleshooting testing process has not correctly sussed out the prime suspect in this case. After all this though, short of some underlying long block issue.. I'd still say it's fuel or ignition related. Realistically, a vac leak still falls under fueling since it's carb signal and AFR related. The leak would have to be decent enough to cause all the bigger issues you describe. Idle/high-idle only?.. or does the motor eventually smooth out as you continue to slowly build rpm with the throttle?
