Thanks for the input. I have the .110 Needle & Seats. I will try lowering the pressure and see. Its a 472 cu. Did you ever have the surging?
So anybody try a wideband O2 on a crossrammed Hemi yet?
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JDJG
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When does it surge Ernesto?
At idle to about 1600 rpm. It idles around 950. If I let out the clutch too quickly it creates a bucking sensation. If you've ever heard a roots blower surge, its like that except milder. No vacuum leaks. I've tried higher idle speed but this screws up the AFR's.
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I'm about to leave for work, but have you tried around 18-20 degrees of advance at idle with a way to limit total timing? My FBO ignition and more advance at idle really helped my 440 6bbl.
I'm at 18 degrees initial and 34 total with MP distributor and a chrome box. I have also tried with and without vacuum advance. I have always leaned toward the cross ram and the lack of a vacuum signal but others running this manifold seem to find the sweet spot. I will continue testing. Thanks
68 HEMI GTS
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Fuel pressure won’t fix the surging. Mine did it for a bit when we first out the TF in. My dad was tuning it at that time. I think he worked on the distributor and fattened the idle circuit a touch. When I swapped to a looser converter it completely disappeared as it was only doing it in gear as I recall. Was never an issue with the 4 speed.
2blader
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Would tapping the carb spacers for vacuum help for the signal
JDJG
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Ernesto just a couple things to check (you likely did already but ..)
Did you check the accelerator pump actuator clearance? E.g. when the throttle is moved do they actuate?
Also wondering if a bit more accelerator cam for the pumps?
Did you check the accelerator pump actuator clearance? E.g. when the throttle is moved do they actuate?
Also wondering if a bit more accelerator cam for the pumps?
My IFR's are .026, Idle Air Bleeds .0938 (just went leaner to help idle AFR), 76 primary jets on D/S carb and 75 primary jets P/S carb, 10.5 power valves, power valve channel restrictor .0520, stock white pump cam, just switched squirters .035 (stock) to .037. As mentioned AFR's are good all around. The squirters are immediate. I have 1/4" spacers that won't allow a vacuum tap. The car runs great all around except for the surge. I am going to plug the PCV as a test next.
I appreciate the help everyone is offering.
So I did a few tests. Plugging the vacuum source for the PCV lowered the idle speed and caused a bit more of a surge. I reconnected the PCV system. I increase idle speed to about 1400 rpm and the surge was gone. The problem this creates is transfer slots are exposed too much. My next move is to open the secondary throttle blades and return the idle speed screws back to square. I will do this tomorrow.
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I appreciate being invited to join in on your quest and the suggestions by our fellow forum members.
I know there were lots of useful suggestions made when I got my first 6bbl setup (it had a V-Code Roadrunner attached to it that was part of the deal). Out of all of the individual tips I was given, many that I used that helped, there's ONE that stood out, head and shoulders above the rest, a true epiphany, that solved the mystery of adjusting the 2 outboard carbs idle mixture screws.
Having a 6bbl and wanting to achieve the best performance from it became a reality I knew I could attain.
I did not get a chance to tune today. I will get to it tomorrow and report.
I did get a chance to do a couple of things to the carbs. I suspected a power valve might be leaking so I swapped in new ones. I opened the secondary throttle blades by 1/4 turn. I went to start her up and the throttle cable pulled out of the cable end and frayed. I couldn't get the cable to thread into the end without cutting it which would make it too short. I have a new one on order and expect it in a few days.
I also pulled apart the linkage, lubed and re-adjusted it to eliminate any binding.
2blader
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Ill be back on here for the original reason soon. Had to eliminate a pesky rear main seal leak, replace the clutch (went dual disk), and install a PCV system. Just getting back together now just in time for the cold weather. Next is addressing a severe idle drop when my fans kick on.
I have been busy like most folks here with holidays, etc. I wanted to follow up with the latest results of my quest to eliminate the surge at idle I was having. I decided to see if the mechanical advance coming in at idle was the problem. My crate Hemi originally came with an MP electronic conversion kit. The crate specs are out as I have since had the engine redone. I ordered the Summit kit SUM 850535-1 for the Mallory-made MP distributors. The kit includes an allen wrench, degree sticks and 3 pairs of springs) silver, blue and black) These distributors also have allen head screws to limit the advance using the degrees sticks. I used 16 degrees. My distributor had 2 identical purple springs which the orignal instructions state they allow the advance to be all in by 2000 rpm. I decided to swap in one blue spring ( the silver seemed too light and the black too heavy) and leave one purple in. My goal was to eliminate any advance coming in at idle. It should be noted that I have never experienced any pinging with the factory curve. My surging is virtually gone and she returns to idle properly. In addition my vacuum gauge isn't swinging from 5 to 13" hg. She is at a steady 9" hg. I pulled 2 degrees of initial timing out as she was idiling at 1300 rpm. This dropped her to 1000 rpm. I am calling this a success as I have been trying to cure this issue for a while now. Thanks for all who offered helpful suggestions.
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I agree and will celebrate with you!
Congratulations and I think you will find even your race track performance is improved, even though WOT has nothing to do with idle surge. If my prediction of a "noticeable" performance improvement isn't proven by cold, hard numbers, I stand by my prediction and I'll bet you will "feel better" overall about your experiences with your car.
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Would you mind going into detail about those 2 items? I have a McLeod RXT dual disc clutch and pressure plate setup that is broken in, but unfortunately STILL haven't had time for a trip to the track, and only a couple of limited flogging events on the rarely trafficked street that runs through the 2 wildlife reserves. I expect GREAT performance from the McLeod.
Also, PCV valve and system setups are of particular interest to me, as I believe they play critical roles, especially in high performance, modded engines that see street duty. I have the M/E Wagner PCV valve, and I'm so impressed by it, the family who designed and manufactures them, and their knowledge, tech support, and positions regarding the importance of a "tuned" PCV valve and system. I immediately got a 2nd PCV valve from them for the 65 421 Tripower GTO.
My 64 is strictly a cruiser so no track time. I too, have been looking at the Mcleod twin disc (RST was recommended to me by Mcleod) for my Mcleod single disc replacement down the line. I have heard there can be an adjustment curve which I am not in favor of as I have a Lakewood Scattershield to remove each time adjustments are needed. Sometimes simple is better.
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