clutchdust Posted May 10, 2009 Share Posted May 10, 2009 just got my rebuild (2.4 block and head with 2.6 rotating assembly) drivable yesterday. i have the arizona Z manifold with the 390 holley. the one thing i noticed is that i get engine acceleration when braking. looking at the carb, it would appear that braking pulls fuel away from the needle. my guess is that the float is lifting from the fuel stacking. can anybody confirm or deny that? if so, what's the fix? also, this is my first overhaul of an L6 so i'm not as familiar with them. i'm getting this 'whiz' kind of sound that matches RPMs. i'm thinking i have some kind of metal on metal interferance, possibly cam gear/chain area. any thoughts on where i should check before wasting a fresh rebuild? is it normal for any kiind of whizzing noise? anybody around vegas that could put an extra set of ears on it? oh ya, one more thing. my balancer has five notches on it but my cheezy hanes manual doesn't really break it down. which one is zero? what degree increments do they indicate? Quote Link to comment Share on other sites More sharing options...
260Zz Posted May 10, 2009 Share Posted May 10, 2009 yes sir im running the 390cfm holley 4 barrel vaccum secondaries barrey grant nascar edition on the 4 barrel intake manifold and the performance header. and to answer your question. im convinced it is the float in the carb because me and my dad have z's he has a 73 240z and i have a late 73 260z we both ahve the intake manifold and the holley 390 and the performance header and he is saying that he has that problem and he said that my z car does to. he said there is a little problem in the float bowl with both of ours Quote Link to comment Share on other sites More sharing options...
jasper Posted May 10, 2009 Share Posted May 10, 2009 If fuel slosh is the issue, center hung race bowls may help. Fuel Bowl Conversion Kits Aluminum Center Hung "V" Bowl Kit - Primary Part #: 134-71S UPC #: 090127663783 Holley Aluminum V–bowls are offered in three different configurations; primary, secondary with accelerator pump provisions, and secondary without accelerator pump provisions. These different options allow you to convert anything from your old 3310 to a Dominator to aluminum fuel bowls. Holley's new Aluminum V–bowls feature a clear, glass sight window for easy, safe fuel level adjustments. They also include all necessary gaskets and fuel bowl screws for a quick installation. The best part is replacing your old Zinc fuel bowls with the Aluminum versions will save you over 1.2lb of weight on top of your engine. Convert anything from your old 3310 to a Dominator to Holley's new Aluminum fuel bowls Quote Link to comment Share on other sites More sharing options...
dhartig Posted May 12, 2009 Share Posted May 12, 2009 I run an Arizona Z intake and a Holley but I'm not sure of the carb number. I have the reverse problem and get a drop in RPM just after stoppoing. There are no issues when braking before the stop. I think I might look into the Holley conversions if I get too frustrated with the problem. Quote Link to comment Share on other sites More sharing options...
clutchdust Posted May 13, 2009 Author Share Posted May 13, 2009 dhartig, does yours have centerhung or sidehung floats? which way is yours facing? i suppose it's possible yours is just like mine only turned 180* on the manifold. i still need tot dial in the tune but it's a good start. i notice a miss at higher RPMs but haven't figured out if it's fuel or ignition yet. anybody have any input on the balancer marks? what about the whizzing sound? sure doesn't sound right to me and i don't want to waste this motor. Quote Link to comment Share on other sites More sharing options...
dhartig Posted May 14, 2009 Share Posted May 14, 2009 My carb is a 8007 which makes it a 4160 model with electric choke, 390 CFM. It is supposed to have side inlet bowls and from what I see in the Haynes Holley carb book it appears to be unmodified. Here's how it is setup in my '72. Quote Link to comment Share on other sites More sharing options...
citjet Posted May 14, 2009 Share Posted May 14, 2009 I'm also running the same setup a dhartig. I also get some rpm dip when braking, particularly when hard braking. I'm swapping a turbo in soon and will be going to the dark side of FI w/MS. Quote Link to comment Share on other sites More sharing options...
citjet Posted May 14, 2009 Share Posted May 14, 2009 Sorry, wrong URL. Here's my setup. Quote Link to comment Share on other sites More sharing options...
dhartig Posted May 15, 2009 Share Posted May 15, 2009 Citjet, sounds like we are of a same mind. I just added a turbo return line bung to my L24 oil pan. I have an L28ET sitting here, but I am going to first put a Turbo Tom system on the L24. The mid-pan location of the L24 fits the TT system better so I will keep it when I swap later to the L28. Quote Link to comment Share on other sites More sharing options...
ozconnection Posted May 15, 2009 Share Posted May 15, 2009 Sorry, wrong URL. Here's my setup. Daniel, how much does that blanket cool things down? Any adverse side effects? I was thinking of building an aluminium plate between the carb and manifold but this seems to be better since the intake manifold if isolated from the updraft of heat as well. What is that material? Nice looking engine bay BTW!! Cheers. Quote Link to comment Share on other sites More sharing options...
citjet Posted May 15, 2009 Share Posted May 15, 2009 Love to see the TT system still in action! I'm going to swap the L28ET over stock first with the ECU and once I have all the bugs worked out switch over to MS. clutchdust, I've never experienced any of the symptoms that you described with my setup, but your wizzing noise could be from your timing chain tensioner. Did you put your engine together after the rebuild or was it someone else? This is a common problem in these engines but I don't know if it would cause that type of noise. Also did you adjust your valves after the rebuild? How much time do you have on the engine? Could be you just need to reset your valve lash. Quote Link to comment Share on other sites More sharing options...
citjet Posted May 15, 2009 Share Posted May 15, 2009 Daniel, how much does that blanket cool things down? Any adverse side effects? I was thinking of building an aluminium plate between the carb and manifold but this seems to be better since the intake manifold if isolated from the updraft of heat as well. What is that material? Nice looking engine bay BTW!! Cheers. OZ, The blanket wasn't really my first choice but it is pretty effective. I was planning on wrapping my header with the copper heat shield from NAPA to make it look a little cleaner, but when I decided on the turbo swap I will be saving that for the new exhaust mani and downpipe. That stuff is expensive! The blanket would look a lot better if I would have cut it to fit but as it was a temp job I just made it work for awhile. I have never had any problem with vapor lock though, and I'm running in Florida heat all the time with no wrap on the fuel line so it obviously is doing it's job. Thanks for the compliment, it is very much a work in progress. I think when I pull the L24 I'm going to Herculine the whole engine bay, at least re-paint and take some time straightening up. Quote Link to comment Share on other sites More sharing options...
Mike C Posted May 16, 2009 Share Posted May 16, 2009 I had a bad brake booster in my car. The vacuum leak gave a similar "throttle on braking" response. You may want to check your booster and line. SOme have an inline check valve that might help. Quote Link to comment Share on other sites More sharing options...
clutchdust Posted May 16, 2009 Author Share Posted May 16, 2009 dhartig, your set-up looks very similar to mine. i've done some more tuning and it's coming along. i still have this strange miss at anything over 3000RPM. i still haven't figured out if it's fuel or ignition. did you change your jetting at all? what have you done to the carb to tune it? Quote Link to comment Share on other sites More sharing options...
clutchdust Posted May 16, 2009 Author Share Posted May 16, 2009 clutchdust, I've never experienced any of the symptoms that you described with my setup, but your wizzing noise could be from your timing chain tensioner. Did you put your engine together after the rebuild or was it someone else? This is a common problem in these engines but I don't know if it would cause that type of noise. Also did you adjust your valves after the rebuild? How much time do you have on the engine? Could be you just need to reset your valve lash. yes, i put the engine together. what's the "common problem" in these engines? i kind of figured it was chain related but i still have been unable to identify exactly where it's coming from. it's an old chain but all new tensioner and guides.still, can anybody tell me what degrees the five marks on the balancer indicate? Quote Link to comment Share on other sites More sharing options...
dhartig Posted May 18, 2009 Share Posted May 18, 2009 Clutchdust, I had my carb "tuned" by some guys who run older Ford trucks and cars. They have years of experience on all types of carbs. I saw a slight improvement after they played with it, but then it always has pulled strong through all RPMs. The only fault is a drop in revs when hard stopping. The Holley was installed by one the PO's of my car and the Ford guys thought the jetting was OK, I'm not sure what it is though. I plan to purchase an AFR unit, probably the Innovate unit, and then datalog to see if I can improve it some more. Quote Link to comment Share on other sites More sharing options...
citjet Posted May 19, 2009 Share Posted May 19, 2009 yes, i put the engine together. what's the "common problem" in these engines? i kind of figured it was chain related but i still have been unable to identify exactly where it's coming from. it's an old chain but all new tensioner and guides. If you don't get the chain staked good to hold it in place than the spring from the tensioner tries to pop out pinning the puck over to the side instead of aligned on the chain. Quote Link to comment Share on other sites More sharing options...
citjet Posted May 19, 2009 Share Posted May 19, 2009 I still don't know if that would cause the wizzing noise that you're hearing but that is all I can think of at the moment. Quote Link to comment Share on other sites More sharing options...
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