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My 72 GT5 currently has a 548 HP 501 torque Balanced blueprinted and dynoed 351C. My problem is the car jumps, and lurches under 1900rpm. I understand it is caused mostley because of the 630/660 lift cam. It also contains solid lifters which are quite noisey. If I want to make this engine much smoother and quieter is it possiable to just replace the cam shaft and lifters with hydrolic stage 4 and get the reslults I want without doing anything else? Presently it is too fast and I don't need all this power. Would appreciate any suggestions on replacement components. THANKS!
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For sure, your NASCAR cam is too much for the street. A hydraulic-lifter cam with new lifters will tone it down. Since you have to pull the intake anyway to access the lifters, swapping the intake manifold to a 2-V type with small ports will radically pick up the low end and make street or driving in traffic more fun, but will fall on its face above 5200 rpms. Both these can be done in an afternoon with the engine in the car. Be sure to check your ignition timing and whether the cam chain is worn sloppy, as long as you're in there. Good luck- J Deryke
good point mark.also , keep in mind that w/ the solid lift cam the engine probably has oil restrictors installed and from what i understand,are not a good idea w/ hydrolic lifters.am i right boss wrench? just a thought . by the way, there is no such thing as too much h.p
if you want i will trade you engines even up
: ) j/k
Ron
I dont really want to give up HP this car is to say the least very impresive. I just want to drive it in town without jumping so much. I have been told timing and lean fuel could be most of it, so I am in process of checking these. Ing system is Accel 300+. Timing shows 18 deg at idle and at 1800 RPM jumps around alot then at 2200 RPM advances to a steady 35 deg. I was concerned about fluctuation at 1800RPM so I wired Mech advance weight to see if that was causing it,NOT it. Is this normal? Bronze gear showed no wear,New rotor cause old one had slop and lower shaft had .008" end play so I shimmed it to .002" Timing still fluctuates at 1800RPM. Am I just chasing my tail with this timing issue.Jim Kuntz (engine builder) says that they all do that and thinks the fuel mixture is most likely my main problem. Its next! Many thanks for your help guys!!!!
The carb is a Barry Grant(B&G) Holley 750 dual mech pump,dual feed. It was built and Dynoed with the eng. I'm not sure if Jim kuntz did any jetting to it when he dynoed the engine. Yes Jim kuntz did build engine in 1996,and I just bought the car last june from Chet Varner in N.C... The bug really bit me after attending Vegas 2000. One last thing...I am having a lot of platic sealer coming out of fuel tank and the elbow banjo fitting is clogging up about every 20 miles. so I am currently removing it for repairs. This car ran smoother when I bought it than now,so I wonder if maybe I have restricted jets.
Thanks again for your help. DJ
I am really excited,after pulling engine and started teardown I was very surprised to see Intake gasket split Big time on cylinders 5&6 They were so bad I guess around 25% of sealing surface was open to outside air. What a releif! My heading should read Too Lean not Too Radical. Jim Kuntz told me it sounded like a lean condition when I first called him for advise. Smart man. Thanks again and will soon be on the road again. Also not able to attend POCONO this year.
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