Guest 77vegasz Posted July 29, 2004 Share Posted July 29, 2004 I am experiencing a stumble, at around 3800-4000 rpm. With the accelerator floored, the car accelerates up to this range where it seems to struggle. If I let off the gas pedal slightly, it will again begin to accelerate and gain rpm. I am running a stock bore 327, with an Edelbrock RPM Air Gap intake. The intake and heads have been port matched to a Felpro medium race port gasket. I have 1.94 and 1.50 valves in 60 cc heads. The exhaust ports have been unshrouded and poliches, the intakes unshrouded. The heads are Chevy camel humps, the valve train is Crane roller rockers at the stock 1.5 ratio. The camhas .447 lift both intake and exhaust with 220 degrees duration at .050. I run a Holly 600 vacuum secondary carb. My redline is at 6000 rpm. Am I having a fule issue with the secondaries? Can one of you guys who is skilled at tuning give me some place to look? I would certainly appreciate it. Jon Quote Link to comment Share on other sites More sharing options...
2126 Posted July 29, 2004 Share Posted July 29, 2004 You didn't mention anything about what ignition you are running! If it's the stock bowtie distributor, it might be that it's just not capable of reliably handling anything above 4K rpm. The distributor could just be worn out. If I remember correctly, 327's had points.........NG for an engine with all those upgrades. Just a thought! I'm sure other guys on the site will chime in and provide you with recommendations. Good luck! Quote Link to comment Share on other sites More sharing options...
Guest 77vegasz Posted July 30, 2004 Share Posted July 30, 2004 I am running a new high performance curve Petronix HEI ignition. So I feel confident that it is fine. Thanks for the suggestion though. jon Quote Link to comment Share on other sites More sharing options...
jt1 Posted July 30, 2004 Share Posted July 30, 2004 Sounds like it's going a little lean when the secondaries open up. Try a little stiffer spring in the vacumn pod to slow the secondary opening down some. Another possibility is the secondary might need jetting up some. John Quote Link to comment Share on other sites More sharing options...
Guest 77vegasz Posted July 30, 2004 Share Posted July 30, 2004 I think your on to something, when I back off the throttle, the secondaries close and I acutally overcome the stumble. I plan on playing with the carb this week end. I will post results, good or bad. Jon Quote Link to comment Share on other sites More sharing options...
Guest 305240 Posted July 30, 2004 Share Posted July 30, 2004 Question. Does it stumble when you rev it up with out a load? If it doesn't, I'd have to say it's starving for gas. My friend took his camaro to the strip and it kept stumbling on him when he shifted out of second into third. (auto) His burn outs were awsome. He was running a beefed up 400 small block shifting around 8500. He told me he made a mistake and grabbed the wrong carb. He had a 750 double pumper on it. He ment to grab the 830 Deamon off his roundy round car. Quote Link to comment Share on other sites More sharing options...
buZy Posted July 31, 2004 Share Posted July 31, 2004 Is your fuel pressure staying even through your entire rpm range?? Another way of fuel starvation. Quote Link to comment Share on other sites More sharing options...
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