My sons 71El Camino

Hello everyone, New member here. I would first like to thank Brent Mills for the warm welcome. The problem I've run into is a stumble with the engine in my sons 71 El Camino. The engine is a 454 big block chev taken from a large 97-98 truck. Before my son got the car an Edelbrock Performer2 intake was installed along with a Holley 750cfm sqarebore Vac. secodary dualfeed carb. A GM HEI distrbutor was used and the stock GM sparkplugs and Accel 8mm copper core wires installed. Keep in mind this was a computer motor. All of that is gone and a Pete Jackson gear drive installed on the stock roller lifter cam. A set of Hooker headers were also installed and the initial timing set to 12 deg. B.T.D.C. The accelerator pump diaphram and check valve have been replaced and the sprayer head upsized. An advance kit for the weights in the distributor has also been installed to get proper advance curves. The Vac. advance also operates properly and the sparkplug gap is 60 Thousands for HEI. The stumbling only occurs at lower RPM if trying to accelerate quickly,otherwise the car will smoke the tires at just about any speed when floored. Thanks ahead of time for any suggestions,Blown Burb.

Hi Denny,Thanks for the reply. What we found in the GM specs. was that for the sparkplugs ( AC Delco ) they came gapped at 60 but we reset them to 50 because we also thought that was a little much. As far as the pump shot we checked over and over and we could not even think about moving the throttle without getting a squirt of fuel. Thats when we thought a slightly larger sprayer jet would help,but it did not make much difference.The distributor was checked when the advance weight kit was installed and everything was virtually new.The fuel levels as well were checked after the replacement of the accelerator pump parts.We just seem to be missing something,Thanks again.

Hi guys. Well its another day.I failed to mention that the Performer2 intake manifold is spreadbore type and the already mentioned carb. is a squarebore. The carb. base spacer is already in place.Still working on it, thanks for the suggestions,Blown Burb.

Hello everyone,Blown Burb here. After still checking and testing just about everything we could think of on my sons 454, I tried adding a couple of small washers to the accelerator arm spring. Another change was the accelerator pump sprayer nozzle hold down screw I have removed and drilled out on a drill press so that it was close to the described Holley part no. 26-12 screw for the nozzle. Im happy to say that either off the line or at various low speeds now there is no more stumble. I suppose its needless to say that the rear tires just can't seem to stay stuck to the pavement. I'm sure there is a stiffer spring available and the jump from the original sprayer nozzle from 25 to35 was only the begining. My son and I will still have to set up the main jets, because even after dropping down from the stock no. 72 jets that the carb. came with, its still running rich. Currently the main jets are no. 68, any suggestions on what may be the smallest jets to go down too with this carb. size before running too lean from past tries with this previously mentioned setup. Well bye for now and I will post any new developments.