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Auto Repair Questions - What's Your Problem?

Olds Options
Scott Renzenbrink, Massillon OH; I just finished reading the story "The $3,500 Challenge" in the Dec. '06 issue. I too have a '64 F-85 Olds with a low-compression '72 455 with a mild cam, a dual-plane Edelbrock, and a 750 Demon vacuum-secondary carb with a close-ratio Muncie four-speed and 3.43 gears. I have completed many of the upgrades made in the article and they work excellently, but I have a couple of suggestions.

I used FlowTech headers that are inexpensive, ceramic-coated units available from Summit for around $200. I also used the ECI Narrow Track disc-brake conversion; it moves the front wheels inboard 1 inch over standard disc brakes and 11/42 inch over the stock drum brakes. This is the best way to get wider tires under the narrow front fenderwells. With a 2-inch drop (stock replacement Moog spring minus one coil), I can get my vintage Appliance 14x7-inch Torq-Thrust knockoffs to turn lock to lock in compression without interference. With the drum brakes, the tires would rub. I also adapted the standard rear (with boxed lower control arms and factory triangulation braces) sway bar and a 1.25-inch front sway bar from a '77 Trans Am. With the heavy 455, I have found this combo works great for keeping the car flat and in control.

These cars are often overlooked when people are looking for a low-budget, high-performance car, and parts are easy to come by on eBay and 442.com. I just picked up a '68 Toronado 455 with C heads, 10.25:1 compression, and a forged crank for $400. It's rated at 390 hp with 510 lb-ft of torque. My parents purchased this car in 1965, when Mom was pregnant. I came home from the hospital in 1966 in this car, and she has been part of the family ever since. Keep up the good work!

Jeff Smith: Thanks, Scott. We also took the time to look up some part numbers for some of the pieces you mentioned. The FlowTech headers you used are 131/44-inch primary-tube headers with a 3-inch collector and are PN 11154FLT for the painted headers and 31154FLT for the ceramic-coated headers. The brake kit you mentioned is from Engineered Components and is PN EC736K using a drum-brake spindle and runs $595 or $625 with 13-inch rotors.

Stumble in
Ben Schrank, via CarCraft.com: I was going through an endless pile of Car Craft magazines when I ran across the Nov '05 issue. I read your Front Man article where you talked about a carburetor stumble. I also have a big problem with that. I just rebuilt my punched-out, 0.030-over 454 with a new Comp hydraulic roller cam with a 0.510-inch lift. I also installed an Edelbrock Performer RPM Air Gap intake, new vacuum lines, and a bunch of other stuff, and I still have stumble problems. I have a 750 Edelbrock. I'm not sure on the jets or accelerator pump size. I am using a stock HEI unit with new weights and copper-colored advance springs installed. The initial timing is 11 degrees, and I also have 0.071x0.047-inch metering rods. My accelerator pump linkage is in the hole closest to the hood.

At about 2,000 rpm, I start to push on the go pedal, and the engine will start to bog. And when I push harder, it will stall, blow a hole in my Xtreme Air Top K&N filter, and then accelerate. I have stretched the piston step-up springs about a quarter of an inch (they are a plain metal color), and that helped a lot. Do you have any remedies, theories, or ideas what is causing this? This engine also did this before the rebuild. Please help me keep my sanity!

Jeff Smith: This is a relatively easy fix, Ben. It sounds like the engine is just lean on tip-in to light acceleration. The difficulty with selling universal-fit carburetors is that the manufacturer, Edelbrock in this case, has to take a stab at air/fuel metering that will both be relatively lean for cruising and still deliver enough fuel at wide-open throttle (WOT) so the engine doesn't go lean and hurt a piston. It sounds like you need a little more accelerator pump and perhaps a little more part-throttle fuel. But before we go into modifying the carb, let's try a couple of other tricks first.

We would recommend adding more initial timing to the engine. This can often cure an off-idle sneeze. We'd bump the initial up to around 16 degrees from the 11 degrees you have now. This will add 5 degrees more to your total-shoot for around 36 degrees of total advance, which is your initial of 16 degrees and whatever mechanical advance the distributor offers. This should be around 20 to 22 degrees, which would then give you between 36 and 38 degrees total, which is a good number for a Rat motor.

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