Over the last couple of years I've been putting together a replacement for the tired 350 in my El Camino. Since it's used primarily for towing/hauling and infrequently driven, brute performance was not a priority. It had to be reliable, torquey, get reasonable mileage and be cheap gas friendly. I started with a Chevy 400 that I had sold to a buddy and immediately bought back. It had 30K on a rebuild but somehow he managed to spin a rod bearing on his second day of ownership. I "warrantied" it because I'm such a great friend :? . The combination I assembled was meant to build strong low-end torque and according to my software makes over 440ft-lbs. at 2000rpm and maintains over 400 past 3500rpm. It now specs out at 415 (.060 over), rebuilt crappy 882 heads, XE256 cam, Performer intake, HEI, stock manifolds and dual exhaust with glass-packs (for now). I was given an Edelbrock 1405 (600cfm with manual choke) by a friend who had more money than skill. When his Blazer started running poorly he just bought a new carb rather than rebuilding this one. I bought a kit, disassembled, dunked, reassembled and added an electric choke kit for convenience. I figure it would be sufficient since 400ci engines frequently used 2bbl carbs, my cruise rpm is 2200, and this one will rarely see 4000rpm.
Last week I did the engine swap, fired it up and broke it in. It ran OK but not great. In my shop it idled great and would rev fine to about 2800 and then start to stutter a bit. On my first test drive it bucked and bogged. Over the next 2 days, a minimum 8 hours, I disassembled and cleaned again. I verified that it had standard jets and rods. I jetted up and jetted down. I spent several hours doing research online. Sometimes it would get better - sometimes worse. Since I had spares, I even swapped plugs, wires and distributors just to eliminate an ignition problem. I didn't want to let this thing beat me but decided to just quit for a day or two and reflect.
Yesterday I was at the PicknPull and decided to just grab another carb to see how it compared. The donor was a '78 Sedan DeVille with a 425 -- the closest displacement to my 415 plus it had electric choke and is actually 800cfm. When I got home I gave it a quick bath, cleaned the inside and replaced the top and base gaskets with extras from my carb kit leftovers. Bolted it on, fired it up and let the engine warm up. I found that the idle mixture was already dead-on. The throttle response was 50% better than the Edelbrock. On my test drive I found incredible torque and mid-range power and it pulled effortlessly to 4500. No hesitation, stutter or flat spots whatsoever! Total cost of carb, cleaner and base gasket- $28 😀 😀 😀. Now I have an Edelbrock carb to add to my swap meet "sell" pile.
What lesson did I learn? There's no such thing as free parts.
Last week I did the engine swap, fired it up and broke it in. It ran OK but not great. In my shop it idled great and would rev fine to about 2800 and then start to stutter a bit. On my first test drive it bucked and bogged. Over the next 2 days, a minimum 8 hours, I disassembled and cleaned again. I verified that it had standard jets and rods. I jetted up and jetted down. I spent several hours doing research online. Sometimes it would get better - sometimes worse. Since I had spares, I even swapped plugs, wires and distributors just to eliminate an ignition problem. I didn't want to let this thing beat me but decided to just quit for a day or two and reflect.
Yesterday I was at the PicknPull and decided to just grab another carb to see how it compared. The donor was a '78 Sedan DeVille with a 425 -- the closest displacement to my 415 plus it had electric choke and is actually 800cfm. When I got home I gave it a quick bath, cleaned the inside and replaced the top and base gaskets with extras from my carb kit leftovers. Bolted it on, fired it up and let the engine warm up. I found that the idle mixture was already dead-on. The throttle response was 50% better than the Edelbrock. On my test drive I found incredible torque and mid-range power and it pulled effortlessly to 4500. No hesitation, stutter or flat spots whatsoever! Total cost of carb, cleaner and base gasket- $28 😀 😀 😀. Now I have an Edelbrock carb to add to my swap meet "sell" pile.
What lesson did I learn? There's no such thing as free parts.
. I think I got lucky on the Caddy Q-jet. It appeared that it had been apart recently and was really clean inside. As an added bonus, the throttle shaft had zero play in it. Hopefully my wasted effort will save someone else some heartache someday.
