I usually post in the 48-56 trucks forum, but I'm looking for help specifically on my crate engine. It's a Blueprint basic 302 (245 hp) with a Holley carb and an HEI. Things started fine. First firing it started like a champ but ran a little less than ideal. It seemed to stay on high idle a long time, in my opinion. My friend tuned things for me. I know he changed the timing, adjusted the choke to open faster, and leaned out the fuel mix. Unfortunately he made these changes one after the other, so I didn't get to see the effects of one at a time. These things seemed to help, and it really idled smoothly and nearly silently, and the truck did wonderfully on its first road test.

Then I noticed it started staying on choke longer. I chock this up to inexperience with a carburetor as I was pumping the gas, but apparently the ignition needs to be providing power to everything but the starter when you pump it. Who knew? I started doing this, and it still stays on choke (and high idle) forever. One day I left it alone and let it time out on its own, and it took 10 minutes, on the fastest choke setting. So now I let it run on high idle for 30 seconds or so and push down the little lever to fully open the choke. Then at least it times out quietly. My in-laws in the apartment above the garage aren't loving the 10 minute high-revving period, and letting it do its own thing would fume out the whole building.

Like I said earlier, it was tuned to run lean, but now it's running super rich. You can see the exhaust, it smells real rich. To give you a sense of how much fuel it's burning I added 6 gallons of fuel to the tank, and it burned it all with half a dozen trips between my garage and my workshop at the other end of the yard. I'd say it burns about 1 gallon for every 10 minutes the engine runs, while idling. It's not like I'm drag racing.

Now it will only run for a few minutes, and it just stalls. Today it limped its way back into the garage and had to be restarted 3-4 times to get through the doorway.

Does anyone have any idea why there is this slow decline in performance with a brand-new engine? I was planning to get a transit permit and drive it to a local mechanic for some tailpipes. Then I decided I should have him look at the tuning. Now I need to tow it to him because it's basically dead. Any advice is appreciated. I called Blueprint to ask about the 10-minute choke, and the tech wasn't very patient with me. I'm going to give them another call on Tuesday. Hopefully I get a more patient tech...

Thanks

 

Your carb is out of whack.

Something is drastically wrong with it.

I would have someone OTHER THAN YOUR FRIEND WHO SEEMS TO HAVE GOOFED IT UP takeit apart and check the jets, float height, power valve and choke.

 

Check the oil and see if the crankcase is filling up with fuel.

 

I checked the oil, and thankfully there is no sign of gas in there.

I'll be bringing it to a mechanic in a couple weeks. I guess we'll see if whatever is going on is covered by the warranty. I'll update later when I get some answers.

 

Check the carb to see if the power valve is leaking. One sign is if the engine won't idle while putting out a lot of black smoke, open the throttle and see if it runs better. The power valve is susceptible to getting blown out by backfires (like from a too lean condition or a bad start).

The power valve can also be working but open up due to too low of manifold vacuum.

 

Update: I called Blueprint to ask how I should proceed and to find out if the warranty would help. After hearing my explanation of what was happening they decided to mail me a new carb. Hopefully that fixes the issue. Sorry I'll probably never know what the real issue was to update you guys.