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I previously had a post about my holly 650 problems. I just bought and installed 2 new proform bodies (using original bowls and jetting) and all seems ok except when first starting. When cold starting I must be getting a belch as both carbs have fire (can blow out !) After that fun it then starts quickly with no problems. Running BBC 468 with 2 650's on tunnel. Any ideas on the fire ?
I previously had a post about my holly 650 problems. I just bought and installed 2 new proform bodies (using original bowls and jetting) and all seems ok except when first starting. When cold starting I must be getting a belch as both carbs have fire (can blow out !) After that fun it then starts quickly with no problems. Running BBC 468 with 2 650's on tunnel. Any ideas on the fire ?
How are you starting it? holding the throttle open?
I start it by usually putting throttle to floor once or twice and holding down. This worked ok before putting on the new carb bodies. Now it flames up. Nothing else changed. Timing about 36 degrees, 8 lbs. fuel pressure. Mechanical holley performance fulel pump. I upgraded the bodies because one was dumping gas out the bottom. New body fixed that.
Backfire:idea:
Maybe an intake rocker too tight, crossed plug wires, or incorrect ignition timing.
If all that's ok try pumping less gas on start-up or different starting sequence.
I'll check the timing again. No wires crossed, valves checked. Maybe more gas is being pumped in with new body via accel. pump jets. I'll try only pumping once.
Why didn't you use the jets that came with the carb bodies? It will more than likely lean out your mains re-using your old jets.
In the original carb setup I use 73's and 80's. I used the same for the new carb body. I didn't look at the jets that came with the new carb body but I think the secondary jets are 84's. With the newer carb body should I rejet ? Not sure about primary size, will check in morning.
You did get the little "needles" under the pump squirters back in place, right? How are the float heights? Any fuel dribbling while the motor is idling? (watch your eyebrows while looking...:eek: ) Sounds to me like you've got fuel dribbling into the motor. Maybe the gaskets behind the power valves?
The pump squirters were installed in the new bodies. The float level is good. Power valve gaskets new. I'll start motor again wed. with water and check carbs while idleing, going to check and set fuel pressure at 7lbs. The problem is when starting only, carbs caught fire on top twice when starting. Before I installed the 2 new bodies not problem with starting or fire.
Sounds like it's a little lean. (If you're starting with the butterflys open, it's REAL lean) Typically an engine is lean until it warms up. That's why you need a choke, to richen things up a little. When you start it, pump it, but then keep your foot off the throttle. The butterflys will act like a choke to some extent. Once it fires, then open the throttle slowly and bring up the rpm to warm it up a little.