I'm having trouble fine tuning my motor. 400 bored .040 over, shaved heads, 224/230 duration with 477/480 lift comp xe cam. 750 cfm carb on a dual plain intake. Recently upgraded to 3/8 fuel system and added a recurve kit in the distributor. Total timing set to approximately 37 degrees. Runs great when it reaches working temp. but runs like crap until then. This time of year it sometimes takes a while to reach working temp (very annoying). It did get worse when added recurve kit, but when warmed up, it definately made an improvement.
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mopar performance distributor recurve kit
- Thread starter moparguy
- Start date
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340mopar
Sorgermotorsports
Sounds like it might be on the lean side, I'd try jetting it up a little.
Chuck
Chuck
69Dart
Well-Known Member
Are you running a choke on the carb?????
Rick
Rick
340mopar
Sorgermotorsports
A cold engine requires more fuel than a warm engine (hence chokes) and if the engine is running on the lean side putting more advance in the timing means you are trying to burn the fuel sooner.
My grandfather used to say all men when born know nothing, it is the man that asks questions that learns and becomes wise.
So ask away,
Chuck
My grandfather used to say all men when born know nothing, it is the man that asks questions that learns and becomes wise.
So ask away,
Chuck
moparguy said:Makes sense, could it just be my choke out of adjustment? Although it does take a good 15 to 20 min. to clear up sometimes. It is currently set in the middle.
Just for the heck of it, try setting the base timing advanced about 8 more then where you have it now. I would do this the night before, then drive it cold the next day to see if it improves.
On the recurve kits they are suppose to have 2 differnent tesnios springs, one to allow partial advance by 1800 RPMS, and the other all in at about 2500-3500 depends on kit. I also have seen some issues that some carbs do not push vacuam to the distributor port when cold. You might want to look at that too. But if all seems ok and the advance helps it, I would use a timing light to graph what your total timing is at idle, 1500, 2500, and 3500 rpms. This input would be helpful. Some kits come in way to late for total timing.
And yes more fuel when cold will help a lean condition. When the engine is hot the fuel atomizes better, and takes less spark to ignite. That being said, things such as heat crossovers in the exhaust pipe and or intake crossovers in the heads or intake being restricted, plugged, or a stuck open vavle in the exhaust pipe for the heat crossover will make it an issue on an lean carb condition very noticable.
Lastly when the engine is hot the intake also heats up and will vaporize the fuel better too.
On new cars running injection they fatten up a bunch the fuel/air ratio and advance the timing when cold. Some even have preheaters in the intake air system.
Get some more details on the ignition 1st before we just throw a lot more fuel at it.
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