Timing... 390/410
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Timing... 390/410
I have a 390 that has been bored out to a 410, does anyone know what the recommended timing would be for this engine? Also what is the dead center for it?
It has a 750 Holley double pumper carb that I think needs to be reworked, but I wanted to check the timing before I start into that.
It has a delay when you stomp on the gas like it is getting bogged down.
I really appreciate the help.
It has a 750 Holley double pumper carb that I think needs to be reworked, but I wanted to check the timing before I start into that.
It has a delay when you stomp on the gas like it is getting bogged down.
I really appreciate the help.
Fleet Owner
Joined: Jun 1999
Posts: 24,552
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From: Creedmoor, North Carolina
MM, Don't know how one would bore out to a .410 because that is achieved by installing a 428 crank in a 390 block. An early stroked engine.
Unless you have one hell of a cam in it the DP is huge overkill, and can't burn the gas that you will otherwise be dumping out on the road through the tail pipes. The Nascar Nationwide series only runs 390 cfms on those big race engines. A good 600-650 should be plenty.
Start out at 8 and adjust til it is happy.
John
Unless you have one hell of a cam in it the DP is huge overkill, and can't burn the gas that you will otherwise be dumping out on the road through the tail pipes. The Nascar Nationwide series only runs 390 cfms on those big race engines. A good 600-650 should be plenty.
Start out at 8 and adjust til it is happy.
John
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MM, Don't know how one would bore out to a .410 because that is achieved by installing a 428 crank in a 390 block. An early stroked engine.
Unless you have one hell of a cam in it the DP is huge overkill, and can't burn the gas that you will otherwise be dumping out on the road through the tail pipes. The Nascar Nationwide series only runs 390 cfms on those big race engines. A good 600-650 should be plenty.
Start out at 8 and adjust til it is happy.
John
Unless you have one hell of a cam in it the DP is huge overkill, and can't burn the gas that you will otherwise be dumping out on the road through the tail pipes. The Nascar Nationwide series only runs 390 cfms on those big race engines. A good 600-650 should be plenty.
Start out at 8 and adjust til it is happy.
John
It bogs down when I floor it, I want to check the timing and the plugs before I mess with the carb, but I had read in other threads that like you said a 750 is too much for this engine...
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So we got into it last night. It was sitting at an 18, we dropped it to a 10 which lowered the high idle, but did not get rid of the lag. The timing would get stuck in an advanced position.
After checking for vacuum leaks and messing with the idle, fooling around with the carb, the distributor (which looks like it sat under water...) and the timing again - we were able to lose the lag, set the idle and the timing. The timing is sitting at a 15 now and running amazing. I am going to put in more work on the carb... and start looking for a new distributor.
After checking for vacuum leaks and messing with the idle, fooling around with the carb, the distributor (which looks like it sat under water...) and the timing again - we were able to lose the lag, set the idle and the timing. The timing is sitting at a 15 now and running amazing. I am going to put in more work on the carb... and start looking for a new distributor.
Lead Driver
Joined: Aug 2003
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From: **** hole San Jose ca.
There's a lot of fine tuning that can be done to a Holley, from pump shooter size, jetting
to 5 different pump cams and Pump size volume 30cc & 50cc. along with the power/jet size. There's a new (A-just a jet) that's an ez way of re-jetting) I really like that setup.. So get a holley carb book on them if you really want to get it dialed in. You'll be glad you did..A lot of people don't like the holleys because they don't understand the tuning of them..So have fun and keep old garage light burning.. my 2cents
orich
to 5 different pump cams and Pump size volume 30cc & 50cc. along with the power/jet size. There's a new (A-just a jet) that's an ez way of re-jetting) I really like that setup.. So get a holley carb book on them if you really want to get it dialed in. You'll be glad you did..A lot of people don't like the holleys because they don't understand the tuning of them..So have fun and keep old garage light burning.. my 2cents
orich
