502 questions
Thread Starter
Racer
Joined: Jan 2002
Posts: 274
Likes: 2
From: Prescott,Az
502 questions
I have questions about carbs & timing. I have a ZZ502 crate motor with alum heads. I am still using the original 850 single pumper Holley that came with this engine package. After a couple of RW dyno pulls it was recommended that I change the air cleaner element to one that takes in air from the lid. I have made this change and some have recommended that I mill down the carb air horn as well. I have rejetted the carb to richen up the mixture and now have jetting at 74 primary and 80 secondary. (Originally had 74/76). Is there any more horsepower/torque tricks left in the carb. This is a street car and never sees the drag strip. (Just want to get the most power out of it).I have heard some guys charge $250-$300 to trick out a carb for more power. What is it that they do inside the carb that's worth that kind of money?
Regarding timing I know that GM recommends 36 degrees total for the timing. I am running 39 degrees as I heard from someone on the forum that big blocks need more timing than stock. Also that same person told me to put the majority of the timing in the distributor ( have 29 degrees) and the balance in the initial timing (have 10 degrees) rather than the reverse (majority in the initial setting).The reason I was told this is that the former makes the engine respond quicker to throttle. The bottom line here is will I pick up any horsepower or torque at the 36 degrees total? I am not having any detonation problems with the 39 degree setting.
Reply's please!
Regarding timing I know that GM recommends 36 degrees total for the timing. I am running 39 degrees as I heard from someone on the forum that big blocks need more timing than stock. Also that same person told me to put the majority of the timing in the distributor ( have 29 degrees) and the balance in the initial timing (have 10 degrees) rather than the reverse (majority in the initial setting).The reason I was told this is that the former makes the engine respond quicker to throttle. The bottom line here is will I pick up any horsepower or torque at the 36 degrees total? I am not having any detonation problems with the 39 degree setting.
Reply's please!
Melting Slicks
Joined: Oct 2013
Posts: 2,054
Likes: 211
From: Central Ohio
For a street car I would not spend the bucks on tricking out the carb as you describe.
By taking off the air horn you loose your choke which will not work real well in the buckeye state except for the middle of the summer.
Work on reliability and drivability first and you will be far happier In the long run.
My big block (454@.040 + 489hp, 540+ft pd torque from 2400 rpm to red line} liked 34 degrees all in with 16 initial. 1 light spring in the dizzy.
I like quick fuel carbs or the Holley street avenger. I would spend the money to have someone work your carb for your combo. Someone that is good at dialing in a carb is worth their weight in gold in my book. They can dial in the tip in speed for the back bowl which sounds like it might be a little slow based on how fat the back jets are now.
By taking off the air horn you loose your choke which will not work real well in the buckeye state except for the middle of the summer.
Work on reliability and drivability first and you will be far happier In the long run.
My big block (454@.040 + 489hp, 540+ft pd torque from 2400 rpm to red line} liked 34 degrees all in with 16 initial. 1 light spring in the dizzy.
I like quick fuel carbs or the Holley street avenger. I would spend the money to have someone work your carb for your combo. Someone that is good at dialing in a carb is worth their weight in gold in my book. They can dial in the tip in speed for the back bowl which sounds like it might be a little slow based on how fat the back jets are now.
