Studder when coming back down from launch

kingsransomracing · 04-27-2009, 07:31 AM

This last weekend was the first time out with a transbrake...and the car was launching fantastic...tires about 1-1.5 feet off the ground and carrying them for about 20-30 feet. I noticed however that when the car was landing it would studder...we have some theories which I have below, but wanted to get your take on it.
What do you guys think it is.

Here are my ideas:

1) On the landing the fuel in the secondaries is coming forward in the bowl and splashing up the vent tube and then into the carburetor make it ultra fat.

2) The "jet extensions" I have which Dave Lange put on are a 1" tube that slips over the jets, rather than having the screw-in type that holley makes.

3) I have my fuel plumbed in coming in from the side to the regulator which is mounted next to the carburetor, someone was talking to a super stock guy and said that with hard launches, the fuel line should go all the way up to the radiator and then come back to the regulator to keep the fuel pressure up at the regulator fro m the hard launches.

As a reference...60' averaged 1.39 with my best being a 1.36.

55 Chevy · 04-27-2009, 09:10 AM

The fuel coming in the front of the carburetor instead of the side I believe is important. Everything is moving back rapidly at launch & it can't hurt to have the fuel moving straight back to the carb. It used to come in the side on mine & I changed it. Car picked up slightly ,could not feel it but e.t. was quicker.
Also put a carburetor angle plate on which helped it from running out of gas as the front end came up. Not sure if that would help you, just an idea.

Dragsinger · 04-27-2009, 09:57 AM

you could try connecting the vent tubes with 3/8 fuel tubing vented at the top.

Lapeeracing · 04-27-2009, 04:17 PM

Ok,I assume you are talking a Holley. If so ,you have rear jet extenders, that's good. The next step is to check if you have a "whistle" in the front block.That is a plastic tube that will keep the fuel from sloshing thru the vent slot at the top of the metering block.Install one in it's original length-DO NOT shorten it for a car that leaves with the wheels up! Hope this helps.

04-27-2009, 07:31 AM	#1
kingsransomracing Junior Member Join Date: Oct 2008 Posts: 14 Likes: 0 Liked 0 Times in 0 Posts	Studder when coming back down from launch This last weekend was the first time out with a transbrake...and the car was launching fantastic...tires about 1-1.5 feet off the ground and carrying them for about 20-30 feet. I noticed however that when the car was landing it would studder...we have some theories which I have below, but wanted to get your take on it. What do you guys think it is. Here are my ideas: 1) On the landing the fuel in the secondaries is coming forward in the bowl and splashing up the vent tube and then into the carburetor make it ultra fat. 2) The "jet extensions" I have which Dave Lange put on are a 1" tube that slips over the jets, rather than having the screw-in type that holley makes. 3) I have my fuel plumbed in coming in from the side to the regulator which is mounted next to the carburetor, someone was talking to a super stock guy and said that with hard launches, the fuel line should go all the way up to the radiator and then come back to the regulator to keep the fuel pressure up at the regulator fro m the hard launches. As a reference...60' averaged 1.39 with my best being a 1.36.

04-27-2009, 09:10 AM	#2
55 Chevy Member Join Date: Feb 2008 Location: Calgary,Alberta area Posts: 221 Likes: 15 Liked 12 Times in 11 Posts	Re: Studder when coming back down from launch The fuel coming in the front of the carburetor instead of the side I believe is important. Everything is moving back rapidly at launch & it can't hurt to have the fuel moving straight back to the carb. It used to come in the side on mine & I changed it. Car picked up slightly ,could not feel it but e.t. was quicker. Also put a carburetor angle plate on which helped it from running out of gas as the front end came up. Not sure if that would help you, just an idea.

04-27-2009, 09:57 AM	#3
Dragsinger VIP Member Join Date: Jul 2008 Location: Liberty City [East Texas] Posts: 1,759 Likes: 5 Liked 99 Times in 60 Posts	Re: Studder when coming back down from launch you could try connecting the vent tubes with 3/8 fuel tubing vented at the top. __________________ Larry Woodfin 471W

04-27-2009, 04:17 PM	#4
Lapeeracing Junior Member Join Date: Mar 2005 Location: Michigan Posts: 17 Likes: 0 Liked 0 Times in 0 Posts	Re: Studder when coming back down from launch Ok,I assume you are talking a Holley. If so ,you have rear jet extenders, that's good. The next step is to check if you have a "whistle" in the front block.That is a plastic tube that will keep the fuel from sloshing thru the vent slot at the top of the metering block.Install one in it's original length-DO NOT shorten it for a car that leaves with the wheels up! Hope this helps.