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-   -   First startup on a rebuild 454 and have flames out the carb (http://www.hotrodders.com/forum/first-startup-rebuild-454-have-flames-out-carb-181582.html)

chevykid90 07-24-2010 02:53 PM

First startup on a rebuild 454 and have flames out the carb
 
i just got done rebuilding my 454 and got it all buttoned up this morning and ready for its first breath of life. i set the cap by twisting it until my #1 plug got spark then moved it counter clockwise about a 1/4 inch. i go to start it up and it will run for about 2 seconds then a 2 foot flame will shoot out the top and die. i have a weind action plus intake and an old Holley marine carb 750 cfm vacume secondarie (believe 1806, no part number on airhorn). i know its back firing but i cant hear it due to just having open headers on the car. and also there is a pinging coming from the valve covers after it shuts off, but it only runs for a max of about 5 seconds.

Timing is the thing i have yet to master, just confuses the h**l out of me.

T-bucket23 07-24-2010 03:17 PM

You need to get a light to check it in the shrot time it is running.
You also should double check your firing order 1 8 4 3 6 5 7 2

Pay special attention to 5 and 7 as they are next to each other on both ends.

Check for an open vacuum port, if you can plug them all until you get it running. Short pieces of vacuum line with a bolt or golf tee work well as plugs.

How did you adjust the valves. Tight valves will also cause issues as the lifters pump up.

Dajerseyrat 07-24-2010 03:19 PM

Flames out of the carburator usually are a sign of a backfire, usually due to improper firing order (would more so be a miss), or mistimed cam. Check the Cam timing again and make sure the distributer was installed properly. What is happening is the fuel mixture is igniting as the intake valves are opening..Cam could be 180 out..

chevykid90 07-24-2010 03:26 PM

firing order is right, and i put the cam straight up with the crank. tightened the lifters just until it pushed down on the lifters. i will plug the vacume ports and see what happens.

Dajerseyrat 07-24-2010 03:39 PM

Quote:

Originally Posted by chevykid90
firing order is right, and i put the cam straight up with the crank. tightened the lifters just until it pushed down on the lifters. i will plug the vacume ports and see what happens.

Swap out carbs...If thats it, then rebuild yours. It's going to be something really silly..It always is..Trust me..

BOBCRMAN@aol.com 07-24-2010 04:28 PM

180 degrees out of time..

poncho62 07-24-2010 04:38 PM

Quote:

Originally Posted by BOBCRMAN@aol.com
180 degrees out of time..


Yep.......or an intake valve way too tight

sqzbox 07-24-2010 04:42 PM

Wrong valve lash. You've got the intakes too tight. Probably the exhaust valves too. :(

Read his method for setting the valves. :nono:

Dajerseyrat 07-24-2010 05:03 PM

Quote:

Originally Posted by sqzbox
Wrong valve lash. You've got the intakes too tight. Probably the exhaust valves too. :(

Read his method for setting the valves. :nono:

I usually set all of mine at 22 thou cold.
He could be too tight, and not fully closing the valves, causing the combustion to come out of the intake, but wouldnt it also come out of the exhaust if the valves all were not fully closing? He also would have really low compression, if that were the case...
OP Did you try a compression test?

68NovaSS 07-24-2010 05:53 PM

Quote:

I usually set all of mine at 22 thou cold.
Not if it's a hydraulic cam and lifters. :nono:

T-bucket23 07-24-2010 06:06 PM

Quote:

Originally Posted by poncho62
Yep.......or an intake valve way too tight

He said it ran for 10 second or so, so it is not likely a 180 out.

I would like a better description of the method used to adjust the valves.

chevykid90 07-24-2010 06:15 PM

non of the above was applicable, lol. it was something really silly. i had it out about 60 degrees. i was getting so upset with it that i just said******and turned it almost a quarter turn counter clockwise and she fired right up. and boy i will tell you what, i will never go back to small block world!!!!

LATECH 07-24-2010 08:22 PM

can anyone say STATIC TIMING?

gofastz 07-24-2010 08:37 PM

hmmm, yeah the valve lash is out bad, the way i do mine is to have someone bump it over for you, and watch the rockers, one is down or bottomed out the one beside it is closed, so adjust it til you cant wiggle the rocker by hand, and do the rest the same, and be sure that you can twist the pushrod, that will get you close, then after the 20 min run let the engine cool so you can take the rocker cover off and then set the lash with the engine running, set to a 1/4 turn after the rocker stops tapping.........

cobalt327 07-24-2010 08:47 PM

Quote:

Originally Posted by gofastz
hmmm, yeah the valve lash is out bad, the way i do mine is to have someone bump it over for you, and watch the rockers, one is down or bottomed out the one beside it is closed, so adjust it til you cant wiggle the rocker by hand, and do the rest the same, and be sure that you can twist the pushrod, that will get you close, then after the 20 min run let the engine cool so you can take the rocker cover off and then set the lash with the engine running, set to a 1/4 turn after the rocker stops tapping.........

If you look at the OP's post above, you will see it was simply timed wrong- underadvanced. An easily made mistake, IMO, and one that'll blow some eyebrow-removing flames from the carb, given the chance. :sweat: :pain:


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