70 Iron Posted May 21, 2014 Share Posted May 21, 2014 Just installed a New out of the box 870 CFM Advenger Carb on the BB 427,It does seem to pull some better and works fine but my problem is after shutting the engine off the gas seems to be trickling in and I'm seeing the vapor still coming out of the carb for at least a moment or so. What adj will I need to do to stop this. Thanks as usual , Terry Quote Link to comment Share on other sites More sharing options...
waupachino Posted May 21, 2014 Share Posted May 21, 2014 Did you check the float level? Sounds like the floats may be set high, or another possibility is that the fuel is getting hot and percolating. Quote Link to comment Share on other sites More sharing options...
70 Iron Posted May 21, 2014 Author Share Posted May 21, 2014 Hi Todd,I haven't tried anything yet,just waiting on some suggestions,I just installed it a day or 2 ago and have been doing the electric choke, fast Idle ect.just noticed this this morning.I will check the float when I get back to it.I started it and let in run in the fast Idle for a short while and not up to temp,so could it still be percolating ? Would a heat shield help? thanks Terry Quote Link to comment Share on other sites More sharing options...
stangeba Posted May 22, 2014 Share Posted May 22, 2014 Perhaps a hunk of junk is stuck in the needle and seat. Did you put a good filter on? The see through, plastic lawn mower filters, are not IMO any good. Is the gas tank vented? What else did you do and how long did it sit with, perhaps, old gas in the tank? Stock fuel pump? After my Quadra-jet was rebuilt, I drove it about 7 miles, stopped at a stop sign and it flooded and stalled. Got it restarted, ran the heck out of it and it has been fine ever since. I assume junk in the needle and seat. Good luck! Bruce Quote Link to comment Share on other sites More sharing options...
70 Iron Posted May 22, 2014 Author Share Posted May 22, 2014 Hi Bruce, This seepage/vapor only started when I replace the carb the other day,new non vented tank (70),new gas,vented cap,all new gas hoses and steel lines, new AC fuel pump ,the carb has new filters in it. I called the Holley tech today and he thinks its percolating as Todd said and to put a heat shield under it so I'm going to try that.He said it wasn't that uncommon for some to boil over and nothing to be too concerned with. I haven't checked the float level yet but will when i get under the hood again.Thanks. Terry Quote Link to comment Share on other sites More sharing options...
waupachino Posted May 22, 2014 Share Posted May 22, 2014 Definitely check the float level first. That will tell you a lot. If it's slightly high, adjust it a little lower. Adjusting it a little lower can also help if it truly is percolating, because it will have more area to expand/boil before it flows into the Motor. Quote Link to comment Share on other sites More sharing options...
wallaby Posted May 23, 2014 Share Posted May 23, 2014 Agreed on the float check. It's simple to do on a Holley. You have to get the engine & engine compartment darn hot to get a percolation problem. If you cruised down the freeway for an hour or more in hot weather, then pulled into a gas station and shut off the engine...you might get percolation. Quote Link to comment Share on other sites More sharing options...
70 Iron Posted May 24, 2014 Author Share Posted May 24, 2014 Hi Guys,Checked the primary/Secondary float levels today and they were fine,I did lower them a Smigget just for the H of it. I'll keep check on it for awhile,not too concerned until I start smelling gas .I was busy with replacing the master cyl and bleeding brakes,it has the bleeders in this one.Also replaced the temp sender unit and repair wire with new insulation with the right one from American Auto Wire.They say our Montes/chevelles takes the threaded stud with a nut/washer for the connection.It seem to be working fine. Thanks for your suggestions on the Holley.I'll still install the heat shield between the manifold and carp.They look good even if it don't help Terry Quote Link to comment Share on other sites More sharing options...
70 Iron Posted May 31, 2014 Author Share Posted May 31, 2014 Another question, I got the heat shield today from Jegs,What is the sequence on all the pcs,there is the lrg aluminum plate,2 smaller aluminum plates and 4 gaskets ,Which is 1st to last ? There is no pics or instructions,I'm thinking you start off with a gasket against the manifold but does the lrg go next ? Thanks for any help Terry Quote Link to comment Share on other sites More sharing options...
wallaby Posted May 31, 2014 Share Posted May 31, 2014 Not done this, but I'd guess: gasket, small plate, gasket, large plate, gasket, small plate, gasket, carb. Quote Link to comment Share on other sites More sharing options...
70 Iron Posted June 4, 2014 Author Share Posted June 4, 2014 Thanks Mark,You're close. I just tried them with my 770 Holley and to avoid much trimming it needs to go gasket, lrg plate ,gasket, small plate, gasket, small plate and gasket.The carb needs to be as far away from the bottom lrg plate and I only need to trim for the fast idle screw arm, when you open the throttle it hits the outer edge of the small plates/gasket. I'll check it again after the trimming is done for any more obstructions.Will likely install it in a day or two,Thanks again. Terry Quote Link to comment Share on other sites More sharing options...
wallaby Posted June 4, 2014 Share Posted June 4, 2014 I forgot to say: "Your results may vary" Quote Link to comment Share on other sites More sharing options...
70 Iron Posted June 4, 2014 Author Share Posted June 4, 2014 I forgot to say: "Your results may vary" Yes you did Mark,I read it between ther lines Terry Quote Link to comment Share on other sites More sharing options...
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