Post by muscleruss77 on May 17, 2015 16:50:48 GMT -6
Hopefully somebody on here can provide some technical support to a strange problem I've encounted.....
I have a Willy's 4412 carb that i'm running on my IMCA sport mod claim engine. Its a 9:1 motor with an Edelbrock EPS intake and Protru pistons. The carb is running very rich at idle. The motor is puffing blue smoke from both headers. This carb ran great the first 4 nights and then started to develop the rich idle condition. I had the carb sent back to willy's and they dynoed it and said there were no issues.
The saga continues.....thinking there is still a problem with the carb, I put my old 4412 back on the motor. The rich idle condition goes away, but the throttle response is suffering. It has a big hesitation off idle and was missing on the top end under load.
I pulled the intake and put gaskets in it. Fel-pro, glued them in as well, it was the second set I put in just to make sure this wasnt the cause. I also replaced the distributor drive gear and set timing to 34 which is where I always run it. Carb flange gaskets were also replaced. Checked compression and all the cylinders were 115-130 during cranking. Vacuum at idle is between 5-8".
Any insights into what may be causing this would be appreciated. My next step is to pull the motor down further.
Post by flipflopoo1oo on May 18, 2015 22:27:57 GMT -6
5-8 is not enough vacuum to close the power valve in most cases! I block the power valves first thing and run 83-86 jets with pump gas but have IGN upgrades that is very hot! I never lock my weights but limit to 6-10 advance and run a vacuum advance to clean it up at idle -( also limited at 10 degrees advance with live vacuum) -- This lets me crank at low timing and run at a higher rate to gain more control of my burn timing!!! Timing can then be raised on up as long as enough fuel! Make sure its not drawing off the flow bars at Idle as to trash in vent tubes to idle circuit! They are so small one grain of sand can give trouble! Be sure it has holes drilled in butterflies as to being able to get idle correct with out drawing off the flow bars!!! Make sure the air cleaner is not restricted --K&N over oiled has caused us trouble to the point of glowing exhaust from too much draw!!!!
Post by muscleruss77 on May 19, 2015 11:17:03 GMT -6
Flipflop, thanks for the reply. I've gathered some more data around this issue and will list it here. Once I get back to my shop this Friday I'm going to try a few things.
Flow bars, I assume you are referring to the idle transfer slots. I looked at my carb and noticed that they were exposed at least an 1/8" which is way to much. Something is telling me that I shouldnt have to have my idle set that high to keep the motor running.
I am using stock fel-pro gaskets and heard these can be notorious to leak even if brand new. Using the "printo-seal" gaskets are recommended. I'm going to pull the intake again and install the printo seal gaskets. I really hope I'm still fighting symptoms of a vaccuum leak.....
I've realized my car was on the trailer while doing all the work. The front end was slightly elevated due to the dovetail on the back of the trailer. I set the floats, but if the car is not on level ground the fuel level may be higher in the bowl. There is no fuel running into the carb from what I can tell but may be contributing to the rich idle.
I'm running a 3.5 powervalve and already replaced it thinking there was a diaphram issue. I've always had power valves and never had issues with them.
I'm going to put some new gaskets in and see what happens. I've adjusted so only a tiny amount of the idle transfer slot is exposed and will attempt to set the idle with the mixture screws. let you know what I found out...
The blue smoke worrys me. Something tells me the intake is still leaking and sucking air/oil, or the motor got dusted and the rings are shot. Clears up when the RPM's are raised so
Post by flipflopoo1oo on May 19, 2015 17:31:57 GMT -6
if HEADS WERE ANGLE CUT OR SHAVED YOU MAY HAVE TO SLOT OR DRILL BOLT HOLES TO MAKE IT ALIGN! I have even had to add a spare gasket in some cases but glue them in place with yellow 3M glue and let them dry before replacing the intake!!! As you turn up or on top end when you need more fuel the power valve shuts it back! We get a harder pull all the way in the corner if needed and helps to cool pistons and hook us up off the corner with less torque for a second or two! We can run it leaner this was and you think its got nitro when it catches up! We can also run higher timing to get more horses on demand! Flow bars are the main flow of fuel up top!! If throttle is too open at idle it will pull out the top all the time due to the off idle feed ports!!! The hole in center of upper butterfly next to shaft lets you get air and idle it back off the ports to idle circuits!!! If you place your hand slightly over carb and it idles up---you have a leak some where! If it goes down --probably not! If you screw the idle screws in one at a time -either should just about or kill the motor-- if not its drawing fuel from some other means and shouldn't! Try upping your timing and just see if the engine perks up-- a bad pick-up coil or weak coil can reek havoc on tune! Feel of your coil or make sure its grounded properly! Check all this before a tear down-- --A valve too tight can also cause vacuum loss-- Are you having a blow by issue as well or loosing oil? Are you running 50w racing oil or some thin stuff like 10-40w? We run no valve seals but use oil restrictors in the back of the block! Good luck with finding the culprit!!!
Post by flipflopoo1oo on May 27, 2015 3:45:23 GMT -6
Good deal there -- Bronze guides are loose-- I use umbrella seals that move with the valve as to never wear out! The PC seals starve the guides for lube with as much gas is washing them off! New steel guides need nothing but the o-ring up top to keep from wearing out! Oil restrictors helps too!!!
Post by muscleruss77 on Feb 1, 2016 19:52:25 GMT -6
I was talking to my machinist the other day about my cylinder heads and this problem I had with these valve guides wearing out awhile back. Not sure why the conversation came up again, but he enlightened me about a discussion he had with Engine Quest about the very issue.
EQ recommend putting liners in right away when these heads are new since they are only drilled cast iron. Morale of the story is you get what you get from a $650 set of heads. Check them over good for quality issues. The ones I bought seem to be a good head over stock, but save yourself some headache and put liners in right away. Also dont buy them assembled. Get a bare set, get liners, check seats, put in some good stainless valves and decent springs, etc. I'm no cylinder head expert, just some things I've learned thus far.