Oil leak and hesitation.
July 26th, 2014, 06:46 PM
#1
Oil leak and hesitation.
Recently swapped carbs to an edlebrock 1406 during an exhaust overhaul (86'd cats and new headers). Not long after the swap I now have a HEAVY delay during W.O.T (dead stop, acceleration or kick down of trans). I've tried all three adjustments for the Accelerator pump to no avail. I pulled the cap and found the rotor to be very loose but even that wasn't the issue. I'm going to put a light on it on my next day off.
During the hesitation experiment I also noticed that when I brought the car to HIGH rpms in park some oil would hit the headers and smoke. The motors dip stick tube broke off awhile back and I havn't fixed it as I have a 350 build in the works. Considering the leak/spray occurs during high rpms only and on the drivers side can I assume its an oil belch from the un-occupied dip stick tube hole in the block or am I facing the "find the oil leak" challenge?
During the hesitation experiment I also noticed that when I brought the car to HIGH rpms in park some oil would hit the headers and smoke. The motors dip stick tube broke off awhile back and I havn't fixed it as I have a 350 build in the works. Considering the leak/spray occurs during high rpms only and on the drivers side can I assume its an oil belch from the un-occupied dip stick tube hole in the block or am I facing the "find the oil leak" challenge?
July 28th, 2014, 07:53 AM
#3
-Ok few things: I checked under, around and behind the drivers side valve covers and no caked or moist oil spots. The solenoid wiring for the starter in-between cyl 3/5 seems to have the most oil on it with a drip pattern ending on the collector.
To clarify. I discovered this when diagnosing the poor throttle response of my new carb and what happens is: Hit accell pump fast and long enough for the secondaries to open and POOF puff of smoked oil leaks up from the collector. When I had the headers put on my mechanic dug out the rest of the old dip stick tube but the replacement I had wouldn't fit which Im guessing is the source of the squirt under the high rpm/pressure. My old man suggested the oil sending unit as the potential culprit but after a review of the chassis manual I don't see anything in that area that would suggest that.
In regards to the Carb; after some research it appears the 1406 is notorious for falling flat upon a stomp on the peddle. I will admit the squirt of the stock pump is pretty wimpy. I am going to swap out the stock piece with a 1468 pump. Based on my research its a simple swap.
Questions: The pump will deliver more fuel than the stock piece but I've also read that it is wise to pump to the .043 nozzle. On an internally stock 307 this seems like overkill but I want to limit the amount of times I'm going to take apart a carb that has >500 miles on it....
Thanks for the feed back!
July 29th, 2014, 06:44 AM
#4
Administrator
Join Date: Oct 2009
Location: Poteau, Ok
Posts: 40,586
On the 1406, the accelerator pump rod has 2 holes. Put it in the upper one to give more fuel per stroke. The other issue I've found with installing the Edelbrock carb is that most don't check to see if the carb is opening up all the way when the accelerator pedal is pressed to the floor. I don't believe you have to up the jets at this time for a 307. In addition some carb problems are actually timing issues.
If you have no dip stick tube installed, bit of blowby will force oil out of the unsealed hole.
If you have no dip stick tube installed, bit of blowby will force oil out of the unsealed hole.
July 29th, 2014, 07:21 AM
#5
On the 1406, the accelerator pump rod has 2 holes. Put it in the upper one to give more fuel per stroke. The other issue I've found with installing the Edelbrock carb is that most don't check to see if the carb is opening up all the way when the accelerator pedal is pressed to the floor. I don't believe you have to up the jets at this time for a 307. In addition some carb problems are actually timing issues.
If you have no dip stick tube installed, bit of blowby will force oil out of the unsealed hole.
If you have no dip stick tube installed, bit of blowby will force oil out of the unsealed hole.
Regarding the timing: Now that I have swapped out the Rochester for the 1406 will that affect the timing? I should still be at 20 degree advance at idle and 36 at mid-range RPMS, correct? My new gun comes in tomorrow so after a deep clean of the timing tabs I will have more info.
Regarding the dip stick tube: I have a 1970 350 on a stand, considering the blocks are identical..can I assume the dip stick tube for that will fit and is there anyway I can get that in without removing the header?
July 29th, 2014, 07:35 AM
#6
Just an Olds Guy
Join Date: Jul 2008
Location: Edmonton, AB. And "I am Can 'eh' jun - eh"
Posts: 24,525
Re: dipstick install? It's going to be a real tight working area. Removal may be the best option. Disconnect the battery though because you're working close to the starter lead from the battery.
July 29th, 2014, 07:49 AM
#7
Administrator
Join Date: Oct 2009
Location: Poteau, Ok
Posts: 40,586
Thanks for the information. I had previously adjusted the accelerator pump (all three setting) to no real avail. I am off tomorrow and I'm going to check the timing and pop in to the new accelerator pump as well and double check for vacuum leaks/issues.
The accelerator pump may work, and yes double check for vacuum leaks around the base and the joints around the manifold to engine.
Regarding the timing: Now that I have swapped out the Rochester for the 1406 will that affect the timing? I should still be at 20 degree advance at idle and 36 at mid-range RPMS, correct? My new gun comes in tomorrow so after a deep clean of the timing tabs I will have more info.
Changing the carb will not effect your timing.
Regarding the dip stick tube: I have a 1970 350 on a stand, considering the blocks are identical..can I assume the dip stick tube for that will fit and is there anyway I can get that in without removing the header?
The dip stick will fit, but getting at the dipstick area may require the removal of the exhaust manifold as the dip stick resides in between the manifold and the block.
The accelerator pump may work, and yes double check for vacuum leaks around the base and the joints around the manifold to engine.
Regarding the timing: Now that I have swapped out the Rochester for the 1406 will that affect the timing? I should still be at 20 degree advance at idle and 36 at mid-range RPMS, correct? My new gun comes in tomorrow so after a deep clean of the timing tabs I will have more info.
Changing the carb will not effect your timing.
Regarding the dip stick tube: I have a 1970 350 on a stand, considering the blocks are identical..can I assume the dip stick tube for that will fit and is there anyway I can get that in without removing the header?
The dip stick will fit, but getting at the dipstick area may require the removal of the exhaust manifold as the dip stick resides in between the manifold and the block.
July 29th, 2014, 10:37 AM
#8
Just an Olds Guy
Join Date: Jul 2008
Location: Edmonton, AB. And "I am Can 'eh' jun - eh"
Posts: 24,525
The other option would be to remove the inner liner on the left side to give more working room.
re: carbs. Not sure why you'd go to a smaller flow 1406. Did you look at QJet replacement? They flow around 750 cfm and the EB 1904 flows 794 cfm. I realize carbs are a personal choice.
re: carbs. Not sure why you'd go to a smaller flow 1406. Did you look at QJet replacement? They flow around 750 cfm and the EB 1904 flows 794 cfm. I realize carbs are a personal choice.
July 29th, 2014, 11:23 AM
#9
Registered User
Join Date: Aug 2013
Location: Nashville
Posts: 177
I'm running a 1406, and it took me a little while to get it dialed in, but it's running 'okay' now. Still not super responsive, but much better than before. Like it was mentioned above, I moved the accelerator pump lever to the hole that's closest to the carb body (faster squirt), and that helped a lot.
Given the lean design of the 1406 and my fear of detonation on a 10.4 compression 330, I also increased my primary jets from .098 -> .100, and moved the primary jets to the secondary jet position .095 -> .098. It's a small bump, but with jets, small changes have huge effects, and I'm happy with that. I'm running a little rich, but that's cheap insurance against detonation.
I also increased the spring pressure on the step up spring. This opens the metering rod a little earlier during acceleration.
One last thing, if you haven't already, hook up a vacuum gauge and get those idle mixture screws set correctly. Too much/ too little gas via the idle mixture screws will make your 1406 tricky to tune.
Given the lean design of the 1406 and my fear of detonation on a 10.4 compression 330, I also increased my primary jets from .098 -> .100, and moved the primary jets to the secondary jet position .095 -> .098. It's a small bump, but with jets, small changes have huge effects, and I'm happy with that. I'm running a little rich, but that's cheap insurance against detonation.
I also increased the spring pressure on the step up spring. This opens the metering rod a little earlier during acceleration.
One last thing, if you haven't already, hook up a vacuum gauge and get those idle mixture screws set correctly. Too much/ too little gas via the idle mixture screws will make your 1406 tricky to tune.
July 30th, 2014, 05:14 PM
#10
UPDATE:
I pulled the top off the carb and installed a #43 pump jet housing (the largest one I could find and a much larger diameter than the stock #31) I also installed a #1468 accell pump and after reassembly the accell pump is in the hole closest to the body of the carb. It has made a very large change in the bog at a dead stand still but it is still there. For the kickdown it is a bit more pronounced but not nearly as bad as it was.
Regarding the timing..The tab is loose.. it actually has play in it and I can't tell if it's missing a cotter pin or what but that had me a bit confused. I scrubbed the gunk from the harm balance and timing tab and that made is "somewhat" readable. I couldn't see the damn marker so I took a piece of blue painters tape and pressed it into the crease on the H.B, unplugged the distributor and I'm at 22 degrees at idle. I've never adjusted total advance timing and when I brought the RPMs up my timing mark vanished and the light I am using is not adjustable.
I have to get a vacuum gauge tomorrow, where should I be? the "ported" or left port on the front of the carb or the "full time" right port? THe owners manual doesn't say.
Also..my tach is off (high) and I've been combing in my chassis manual for an explanation. Any help would be nice.
Just a run down in case I have not been specific enough.
Original motor (about 100k). 1406 carb with the list adjustments, 1" spacer. headman headers-xpipe-2.25 flowmasters. I yanked every piece of emissions tubing, piping, pumps you name it off when I was a teenager and have since plugged everything. New plugs (today).
....This is motivating me to have that 350 built, that I can say with confidence.
I pulled the top off the carb and installed a #43 pump jet housing (the largest one I could find and a much larger diameter than the stock #31) I also installed a #1468 accell pump and after reassembly the accell pump is in the hole closest to the body of the carb. It has made a very large change in the bog at a dead stand still but it is still there. For the kickdown it is a bit more pronounced but not nearly as bad as it was.
Regarding the timing..The tab is loose.. it actually has play in it and I can't tell if it's missing a cotter pin or what but that had me a bit confused. I scrubbed the gunk from the harm balance and timing tab and that made is "somewhat" readable. I couldn't see the damn marker so I took a piece of blue painters tape and pressed it into the crease on the H.B, unplugged the distributor and I'm at 22 degrees at idle. I've never adjusted total advance timing and when I brought the RPMs up my timing mark vanished and the light I am using is not adjustable.
I have to get a vacuum gauge tomorrow, where should I be? the "ported" or left port on the front of the carb or the "full time" right port? THe owners manual doesn't say.
Also..my tach is off (high) and I've been combing in my chassis manual for an explanation. Any help would be nice.
Just a run down in case I have not been specific enough.
Original motor (about 100k). 1406 carb with the list adjustments, 1" spacer. headman headers-xpipe-2.25 flowmasters. I yanked every piece of emissions tubing, piping, pumps you name it off when I was a teenager and have since plugged everything. New plugs (today).
....This is motivating me to have that 350 built, that I can say with confidence.
Thread
Thread Starter
Forum
Replies
Last Post
