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Supercharged, flooding in turns

2K views 23 replies 9 participants last post by  bentwings 
#1 ·
I'm hoping the blower guts will jump in here.

I suppose it seems strange to post this after living with it for 6-7 years.

Here it is...my Willys has a 355 sbc with a 6-71 blower and two 750 dp blower carbs. I've squeezed about all the stuffing out of these carbs possible.,I get reasonable mileage and incredible throttle response. The motor starts and runs very well regardless of weather.

Going around turns such as clover leaf or round abouts I have to be carefull not to get too"sporty car" or the carbs will flood out. You can clearly see this on the AFR gage. My carbs are mounted sideways as most are on this application. The motor has about 4-5 deg down rake to the rear relative to the ground....gravity.
I have to run the floats a little lower than normal do to this. All 4 are dead even to each other.

It will flood out both left and right turns...right turns usually are tighter so more critical. This would indicate the secondaries are sloshing up the side wall and flooding either out the vent or up the main jet wells....I think. I've tried raising and lowering the floats and the current position works the best.

So asking a couple circle guys what they do for accelerating or braking to prevent this, I get conflicting answers. There is some kind of anti slosh baffling but I haven't been able to find it. I do have the tapered floats, maybe I should go back to the straighter floats. It seemed at the time I changed this, the problem got better.

This all came up again cruising this week. I was tail end Charlie with 35 cars in the group. I got caught at a long stop light and the guys got away. They made a turn onto the freeway that I missed so I had to do a quick u turn then dashed down the cloverleaf. I goosed it a little too hard and out of the corner of my eye I saw the AFR drop to 9's and the motor sagged. I let up a little as it caught and I took off. So here we are.....i gotta fix this.

Any of you blower guys go a fix for this?
 
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#5 ·
I've already been up and down on the floats. Up its easy to make it a lot worse. I went the other way a couple flats at a time until the problem more or less went away. Now that I've got handling much better I can corner harder. Where it shows up is coming out of a tight corner then stepping on it....with the blower it's easy to get carried away entering the freeways. The floats are well below the sight holes. Compounding the problem is the down angle on the motor of 4-5 deg. I just checked again with a couple lcircle track parts suppliers and just got blown off. I know they use some kind of porous foam but I have not been able to find it.

I've got an AN 8 line from the tank through the regulator and up to the tee at the carbs, then each carb gets fed by an AN 6. We have very clean gas here from the high volumn stations so I don't use a filter. I never see trash in the bowls. I have a filter on the vent line.

I should just pick up a cheap carb at the swap meet and play with it to see where the fuel is coming out. I thought it was the vent but vent whistles prevent this. I'm pretty sure it's going up the main discharge passage and out the venturies looking at my carb books.

Thanks for suggestions.
 
#6 ·
I finally got through to Brasswell today and talked to him. He suggested a flat viton needle and seat. He says the circle track guys use them. Never heard of them. He said he has them as do all the major carb players. He said he knows exactly what the problem is. Also suggested the road race type floats.

There actually are springs as suggested. I'll order some of these.

Tomorrow after the morning cruise I'm going to go to the carb shop and chat with him. He is a very large rebuilder of Edelbrock carbs as well as Holley and others. He is only open to the public a couple hours a day so I need to be on time...hard to do when you are retired. The only time that matters is how much you have left...haha. I'll possibly get a G reading too.

I'm going to look for some open cell foam that is gas proof. I know you can buy fuel cell foam but I suspect that it is too coarse.

I have a g force app so I'm going to record the level this is happening at.

Also check YB out.
 
#10 ·
Thanks for the replys ....not offended in any way. There are lots of very high powered blown cars using the same configuration. I see wheel stands all the time. Just look at the gasser guys. However they all go in a straight ??? Line. In fact they were the ones that came up with the side ways mount many years ago.

The problem with in line carbs was that fuel flattened against the main jets in the primary and completely away from the jets in the secondary. So jet extensions were created to fix this.

Ultimately the side ways mount worked better. I think it also has to do with the volumn of fuel in the bowls and where the level is. Normal is somewhere around the sight threads. Significant Acceleration stands it vertical, the upper level just past the front most jet. Because only half the float at best is in the fuel it really can't close the needle/seat so fuel keeps flowing and the motor keeps gulping.
But again this is straight line.

Back to turns. Especially to the right. A relatively high G turn causes the fuel to wash up the primary metering plate, high enough to flow out the vent. The fix for that is the vent "whistle" there are several. I already have these. It appears that the fuel can simply flow out the venturies.

So I think the cure is a porous foam like fuel cells have but a bit finer, carefully contoured so the float still operates properly. I haven't found any specifically for carbs.

Holley...blew me off. "You are using the carbs out of design configuration...."

Yeah, I could come up with an angled plate to flatten the carbs out. I think they are about 150 bucks. I just don't think this is the answer. A secondary issue...a bit of vanity here, is appearance on the car. I know sometimes this gets in the way of rational thinking. Take a look at the picture and consider what a level scoop would look like.

Thanks for all the replys. I'm going to do a " g" load test this week end if the Parkin lot is empty. Possibly I'll get to do something with the float adjustments.
 

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#12 ·
That's a good point about the floats. The problem however has existed since day one about 5-6 years ago. I got to a reasonable point and simply began enjoying the car. Gradually I began refining things, making it a little better here and there. It's possible that the floats have deteriorated. Or maybe I'm just driving a lot harder than I used to. I know the cruise group is moving along quite a bit faster than we used to. We used to cruise about 50-55 most of the time but now we are going 60-65 but still within the speed limits. Riding at the back of the pack is fun in a way as I get to stretch my " legs" to catch up but I'm uncomfortable going excessively fast. I know I push the round abouts and cloverleafs much harder than I used to and this is where the flooding happens. So I'm back to tweeting it again.

I see a few guys with tunnel Rams with carbs mounted side ways but they have so many other problems they never get to this. There are a few other blower guys too, some with a lot more power than I have but they just aren't out in traffic like I am.

I'm kinda my own demon.

The floats and sloshing seem to be the key to reducing but not eliminating the problem. I would guess that converting to throttle bodies and EFI would solve the problem, however it would bring a host of new problems....plus a major expense.

Needles/seats ;
I haven't been able to track these down. There are lots of needle/seat assemblies but none listed as flat. I've considered that the ones I have are just getting worn, stick occasionally and need replacement. It would be nice to replace then with something better at the same time. I would think a flat surface would be very sensitive to dirt or trash but maybe self cleaning to some extent...I don't know. I've not seen them mentioned in the carb books either.
 
#14 ·
The fuel pressure is 5 psi rock steady. Even at full throttle.
Yes there is a regulator near the carbs. I have an AN 8 (1/2 inch) aluminum line from the tank to the regulator. AN 6 (3/8 inch) to each carb. Along the way is a Mallory gerotor elect pump. Very quiet solid pump.

The fuel tank has an anti surge baffle and a gallon sump. Filtered vent. New filter this year.

I had not thought about the rock crawlers...I'll dig into their nest tonight. It raining again so the cruise for the evening is cancelled.

I've considered the EFI for a long time. Cost has always been a big thing. Up until the last couple years throttle bodies didn't really work as a pair. The only thing that was available was a hat style throttle body/injector. Very expensive and questionable performance. Today If I was starting from scratch I'd go with dual throttle bodies. I'm stuck with old school.

Thanks again guys
 
#15 ·
a few years back.. i brought up a similar possible issue in the circle track magazine forums..

a few months later.. this showed up. https://youtu.be/LvVK6neQ4q4

my thinking is that with conventional front and rear float bowls.. during high banked operation.. during cautions the left side is flooding.. during high speed race time.. the right side might be running rich..

i recall a 4150/60 float bowl set from the very early 80s that was cast in transparent plastic. might have just been a display version.. i never needed a set so i did not ask..

what you could do.. find a container with similar dimensions to the float bowl.. fill it part way with colored water.. wedge a block of something in it to substitute for the displaced volume the float takes up. mount it on the back of the carb so you can video tape it as you drive to watch the fluid level angle changes.

i would think that the cornering effect even effects edelbrock/carter AFB/AVS/TQ designs as fuel levels from lateral directions still slosh thru the side ways passages..

the only thing i have ever come up with is crazy but it would work... i will have to cut a float bowl up to see if it could be plumbed..

you have seen the press on jet extension tubes. same thing.. but with right angle bends.. the left main jet pulls fuel from the right side of the float bowl.. and the right main jet pulls from the left side.. they may only need to extend 40 or 50 percent one would have to build a tilting carb adapter to allow the carb to be tilted on either the flow bench or engine dyno.. checking the individual flow from the carb... how to do that is to divide the plenum for this test.. individual a/f meters in the headers would be required to verify..

i totally agree that it sounds crazy but it might just work.. to bend tubes that tight would require probably hydroforming like they do to make copper sweat fittings.. but tiny brass sweat fittings are available.. might be usable..

607 - 90° Elbow Close Rough C x C - Wrot ells. or street ells.. 607-2 - 90° Fitting Elbow Close Rough Ftg x C - Wrot

cutting down to make them as close to the jet as possible.. i don't really think they will restrict jet flow.. but they will effect the fuel level during cornering.. cost .. might be less than 30 bucks for a hand full and come copper tubing or even better thin brass tubing.

this is just an idea...

after i posted my question.. i had actually ask one of the aftermarket carb manufacturers about the flames coming out of sprint cup cars during engine braking going into corners... the extra high manifold vacuum pulling excessive fuel for the amount of air and it going thru.. washing down the rings and the MPG going right out the tail pipe.. about 3 races from the end of the next season.. the announcers noted that the guy leading the race did not have any flames out his tail pipes during cornering.. then they looked at the specs.. everybody was running out of fuel at 51 or 52 laps.. he was going 56 and 57 laps between pits.. and yes he won that race on fuel economy.

my idea was with billet metering blocks.. plungers built into the metering blocks that are spring loaded up. they cut off fuel flow to the idle circuits above 18 inches of vacuum .. i was actually jumping up and down. then the coverage cut short.. turned out that was the last season of carbs.. when they went to fuel injection. they had trouble filling the tanks.. i posted why not use different percentage of opening foam in the fuel cell. course foam at the bottom.. tighter foam at the top.. but the trick is.. the fuel fill tube extends thru into the course foam.. so the tank fills from the bottom up.. not the top down.. did anybody read my post.. who knows. i have a few holleys kicking around here.. and a home depot across the street.. i will probably have to go to OSH though. to rig up something for photos.. but it will be days before i could do this.
 
#16 ·
Good thoughts!

I've thought about altering a carb so I could see thru it in places. Not an operating one however. I may just go to swap meet and pick up a junker.

Looks like rain again but Willys and I are going to breakfast regardless. I have a spray bottle of Simple green that I spray under the car and let the road water wash it. Hey, it works!
 
#17 ·
Bentwings,
I have no input that hasn't already been offered up, but please keep us posted on the progress. Someone has had and resolved this issue - there has to be a solution!

Great thread and it would be great to see it come to conclusion with a documented resolution.
 
#18 ·
I read the site posted. It's got an interesting solution that would probably solve my problem. It's more than an afternoon project however. Moroso makes a float foam apparently. I'll investigate this. It's something I've been looking for.

Thanks

Pouring rain again. Haha I was the only guy that drove a streetrod to Sat breakfast. I reminded them I have more miles on my car in the rain than most of them have on sunshiny days.
 

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#19 ·
i love the flattened AED jet extensions.. now to put a left bend and then a right bend in a pair with the ability to pass over each other. i may have to call AED.. those were the people i was talking to about the billet metering block mods for nascar MPG.

oh... and driving in the rain a lot... just curious if you have changed the bowl vent tubes to marine J shaped versions to reduce any possible rain from coming in and contaminating the float bowls.

free water injection during rain... are there any issues with the distributor.. i am taking you have dielectric grease under the spark plug wire cap boots on the distributor cap. so water behind the scoop does not really effect the high voltage.. might also use it to water proof the cap to distributor base or cap to cap adapter joint also. changing the cap vent to a vacuum hose to the firewall would also work to keep water out. but you have it handled.

to duplicate the clear effect.. think small food removable top container.. heck even a soda bottle would work for angle viewing..
 
#20 ·
Surprisingly I haven't had any water problems with the big scoop. I drove 9 hours in the rain one day. One other time I just taped a deflector in front of the scoop. You don't have much air going in the scoop cruising. I think at cruise speed the air actually forms a dam so the unused air just goes around it. I did see about a half point difference in the AFR gage but that may have been just the very humid conditions. I have K&N air cleaners that have a rubber base so they seal up pretty well. They are full of oil so water just runs off them. A little water seeps around the scoop base but the top of the motor is pretty warm so it just evaporates.

Yeah, I have dielectric grease on the plug wires, more so they are easy to remove than anything else. No rust in the distributor. There are a couple of vent holes in the cap and body.

There is not much room between the vents ant the top of the air cleaners. Maybe an inch.

I suppose if we get "....40 days and 40 nights, the rains came...." I might turn the scoop around. Haha
 
#21 ·
Thinking about your carbs mounted sideways, and the fact that hard turns left and right cause different results. The pivot point for your floats is on the side, so as fuel is pushed to the outside of your turn it's either going to pile up at the pivot side, which the float sees as a lower level; or to the float end, which the float will see more as a high level during the max G point of the turn.
I would think that having your float level biased more to the high side would give you a more consistent level. Biased high there is less "head room", and thus less direct impact to the floats. Seems right to me, anyway.
 
#22 ·
That's a thought, however I think as a turn tightens or g's get higher the fuel simply forces the float to drop as the fuel climbs vertically over filling the bowl. The double angle floats are supposed to limit this but one side or the other floods.

I found the Moroso fuel cell mods but they have been discontinued.

It's really a tricky problem. Maybe I just need to slow down and drive like the old guy that I am, haha

It rained again all day so I didn't get to try my " skid pad". It's supposed to be nicer tomorrow.
 
#24 · (Edited)
I did go over to the parking lot but he has a bunch of transport trailers parked there and I just felt uncomfortable trying power turns with these around. It also has become sandy so it is more than just slippery so fo now I'm on hold here.

There are two new round abouts that just opened. I tried going 360 around one of these but I forgot to set up the g force app. I was able to see the AFR go rich however but it is a lot higher " g" than is comfortable plus the round abouts have negative slope to them.

I wish I could say I had better progress but I had an opening in the shop to do some work on my truck so I'm side tracked on that temporarily.

I'm going to get some new needle and seats and start there. The problem seems to come and go plus I've seen the AFR go rich just driving lately so I'm thinking this may be part of the problem. One of the cruise guys said that he has seen floats lose buoyancy due to the ethanol gas we have. Ours can go up to 15 % here. This can get after aluminum if there is water presen. I've checked my tank and I have a low point drain but I don't see any water. There is no coorosion in my aluminum tank either.

The car runs great but mpg has dropped. We are going much faster on our cruises and I seem to get stuck at the back of the pack so I'm accelerating and braking much harder.
 
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