what causes vapor locking

[NIsaacs]

What are you using for a fuel filter and where is it in the system? If your fuel tank was allowed to set for several years with old gas and non use, such as some of these old cars with different owners have subjected them to, can create a really fine sand from corrosion of the old gas. It can be almost impossible to filter and can flow through several inline type filters. What happens then, is the sand is so fine, it gets in the needle and seat and can stick shut or open. Causes flooding one minute and starvation the next.

 It is so fine you can't see it, unless there is a bunch, like in the bottom of a sediment bowl type filter. However when you manipulate the needle by hand, like when you open it up to check for problems, you can hear it grind. The only way I have been able to stop this issue is with a sediment bowl type filter, the sand is tiny but heavy and will sink out of the gas and not flow through the filter.

Nick

[fryedaddy]

it may be sand left from dried gas.the first carb i had on it was a old 850 that ran great.then about a week or two after i got my new motor running that carb went south.i have a inline filter a foot from the carb but it is the regular type.my car set 4 years before i put this engine in.i noticed when i adjusted the float on the front,it did not feel right when i went to tighten it back while holding a wrench on the nut they wanted to turn together and the screw would tighten before the nut under it would like something was interfearing

[fryedaddy]

ok 110 octane in a clean tank and a new bowl type inline filter.i dont see why that shouldnt fix it.this problem started all at once a few days ago,but it may have taken a while to get some sand in the wrong place.

[fryedaddy]

i hate to bore you guys but i got a ton of info off you all on this topic.

[NIsaacs]

We are not bored at all! What's boring, is when nobody posts anything

Nick

[bn69stang]

how much rubber line , ? , you can insulate your fuel line , do you have an insulating spacer between carb and manifold , how much upper aluminum do you have , and are your filters plastic ? , ethanol  eats at plastic and clogs them .... an electric pump helps , you can also run a return line .. small one .... , how close is your fuel line to the block , manifold ... Bud

[fryedaddy]

how much rubber line , ? , you can insulate your fuel line , do you have an insulating spacer between carb and manifold , how much upper aluminum do you have , and are your filters plastic ? , ethanol  eats at plastic and clogs them .... an electric pump helps , you can also run a return line .. small one .... , how close is your fuel line to the block , manifold ... Bud

my lines are rubber under the hood,i have a 1 inch spacer,metal fuel filter,i dont have a return line.i dont know how to do a return line,i have never seen one or how they work.i put 110 in it yesterday,its doing fine now,but im worried the summer heat will effect it

[bn69stang]

Do you run rubber from pump to carb under hood ? if so does it contact the engine or manifold any where ? ..

[machoneman]

i dont know how to do a return line,i have never seen one or how they work.i put 110 in it yesterday,its doing fine now,but im worried the summer heat will effect it
[/quote]

Check out this vid on how-to:  https://www.youtube.com/watch?v=YUmaAQoHggM

[390owner]

Do you have a spacer under your carb. Sometimes that will help keep the carb a little cooler.

[NIsaacs]

i have a 1 inch spacer

yes 1 inch

Nick

[Lenz]

Hey Bob, thanks for the video link!  This thread got me thinking too.  Last year I was at a large show and cruise and after 20 minutes of unplanned idling in traffic my cooling system started to lose ground (I have addressed that).  Problem was once she got warmer and sat idling she lost all power and then shut down long before an actual overheat.  After a 10 minute wait with the hood up I was able to re-fire, get by the issue and then out into traffic as normal.  My headers surround the fuel line (Hooker SC's), so even though I routed the line away from them I still have 1 tube that passes beneath the line, figure that fuel was just sitting too long in one place.

Return line next on the list for drivability in all situations, other factors could have caused my problem (as described in this excellent thread), but this is just a smart move in my view-

[machoneman]

Hey, you're welcome. Always glad to help. 

[fryedaddy]

i have been driving around for 2 days with no issues.ever since i put the 110 leaded racing fuel in, my car has been doing fine.i watched a few youtube videos,and looked up gas boiling points on the net.i am convinced running cheap winter grade fuels on warm spring days will cause heat soak,gas boiling,vapor locking,etc. im still going to do a few mods to help keep my fuel and engine bay cooler,but the cheap fuel was 90% of my problem. thanks im glad i joined this forum!!

[Lenz]

i have been driving around for 2 days with no issues.ever since i put the 110 leaded racing fuel in, my car has been doing fine.i watched a few youtube videos,and looked up gas boiling points on the net.i am convinced running cheap winter grade fuels on warm spring days will cause heat soak,gas boiling,vapor locking,etc. im still going to do a few mods to help keep my fuel and engine bay cooler,but the cheap fuel was 90% of my problem. thanks im glad i joined this forum!!

Glad it worked out for you.  I only had the problem that 1 time, I run corn-free 93 pump gas in my 9.8:1 dish 445.  You may even be able to come down from where you are to save cost.