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hard starting when motor gets warmed up

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    Posted: Jul/30/2018 at 1:55pm
hi .. have a 1969 rambler with a 199 6 cylinder with a carter rbs 1 barrel carb .. put a 1/2 spacer between carb and manifold to keep heat away from carb .. didn't help .. figure gas is getting warm and causing hard warm engine starts .. any ideas ..thanks
rj
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: Jul/30/2018 at 2:40pm
We have to establish what "hard" is.

When you go to start the engine hot, first push the throttle half open before you crank the starter and hold the throttle there as you crank. Release the throttle after it starts. 

They should start in 5 seconds, maybe a little longer if it's a really hot day. That is normal for just about all carbureted engines and that is the normal starting procedure for them. If it's taking much longer than that, we can say it is starting "hard". 
'66 Marlin: 327/T10/3.54 Twin Grip
'72 Wagoneer: 360/TH400/3.31
'73 Ambassador: 360/TF727/3.15
'77 Hornet: 232/TF904/2.73
'84 Eagle: 258/TF998/2.35
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Post Options Post Options   Thanks (0) Thanks(0)   Quote vinny Quote  Post ReplyReply Direct Link To This Post Posted: Jul/30/2018 at 2:42pm
Same symptoms here with a 232 2 barrel WCD carb. It does start a lot better after it has cooled down.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jul/31/2018 at 12:45am
i disagree on that being "normal for a carbureted car". each fall i set the choke one not richer, then leaner in spring. one press of the pedal to set the choke/fast idle, crank, starts in one second. i don't get a lot of cold here, but a lot of hot. no difference in 110F weather.

hot starting shoudl be BETTER than cold start. lubricants are closer to operating viscosity, gas puddles less, etc. spark is spark.

less than that and something is wrong. my partners' 72 258ci hornet with YF, which gets at best an annual tuneup and no more, is the same. ditto all my carb cars back 20 years.

my 63 american did have a "vapor lock" type problem, if it was parked after a very long desert/highway run. it would start fine, but "run dry"  about 20 seconds later, for about 5 seconds. scare the crap out of me after pulling back into the road. solved it by replacing steel line under the hood with rubber (heat soak).

1961 roadster american
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T5z, 3.42:1 mustang axle
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: Jul/31/2018 at 5:05am
Allow me to be more specific. In my experience on quite a few carbureted cars...

Most will hot start with just a quick flick of the key if they are started within a few minutes of being shut off. Yes.

However, if they sit for more than a few minutes after being shut off hot they will take excessive cranking to restart unless the throttle is held partially open while cranking. Doing so will make them start in less than five seconds in most cases. Sometimes sooner, sometimes later. It's caused by heat soak vaporizing the fuel in the carb itself. The vapor partially floods the engine. A few seconds of cranking with the throttle open a little clears out the excess vapor so the engine can start faster than with the throttle closed. 

These are engines that have nothing wrong with them other than being restored to stock. It's just how a lot of them are. Many owner's manuals actually say to hold the throttle partially open for hot starts too. 

I do it so much that it's an ingrained habit. I sometimes mistakenly hold the throttle partially open on an EFI car when I hot start it because I drive carburetors most of the time. 


Edited by FSJunkie - Jul/31/2018 at 5:27am
'66 Marlin: 327/T10/3.54 Twin Grip
'72 Wagoneer: 360/TH400/3.31
'73 Ambassador: 360/TF727/3.15
'77 Hornet: 232/TF904/2.73
'84 Eagle: 258/TF998/2.35
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Post Options Post Options   Thanks (0) Thanks(0)   Quote its RJ Quote  Post ReplyReply Direct Link To This Post Posted: Jul/31/2018 at 11:30am
thank you for your info and help .. bob
rj
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Jul/31/2018 at 12:36pm
Other then the above mentioned fuel and carb, heat:
- can make a weak battery or alternator provide less current, what's the voltage cold, running, hot
- can increase resistance in the starting motor, might want to have it checked if nothing else solves your problems.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Thikstik Quote  Post ReplyReply Direct Link To This Post Posted: Aug/08/2018 at 10:35am
I doubt this is happening to you, but when i used the Holley spacer gasket (1/4 thick) on my 390 cfm, i would get some very rich hot soak starts. So, perhaps its those gaskets.   i reckon they seal better when hot soaked due to expansion, thereby richening mixture too much at times.  Then when cooler, they settle to where carb was set. So ironically, a leaking base gasket/s can set this scenario up causing an overly rich mix.   
75 gremlin x, jeep 4L headed 258,Clifford cam, intake,header. 390 holley. I want a 282 VAM motor!

AC/PS/PDB.

72 AMX , 304 2bbl, 3speed, now disks...probably will sell, want an automatic /AC.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Thikstik Quote  Post ReplyReply Direct Link To This Post Posted: Aug/08/2018 at 10:36am
tomj, You made the hotrod Power tour I do believe?!!
75 gremlin x, jeep 4L headed 258,Clifford cam, intake,header. 390 holley. I want a 282 VAM motor!

AC/PS/PDB.

72 AMX , 304 2bbl, 3speed, now disks...probably will sell, want an automatic /AC.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Aug/08/2018 at 11:21pm
Originally posted by Thikstik Thikstik wrote:

tomj, You made the hotrod Power tour I do believe?!!


yup. 6500 miles. drove it hard-ish, 65 - 70 mph (195.6 OHV, remember!), changed jets New Mexico to Oklahoma (continental divide and mountains, 4000 ft and over), three quarts of oil (a quart every 2000). changed when i got home.

1961 roadster american
195.6 OHV, modded
T5z, 3.42:1 mustang axle
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