Gets hot and stalls out

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itsfishy said:
I have a 67 Barracuda with a 408 and iron heads, which means it likes to get hot. This past weekend I took the car out for a quick spin to test a new alternator (Powermaster 95 amp). I pulled into a parking lot and hit stop-and-go traffic; the car got to 210 but held there (weather: 85 degrees and overcast). I shut it down for about 5 - 7 minutes while I ran a quick errand. When I got back and hit the key, it was over 210 but that was to be expected. I started it and pulled out of my space...and it stalled. Tried starting it several times and it would catch and then immediately die again the first couple of times, and then after that it wouldn't catch at all but you could smell the fuel. Ended up having to push it back down the parking lot aisle to get out of the way. It's not unusual for it to take a minute to start after it's been sitting and the temp climbs, but this is the first time it stalled out on me. After about two hours it started up again - and of course had cooled down significantly. It has an MSD 6AL and Blaster 2 coil, MSD plug wires, Holley 750 cfm carb. It does have a hood liner that I've been thinking about removing to try and get the engine bay temps down. It could just be a fluke this time but I'd prefer to not have to push it again if I can help it, so looking for any "preventative medicine" and/or suggestions as to why it happened this time. Many thanks!
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You need to fix your cooling issue. Whether it be a water flow issue or lack of fan at low speed or even and your timing is wrong
 
itsfishy said:
Understood. I’ve got a mechanical fan on the car; maybe I need to look into a high volume pump. I know the modern cars run at 210 and are fine with it, but I’ve always thought that to be an apples-to-oranges comparison. Plus (to be honest) I’ve already melted down one motor so I’m hypersensitive to temps.
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They run them that hot for emissions. It's not for power or anything else.

Guys claiming 210 isn't too hot are sadly mistaken.
 
itsfishy said:
It looks like I’ve got some sleuthing to do. Dana67Dart gave a whole list of stuff, but I think hitting the tank and seeing how efficient it is makes a ton of sense as a starting point. I’ll also check into a return system; that makes sense to me as well just because it seems like it will help with one of the possible causes (and possibly be a preventative measure too). I’ve got a lot to learn- thank you all for the expertise.
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It's a shame we have to resort to a return system but also a good thing. There's some cost involved, but the benefits far outweigh that small cost and any trouble it takes to install it. I've preached the benefits of a good return system on here for years and it either falls on deaf ears, I get run over with a freight train, or it's totally ignored. I don't have a return system on either of my older vehicles. A 64 Valiant and a 75 Ford F250, but it's because of finances. Things are always real tight for us, so I have to do things in really small increments. One last thing. If you do plumb in a return system, I also recommend a fuel pressure regulator plumbed into the return line as then it doubles also as the restrictor for the return system. It doesn't matter "where" in the system the regulator is, it will regulate fuel pressure regardless. You'll need what's called a "bypass" pressure regulator and not a "dead head" regulator. Just more information for you.
 
Yes, modern engines run at 210*; but they also have detonation sensors & all types of other sensors that allows safe running at those temps. The old bangers do not have this....

What cam is in this engine & what is the ign timing at idle?
 
Beginning in 1963 Chrysler mounted fuel filters so the outlet would let the vapor out, minimizing vapor lock.
Carburetion and Performance Diagnosis (Session 188) from the Master Technician's Service Conference

1970 basically same position shown in the Dodge Service Manual
1712234720644.png


Then to address restart problems with newer fuels and hotter engine bays the fuel pump was made with an internal bypass. A kit could be added if the fuel pump didn't have this bypass. As explained in the 1972 bulletin, its a tradeoff ( and in my opinion not as good as the return to tank used later). Shown here.
and here
www.tapatalk.com

racingfuelsystems-What to do about Winter Fuel in hot temperatures?

Not sure where to post this, but the carb is a Holley and the problem was it wouldn't take a load at interstate speeds when the air temperatures were
www.tapatalk.com www.tapatalk.com

PS. That braided line is not a great insulator. Get some stainless in there and cover as much as possible with aluminized fibreglass or insulating firesleeve.
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I don't know why a 408 should run hotter than any other engine. Its doing the same work with a different stroke.
Take a look at the factory thermostats, and also the information about gages. We've had these discussion before.
 
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RustyRatRod said:
It's a shame we have to resort to a return system but also a good thing. There's some cost involved, but the benefits far outweigh that small cost and any trouble it takes to install it. I've preached the benefits of a good return system on here for years and it either falls on deaf ears, I get run over with a freight train, or it's totally ignored. I don't have a return system on either of my older vehicles. A 64 Valiant and a 75 Ford F250, but it's because of finances. Things are always real tight for us, so I have to do things in really small increments. One last thing. If you do plumb in a return system, I also recommend a fuel pressure regulator plumbed into the return line as then it doubles also as the restrictor for the return system. It doesn't matter "where" in the system the regulator is, it will regulate fuel pressure regardless. You'll need what's called a "bypass" pressure regulator and not a "dead head" regulator. Just more information for you.
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I was considering swapping from a carb setup to a Sniper setup, which (I believe) requires a return line. Seems like a good way to kill maybe more than two birds with one stone.
 
itsfishy said:
Holley 750, Edelbrock Performer RPM intake manifold.
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I like to start diagnosing at the simple and inexpensive stuff first.

Check your distributor pickup gap at .008 (a dollar bill folded in half is .008)
Also check your distributor to harness connection.
Heat expands things, and I have seen both of these cause no start/restart issues when hot.
 
itsfishy said:
I was considering swapping from a carb setup to a Sniper setup, which (I believe) requires a return line. Seems like a good way to kill maybe more than two birds with one stone.
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Or to open a whole new can of worms.
 
Bewy said:
Yes, modern engines run at 210*; but they also have detonation sensors & all types of other sensors that allows safe running at those temps. The old bangers do not have this....

What cam is in this engine & what is the ign timing at idle?
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I agree with your modern engines statement; that's why I think it's an apples-to-oranges comparison. Plus they're typically all aluminum, computer designed as a single unit, and (normally) put together by robots in a factory. Sure, the basic engineering is the same - it's still an internal combustion engine with most of the same primary parts and pieces - but past that I just think the gap widens. Plus, to combine what someone else posted earlier with my current situation, 210* doesn't leave a lot of "cushion", and if you happen to be out on a 100* west Texas day in stop-and-go traffic I want all the cushion I can get!

Cam is a Comp Cams, 287/304 duration, .497/.483 lift, 107 LOA. No idea about timing (more on the learning curve for me). You guys are lightyears ahead of me on this, but with some time, help from the forum and probably a few tools I don't currently own, I'll get it down.
 
itsfishy said:
No idea about timing (more on the learning curve for me)
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OK. Well that's important. If timing is far off it can put significant heat into the cylinder walls while still operating. (This was done on purpose at idle during the early emissions reduction years). Your car is a street car so timing has to be set for heat soaked conditions (unlike drag racing). Regardless, many of the other tools suggested I think are distractions. But a timing light, tach, and timing tape are essential. You can buy a timing light with tach display and dial back and skip the seperate tach and timing tape. Not quite as accurate but will be functional. Make sure you look at the arrow on the inductive clamp when setting up.
 
Mattax said:
Beginning in 1963 Chrysler mounted fuel filters so the outlet would let the vapor out, minimizing vapor lock.
Carburetion and Performance Diagnosis (Session 188) from the Master Technician's Service Conference

1970 basically same position shown in the Dodge Service Manual
View attachment 1716231336

Then to address restart problems with newer fuels and hotter engine bays the fuel pump was made with an internal bypass. A kit could be added if the fuel pump didn't have this bypass. As explained in the 1972 bulletin, its a tradeoff ( and in my opinion not as good as the return to tank used later). Shown here.
[/URL]
and here
[/URL]

PS. That braided line is not a great insulator. Get some stainless in there and cover as much as possible with aluminized fibreglass or insulating firesleeve.
--------------------------------------------------------
I don't know why a 408 should run hotter than any other engine. Its doing the same work with a different stroke.
Take a look at the factory thermostats, and also the information about gages. We've had these discussion before.
Click to expand...
Great info, thanks. According to the Session 188 material, Chrysler started mounting fuel filters at either vertical or 45* positions specifically for heat issues. I'm not totally vertical, but certainly a long way from horizontal, but I can change that. I was also studying the pics that Oldmanmopar posted and noted the heat shielding on his lines and was going to ask about that, but I think you've answered it. I'm planning to change the filter anyway, so I'll change the line to stainless at the same time.
 
Mattax said:
OK. Well that's important. If timing is far off it can put significant heat into the cylinder walls while still operating. (This was done on purpose at idle during the early emissions reduction years). Your car is a street car so timing has to be set for heat soaked conditions (unlike drag racing). Regardless, many of the other tools suggested I think are distractions. But a timing light, tach, and timing tape are essential. You can buy a timing light with tach display and dial back and skip the seperate tach and timing tape. Not quite as accurate but will be functional. Make sure you look at the arrow on the inductive clamp when setting up.
Click to expand...
Any recommendations on the light/tach/timing tool?
 
Re: Timing.
and a golf tee to plug the hose while setting and measuring baseline (aka initial) timing.
It is critical to measure the rpm for timing measurements. We have no way to know beforehand whether the centrifigal advance begines at 500 rpm or 900 rpm, or even higher.

Chrysler's instructions hold true regardless of whether its a stock engine or a modified one. Clipped and posted here
 
TrailBeast said:
I like to start diagnosing at the simple and inexpensive stuff first.

Check your distributor pickup gap at .008 (a dollar bill folded in half is .008)
Also check your distributor to harness connection.
Heat expands things, and I have seen both of these cause no start/restart issues when hot.
Click to expand...
Me too, and hopefully learn a bit along the way. I did check the connections (as well as plug wires for any signs of melt or cracking) but didn't check the distributor itself. Also why I thought about the coil as someone else had previously mentioned.
 
itsfishy said:
Well...yeah...but I've got one can going, worst case I'll just add more worms!
Click to expand...

Note that I am in AZ.
I run a Holley 770 on my magnum.
3/8 lines up and back for a return system with both lines routed up the corner of the firewall and inner fender insulated then across to attach to a flipped backwards
dual fuel feed hard line.
My return T is right before the hard line that screws on the carb bowls.
I put a gauge in the main feed and a restriction orifice in the return to give 7 pounds at the carb. (no regulator)
I run an electric pump, but see that you use the mechanical, so obviously you pretty much have to have the pump to carb line up front in all that heat.

If you put a return type filter on it you will want to put it as close to the carb as possible to get as much of that hot fuel out of the main feed as possible before it goes into the carb.

The return will very likely solve hot fuel and possible vapor lock issues, but it sounds like you also have an electrical problem somewhere caused by temperature.
 
TrailBeast said:
Note that I am in AZ.
I run a Holley 770 on my magnum.
3/8 lines up and back for a return system with both lines routed up the corner of the firewall and inner fender insulated then across to attach to a flipped backwards
dual fuel feed hard line.
My return T is right before the hard line that screws on the carb bowls.
I put a gauge in the main feed and a restriction orifice in the return to give 7 pounds at the carb. (no regulator)
I run an electric pump, but see that you use the mechanical, so obviously you pretty much have to have the pump to carb line up front in all that heat.

If you put a return type filter on it you will want to put it as close to the carb as possible to get as much of that hot fuel out of the main feed as possible before it goes into the carb.

The return will very likely solve hot fuel and possible vapor lock issues, but it sounds like you also have an electrical problem somewhere caused by temperature.
Click to expand...

If you were ever to go to the drag strip they may not allow the fuel line going up the fire wall like that.

Just an FYI to anyone routing fuel lines. Of course, if yo never go to the track it doesn't matter.
 
Newbomb Turk said:
If you were ever to go to the drag strip they may not allow the fuel line going up the fire wall like that.

Just an FYI to anyone routing fuel lines. Of course, if yo never go to the track it doesn't matter.
Click to expand...

Yea I know, couldn’t care less about tracks.
Super reliable driver was the goal building this car, and it has been.
Well, until Classic Auto Air got involved.
Now all the trust has to be re earned. :D
 
TrailBeast said:
Note that I am in AZ.
I run a Holley 770 on my magnum.
3/8 lines up and back for a return system with both lines routed up the corner of the firewall and inner fender insulated then across to attach to a flipped backwards
dual fuel feed hard line.
My return T is right before the hard line that screws on the carb bowls.
I put a gauge in the main feed and a restriction orifice in the return to give 7 pounds at the carb. (no regulator)
I run an electric pump, but see that you use the mechanical, so obviously you pretty much have to have the pump to carb line up front in all that heat.

If you put a return type filter on it you will want to put it as close to the carb as possible to get as much of that hot fuel out of the main feed as possible before it goes into the carb.

The return will very likely solve hot fuel and possible vapor lock issues, but it sounds like you also have an electrical problem somewhere caused by temperature.
Click to expand...
Noted, though the summer temps and shade in Phoenix are a bit different than Flagstaff or even Kayenta, so I'm not sure if you're stupid-hot in the summers like us or more human-compatible. (I used to live in Farmington, NM, and love Sedona!)

OK, so it really looks like a return system along with shielding the fuel lines will really help with any fuel boil or evaporation regardless of a FI system or a carb, so a good place to start. I also need to know where my timing is, though at this point that'll just be data and I'll need help understanding what that means. But I want to go to your statement about electrical caused by temp, because based on the conversation the temps seem to be the root of the problem (high temp causes fuel boil, vapor lock, possible expansion in the coil and distributor, i.e. electrical problems). It seems to me that getting the temps down into more of a 190* range will help resolve, if not solve, a lot of the other problems. Am I right in that line of thought? If so, shouldn't the vast part of the initial effort be to get the heat knocked down first and see how the motor reacts before chasing down issues that may resolve from that?
 
itsfishy said:
Noted, though the summer temps and shade in Phoenix are a bit different than Flagstaff or even Kayenta, so I'm not sure if you're stupid-hot in the summers like us or more human-compatible. (I used to live in Farmington, NM, and love Sedona!)

OK, so it really looks like a return system along with shielding the fuel lines will really help with any fuel boil or evaporation regardless of a FI system or a carb, so a good place to start. I also need to know where my timing is, though at this point that'll just be data and I'll need help understanding what that means. But I want to go to your statement about electrical caused by temp, because based on the conversation the temps seem to be the root of the problem (high temp causes fuel boil, vapor lock, possible expansion in the coil and distributor, i.e. electrical problems). It seems to me that getting the temps down into more of a 190* range will help resolve, if not solve, a lot of the other problems. Am I right in that line of thought? If so, shouldn't the vast part of the initial effort be to get the heat knocked down first and see how the motor reacts before chasing down issues that may resolve from that?
Click to expand...

Absolutely agree on concentrating on the heat levels first, as that is your most important issue.
It gets just a hair over 100 where I am, but I sometimes drive through Needles and Death Valley on my way to the beach.

BTW, my fuel lines are wrapped 3/8 fuel injection nylon 12 all the way from the tank to the carb and back.
(Picks up less ambient under car temps with hedders)

Not saying you should do this, it’s just some of the things I did to keep the fuel temps down.

Engine running temps are a whole nother can of worms.
3 row core radiator with 5/8 tubes.
Mechanical 8 blade water pump.
Hi flow thermostat.
Mechanical steel 7 blade clutched fan.
190 thermostat.
Might get to 195 on a real hot day in traffic.
 
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