Hot Rods Hard Starting Old School 327

I've been doing this for more years than I can count but never too old to learn something new. Looking for suggestions regarding the problem. We have a very HAMB friendly 31 coupe built in the 80-90s in the old school manner, built not bought. It has a nicely built 10.5 cr 327 with good heads solid cam, Rochester tri-power and Mallory ignition. It runs like a top and still goes like a bat BUT when cold will not start without ether. After the first start it will start all day. We're running on 91 non-ethanol to keep the fuel system alive but it does the same on 93. I know when it was first built fuel was much better and higher octane but I still think it should start. Any suggestions gratefully received and we'll try anything, this is becoming a PITA. Thanks

 

Before you do the next cold start pull the air cleaners and see if your accelerator pumps are squirting. Sounds like the float bowls are drying out after it sits. Percolation of fuel from heat and then sitting over night? Octane rating makes no difference.

 

^ this, or fuel draining back.

 

Thanks for the tips, carbs are not dry and pumps work fine. We have an electric pump boosting the mechanical pump mostly to fill the system after storage. Another odd thing is that when we do go to ether after attempts with only fuel it acts like it is flooded when it does start. If thinking of a poor spark that thing might cause heart failure if hanging on a wire i.e. a good blue spark.

 

Have you looked at the spark plugs? Does it blow black smoke out the exhaust when it does start? Maybe post some pictures of your system.

 

check to make sure you have a good hot spark and change your spark plugs....when was the last time you did
If you are sure you have fuel and compression...then it is spark

 

primary carb have a choke?

 

. . . And if so, is it working and adjusted properly? If it's an automatic choke, is the choke pull-off working and adjusted properly. Does the fast idle cam move freely when opening and closing the choke valve?

If it's been running rich and/or badly flooded a new set of spark plugs would be a good investment.

 

Also check the timing. Your advance mechanism might not be working correctly, and not returning to the base timing. Just a thought...

 

Thanks for all the suggestions, all have been investigated. It really seems like the issue is the old school hi-comp engine and the crap fuel available today. My next experiment will be to replace the fuel with race fuel just to see if the octane is the problem. An added fact is that 100 airplane fuel is not the answer, I have been in the airplane business for over 50 years and aircraft fuel octane is not measured the same way. 100 aircraft is pretty close to 91 auto with low lead. Still listening. Thanks.

 

Find an AC pump that's screwed together, from the'60s - '70s & rebuild it - or go with an electric.

 

I would knock the initial timing back a couple degrees...?

 

That just made me think about a stretched chain that gives more top end power.
Can cause lower pressure on the bottom. ie: cranking speed.
Check that.

 

Is the ignition properly wired with a resister? A typical points system would be set up so the coil gets 12V while cranking (resister bypassed) and 6V (through the resister) while running. If the bypass wire is missing the voltage to the coil while cranking will be very weak and make cold starts difficult.

 

I've ran 10.5 -1 motors on regular 93 octane and had zero issues, it's not your compression.
Did you try a hot wire to coil off the starter so it gets a full 12 volts at startup ?

 

Are you setting the choke by opening the throttle and letting it return before a cold crank? Before you make your cold start, remove the air cleaner and see if the choke is fully closed (I assume it is on the center carb). Even open a little is like no choke at all on a cold engine. You will have to open the throttle a bit to get the choke to close. The choke should be closed, but not real tight. I like to set them to just close. I've got a 401 nailhead with an AFB, 10:1 compression and a bit hotter than stock cam. It lights off instantly when cold. I had a 348 with Rochester tri-power and it also started instantly.

If the carb has fuel and the accelerator pump is working along with the choke properly set, the only other thing would be a weak spark during cranking. Are you getting full cranking voltage to the coil?

 

That's where I'm at too.

 

Points ignition? Have you checked dwell or at least points gap? How much vacuum does it make at idle when it is running?

 

Just add one of those "noisy" flow through Facet fuel pumps to prime the engine [approx $20]
Wire it to a relay connected from the fuse box on the secondary side
The primary side of the relay is also from the fuse box [or ignition] but ground it via the oil pressure light sender.

As soon as the engine starts [with oil pressure] the pump switches off, and the mechanical pump can draw fuel through it.

I did this on my 57 Chevy and after parking it for 18 months it started within a minute of priming.

Connect it like this


Terminal # 30 to a switched output on the fuse box
Terminal # 87 to the Facet fuel pump
Terminal # 86 is Bridged over to Terminal # 30
Terminal # 85 to oil pressure sender [ground]
Terminal # 87A [optional] to electric choke

:Terminal # 30 and # 86 is dead until the ignition is switched on [the whole relay is dead]

:The fuel pump is only priming with the ignition on until the engine starts

:If an electric choke is used, it doesn't cycle until the engine is running

:Terminal # 85 should be used for ground because a lot of relays are diode protected [ shown] I try to make this a good practice

This also gives the starter motor and battery a fighting chance of survival

 

Maybe the engine hasn't got as much Hi Compression as you think? Could be a bit tired.

 

Off the wall thought here, but....
Prior to starting, when you set the choke with the throttle pedal, are the other two carbs squirting fuel? That would give you the "flooded" condition you mentioned. Check your linkage adjustment.
Good luck!

 

Is the spark blue when cranking, or just blue testing at the points?

A dirty ground connection could cause lower voltage when cranking.

I read your comments. The comment that after the first hard start it will start all day REALLY sounds like dry carburetors, and yes, I did read where you said the carbs were not dry.

I would be interested to know: Before you go to start a cold engine in cold weather, remove the air cleaner(s) from all three carbs, and have three people looking for squirts from the different carbs. Do you get a squirt on the first pump? How about the second?

As others have mentioned, the octane is NOT a starting issue. My shop truck has 10.25:1 compression. I run 87 octane except when pulling a 16' trailer then I use 91 octane. I have chokes on both carbs. At -15 F. pump the footfeed three times and set the chokes. If the battery will turn it over, it will start (points, not electronic).

If the carbs are not empty, all of your pumps function, and you set the choke, and it won't start; then there is an ignition issue.

One other probably totally off the wall possibility. I have one off-topic vehicle that came from the factory with an electronic ignition. Intermittently, the ignition will leave the advance at whatever it was when the engine was shut down, making it difficult to turn over and/or start. The solution has been to quit cranking, and turn off the ignition. It normally works correctly on the second attempt.

Jon

 

These guys have covered all the bases and you seem to have a good handle on the basics, but I will add one more thing that is commonly used for HOT engine starting, not cold. It may help with diagnostics.
Set it up to crank, then give it ignition. Depending on how it's currently wired, this may involve some jumper wires and a bump switch.

If nothing seems to help, go back to basics. Run the valves, check compression, check dwell, timing and spark. make sure fuel is squirting with throttle opening.

 

That reminds me of my grandma. My uncle had a truck that sat most of its life. The battery would go dead quickly, and she always said it was because it was "so powerful". No, the truck had a draw somewhere.

I'm not convinced that it's because it's an old high-performance engine. If your car truly has 10.5:1 compression, it should run perfectly fine on 91 or 93. Have you done a compression test when it's cold?

I think the guys discussing ignition voltage when cranking are pointing you in a good direction.

 

Yup. Hot wire the coil, 2 or 3 pumps, start the motor. When it starts you have a direction to look. Why does it fire on ether? Cuz the voltage is low but ether is very susceptible to any spark and ignites fiercely. My .02...

 

I always remember one thing my old Daddy told me about Ether .
We had heavy equipment,,,,,and he always said to use it sparingly .
He said that a motor will get where it won’t start without it ,,,,,,and then you are in trouble .
Ether is very strong and it will start an engine with almost no compression .

Like these guys have said,,,,,check all your support systems,,,,,timing,,and timing chain,,carb,,,ignition ,,,plugs .
If you suspect the cam timing,,,,,get it started,,,,and connect a vacuum gauge,,,it will let you know about your timing chain .

Your compression will have nothing to do with it,,,as long as it is adequate .
And don’t use any Ether please,,,,,eventually it will never start .
I have seen people use a fairly long shot of it,,,,,and then cuss the engine .
A good sound engine should fire right up .

Tommy

 

I raced Honda 125 powered shifterkarts, had trouble starting at times, starting fluid worked great but was told that's not the best on two strokes.

 

Thanks again for all the help. I knew the problem was not lack of fuel so we back at it looking at ignition. A previous owner had installed a Unilite along with the correct coil, etc. His helper convinced him he needed an MSD box. I pulled that out and it starts fine so I think we got it. I don't need MSD to go for coffee. As to the ether it does have to be used sparingly. I recall back in the late 60s we had a farm supply and installed ether kits that used a spray can along with a cable to spray through a tube directly into the intake. This was in a very cold area where every diesel had a engine heater and of course, long before electronic fuel injection. Thanks again.

 

This is the 2nd or 3rd example in less than a month about how an MSD box was pissing in a car's corn flakes. At the start (no pun intended) I'll say I recall different ways to wire an MSD and I always did the easiest "2 wire" version, but it's been a loooong time since I did one. Glad you seem to be moving in the right direction now. I'd think the Unilite is more than up to the task without the MSD. There's probably a way to make the box work and get the benefits of it but yes, not a necessity.

 

Check the grounds and verify 12volts to the starter, fixed my slow crank issue.