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Scott
05-15-2006, 07:07 PM
I just started noticing the rebuilt engine (289) in my 1962 hawk starts missing at high RPM (say at 45+ mph). It only happens when the engine temperature gets to about 160 or more. It makes it very rough at highway speeds, though.

The miss does not happen at the same speeds when the engine is even as warm as 140 degrees. It also is not noticeable when the car is warm, but going slower.

The mechanic who worked on the car today says he thinks he sees evidence of arcing from a couple plug wires - one near the alternator and one near the brake booster.

I believe the plug wires were new with the rebuild, but I vaguely recall the guy who put the engine back said the old wires were OK.
[:0]

Anyway, can arcing happen or become a problem when warm, and not when cold?

N8N
05-15-2006, 07:11 PM
a lot of problems can show up when warm, but my first guess would be the coil as it is mounted right on the intake manifold.

nate

--
55 Commander Starlight
62 Daytona hardtop
http://home.comcast.net/~njnagel

Dick Steinkamp
05-15-2006, 07:13 PM
quote:Originally posted by Scott



Anyway, can arcing happen or become a problem when warm, and not when cold?


Probably not, but to find out for sure, warm it up and park it in a real dark spot...open the hood, rev it a little, and watch for the arcing from the spots the mechanic indicated.



http://thenobot.org/images/s2d/s2d_01.jpg

bige
05-15-2006, 09:26 PM
What does the miss feel like? Engine smooth then sputters a little and smooths again or a surge that feels like a strong wind is hitting you square in the front?

Ernie

R2 R5388

imported_n/a
05-15-2006, 09:36 PM
Does sound like plug wire(s). It would be more evident under load.

Scott
05-15-2006, 11:05 PM
The miss feels like no firing, so that there is significantly more vibration and the usual loss of power. I hear no pinging or slapping sounds, though. Also, it doesn't seem to clear up or really change. Once it starts to do it it's consistent.

Mike Van Veghten
05-16-2006, 02:55 PM
1. Weak coil
2. Weak condensor
3. Misadjusted points
4. Bad plug wires
5. Too big/uneven a spark plug gap
6. Carbon tracking in the cap or rotor
7. [u]Inexpensive</u> plug wires arcing on other items (including rubber products!)
8. Loose and or dirty connections between the cap and plug wires.

Yes arcing can show up more when warm thAn cold. It's easier for the electrical power to find an easier path to take.

There's a few to start with.

Mike

dpson
05-16-2006, 03:24 PM
Check your exhaust heat riser valve, if it's stuck closed it will force half the engine exhuast back through the intake manifold and with todays gasoline it could affect the operation of the carb. You may want to check to make sure it was installed correctly, it has to have the correct side up for it to function. Also check the distributor vacuum advance for a bad diaphram (not sure why hot or cold would make any difference, but it wouldn't hurt to check it).

1960 Lark Convertible
1962 Lark Regal Convertible

Scott
05-16-2006, 03:32 PM
Thanks guys. I'll try to check out as many of those things as I can. It shouldn't be anything in distributor, but you never know. I don't remember if the coil is really old or if it's new. I'll check that, too.

Scott
05-16-2006, 05:04 PM
Question: How can I tell if I have a weak coil?

ROADRACELARK
05-16-2006, 06:53 PM
I ran across this once when a car owner replaced the points in his Lark.
He said it ran fine at low RPM, but at higher RPMs it began to miss. Upon closer inspection I discovered he had left out the tension spring for the points. He said there was not one in the box with the new set of points. Simple to find. Remove the dist. cap. Try to open the contact arm with your finger. It should be pretty stiff. If it's not, look real close to see if the tension spring is in place. It's shaped just like the (sometimes copper) arm the actual point contact is made onto. The tension arm should be "outside" of that arm. Look closely. Shop manual will show you a picture. If all else fails, buy a new set of points, it should be in the box. Hope this helps.

pete
05-31-2006, 05:31 AM
the engine miss can be electrical but make sure the tappets are not too tight adjustment is important to get right heat does expand metal of course so incorrect tappet adjustment will upset running of motor

Scott
05-31-2006, 11:24 AM
Pete,
Is this something that can get out of adjustment with about 4,000 miles on the rebuilt motor?

Roscomacaw
05-31-2006, 01:14 PM
I'll answer that, Scott. Yeah, this could happen after 4K miles. If the valves were adjusted too tight to begin with (something that happens because the unknowing think they should be adjusted until there's absolutely NO tappet noise whatsoever)and they start to get seated from use.[^]

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1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe
1957 President 2-dr
1955 President State
1951 Champion Biz cpe
1963 Daytona project FS

studeclunker
06-01-2006, 01:45 AM
Heloooo Does everybody remember when I had this same problem??? Check your exhaust! Especially that riser valve.

Start with the exhaust. Don't make my mistake.;) I replaced plugs, points, condenser, plug wires, and of course the much maligned... coil. Now, don't get me wrong. After all those improvements the car runs great! But, (and she's got a broad one:D) The exhaust solved the problem.[^]

Lotsa Larks!
K.I.S.S. Keep It Simple Studebaker!
Ron Smith

Scott
06-01-2006, 10:26 AM
Was it too much back pressure? Why would it happen only after it's all warmed up and at higher speeds?

buddymander
06-02-2006, 01:18 AM
I had a car do that once and it was from a worn distributor shaft. It changed the dwell enough to affect the timing on random pulses. Hook up a dwell meter and drive it. Good luck, and "Keep it simple Studebakerers"

Scott
06-02-2006, 10:10 AM
Well, that's a lot of stuff to check, but I'm sure one or more of them is right. Intermittent problems are always the worst.

studebakerkid
06-03-2006, 03:17 AM
Well it happens because the seats have cut in and decreased your tappet clearance and heat decreases it a bit more. Your mechanic should have left extra clearance to allow for valve seat in but he probably hasn't seen that many mechanical lifters.

If you car is ugly then it better be fast.....

65 2dr sedan
64 2dr sedan (Pinkie)
61 V8 Tcab
61 Tcab 20R powered
55 Commander Wagon
54 Champion Wagon
46 Gibson Model A

DEEPNHOCK
06-03-2006, 07:12 AM
Easiest 'back yard' way is to warm up the engine a bit, and then grab the coil with your bare hand.
If it is too hot to hold on to, the coil is bad.
Jeff[8D]


quote:Originally posted by Scott

Question: How can I tell if I have a weak coil?

N8N
06-03-2006, 07:19 AM
Do not do this while the engine is running unless you know your coil wire doesn't "leak." :)

nate

(my left arm is a finely calibrated spark tester)

--
55 Commander Starlight
62 Daytona hardtop
http://home.comcast.net/~njnagel

Scott
06-03-2006, 05:41 PM
Are you guys serious about testing the coil by grabbing it? I never heard that one!

ROADRACELARK
06-03-2006, 08:06 PM
Not the terminals or the coil wire, just the main body of the coil.
Dan

hank63
06-04-2006, 08:51 AM
The coil is just a little transformer, and they don't like heat that much. An easy check is to "borrow" a known good coil. If the problem goes away, you've found the cause.
/H

DEEPNHOCK
06-04-2006, 10:03 AM
Yes, just put your hand on the cylindrical cannister part of the coil.
If it is too hot to keep your hand on it, it is bad.
Warm is normal.. HOT is not.
Just stay away from the sparky end... (That's Nate's job;))...
Jeff[8D]


quote:Originally posted by Scott

Are you guys serious about testing the coil by grabbing it? I never heard that one!

Scott
06-04-2006, 05:34 PM
I ran the car for 10-15 minutes. The water temp got up to 140 or so. I kept feeling the coil. It finally got warm, but never close to hot. I don't think that's the problem. I would have been surprised if it was because I think the coil was new with the rebuild. It seems OK.

Now on to the other ideas.

Scott
06-04-2006, 05:34 PM
I ran the car for 10-15 minutes. The water temp got up to 140 or so. I kept feeling the coil. It finally got warm, but never close to hot. I don't think that's the problem. I would have been surprised if it was because I think the coil was new with the rebuild. It seems OK.

Now on to the other ideas.

GTtim
06-04-2006, 10:43 PM
A lot of the new high resistance plug wires are not suited to old cars and their relitively low output coils.


Tim K.
'64 R2 GT Hawk

r1lark
06-05-2006, 12:36 PM
quote:Originally posted by DEEPNHOCK

Easiest 'back yard' way is to warm up the engine a bit, and then grab the coil with your bare hand.
If it is too hot to hold on to, the coil is bad.
Jeff[8D]


quote:Originally posted by Scott

Question: How can I tell if I have a weak coil?



As an aside......not really applicable to this discussion.....

I had a car years ago (a Datsun, somewhat modified&lt;G&gt;) that all of a sudden would not start when it was cold (30 deg or below). Once the day warmed up, it did fine. I messed with that thing for weeks. New wires, checked all connections, points, condenser, etc, etc. Finally replaced the coil out of frustration, and it started every time. I had never heard of a coil failing when COLD, only when hot like you say Jeff.

These type of things only seem to happen to me......

Paul

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