350 running hot, backfiring
Jeff Silva
The car is a '62 Chevy Bel Air with a '77 350 V8 in it. I posted some
questions a few months ago about it not running. Well, it's running now(very
powerful too I might add :) and has a few problems. Here's what's on it:
- Edelbrock Performer Intake & Performer 600 CFM carb
- MSD Pro-billet ready-to-run distributor
- MSD Blaster 2 Chrome coil
- Borg Warner 7mm spark plug wires
- Autolite plugs
- Equal length headers
- 3-speed manual tranny (I hate it! want a TH350!)
- Performance cam(the previous owner forgot what kind)
I have the plugs gapped at .045 and the timing at 14-15 degrees. It idles at
800-900 rpm. Here are the problems:
- Backfires through carb. Usually while going uphill in first or second
gears. Also backfires while cruising in third.
- Runs HOT! With thermostat installed it can get up past 250 degrees when
idling. New thermostat didn't help. As a temporary fix I removed the
thermostat and it runs ok. Flushed coolant system and added fresh
coolant/water mix.
Any help is very much appreciated! Thanks!
-Jeff Silva
jeff-do...@gte.net
(To send email, replace -dot- with a ".")
Robert Hancock
overheating.
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from rhan...@nospamsk.sympatico.ca
Home Page: http://www.geocities.com/TimesSquare/Arcade/9967/
Jeff Silva wrote in message <74nksn$20v$1...@news-2.news.gte.net>...
Bob Nixon
<jeff-do...@gte.net> wrote:
>I hope someone can help me, cause I'm still small-block Chevy illiterate. :)
>
>The car is a '62 Chevy Bel Air with a '77 350 V8 in it. I posted some
>questions a few months ago about it not running. Well, it's running now(very
>powerful too I might add :) and has a few problems. Here's what's on it:
Late valve timing, or slipped a tooth, would cause both the
overheating and backfiring.
1) You sure the cam gears were aligned properly during installation?
2) Do you know the cam is right for this engine?
3) Could the distributor have been 'dropped in' one notch back? See
if the rotor lines up with #1 with the timing mark on the crank at
TDC.
4) Is it hard starting and seem under powered?
Bob Nixon big...@home.com
das...@aztec.asu.edu
http://members.home.net/bigrex/
Bob
>
>I have the plugs gapped at .045 and the timing at 14-15 degrees. It idles at
>800-900 rpm. Here are the problems:
>
try running 4 degrees advance and .075-.080 on the plugs
Chuck Biewer
cam or not, 250 degrees temp is BAD. In my book, the overheating is due to
high friction, not so much combustion temperature. If recently rebuilt, did
the rebuilder clean out the ring grooves of the pistons? That would be my
first worry. If you take out the thermostat altogether, and you're still
overheating, you have a serious mechanical problem. A non-thermostated
engine with good coolant flow should barely keep 160 degrees at normal
performance.
And perhaps poor radiator performance. How wide is the radiator you're
using? How many columns of fins across? For this application, you need a
higher capacity radiator. A NEW one would be best, skip the boneyard here.
As for the backfiring, it is often a timing problem, but can be a result of
a leaking intake valve, and it would only take one intake valve to cause the
backfiring. If the valve is not seating well, the ignited gas charge will
escape back into the intake manifold, and will cause the incoming gaseous
feed from the carb to ignite, causing the backfire. If the valve grind was
good, then the hi-lobe cam timing may be off, but more likely is the wrong
cam for the application. If the lobes are too high, and your lifter springs
are not strong enough, your valves may float, which means they get pushed
too far and don't have a chance to return to the closed position for the
compression stroke before the lobe starts picking it up again for the next
cycle. So, you may need to get stronger springs, and if very strong, then
roller lifters and stronger push rods, too. Once you start messing with cam
lobe lift, you also have to be wary of the other components in the valve
train, including lifters, springs, push rods, and rockers.
I know there are very good books available at car shops written to help you
hype up chevy small blocks correctly. For a $25 investment (or so), and
some time reading, you can save yourself a lot of worry, and become better
informed and build a better engine.
Hope this helps and good luck,
Chuck
Jeffrey J. Potoff
I was going to suggest this also. I had an engine where the builder degreed
the cam in wrong. The thing overheated big time and ran like crap. The
big difference in this situation is that the original poster says he
has good power. Hmmm...
Jeff
Jeff Silva
Chuck Biewer wrote:
>
> Did you rebuild the block, put in new piston rings? Lean or rich, hi-lobe
> cam or not, 250 degrees temp is BAD. In my book, the overheating is due to
> high friction, not so much combustion temperature. If recently rebuilt, did
> the rebuilder clean out the ring grooves of the pistons? That would be my
> first worry. If you take out the thermostat altogether, and you're still
> overheating, you have a serious mechanical problem. A non-thermostated
> engine with good coolant flow should barely keep 160 degrees at normal
> performance.
I have no clue as to the quality of the engine rebuild. It was done by
the previous owner.
I forgot to mention that the fan is a flex fan and is about an inch
outside of the fan shroud. And it's on a short water pump. I'm going to
dig up an old fan and a fan spacer to bring it closer to the radiator.
And a buddy of mine thinks the water pump is bad. I'll be testing that
out later.
>
> And perhaps poor radiator performance. How wide is the radiator you're
> using? How many columns of fins across? For this application, you need a
> higher capacity radiator. A NEW one would be best, skip the boneyard here.
According to what the previous owner told me, the radiator is out of an
Impala SS with a 327 SB. I'll measure it and see later when I get home.
>
> As for the backfiring, it is often a timing problem, but can be a result of
> a leaking intake valve, and it would only take one intake valve to cause the
> backfiring. If the valve is not seating well, the ignited gas charge will
> escape back into the intake manifold, and will cause the incoming gaseous
> feed from the carb to ignite, causing the backfire. If the valve grind was
> good, then the hi-lobe cam timing may be off, but more likely is the wrong
> cam for the application. If the lobes are too high, and your lifter springs
> are not strong enough, your valves may float, which means they get pushed
> too far and don't have a chance to return to the closed position for the
> compression stroke before the lobe starts picking it up again for the next
> cycle. So, you may need to get stronger springs, and if very strong, then
> roller lifters and stronger push rods, too. Once you start messing with cam
> lobe lift, you also have to be wary of the other components in the valve
> train, including lifters, springs, push rods, and rockers.
Yikes! I didn't know it could be such a big problem. I've recieved a
lot of tips on adjusting the timing so I'll go that route first.
One thing I didn't mention was that a lot of water vapor comes out the
tail pipes.
>
> I know there are very good books available at car shops written to help you
> hype up chevy small blocks correctly. For a $25 investment (or so), and
> some time reading, you can save yourself a lot of worry, and become better
> informed and build a better engine.
I'll go get a book when I leave work today. Recommendations?
>
> Hope this helps and good luck,
> Chuck
Thanks for your help!
-Jeff Silva
PS: A co-worker offered to sell me the 350 SB out of his El Camino
today. It's dynoed at over 700 hp!
pcme...@boi.hp.com
: You could be running lean - this would explain the backfiring as well as the
: overheating.
What he said. Backfiring is a symptom of being lean. How is the manifold
vacuum at idle? I'll almost bet money you have a leaking intake manifold
gasket.
paul
: --
: Robert Hancock Saskatoon, SK, Canada
: To email, remove "nospam" from rhan...@nospamsk.sympatico.ca
: Home Page: http://www.geocities.com/TimesSquare/Arcade/9967/
: Jeff Silva wrote in message <74nksn$20v$1...@news-2.news.gte.net>...
: >I hope someone can help me, cause I'm still small-block Chevy illiterate.
: :)
: >
: >The car is a '62 Chevy Bel Air with a '77 350 V8 in it. I posted some
: >questions a few months ago about it not running. Well, it's running
: now(very
: >powerful too I might add :) and has a few problems. Here's what's on it:
: >
: >- Edelbrock Performer Intake & Performer 600 CFM carb
: >- MSD Pro-billet ready-to-run distributor
: >- MSD Blaster 2 Chrome coil
: >- Borg Warner 7mm spark plug wires
: >- Autolite plugs
: >- Equal length headers
: >- 3-speed manual tranny (I hate it! want a TH350!)
: >- Performance cam(the previous owner forgot what kind)
: >
: >I have the plugs gapped at .045 and the timing at 14-15 degrees. It idles
: at
: >800-900 rpm. Here are the problems:
: >
: >- Backfires through carb. Usually while going uphill in first or second
: >gears. Also backfires while cruising in third.
: >- Runs HOT! With thermostat installed it can get up past 250 degrees when
: >idling. New thermostat didn't help. As a temporary fix I removed the
: >thermostat and it runs ok. Flushed coolant system and added fresh
: >coolant/water mix.
: >
: >Any help is very much appreciated! Thanks!
: >
: >-Jeff Silva
: >jeff-do...@gte.net
: >
: >(To send email, replace -dot- with a ".")
: >
: >
--
Return address: pcme...@hpbs4922.boi.hp.com
The views expressed are the exclusive views of Paul C. Menten
and do not reflect the views of the provider of network access.
Powell G and J
>overheating, you have a serious mechanical problem. A non-thermostated
>engine with good coolant flow should barely keep 160 degrees at normal
>performance.
>
it wont stay in the radiator long enough to cool properly, then is pumped
back into the block still hot and uppon return again its even hotter......
Jeff Silva
everyone, I spent a few hours tinkering around with timing, air/fuel
settings and idle settings. It runs good now, with just a little bit of
water vapor out the rear.
But that damn overheating...
When I had it idling when I was tinkering with it it ran just below 180
degrees. Then after a few test runs and more tinkering it was running at
200. After I shut the engine off the temperature sky rocketed(I'm guessing
because the coolant isn't flowing through it and the heat is radiating up
through the engine). But not for long. After about twenty minutes the temp
dropped down below 165.
I checked under the valve covers and all the rocker arms and pushrods are
moving up and down nice a smoothly. I also checked some casting numbers:
Block: 3970010= 350 CID V8, 69 - 79, 145 - 375hp levels and 2 or 4-Bolt
main caps
Heads: 333882= 350/400 CID V8, 70-80, 1.94/1.50 valves, 150-180hp levels,
76cc chambers, Intake flow 137.2 CFM, Exhaust flow 95.4 CFM. These are prone
to cracking.
And I measured the radiator. It's 23" W and 21" T. It looks like it might
be the original!
I'm going to try and stretch that fan out towards the radiator so it's
inside the shroud at least.
Suggestions? Comments? Please let me know. Thanks for your help!
life_...@hotmail.com
Jeff Silva <jeff....@gte.net> wrote:
> One thing I didn't mention was that a lot of water vapor comes out the
> tail pipes.
That's a pretty important detail. Could be a blown head gasket, or cracked
head. Both tail pipes, or mostly one?
> PS: A co-worker offered to sell me the 350 SB out of his El Camino
> today. It's dynoed at over 700 hp!
That's pretty optimistic. An unblown small block that can put out 700 HP would
definitely require race fuel, and would be far from streetable. Sure he's not
exaggerating a bit? :)
--
- Lifespeed
-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
dbug
<jeff-do...@gte.net> wrote:
You haven't mentioned replacing the cam, but, the 350 in the late 70's
had some cam problems with the lobes wearing very quickly because of
insufficient hardening. Lobe wear will cause a multitude of problems
including backfiring and overheating and, less power than the engine
should produce. The best way to check is by removing the rocker
covcers and go through each valve's movement with a dial indicator.
all you need is one or two to really screw it up and make it heat.
The problem is usually the exhaust lobes. Even if the cam has been
replaced, it should be checked if everything else checks out. A new
cam not properly run in in the first 10-30 minutes of engine operation
can kill a cam PDQ.
Bob Vail
cheap at scrapyards. Take a tape
measure and get the biggest diameter possible. Use the plastic shroud.
Make your own brackets to mount it between the motor and radiator.
Mount it to one side slightly if there is a pulley clearance problem.
Toss the original metal fan onto the pile.
and...Discount Auto parts sells an adjustable-thermostat relay for
around $10-$12. It will sense heat from the seam at the side of the
radiator, so you don't really have to poke it in the side of the radiator
hose. Wire the relay ground side to a toggle switch (less than $2 at
Radio shack) under the
dash. When the temp guage reaches 160-190, with the switch sending ground
to the relay, adjust the t-stat to start the fan.
In traffic (heating up) flip the switch to ground, and the fan cuts itself
on only as needed. Flip the switch off when you get air coming thru the
radiator so as not to kill the fan motor.
Because...at interstate speeds, air coming
in will spin the fan faster than the electric motor can spin it and may
damage the electric motor, so you need to be able to cut it off.
With the electric thermostat, it will cut itself off after it has cooled
down-long after you have parked it and walked away.
I hate to sound mercenary;
If seriously considering it, send me a snail-mail address and for $2
and a SASE, I will send you the details; down to wire sizes, fuses
and part numbers; saving you far more in hassles.
Have a great Day! :)
--
Did our actions today set the proper example for those we lead?
Aim Higher! Bob Vail
sff...@scfn.thpl.lib.fl.us
On Thu, 10 Dec 1998, Jeff Silva wrote:
snip
> But that damn overheating...
>
> When I had it idling when I was tinkering with it it ran just below 180
> degrees. Then after a few test runs and more tinkering it was running at
> 200. After I shut the engine off the temperature sky rocketed(I'm guessing
> because the coolant isn't flowing through it and the heat is radiating up
> through the engine). But not for long. After about twenty minutes the temp
> dropped down below 165.
snip)
> And I measured the radiator. It's 23" W and 21" T. It looks like it might
> be the original!
>
> I'm going to try and stretch that fan out towards the radiator so it's
> inside the shroud at least.
>
> Suggestions? Comments? Please let me know. Thanks for your help!
snip)
mitch...@yahoo.com
I dont think anyone's mentioned this yet and I'm no expert but I built and
drive a v8 s10 and my solution to the heat prob was to use the aluminum
radiator from a 4.3 v6 s10 which is slightly larger than the vette radiator
and I've not had any cooling probs since then. I run 2 elec fans on it but
if I had the room, I think a flex would be just as good. If u do replace the
radiator, u might want to give this one a try. I have a 180 thermostat and
it never runs past that.
Just my .02
kba...@tampabay.rr.com
engine is not running a bit too lean and possibly back off the timing to
around 10-12 degrees.both of these items will cause the engine to
backfire and can also raise the operating temperature.If your running a
clutch type fan,make sure it is in good condition and of the heavy duty
type.The light duty versions aren't as tight and have more of a tendancy
to cause overheating at idle.you could try a flex fan setup or an
electric fan setup.I have a simular setup that would also run too hot.I
run a heavy duty clutch fan,a 3-core radiator,10 degrees timing and the
stock jets that came with my 600cfm.I also use a 160 degree
thermostat.on a real hot day using the air conditioning,it might climb
as high as 180,but rarely.I used to have severe overheating at idle and
during heavy stop and go traffic.Since i put the heavy duty clutch fan
in,I have no more problems.
Bob Nixon
(Fumble-FingersŽŠ˝) wrote:
>On Thu, 10 Dec 1998 22:30:26 -0800, "Jeff Silva"
><jeff-do...@gte.net> tripped on the cord to the keyboard and this
>is the result:
>
>>But that damn overheating...
>>
>>When I had it idling when I was tinkering with it it ran just below 180
>>degrees. Then after a few test runs and more tinkering it was running at
>>200.
>
>Here's your clue. You still have the timing too far advanced. Retard
>it just a couple of degrees or so, and see how that works. With a
>SBC, I start my perfect timing search around 5 - 6 degrees BTDC.
>Depending on the engine, I have wound up anywhere from 0 degrees to
>around 10 degrees. If you need more advance for performance, check
>the vacuum lines to the advance can on the distributor, or check into
>heavier mechanical advance weights. You had good idle properties and
>advanced the timing slightly to get better performance. Back it up
>and check the advance system out. MSD distributors do offer an
>adjustable advance on most models.
>
>I am not familiar with that particular distributor, and you didn't
>mention if you had converted the older car to electronic ignition. If
>this thing has points, drop everything and set the gap. From looking
>at a couple of different catalogs, and from your original description,
>I'm not sure just what you do have. <G> The MSD Pro Billet is an HEI
>distributor, but the MSD Blaster Coil is used with points. Is it
>perchance a MSD-8360? If so, you need to check the points, then start
>all over with the timing. If it is an HEI distributor, then this
>whole paragraph means nothing. <G>
>
>Most of the talk about the fan missed the relevant point. The fan
>isn't in the shroud. The shroud is there to insure that air is pulled
>through the entire core, and if the fan is not in the shroud, it won't
>do an optimum job of that.
>
>After many years of troubleshooting problems in cars, radios, and
>other devices, I have learned that when I am giving myself a headache
>from banging my head against the wall over a problem, I am usually
>making it more complex than what it really is. Yes, there MAY be
>cooling system problems, but from what you have written, I don't think
>that is your problem. Bad timing can look like a multitude of
>problems. I have to remind myself constantly to use the KISS method.
>(Keep It Simple, Stupid) Once you have the engine idling right, and
>not overheating, THEN work on the performance. If the performance
>adjustments mess up the idle properties, then back up. A street car
>has to idle. Adjust ONE thing then check it. That way you don't have
>to wonder which one of the 5 things you just did screwed you. <G>
>
Nice RANT but the overheating would indicate timing that is TOO slow
<retarded> not TOO far advanced.
Kevin Mouton
Bob Nixon wrote:
> On Wed, 23 Dec 1998 16:52:38 GMT, thes...@innocent.com
> (Fumble-Fingers®©½) wrote:
>
> >On Thu, 10 Dec 1998 22:30:26 -0800, "Jeff Silva"
> ><jeff-do...@gte.net> tripped on the cord to the keyboard and this
> >is the result:
> >
> >>But that damn overheating...
> >>
> >>When I had it idling when I was tinkering with it it ran just below 180
> >>degrees. Then after a few test runs and more tinkering it was running at
> >>200.
> >
> >Here's your clue. You still have the timing too far advanced. Retard
> >it just a couple of degrees or so, and see how that works.
>
> Nice RANT but the overheating would indicate timing that is TOO slow
> <retarded> not TOO far advanced.
>
> Bob Nixon big...@home.com
> das...@aztec.asu.edu
> http://members.home.net/bigrex/
I'm afraid Fumble Fingers®©½ is correct on this one. Overly advanced timing
increases the heat load on the cooling system.
Kev
--
To reply, replace "NOSPAM" in return address with "eatel"
http://www.eatel.net/~kevinm/homepage.htm
************************************************
Kevin Mouton - Automotive Technology Instructor
************************************************
"If women don't find you handsome they
should at least find you handy!"
Red Green of Possum Lodge
************************************************
GregB
Kevin Mouton <kev...@NOSPAM.net> wrote in message
news:36819519...@eatel.net...
the heatload on the cooling system.
GregB
Bob Nixon <big...@nospam.home.com> wrote in message
news:3684a92c.419500802@news...
>On Wed, 23 Dec 1998 19:12:57 -0600, Kevin Mouton <kev...@NOSPAM.net>
>wrote:
>
>>
>>I'm afraid Fumble Fingers®©½ is correct on this one. Overly advanced
timing
>>increases the heat load on the cooling system.
>>Kev
>
>the starter would be doing some serious complaining.
I agree Bob. Not to mention the fact that idle speed would be sky high. Add
to that, you wouldn't even be able to part throttle it without hearing the
death rattle. However, retarded timing will backfire through the carb and
diesel when you shut it down. My advice is to power time it. Warm it up,
make a full throttle run, advance the timing, and keep doing this until you
run it into detonation. Then put the timing light on it and back it off 3-4
degrees. I've done this with every car I've owned. Although my pickup ended
up at 7 BTDC, my pretty much stock 350 in my 78 Camino is about 16 BTDC.
Bob Nixon
Uncle Dodo
>make a full throttle run, advance the timing, and keep doing this until you
>run it into detonation. Then put the timing light on it and back it off 3-4
>degrees. I've done this with every car I've owned. Although my pickup ended
>up at 7 BTDC, my pretty much stock 350 in my 78 Camino is about 16 BTDC.
>
>
>
>
>
>
I agree. I threw my timing light under the work bench a long time ago. I want
the most initial I can get without detonation under load. I get it hot and
power brake it to fine tune.
Only thing you have to be careful of is vacuum advance. I have unhooked it on
some of my older hopped-up street cars. Some of the 80's chevys used full
vacuum at the dist at idle( I guess for extra gas mileage).
Jeff Silva
Since my first post I've tried most of the recommendations made by
everyone and now the engine is running fine. It's been staying between
170-190 degrees and I'm able to make some killer burnouts! Thanks
everyone!
Jeff Silva
jeff-do...@gte.net
(replace -dot- with a .)
Fumble-Fingers®©½ wrote:
>
> On Wed, 23 Dec 1998 19:20:01 -0800, "GregB" <gre...@jps.net> tripped
> on the cord to the keyboard and this is the result:
>
> >
> >Bob Nixon <big...@nospam.home.com> wrote in message
> >news:3684a92c.419500802@news...
> >>On Wed, 23 Dec 1998 19:12:57 -0600, Kevin Mouton <kev...@NOSPAM.net>
> >>wrote:
> >>
> >>>
> >>>I'm afraid Fumble Fingers®©½ is correct on this one. Overly advanced
> >timing
> >>>increases the heat load on the cooling system.
> >>>Kev
> >>
> >>If it were far enough advanced to cause backfiring and overheating,
> >>the starter would be doing some serious complaining.
>
> Can't argue much with that.
>
> >> Bob Nixon big...@home.com
> >> das...@aztec.asu.edu
> >>http://members.home.net/bigrex/
> >
> >I agree Bob. Not to mention the fact that idle speed would be sky high. Add
> >to that, you wouldn't even be able to part throttle it without hearing the
> >death rattle. However, retarded timing will backfire through the carb and
> >diesel when you shut it down. My advice is to power time it. Warm it up,
> >make a full throttle run, advance the timing, and keep doing this until you
> >run it into detonation. Then put the timing light on it and back it off 3-4
> >degrees. I've done this with every car I've owned. Although my pickup ended
> >up at 7 BTDC, my pretty much stock 350 in my 78 Camino is about 16 BTDC.
> >
> I have never gone about it quite this way, but I will give it a try
> the next time I have to set one up.
>
> I'm always open to new tricks. <G>
>
> Fumble Fingers ®©½
> --
> "Cats aren't clean, they're just covered with cat spit."
Bob Nixon
<jeff-do...@gte.net> wrote:
>Since I started the thread I'll put in my $0.02
>
>Since my first post I've tried most of the recommendations made by
>everyone and now the engine is running fine. It's been staying between
>170-190 degrees and I'm able to make some killer burnouts! Thanks
>everyone!
What was the fix, or did you just try everything until in run OK?
Jeff Silva
once I start moving it goes down.
And I just found a new engine wtih a new TH350 auto. I'll be putting the
auto tranny on my current engine and I'll be tinkering with the new engine.
Thanks again everyone!
-Jeff Silva
jeff-do...@gte.net
(replaced the -dot- with a .)
Bob Nixon wrote in message <368f284f.254189252@news>...