Air Cleaner

[larry & kaye kepple]

[Admin note - bounced as a "nonmember submission". Bad "From" header.
Patrick]

I recently had my carb. rebuilt for current fuels by Cinnabar. Then I
had the timing power tuned (while romping on it). I noticed a loss of
power when I put the air cleaner back on so then I tried out my favorite
hill both with and without air cleaner. Without aircleaner I could top
hill at 62 MPH but with it I could only get 52-57 MPH. I have HEI
ignition and the air cleaner has been modified to allow it but the
ignition wires are crammed next to it. So I wiggled them around and the
put a strip of ceramic insulation between them and the air cleaner. Then
I went up the hill at 60 MPH. My next step is to get the new better
insulated ignition wires but my mechanic who specializes in carbuerator
ovehauls also suggests I get a new air cleaner that eliminates the
venturi inlet which also eliminates the vacuum valve. Wes Caughlin says
I shouldn"t do that as it is needed in cold weather. Instead he
suggests I get an air cleaner from a junk yard off a later model
Toranado or Cadillac. The local mechanic says I won't have that much
problem in cold weather. He says it will just lose power until the
engine gets warmed up.

Any suggestions?

 

[philip l. stewart]

Larry Kepple,
After you had your carburetor tuned at Cinnabar's shop you wrote

>> > Then I had the timing power tuned (while romping on it).
>>
Please explain for me (and possibly us) what you mean by having the "timing
power tuned". Thanks.

Phil Stewart
'76 Transmode, TN

 

[john wright]

Larry & Rick
Dick Patterson made several presentation on engine mods at the Rally at
Mrytle Beach. The cold air package is cheap power gain. The rule of
thumb that he presented was that each 10 degrees drop in inlet air temp
to the carb equals a 1 percent gain in horsepower.

J.R. Wright

>

>
> > my mechanic who specializes in carbuerator
> > ovehauls also suggests I get a new air cleaner that eliminates the
> > venturi inlet which also eliminates the vacuum valve. Wes Caughlin says
> > I shouldn"t do that as it is needed in cold weather. Instead he
> > suggests I get an air cleaner from a junk yard off a later model
> > Toranado or Cadillac. The local mechanic says I won't have that much
> > problem in cold weather. He says it will just lose power until the
> > engine gets warmed up.
>
> Larry,
> If you live in L.A., or maybe Arizona, he's probably right. Otherwise,
> he's not. (You have no idea how hard it was NOT to insert a snide remark
> here!!!)
>
> The temperature-controlled air cleaner inlet has several functions:
>
> 1 Reduce emissions by maintaining a fairly constant intake air temperature
> once the engine is off choke. This allows more precise and/or lean mixture
> adjustment, without stumbling or stalling.
>
> 2 Allow the choke to be opened sooner, for better mileage, lower emissions.
>
> 3 Prevent carburetor icing. This is a concern in most of the country.
> Usually occurs between 30 and 40 degrees F., when the relative humidity is
> fairly high. At idle and low speed, the air passing the barely open throttle
> expands greatly, lowering its pressure AND its temperature. Evaporating fuel
> adds to this effect. Any moisture in the air immediately precipitates and
> freezes to the nearest object, like the throttle plate/throttle body. This
> can quickly block the flow of air and cause stalling. (When I lived in New
> England, I experienced this many times. Sitting at a traffic light, and
> "cough, wheeze", it would die. Usually stopped when the engine warmed up a
> little and the thermostatic air cleaner received warm air.) This is even
> more of a problem if the exhaust crossover has been blocked off.
>
> FWIW, a missing preheat system will not cause any noticeable loss of
> power, IF none of these problems arise. It may cause roughness and misfire,
> especially at light throttle. I sure wouldn't remove it.
>
> My .02.
>
> Rick Staples
> '75 Eleganza
> Louisville, CO

 

[larry & kaye kepple]

[Admin note - Bounced due to bad "From" header. Patrick]

To Phil Stewart. By "power tuned while romping on it" I meant the
mechanic adjusted the timing while driving and I had the throttle to the
floor."

 

[terry skinner]

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>
but my mechanic who specializes in carburetor
overhauls also suggests I get a new air cleaner that eliminates the
venturi inlet which also eliminates the vacuum valve
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
I agree with the guy. That is an emission/startup thing.
My idea is to move the Ventura out to the grill where it will get cool,
clean, fresh air. The opening of the ventura should be as large as the bore
of the carb. Then it enlarges to what is practical. I think I can get a 6"
tube down through there. The taper should be approx... 5 to 1. When the air
enters the ventura it starts slowing down and compresses. At cruse this
should provide an increase in pressure at the air cleaner. And its free.
If you wonder if it will work, I don't know, just hafta' try it. But there
is one on every Indy car.

Terry Skinner
Webfooted in Washington
'76 Glenbrook

P.S. This is coming from the guy that mounted a heater blower on top of the
air cleaner in a 40 ford.

 

[richard waters]

My previous owner installed an external air supply to the carburetor. It's merely
a piece of metal dryer vent hose connected to a scoop that he bought from Ragusa.
Otherwise the engine just gets its air from the engine compartment. That doesn't
sound good to me.

I also don't like the idea of the A/C getting its fresh air from the engine
compartment
as Arch pointed out. I'm going to do something about that before it turns to
Summer
here (July) in Michigan.
Richard Waters '76 PB, Troy, MI
- -----

> Larry & Rick
> Dick Patterson made several presentation on engine mods at the Rally at
> Mrytle Beach. The cold air package is cheap power gain. The rule of
> thumb that he presented was that each 10 degrees drop in inlet air temp
> to the carb equals a 1 percent gain in horsepower.
>

 

[richard waters]

Scott,
I agree that standard HVAC sheet metal parts should work for the scoop. The
metal
dryer vent duct that goes back to the air filter is standard issue. The vent
duct does
not fit the "air horn" exactly. The previous owner just sort of pushed it on.
I hope
to make it fit better and therefore get more of the ram air during cruise into
the air
cleaner.
Richard
- ----

> In a message dated 5/6/99 9:13:05 AM Eastern Daylight Time,

>
> > It's merely
> > a piece of metal dryer vent hose connected to a scoop that he bought from
> > Ragusa.
>
> Hi Richard!
>
> I'm going to do the scoop thing but since I am one step above the poverty
> level my thoughts are using heating sheet metal duct parts like take-off
> fittings or register boots off, or stack boot at the grill and then running
> the 4" flexible duct to the air filter. There are so many different duct
> parts available that something has to be able to fit. I'm just not there
> yet.
>
> Scott Odds and
> Ends(Bogie Frame Repair)
>

 

[richard waters]

Emery,
Thanks for setting me straight. It didn't make sense that GM would
take the air from the engine compartment, but then what do I know?
Richard

>
>

 

[philip l. stewart]

> [Admin note - Bounced due to bad "From" header. Patrick]
>
> To Phil Stewart. By "power tuned while romping on it" I meant the
> mechanic adjusted the timing while driving and I had the throttle to the
> floor."

Larry,I'm impressed with your mechanic. The last time I timed my HEI I
almost fell into the fan while hanging over the open engine compartment to
get the timing light's strobe to hit the timing mark just right.. And this
was with the transmission in park and coach sitting motionless in the
driveway. Your guy's got some sense of balance! .
Phil Stewart
'76 Transmode, TN

 

[patrick flowers]

I've been stuggling with this "balancing act" too. Finally wised up
this past Friday and cut two pieces of 5/4X6 decking boards 34.25 inches
long. I can lay one or two of them across the engine compartment on the
aluminum tracks that hold the engine cover and then I place a folded
beach towel on top(I guess I could get fancy and upholster them). It
makes working on the front of the engine much easier.

Currently in the process of converting to HEI!
Patrick

>
> Larry,I'm impressed with your mechanic. The last time I timed my HEI I
> almost fell into the fan while hanging over the open engine compartment to
> get the timing light's strobe to hit the timing mark just right.. And this
> was with the transmission in park and coach sitting motionless in the
> driveway. Your guy's got some sense of balance! .
- --
Patrick Flowers
Mailtoatrick

The GMC Motorhome Page
http://www.gmcmotorhome.com

 

[john dolan]

Emery...

I've done this too, but I don't have a HEI distributor. Phil has a HEI
and I have never grabbed a hold of a running HEI. Maybe it is possible
to do so without a shock if you stay on the rug, and don't touch the
aluminum frame around the hatch. Sometimes I have gotten a medium level
shock from my OEM 74 distributor and I still get a little jumpy just
before I grab the top of that insulating cap with the 9 wires come out of
it.

I have done it but every book I have read says never allow your system to
be power tuned... comments?

> While on a trip last summer my wife rotated the distributor while I
> drove because we either had a bad batch of gasoline or something that
> caused a lot of pinging on hills. In this case we retarded the timing
> a little.

- --
"I do whatever my Rice Krispies tell me to..." John said, from inside a
1974 Glacier.

 

[voyager]

I set my timing while the engine was running. I
was alittle leary of touching the cap...but
since I didn't have a helper I had to move it
myself. No shock...but I have new plug wires
installed.
Rob Teed 74 Painted Desert
( 6 days away from the Florida Keys trip )

> -----Original Message-----
> From: owner-gmcmotorhome
> [mailtowner-gmcmotorhome]On Behalf Of Patrick Flowers
> Sent: Sunday, May 09, 1999 11:05 PM
> To: gmcmotorhome
> Subject: Re: GMC: Air Cleaner
>
>
> I've been stuggling with this "balancing act" too. Finally wised up
> this past Friday and cut two pieces of 5/4X6 decking boards 34.25 inches
> long. I can lay one or two of them across the engine compartment on the
> aluminum tracks that hold the engine cover and then I place a folded
> beach towel on top(I guess I could get fancy and upholster them). It
> makes working on the front of the engine much easier.
>
> Currently in the process of converting to HEI!
> Patrick
>

> >
> > Larry,I'm impressed with your mechanic. The last time I timed my HEI I
> > almost fell into the fan while hanging over the open engine
> compartment to
> > get the timing light's strobe to hit the timing mark just
> right.. And this
> > was with the transmission in park and coach sitting motionless in the
> > driveway. Your guy's got some sense of balance! .
> --
> Patrick Flowers
> Mailtoatrick
>
> The GMC Motorhome Page
> http://www.gmcmotorhome.com
>