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Tom & Janet Salhus · 10-07-2003, 02:14 PM

Hello, We are new to the forum and new to the Airstream Motor Home. We have had the 90- 345 LE for about three weeks now. I am in the process of tuning it up now and am trying to check the timing on it but that does not apear to be as easy as it is on my 51 Mecury with a flathead in it. We have the 454 chevy with the banks power pack. I cant get to the timing mark from the top, is there a beter way to approach timing of this motor

PeterH-350LE · 10-07-2003, 02:24 PM

Check if you have secondary timing marks installed. Mine are bolted to the oil pan and easily accessible from the bottom. Instead of using cyl #1 for setting the timing, you will have to use #5 or #8 (to make up for the 90 degrees offset to the factory timing marks.)

Tom & Janet Salhus · 10-07-2003, 02:48 PM

Thanks Peter H, I just went out and looked and shure enogh there are timing marks right where you said they should be. Thanks very much. We are planing our first trip with it for the end of November. We are brand new to this Motor Home thing and we are looking forward to our first trip but I want it to be a successful fun trip for my wife especialy. I am a retired owner operator, coast to coast, over the road driver so it is going to be great for us with this Airstream. Thanks Again, Tom

PeterH-350LE · 10-07-2003, 03:14 PM

Tom, no problem, glad I could help.
That sure is a nice rig, the 1990 345LE. I am sure you will enjoy driving it a lot after being a big rig operator.
If you happen to find your timing being advanced to factory specs, think twice about changing it. There are some weird gearheads out there (I am one) who believe that the BB chevys run better advanced, especially in extreme mountain driving.
BTW, welcome to the forum!

Tom & Janet Salhus · 10-07-2003, 03:29 PM

PeterH, Have you had any experienenc, pros or cons of instaling a spliter gear box, US Gear or Gear vender? I have been thinking of instaling on or the other but not shure about it. On pulling grades I would think it would be very good but I don't know if the motor, 454, is designed for the higher RPMs on a pull. Any comment is great

PeterH-350LE · 10-07-2003, 03:40 PM

Tom, there are some MH owners on the forum who installed a gear vendor.
No personal experience other than the desire for one and a recommendation from my local transmission guy.
My primary reason for installing one would be the OD function for hwy travel. Never had to use 1st gear when climbing 10k + passes.

Tom & Janet Salhus · 10-07-2003, 03:48 PM

Thanks for the comeback PeterH, I will do some checking out on the form. It makes sence to me to split the long gap betwen 2&3 but I think I had better take a few trips and get the feel of the unit. Tom

74Argosy24MH · 10-08-2003, 06:31 AM

I put in a U. S. Gear overdrive. I asked several places about one being significantly better and didn't really get a definitive answer, so I bought the cheapest one I could off ebay. It came out of a mh that had burned so I had to get the control unit also, but installation was easy, the od replaced the tail shaft housing, run 4 wires, mount the control box and switch. The hardest part was finding a decent price to get the drive shaft shortened.

I got the od because of the decrease in engine rpm and mileage. My mh is quite a bit lighter than yours so I am not as concerned about hills. The underdrive ratio is 1.25 so it will significantly increase rpm, but it will be for a relatively short time and shouldn't affect the engine unless it is already weak.

John

loulemons · 12-02-2009, 08:45 PM

i just read your answer to the timing marks on a chevy 454 . i was wondering the same thing about accessing the timimg marks and i also found the ones on the bottom by the oil pan. then i read futher about using either num 5 or num 8 sparkplug wire to read from to counter for the timing tab be located 90 degees out my quetion is what one is the correct wire to read from it seems to me one isnt the easiest most acurate way i mean one had to be correct and one has to be off so is it number 5 or number 8 plug we connect the timing lite to?

Robfike · 12-08-2009, 03:37 PM

Tom & Janet, Welcome to the group.

QuietWater · 12-20-2009, 03:01 PM

May I suggest that you take a look at this thread in RV.net. Of course it isn't an Airstream but a lot of the coach features are similar or the same. The OP just got a new Quadrajet carb and is in the process of installing it. He just got through timing it. He used number 5 cylinder. So far this thread is 36 pages long and is almost a mandatory read for anyone just starting out with an older motorhome.

RV.Net Open Roads Forum: The old girl is back - where to start

ROBERTSUNRUS · 12-21-2009, 01:02 AM

Hi, you can set your timing the old fashion way. With a vacuum gauge connected to manifold vacumm, you want the highest reading at idle that you can get. The other way is to advance your distributor until you hear your engine gas ping under hard acceleration, then retard it just enough to stop the pinging. This method will work if you don't have a timing light or can't see the timing marks.

loulemons · 12-22-2009, 07:24 AM

heres an old hot rodders trick to timing your 454 use a vacuum guage attach it to any non ported vacuum connection on the intake for an example disconnect the vacuum directly underneath the carb that goes to your vacuum assist power brakes then adjust your timing untill you have the maximum reading on your guage this may take several adjustments to allow for advance and retard once you have achieved maximum vacuum back it off about 5 inchs say you have 23 inchs of vacuum then you retard the timing untill you have about 18 what ever your reading is just back it off 5 inchs this should be perfect .this was an old trick i learned from drag racing it works perfect everytime

ROBERT CROSS · 12-22-2009, 08:33 AM

POI

Had a Banks powerpack on our 454, if you have the paperwork check for timing recomendations. If I remember correctly the timing is advanced 3-5 degrees over stock.

TomW · 06-05-2010, 09:34 AM

I went out to check the timing on my 454 this afternoon, and the strobe light could not find the mark on the harmonic balancer even after I verified the strobe was connected to cylinder number one's spark plug wire.

The only work done up until this point was to pull & clean the rotor and check the cap for cracks. Both the rotor and distributor cap only go on one way, so I don't think I screwed up anything there. The truck fired right up afterwards.

Out of curiosity, the strobe's inductive pickup was moved from wire to wire until the timing mark was finally visible after connecting to cylinder seven's wire. This cylinder is six cylinders away in the CW firing order (1 8 4 3 6 5 7 2).

Everything was fine two years ago when the timing was last checked.

The harmonic balancer looks okay and does not appear loose in its mounting.

If I were to trust what is lighting up while connected to plug #7, the timing is off two degrees.

Would anyone care to offer insight into what has happened?

Thanks,
Tom

overlander63 · 06-05-2010, 12:20 PM

Quote:

Originally Posted by TomW

Would anyone care to offer insight into what has happened?

Thanks,
Tom

What could have happened is the weight on the balancer has shifted. It is also possible there is a second set of timing marks you may have forgotten about since the last time you checked the timing. There may be a second timing mark on the bottom of the engine that would align the mark with #1 cylinder.

TomW · 06-05-2010, 12:35 PM

Quote:

Originally Posted by overlander63

What could have happened is the weight on the balancer has shifted.

I wondered about that. But to shift that much, I figured there would be some evidence. The strobe lighting up almost within spec on a different cylinder, though has me stumped.

Quote:

...It is also possible there is a second set of timing marks you may have forgotten about since the last time you checked the timing. There may be a second timing mark on the bottom of the engine that would align the mark with #1 cylinder.

I wondered about that too. Nope - I sanded, chalked, and fondled

the balancer's perimeter with no discovery.

Checking the timing was supposed to be the easy step in verifying I might have had bad gas on a previous trip, and not a burnt valve.

Ain't nothing ever easy these days...

Tom

68 TWind · 06-05-2010, 01:28 PM

Tom,
Since you checked that the plug wires are indeed in the new cap in the correct firing order, the only thing I can think is that the balancer is bad and the rubber has let the outside spin. A couple of things you can do. First mark on the outer case the position of the #1 lead and then take the cap off the distributor. Bump the engine till the rotor is pointed to the #1 lead. This should be close enough and then check and see where the mark is on the balancer. If the wires are right and the rotor is pointed to the #1 terminal then the timing mark should be visible close to the pointer on the block. The most accurate way it to find true TDC is with a piston stop but I have used the shade tree method with a dowel stick through the spark plug hole on the compression stroke. Takes a big breaker bar to rotate the engine and it is much easier with all the plugs out. PUt your finger over the #1 hole and rotate till you get pressure indicating the compression stroke and then insert a clean rod to rest on the top of the piston to see when you get to TDC. Make sure it is on the compression stroke. I don't know with the angle of the plugs on the 454 heads if that is possible to use that trick, but I have used the dowel trick on everything from old jeeps to a Continental 0-470 in a Cessna. The easy way is the rotor on the distributor method. I'd bet your balancer is toast.

TomW · 06-05-2010, 02:04 PM

Quote:

Originally Posted by 68 TWind

...I'd bet your balancer is toast.

My first thought too.

I just can't get over how doggone close cylinder #7 times to what I expected to find on cylinder #1.

Perhaps during tomorrow morning's sermon, the resolution will present itself to me.

Tom

ROBERTSUNRUS · 06-05-2010, 02:37 PM

Hi, are you sure you are on #7 wire? Are you using in inductive type timing light? Are you connected at the number one wire at the number one plug? Or are you at the distributor cap area. I have seen people install the distributor incorrectly and rotate the plug wires to make it work. Did you disconnect the number one plug wire at both ends and check for continuity? Chevies are known to have the timing marks on both sides of the timing chain cover, [different applications] could you have a left hand mark and be using a right hand marked dampner? Or vise versa, correct dampner and wrong timing chain cover.