454 chevy timing

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-79MH · 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-79MH · 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-79MH · 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.