454 chevy timing

Tom & Janet Salhus · 10-07-2003, 03:14 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, 03:24 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, 03:48 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, 04:14 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, 04:29 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, 04:40 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, 04:48 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, 07:31 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