Rebuild or Replace 454

[palerider]

Some of the folks here have the best advice. If the rig ran and pulled better before the work was performed then take it back the "mechanic" that did the work and give them-him a chance to make it better. If they can't-won't stand behind their work, ask around until you find a good one that will completely check it out and try and see what's wrong. 454 is a strange beast and a crap-shoot weather what you are doing to it will make it better or worse. I could tell you some real horror stories about 454's. If you ever get the thing running again, to your satisfaction, I would consider a lower gear rather than new unknown motor (more horror stories)

[PeterH-350LE]

Originally Posted by Keyair

Something is wrong with your Motor, unless your brakes are stuck on.

.

Great point to start before you go on the wild goose chase.
MAKE SURE your brakes are free. Has the Master Cylinder been replaced recently? The first thing that will go with a "pre-load condition" of the brake system is the transmission. A laser thermometer and a short trip around the neighborhood will tell.
Incidentally, I experienced this issue with a 1986 345. More info available if you find that to be the cause.

[prairieschooner]

1) Compression Test! have this done 1st.
2) Check the Distributor. If you know how to use a timing light you could check for timing and full advance at the correct RPM, otherwise take it to a distributor shop and have them spin it for you. The timing light can also help to make sure that the other cylinders are firing.
3) That Quadrajet can be a source of problems and should be checked/repaired for any carbureted engine you decide on. Luckily there is a shop here in So Cal that "knows their stuff". I wouldn't be at all surprised if this is not a big part of you problem;
https://www.smicarburetor.com/

[freedombro]

Quick update. It appears the vacuum advance on the distributor was not functional. Seems to be running MUCH better. Secondaries were working, but no advance caused the loss of power I'm told. There is still a slight hesitation at launch that concerns me (with a faint grinding feel) but once I hit 5mph it seems to go away and the rig pulls strong. Not as strong as I would like, but MUCH stronger than before. Going to trouble shoot the grind this weekend. Any suggestions? Thanks to everyone for your input!

[Isuzusweet]

Originally Posted by freedombro

There is still a slight hesitation at launch that concerns me (with a faint grinding feel) but once I hit 5mph it seems to go away and the rig pulls strong.

The grinding could be the front brake pads as a result of a stuck on calliper; which would also explain the slow initial launch as the brake on one side is still on. I would check the calipers for bounce back and nearby soft brake lines.

Sometimes it's hard to tell that a brake line has gone bad on the inside which impeeds the flow of brake fluid back to the master cylinder to allow the calliper to release fully.

Cheers
Tony

[tevake]

Tony may well be onto something there about the brakes.
Those lazer handheld thermometers that Peter mentioned are great for checking temps after a drive.
If the brake is dragging it should be hotter than the other wheels.

Also tony's comment about the brake hose deteriorating inside is real, and not visible from the outside.
Changing old brake lines is an inexpensive step and naturally leads to doing a brake fluid flush at the same time.

Be careful while getting tips from a Hotrod / race shop for the 454 in your motorhome. Their goals in engine building are a bit different than what is best for dragging around a heavy beast like our coaches.

Cheers Richard

[WayneG]

I got better performance by replacing the Qjet with a TBI kit with electronic distributor. I cant say the performance was a lot better, but it was better. They tell me headers is another performance boost, but out of my price range. If you are not good with mechanical goodies, it will cost you to have someone else do the work.
Also check your fuel supply, the 454 sucks gas faster going up hill than I can drink beer double fisted when parched. Check the fuel filters, fuel pump, and the lines, be sure all is good before you invest a lot of cash.

Oh, and if you are in Upstate NY in June check out the Harley Rendezvous. You will find my 84 Excella in the staff area, I will show you the TBI conversion.

[Keyair]

Yes, could be a caliper or line.

Also could be the parking brake or a fav of mine is driveshaft.
I think there is a slip joint somewhere that needs lube regularly. That joint slides when you apply power and the axle pushes forward. Frequently missed on the lube schedule. My old Suburban did it regularly as the grease was old and dry. Also could be a UJ too.

[freedombro]

Thanks again to all for the input. I will ck the brakes first and continue down this list. If I lift the wheel and it doesn't spin freely...that's a good indication, no? I'm thinking the front passenger side could be the culprit. I here noises emanating from that area. Cheers!

[PeterH-350LE]

Originally Posted by PeterH-Airstreamer

Great point to start before you go on the wild goose chase.
MAKE SURE your brakes are free. Has the Master Cylinder been replaced recently? The first thing that will go with a "pre-load condition" of the brake system is the transmission. A laser thermometer and a short trip around the neighborhood will tell.
Incidentally, I experienced this issue with a 1986 345. More info available if you find that to be the cause.

Originally Posted by freedombro

Thanks again to all for the input. I will ck the brakes first and continue down this list. If I lift the wheel and it doesn't spin freely...that's a good indication, no? I'm thinking the front passenger side could be the culprit. I here noises emanating from that area. Cheers!

It may be all of your wheels. I have a way to test the theory above, but its radical and I do not want to put it out here, unless you find that you may have that condition.

[inguza]

For all you 345ers I have just rebuilt our 345,I started with the brakes and worked slowly forward,I will start with with the motor (engine) this I removed the original and dumped it,I found a 1994 454 gen6 out of a college bus with low miles on it, it was fuel injected ( I am a fuel injection freak ) I got a lot of parts out of the donor bus including a 4L80e tranny I decided not to use the 4l80e tranny,this is another story.Removing the motor and installing the new one was rather easy, once in I decided not to use the original electrical harness and ECM, I had a new one made installed it and all ran the first time.We were in the Smokey a few weeks back and I am pleased with this set up.
If any of want to ask me any questions my email is moldnw@aol.com
Regards Neville.

[chriscraw]

You were indeed fortunate to find a 454 with low miles. I've just spent a small fortune rebuilding my 454 (now a 468!). I did consider a transmission swap to replace the T400 and get the overdrive but (a) a 4L80e was expensive and, (b) retrofitting the electronics to drive the transmission was not for the faint-hearted it seems! In the end, as I only plan on limited highway miles it just was not an economical decision.
I'd be interested to hear your "other story" as you appear to have reinstalled the existing T400?
Chris

[freedombro]

Looking at having Harbor Chevrolet in Long Beach CA replace all the brake lines. Any idea how much that should cost me....Approximately? Are there other items I should consider replacing during this procedure? I saw a "boat guy" character on an American Dad cartoon that summed up vintage RV ownership pretty well. His quote was: "When my friends ask me what it's like to own a boat (or 345) I tell them to stand under a cold shower and tear up $100 bills." My wife didn't think it was as funny as I did...

[Waipio Rim]

As a point of reference, Mill Supply lists a set of brake lines for a step van with ABS (that won't be you) for $171, https://www.millsupply.com/front-rea...00.php?p=44513. GM parts will probably be higher. Add a couple of hours of shop time, and you will be at the magic $500 number that I never seem to be able to get out of a dealer's shop without reaching. If you don't know when or whether the brake fluid has been flushed and replaced, this would be the time for it.

[freedombro]

Greetings Gents (& ladies too of course)-

Much work done to the Unleaded Zeppelin in preparation for our 5 day gig at the Stagecoach Music festival in Cali next week. If any of you Airstreamers make that show...swing by the Bandit Brand booth in the vendor section and say hi. My 345 lounge is the backdrop for their footprint.

I just picked the rig up from another costly 2 week stay at a very reputable repair facility in Camarillo. Running much better and the brakes/lines are all dialed in. One problem...at launch it stumbles, and coughs and sometimes backfires (1st time this has ever happened.) Above 30mph it pulls like a freight train, but when I launch and put my foot into it there is a problem.

When I dropped it off the guys said the rebuilt quadrajet gasket was installed improperly and a gaping hole eliminated my vacuum pressure. They fixed that. They also replaced the distributer cap saying that one pin was broken...could have been the cause of the tickticktick I heard before, but is now eliminated. To recap I had the quadrajet rebuilt and added headers and flowmasters last year. I have replaced the entire cooling system as well as the water pump, alternator, and fan clutch with oem parts. I had to replace the transmission in Utah on my failed trip to Sturgis.

Any thoughts on what could be causing the engine hesitation at launch? I'm told it smells like it is running rich. Also...it was recommended that I use 91 octane, and I did put the first tank of that in before this started happening.

Any input is appreciated. Thanks for your time!

[WayneG]

It could be the vacuum advance, maybe the accelerator pump?
Lots of variables in the old fuel & spark system

[Waipio Rim]

The backfiring says "ignition problem" to me. Assuming that the vacuum hose is still hooked up between carburetor and distributor, one cheap and easy thing to try is replacing the ignition coil. It's probably overdue anyway.

[cliffcharb]

A backfire from the carb indicates a lean condition, through the exhaust indicates rich. As your carb was just completed I'd make sure it's tuned properly.

[freedombro]

The saga continues... They found the backfire problem...burnt spark plug wire. Fixed. On the drive home the transmission would not stay in 3rd for long. It preferred 2nd no matter the speed or incline/decline. I called the my transmission guy, and he said they probably attached the transmission vacuum hose to a manifold port instead of a ported connection. He says that will cause the tranny to hunt continuously. Does that make sense? He says it's an easy fix, but I took a look at the quadrajet vacuum lines...it is a spaghetti bowl that I'm sure I will make worse. Any thoughts??? Trying to stay positive. Haha!

[3wd67rg]

Our Airstream does a lot of backfiring when we are driving up hill or anytime we use extra power, (e.g. Passing). We believe it's water in the gas tank. After we come back from a long trip, (San Antonio, Texas to San Diego, CA), we park a very warm Airstream for the winter. The tank is a quarter to half full at most. Condensation happens inside the gas tank when it is not full, when the Airstream is parked for six months, that is a LOT of nights to collect condensation. I told Chris we should stop and gas up before parking this last September, but he was tired and only wanted to go home. So I guess we can expect the same kind of obnoxiously loud and annoying backfiring this summer trip too. Ugh