Griff in Fairbanks wrote:
Ballenxj wrote:
Thanks Griff, that would explain the coaxing the engine to higher speeds until it smooth's out. I had a 340 do that to me once. (same basic block as a 360)
Once the chain gets loose, I've seen all kinds of erratic behavior as described. Once it's loose enough to jump, it can go any which way if you keep driving it.
Anyway, just my two cents.
You're welcome. IIRC, OEM sprockets were a composite material and OEM chain was an 'economy' version. Replaced with metal sprockets and premium chain. Lasted at least 150,000 miles that I know of. (Sold the van when USAF transferred me out of Alaska the first time so I don't know how long the timing chain actually lasted.)
Valve stems seals disintegrated around 100,000 miles, causing unusual oil consumption. Had heads rebuilt when I should have just replaced valve stem seals. (Rebuilding heads without addressing the cylinders transfers oil consumption and other problems from the valves to the piston rings ... now I hone and re-ring or -- preferably -- rebuild the short block if the heads need work.)
Note: Leeann has a big block and (IIRC) four barrel carburetor. JoninFountain has a small block with a two barrel carburetor. (Probably a Carter BBD.) Different engine families, different carburetors may mean different problems ... Leeann is good but I'd be cautious transferring her solutions to your engine.
Back to '77 B200 with LA small block and Carter BBD. Had to rebuild carburetor almost yearly, due to problems similar to JoninFountain's.
Turns out it was due to using 'economy' gas-line antifreeze with every fill-up. (Won't mention brand name but it was the inexpensive one that comes in yellow bottles.) The ethanol in the antifreeze was eating up the carburetor seals ... gasohol will do the same thing on carburetors that predate gasohol.
Forgot -- or didn't listen to -- an oldtimer who warned me about this, way back when I was in high school.
Modern carburetor rebuild kits have seals that resist ethanol/gasohol. Main problem is if you get a NOS rebuild kit that's been on the shelves for a while.
Going to check chain this weekend
