amc 401 V8 w/issues

[datablitz]

we bought a truck with a 401 amc v8 in it, and have been fixing up the body, now that we have that done, we are working on the engine. it just isnt right. it was "rebuilt" shortly before we bought it apparnetly... . here is some of what it does:

with timing set to spec. it harly has enough power to move the truck, and with timing at 15 after (i think) it runs better, but not perfect... . but then it will barly restart when it is hot.

i think with a new carb (the current one has issues imo, but my dad disagrees) it would run better at 15 timing, because i don't think the secondaries are functioning correctly.



any info out there?

 

[CFAR]

What year?

Does it have vacuum advance on the distributor?

If so it might not be working.

 

[datablitz]

74

yea, the advance is working, with it hooked up and give it throttle, you can see the timing advance via the light

 

[Peter Campbell]

You might need to check the timing on the balancer - may be off. The dial indicator in #1 sparkplug hole or the threaded rod ( rounded end)run through a tapped out sparkplug " outer metal" - all the porcelain bashed out. When the piston hits the all thread rod make a mark. Reverse the rotation and when hits again make a mark. TDC is between the marks. Old harmonic balancers slip. Third world rebuilt components ( engines harmonic balancers )are not always factory spec. Also check the centrifugal advance- if it has one the weghts should be free on thier pivots- except for spring tension

 

[CFAR]

You might also want to check the compression.

 

[Scot]

Check and see how much mechanical and vacuum advance you are actually getting. I have seen old distributors get worn and advance >50*.



Might also degree the cam and see if it got installed off a tooth or two.

 

[datablitz]

yea, will check that... my dad suspects the cam teeth as well, i will check the ideas i have from here and see where we get.





Thanks for all the info

 

[NVR FNSH]

The 304 in my CJ had the distributor one tooth off and it drove me nuts trying to figure it out - it ran but it sure didn't run right.



Brian