71 LA 340 timings moved!! how?? looking for help

Marcohotrod said
have you checked tdc with the tool yet, to check that fabricated timing tab? with a chrysler ignition box and no ballast resistor any coil will overheat and die, try it and get back to us

Yes checked TDC with tool and its correct, I think I'll go back to either a stock coil or add the GM HEI module to save the headache.

67Dart273 said
I'm leaning towards incorrect cam timing.............not that it has "slipped," but rather was never correct. If you look up the cam specs, or estimate them if you don't know them, you can judge cam cam timing by putting an indicator on the no1 valves or even just watch them and obtain opening / closing events. Mark the balancer if needed.

Did this engine EVER run right?

What ARE the cam specs do you imagine?

What are you using for a timing light? Is it just a "straight" timing light, or is this a fancy "dial back" setup? These have screwed up sometimes

Just some rough general guidelines:

A dead stock low performance 273/318/360 should idle "ok" at anywhere from TDC to 15 BTC or maybe approaching 20 BTC. I AM NOT SAYING "run" it there, I am saying a healthy engine should idle OK

A hotter cam, equivalent to the factory 340 cams, should idle maybe anywhere from 8BTC to 20BTC or more

If you have a "real thumper" of a cam, then you would not want to try and idle it less than say, 15BTC, but it might run at 20.

In other words, "let's say" I have an unknown "startup" situation, an engine I have never encountered, and want to "fire it up". Maybe I have to install a distributor, because there isn't one, or because it's a greasy POS. I should be able to drop one in with the above "general ranges" and at least get the thing to run on it's own.

If it won't do that, I'd look elsewhere, cam timing, stuck valves, other engine interal problems, carb problems, vacuum leaks, etc, in no particular order

Hey Dart.. Yes it run perfect for almost 1000 miles since complete rebuild, I say perfect but it was a bugger to start but that was a choke issue and choke now totally removed.

The cam is a Comp cam XE274H which is 242 duration @.50 .492 lift.

For timing light its a cheap basic light with a trigger, + and - lead and No 1 cyl lead.

its pretty modified and 500bhp ball park, stroker 418, balanced, 10.75:1 compression ratio, etc.. as we know it was idling at 32!!! only found this when it suddenly started popping if more than 1/4 throttle was applied, right or wrongly I assumed it had shifted as it seemed just way to high. Oh and vac timing is not connected and is plugged.

Anyway I knocked it back to 17 but also fitted the MSD Blaster 3 to add confusion, but since then weather turned, so will be putting the Blaster 2 back in and trying again.

You guys don't know how lucky you are with no doubt a list of local garages that could solve this in an hour lol!! or of course have the knowledge yourself, sadly we all start somewhere... I'm new to the older stuff, but give me a LB7 or 7.3 Powerstroke and I know my way around them, had to do the injectors on the Duramax, what a job!! even rebuilt and uprated the Allison 1000 trans as was pushing 450bhp and hauling a 34' Newmar 5th wheel...