Question for those running Langdon HEI

[steveplym]

I've been running mine at about 5 degrees advanced. What is everyone else running theirs at? Langdon advises to run it at almost 15 degrees advanced, but after blueskies adventure with damaged wrist pin bushings, I didn't want to push it.

It just feels like to me it could run a whole lot better a bit more advanced, but maybe I am just too picky.

[randroid]

Steve,

I don't run Langdon so I can't help you with the specific unit, but judging from past experience an engine will run faster and faster the more the distributor is advanced until it suddenly reaches the point where it won't run any more. Fifteen degrees sounds like where it might be supposed to fire at idle with the vacuum advance connected so maybe Langdon has a typo in their instructions or simply made an omission or maybe you pulled a 'randroid' and misread the instructions. There is a sweet spot between where the engine begins to run crappy at retarded and where it runs crappy at advanced and try to split the difference. Then check with your timing light when the vacuum advance hose both connected and plugged and I have a sneaky suspicion you'll be able to narrow the gap and get the right answer.

An engine will start easily when retarded but have little on the top end and when advanced too far be difficult to start but go really fast, which is why racing engines make such funny noises when they idle. Well, that and weird cams, etc., but that's a different topic. Five degrees BTDC is about where the factory recommends timing be set for the best all-around running so I think perhaps the problem lies somewhere other than with you or your engine. Good luck, and please get back to me when you're finished tinkering because your have my curiosity up.

-Randy

[steveplym]

Sure will Randy. Thanks for the reply. I think I'm going to try advancing it a bit and see how it runs. It starts great, but it isn't as great going down the road.

It has all new plugs, wires, ignition, and coil. Carb is rebuilt as well. I'll see if I can improve the performance a bit, and if not I'll leave it alone. That is the one thing I seem I can't do is leave stuff alone.

[jd52cranbrook]

I run about 8 degrees on my HEI. Works fine. The plug gap is pretty big on these also, makes a difference.

[martybose]

I run about 8 degrees on my HEI. Works fine. The plug gap is pretty big on these also, makes a difference.

I've been running 4 degrees BTDC, with manifold vacuum connected to vacuum advance to add additional timing at light throttle cruising.

This puts me at odds with everyone else who runs ported vacuum, because it makes no sense to me to have no advance at idle, followed by advance at part throttle, then down to no advance at full throttle. With manifold vacuum I have full advance at idle and light throttle, which tapers off as the throttle is opened.

My HEI has centrifugal advance that starts at 1300 RPM and adds a total of 13 crankshaft degrees by 2800 RPM; the vacuum advance adds 19 crankshaft degrees when the throttle is closed. My plugs are set to 0.060" gap, which isn't easy.

Marty

[jd52cranbrook]

Marty,

I set my initial timing to achieve 32-34 degrees when starting WOT, which, I was told was optimum advance for engines on aceleration. 1200 rpm is when starts, and ends at about 2800

[MacGyver]

I'm running 8deg advance, plugs gapped to 0.060" and it runs smooth as silk. All in all the HEI is the most pleasing upgrade I've made.