74 super 1835. Valve timing issue?

[dpd]

I installed an unknown rebuilt 1835(who knows) and have gotten the blues trying to dial it in. 1st carb was chinese junk one fits all. Ran too rich. 2nd was rebuilt and rejetted 34. Better but still too rich(carbon fouling and poor idle etc) I have rebuilt a set of kadron 44's with mods made according to altitude and supposed engine size etc. Kaddie Shack sent kits. Runs better but idle is still rough and if I goose it a slight spray of fuel is noted coming out of the carb throats. Any ideas or suggestions? When I pull one spark plug wire at a time, #4 is the only one which has a NOTICEABLE rpm drop(nearly dies)

[FJCamper]

Hi DPD,

First, the basics. Good valve adjustment and compression test.

If no obvious problems show up, your rebuilder may have the cam timing off. The symptoms of this are similiar to what you've described so far, but vary depending on if you have advanced timing or retarded timing. That means the cam gear indexing is off a tooth or two from the crank gear. Much more than a tooth ot two off usually means you can't keep the engine running if you do get it started, as you twist the distributor back and forth trying to set the timing.

Too much advance will make the engine hard to start, and it could "kick back" (that means try to reverse rotation) on starting. Too much advance also means overheating under normal driving.

Retarded timing means easy starting, but poor power and poor running in general.

If you do have either of these situations (and I hope you don't) the only way to fix it is to split the case. And there is no certain way to look at the engine externally and know if the timing index is off.

Good Luck,

FJC

[Marc]

...the only way to fix it is to split the case. And there is no certain way to look at the engine externally and know if the timing index is off...

Actually it's quite easy to check by pulling the oil pump (or even just the cover and drive gear). And if the builder happened to use an adjustable gear it could even be possible to change through the pump opening - but not enough to fully correct for being a tooth off. I seriously doubt that this is your problem, though, as it would affect more than just one cylinder...it's normal for one cylinder on each side to run stronger at idle with dual 1-bbls, but not for only one to be doing all of the work. DO check the compression and reset the valve lash if needed, if the engine's not a good airpump it can never be a good motor either regardless of the carbs used. A 34PICT is just barely adequate for the mildest of 1835s, and even then it can be a challenge to get it to idle nicely.

...although you can't see the cam & crank gear timing marks through the oil pump hole you can infer their position since the oil pump drive slot points at the one on the cam gear and the pulley woodruff key is 180° from the two on the crank gear. When the engine is set to #1TDC ready-to-fire, the woodruff key should be at 9:00 - rotate the crank 90° clockwise from there to put the woodruff key at 12:00 and the slot in the cam should be exactly vertical (actually you don't even need to remove the pump to check this, only the pump drive gear). On a 3-rivet cam, if it's off by 120°, the gear is bolted to the cam incorrectly - that can be remedied without splitting the case by working through the pump hole. If it's off by any amount other than 120°, it's teardown time.

[dpd]

Thanks for the advice, compression and everything else tuning is good. When i view the carb throats as I rev a very slight cracking or popping can be detected which created a king of back pressure out of the dual port carbs, this is when radical acceleration is initiated. Normal acceleration does not produce this. I will check through oil pump plate

[Marc]

If the cam timing were advanced, or an intake valve failing to seal, that might explain "sneezing" out the intake tract - but more likely it's a delayed or inadequate accelerator pump "shot". The physics involved are hard to comprehend, so just accept the fact that a lean mixture is prone to causing this behavior...if the pump doesn't inject enough fuel soon enough to cover for the momentary lean condition caused when the throttle is cracked open, there will be spit-back.
You should have adjustment nuts on the accelerator pump actuation rods, crank them in until the injection event occurs immediately when the throttle is opened. Making them overly sensitive does have the undesirable side-effect of impacting your fuel economy, so you may choose to back them off slightly from the "hair-trigger" point and compensate by slowing your right foot down in order to save a little gas