distributor vacuum advance can - '61 - 283

[John H.]

I just noticed that my vacuum advance can is making a lot of noise (rattling). When I pinch the hose the noise stops. I installed the 350HP/327 cam advanced 4 degrees. Is it possible that vacuum pulses in the intake manifold are causing this? If so, how do I correct the problem?

[Joe L.]

Re: distributor vacuum advance can - '61 - 283

John-----

I don't know about "vacuum pulses" but it's very possible that the vacuum characteristics of the '151' cam are inconsistent with the vacuum control on your original distributor. It's also possible that the original vacuum control is just worn out.

Keep in mind that the original engine configuration was a FULLY ENGINEERED piece. In other words, many parts were used which were designed to work properly with other parts. Whenever a component is changed, especially a component that has wide-ranging operational implications like a camshaft, many of the other original components may not "work in harmony".

This sort of situation may require "re-engineering". For most of us, that will probably involve trial-and-error type of "engineering".

[William C.]

Re: distributor vacuum advance can - '61 - 283

If you installed the 350 hp 327 cam in a 283 it is probable that the vacuum at idle is marginal for the vacuum can to stay at full advance during idle. for starters you should use th vac advance form the '65 327/350 hp engine or equivalent. That is a LOT of cam for a 283.

[Duke W.]

Re: distributor vacuum advance can - '61 - 283

The OE Delco vacuum can number for L-79s ended in 236 and provided a maximum crankshaft advance of 16 degrees @ 8". A readily available replacement is the NAPA/Echlin VC1810 - about ten bucks.

Your idle vacuum should be about 12-14" about 800, so this can will keep full vacuum advance "locked" at idle, which is what you want.

Duke

[Duke W.]

Re: distributor vacuum advance can - '61 - 283

Actually, the effective duration of the L-79 cam is about the same as the Duntov, but with centerlines of 110/118 versus 108.5/112.5 it has a bit less effective overlap with a very slightly later closing inlet valve and somewhat earlier opening exhaust valve.

It should provide a very similar torque curve as the Duntov, with slightly better idle quality and vacuum.

Duke

[John H.]

Re: distributor vacuum advance can - '61 - 283

Thanks or the responses gents. Tomorrow, I will install the VC1810 that Duke recommended and see what happens. John.

[John H.]

Re: distributor vacuum advance can - '61 - 283

Follow-up on the new vacuum advance can - installed the new NAPA "ECHLIN" VC1810 and now there is no noise/chatter from the can. The engine idles better also. Haven't taken it out on the road yet to see how it performs. Thanks for the help. John.