After setting the timing to the recommended value with the vacuume line disconnected and plugged, how much does the timeing change when the plug is removed and the vacuume line re-connected?
Thanks,
DP
Thanks,
DP
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Re: Another timing question.....
It depends on the specifics of the vacuum can you have on the distributor and what year car, early cars were hooked to a manifold vacuum source and at idle will pull the can to full advance, which can be 14-20+ degrees, depending on the can used. later cars used a "ported" vacuum source that does not provide vacuum until the throttle is opened undeer a light load. So the answer can be anywhere between 0 and 24 degrees. If you want to verify proper operation on a ported vacuum system, the easiest way is to use a hand vacuum pump to provide vacuum to activate the advance can. and read the timiing change with a timing klight. If the can does not hold vacuum, then you know for sure it is junk.Bill Clupper #618 -
Year and engine option? *NM*
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Re: Year and engine option?
It is a small block....1965 327/300Comment
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Re: Year and engine option?
For the 1111076 distributor, The proper vacuum can is part number 1116238, providing 12.5 +/-1 degree of Distributor advance (25 +/-2 crankshaft degrees) at 12-14 inches of Vacuum.Bill Clupper #618Comment
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Re: Year and engine option?
Bill -
The distributor chart in the back of the '65 Shop Manual Supplement, under the 1111076 distributor, shows a vacuum advance spec of 0* @ 4" Hg. with 16.5* @ 8.2" Hg. (crankshaft degrees). Are there two different charts?Comment
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Re: Year and engine option?
Chart in Shop manual not in agreement with Delco Remy service spec book or specs in Glenn's Automotive service manual, both of which indicate 1116238 can to start at 5-7, (so 0@4 would agree spec at 8.2) max at 12-14 inches of vacuum, and 12.5 degress of Distributor advance. DR info published 1-1-77, Glenn's published 1967. Can say if shop manual was written prior to final design, or id specs are wrong, but the ones I've had on the machine look pretty close to the DR specs. Numbers you have quoted are correct for 1116201 vac can used on 250-300hp in 1963 distributor 1111024.Bill Clupper #618Comment
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Re: Year and engine option?
Bill -
Interesting - the shop manual chart doesn't have the vacuum advance unit part number, just the distributor part number and advance specs. Thanks!Comment
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Re: Year and engine option?
Corvette News lists '65 250/300 HP engines (076 dist.) as 0@6, 24@13, which was different from both '64 and '63. Max centrifugal is 26@4100.
For '66 the 355 can is 0@6, 15@12, and the centrigual was increased to 30@5000. Initial timing is speced at 6 with a range of 6-12. These specs carried through to '67 (according to CN) even though the dist. number changed The above does not apply to AIR, and for '68 all dist. calibrations changed to meet tailpipe emission standards.
Being as how the 300 HP engine saw only minor other changes (cam and carb) between '62 and '67, my hunch is that the last configuration is probably best as it must have been the result of continued development and testing.
A 12" can is really more aggressive than needed for an engine that pulls 17-18" at idle (manual trans), so I recommend a 15" can as it may help stave off detonation, however, for PG I recommend the 12" can since PG will loose a few inches at idle in Drive, and the can should provide full vacuum advance at no less than 2" below typical idle vacuum if at all possible.
DukeComment
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