What timing numbers are you guys ending up around with the cammed 5L's ?
Also what is your timing down low at take off & cruising area's, that will have a lot to do with its manners
Big cam 304 Tuning help needed
Re: Big cam 304 Tuning help needed
If the heads are cleaned up especially the chamber it will effect the amount of timing it will take
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vlad01
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Re: Big cam 304 Tuning help needed
Only way to determine timing other than at idle with any accuracy is a dyno.
Generally I found with a bigger cam, timing increases at low rpm cells and idle, but decreases in the mid to high rpm and that seems to be regardless of CR, but of course CR will lift the the lot up or down but not really the shape of the map.
Exhaust headers also have a significant roll in timing too, short and choked primaries like OEM or cheap nasty headers will decrease timing and lower knock threshold, long and correctly tuned headers will lift the knock ceiling and timing to get to MBT will increase as well.
At idle, you simply up or down the spark and watch for max vac. Normally most larger cams want around that 28 deg at idle. Ranging between 25-30. Most stock are like 20 deg.
Generally I found with a bigger cam, timing increases at low rpm cells and idle, but decreases in the mid to high rpm and that seems to be regardless of CR, but of course CR will lift the the lot up or down but not really the shape of the map.
Exhaust headers also have a significant roll in timing too, short and choked primaries like OEM or cheap nasty headers will decrease timing and lower knock threshold, long and correctly tuned headers will lift the knock ceiling and timing to get to MBT will increase as well.
At idle, you simply up or down the spark and watch for max vac. Normally most larger cams want around that 28 deg at idle. Ranging between 25-30. Most stock are like 20 deg.
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Wade
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Re: Big cam 304 Tuning help needed
In the Greg banish tuning book he talks about idle timing and retarding it as much as 10deg from mbt and from the main spark table. If you match both tables it can make it feel flat during the transition from idle to main spark tables. Plus having spark in reserve at idle allows idle control to advance idle timing if needed. If idle timing is already at mbt then it’s got nothing left ect.