i am about tune up my 74 2.0 engine w/ dual weber 40,s (stop laughing), believe it has a stock cam. valves are adjusted, points set, will set the dwell and then there is my question.
on the pelican site there are 2 ways of timing the engine 27o btdc @ 3500 rpm,s and 34-35o btdc @ 3200 rpm,s, the second way is specifically for carbs. is this the one i should use?
thanks
Full Version: timing with carbs
What distributor are you using?
Both settings will work...
When you rev the car to 3000 rpm or a bit more, your distributor is now at full advance...so that is why you should set the timing in that way.
This timing question is very dependant upon the camshaft, elevation, and fuel settings.
Start at 27 degrees and work up to the 32 degrees. but be patient and do it one or two degrees at a time after you drive it.
Ideally you read the plugs, check your EGT, or do all this on a dyno with an O2 sensor....but...you could learn to read plugs...its the easiest way to get it right...and its free (my favorite thing) and we have done it that way for many years..
O2 sensors are really accurate..way better than reading plugs.
EGT sensors are the best way to tune carbs imho...but I digress.
Rich
Both settings will work...
When you rev the car to 3000 rpm or a bit more, your distributor is now at full advance...so that is why you should set the timing in that way.
This timing question is very dependant upon the camshaft, elevation, and fuel settings.
Start at 27 degrees and work up to the 32 degrees. but be patient and do it one or two degrees at a time after you drive it.
Ideally you read the plugs, check your EGT, or do all this on a dyno with an O2 sensor....but...you could learn to read plugs...its the easiest way to get it right...and its free (my favorite thing) and we have done it that way for many years..
O2 sensors are really accurate..way better than reading plugs.
EGT sensors are the best way to tune carbs imho...but I digress.
Rich
QUOTE(nycchef @ Jun 12 2009, 03:09 PM) 
i am about tune up my 74 2.0 engine w/ dual weber 40,s (stop laughing), believe it has a stock cam. valves are adjusted, points set, will set the dwell and then there is my question.
on the pelican site there are 2 ways of timing the engine 27o btdc @ 3500 rpm,s and 34-35o btdc @ 3200 rpm,s, the second way is specifically for carbs. is this the one i should use?
thanks
Rich, as Rich T says, start at 27 deg - you need to get the dizzy fully advanced - if its a 009 it will be at 3500 rpm - then road test, go up slowly until about a max of 32 unless you know you have a wild cam - i'm running 32 at 3500 on my setup which is a big bore with the same carbs and 009 , at sea level ( san diego = nyc!) and she is sweet!
Having a couple of years experience, maybe more (!), I suggest you set the timing at not more than 30 degrees BTDC at 3000-3500 RPM. You're not exactly well versed in this stuff yet, and you're not likely to want to detonate your engine to death just yet. The Cap'n
QUOTE(Cap'n Krusty @ Jun 12 2009, 05:42 PM)
Having a couple of years experience, maybe more (!), I suggest you set the timing at not more than 30 degrees BTDC at 3000-3500 RPM. You're not exactly well versed in this stuff yet, and you're not likely to want to detonate your engine to death just yet. The Cap'n
Rich, Listen to the Cap'n - less is better (safer) in this case!
QUOTE(neil30076 @ Jun 12 2009, 04:52 PM)
QUOTE(Cap'n Krusty @ Jun 12 2009, 05:42 PM)
Having a couple of years experience, maybe more (!), I suggest you set the timing at not more than 30 degrees BTDC at 3000-3500 RPM. You're not exactly well versed in this stuff yet, and you're not likely to want to detonate your engine to death just yet. The Cap'n
Rich, Listen to the Cap'n - less is better (safer) in this case!
do not want to detonate anything. just looking for a peppy daily driver, don,t auto cross so i will be happy to stay @ 27o. dizzy is a stock 2.0 scott set it there last week, but we did not set the dwell.
just got my meter and light, neil, great tip about amazon. $40. cheaper and at my door in 36 hours. o.k then, will do this sunday balance the carbs and post the results. maybe driving soon weeeeeee
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