Re: Bog when Engine is Warm
[Re: cjskotni]
#1668002
09/07/14 01:31 PM
09/07/14 01:31 PM
|
Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
|
About to go away
Joined: Sep 2007
Posts: 14,889
up yours
|
Problem with most dyno tunes is that the tune WOT. Transition and driveability are not addressed other than to make sure it isn't totally horrible.
Your best best bet is to install a wideband O2 and data logger to tune it right. Otherwise your sorta guessing what needs to be done.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
|
|
|
Re: Bog when Engine is Warm
[Re: davenc]
#1668005
09/14/14 01:20 PM
09/14/14 01:20 PM
|
Joined: Jul 2007
Posts: 1,526 North Carolina
cjskotni
OP
pro stock
|
OP
pro stock
Joined: Jul 2007
Posts: 1,526
North Carolina
|
Quote:
On a dual-plane manifold, a 042 shooter seems quite large. As others have mentioned, the pink cam may not be the best for a street car since it is lazy in lift right off idle. I would suggest changing the pump cam first, and then come back down on the shooter. Every setup is slightly different. Try an orange cam to start. I suspect the shooter can come down into the range of 031 with the right cam but change one thing at a time. In my opinion, the cam is the more important of the two on a street car.
FWIW I have the MP single plane manifold, not a dual plane.
I played around a little today with the car (more trying to test for vapor lock) but got it good and hot and tried to note this issue. It seems the bog only occurs if the throttle is blipped pretty fast and over 50% or so. Just giving it some moderate pedal or a blip under half throttle seems fine...no bog.
If the bog occurs at quick throttle opening over 50%, this means I need a cam that gives more fuel in that range (>50%)?
Either way, I will get my buddy's set of cams and try the red or orange and see what happens. I have a 32/38/42 squirters here I can try later if that helps the problem.
Thanks so much guys!
|
|
|
Re: Bog when Engine is Warm
[Re: davenc]
#1668007
09/14/14 08:45 PM
09/14/14 08:45 PM
|
Joined: Jul 2007
Posts: 1,526 North Carolina
cjskotni
OP
pro stock
|
OP
pro stock
Joined: Jul 2007
Posts: 1,526
North Carolina
|
Quote:
Was the "blip" with no load on the motor, or while the vehicle is in motion?
I did the blip with the car rolling and/or at a standstill in gear so under a load. The engine doesn't stumble at all when it's out of gear so not that far off!
|
|
|
Re: Bog when Engine is Warm
[Re: cjskotni]
#1668008
02/23/15 06:05 PM
02/23/15 06:05 PM
|
Joined: Jul 2007
Posts: 1,526 North Carolina
cjskotni
OP
pro stock
|
OP
pro stock
Joined: Jul 2007
Posts: 1,526
North Carolina
|
Ok guys, I know it's been awhile since I posted this but I finally have the restoration part of the car done so now I have more time to circle back on these little mechanical gremlins. I got the Holley tuning kit and swapped in the red cam (from the pink there) and went to a 37 squirter (from 42). I had to shorten up the accel pump lever adjustment screw a lot...like 7-8 turns to get it where it was just resting on the pump lever with the throttle closed. I did the 15 thousandths feeler gauge as well on open throttle to make sure it didn't over extend the arm and all is good there. Whoa what a difference! I scared myself a time or two when I blipped the throttle. Now I can break the tires loose at 40 mph when I blip it! Of course now I notice that when I have it under WOT for more than 2-3 seconds, it is pinging a little bit so I guess it's time to roll the timing back a degree or two. Man that stroker can pull now! Thanks guys!
|
|
|
Re: Bog when Engine is Warm
[Re: RapidRobert]
#1668010
03/07/15 05:43 PM
03/07/15 05:43 PM
|
Joined: Jul 2007
Posts: 1,526 North Carolina
cjskotni
OP
pro stock
|
OP
pro stock
Joined: Jul 2007
Posts: 1,526
North Carolina
|
Quote:
Quote:
what a difference! I scared myself a time or two when I blipped the throttle. Now I can break the tires loose at 40 mph when I blip it!
Of course now I notice that when I have it under WOT for more than 2-3 seconds, it is pinging a little bit so I guess it's time to roll the timing back a degree or two. Man that stroker can pull now!
Thanks guys!
You sound pumped! On the timing you might go to a slightly heavier spring for either of the two springs in there (I'm assuming 2 light ones) until the pinging stops under WOT, since if your initial and total are correct as is you would not want to compromise them for the pinging
I measured the total timing which is 36 degrees...so 20 degree advance (16 initial). Do you have a part number and a recommendation as to what springs I need to use to back this down to maybe a 16-18 degree advance? This is the standard MP distributor.
Thanks!
|
|
|
Re: Bog when Engine is Warm
[Re: cjskotni]
#1668013
03/08/15 01:49 PM
03/08/15 01:49 PM
|
Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
|
Quote:
Wouldn't it be better to shorten the slots to just limit the timing advance? Any ideas? Does it work?
(1) no (2) of course! (3) yes I hear the FBO plate works OK but 36 total is fine but it coming in too fast. 35 is a tried & true total for a std sb but strokers do have alightly different tiotal requirements but 36 ain't a dealbreaker. I am a fan of experimentation & wouldn't see an issue with trying the plate and or going to a heavier spring & seeing which one of the two works the best for your app. I'm sure the plate is cheap. EDIT Do you have a BB or SB? If BB I would stay at 36 & go to a heavier spring
Last edited by RapidRobert; 03/08/15 02:44 PM.
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: Bog when Engine is Warm
[Re: cjskotni]
#1668015
03/08/15 04:12 PM
03/08/15 04:12 PM
|
Joined: Aug 2003
Posts: 43,719 Bend,OR USA
Cab_Burge
I Win
|
I Win
Joined: Aug 2003
Posts: 43,719
Bend,OR USA
|
Quote:
I had to shorten up the accel pump lever adjustment screw a lot...like 7-8 turns to get it where it was just resting on the pump lever with the throttle closed. I did the 15 thousandths feeler gauge as well on open throttle to make sure it didn't over extend the arm and all is good there.
Whoa what a difference! I scared myself a time or two when I blipped the throttle. Now I can break the tires loose at 40 mph when I blip it!
Of course now I notice that when I have it under WOT for more than 2-3 seconds, it is pinging a little bit so I guess it's time to roll the timing back a degree or two. Man that stroker can pull now!
Thanks guys!
Two suggestions, try a 32 or 35 squirter next,get the smalest one in it that won't bog with the accelerator pump arm set up properly At the same time back the timing up to 34 degrees total with the motor at or above 4000 RPM Don't change the amount of mechanical advance , just the initial If it still pings try a colder plug by one heat range lower BTW, what brand and heat range, plug number, are you running now? Now that you have opened the door to more power we need to maximise it so you can really get pump up, scare the poop out of you Mopowered
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
|
|
|
Re: Bog when Engine is Warm
[Re: Cab_Burge]
#1668016
03/08/15 04:22 PM
03/08/15 04:22 PM
|
Joined: Jul 2007
Posts: 1,526 North Carolina
cjskotni
OP
pro stock
|
OP
pro stock
Joined: Jul 2007
Posts: 1,526
North Carolina
|
With the dizzy advancing 20*, this would mean only 14* of intial timing. On the dyno, we determined that the engine made the most power with 18* initial but of course pinged when you opened it up. I don't think rolling back to 14* is enough timing? I am running Champion RC12YC. EDIT: I am going to try Autolite 3923 which is one heat step down from these Champions. I am guessing with the 10.4:1 compression this might not be a bad idea.
Last edited by cjskotni; 03/08/15 04:49 PM.
|
|
|
Re: Bog when Engine is Warm
[Re: RapidRobert]
#1668018
03/09/15 08:45 AM
03/09/15 08:45 AM
|
Joined: Jul 2007
Posts: 1,526 North Carolina
cjskotni
OP
pro stock
|
OP
pro stock
Joined: Jul 2007
Posts: 1,526
North Carolina
|
Quote:
Quote:
I am guessing with the 10.4:1 compression this might not be a bad idea.
You need more octane, if you build a monster you gotta feed it want it wants (needs). You're timing numbers ain't out of line but your SCR (& therefore DCR) is too high for your (current) choice of fuel.
I realize this number is high but I am running aluminum heads. I know people here have run much higher with pump fuel.
BTW I did take it out today with the colder plugs and took it up to WOT for a few seconds...enough to open the the secondaries and I didn't hear any pinging. I will keep testing and maybe try a heavier spring as well...
|
|
|
|
|