?'s about tuning, pinging, and Compression

-
M

Mopardude

Well-Known Member
Joined
May 22, 2004
Messages
843
Reaction score
3
Location
Elkhorn, WI
When I got my motor going last night the tunning was pretty good for a first start up so I didn't mess with it and took it out to a car show at the local Culvers. She ran real good and the tunning was not that far off. This morning I decided to put the timing light on it to see where I was sitting. It was about 40 degrees advanced. Now my compression is around 11.1 and I have Alum heads and running 93 octane. Quite a few people have told me I am going to have to run retarded so that my engine doesn't ping like crazy. So out of curuoisity I retarded it 10 degres and it runs like crap and kinda ruff. I than bumped it up to about 20 degrees advanced much better but still not as good as it did at 40 degress.

I guess my questions are were they BS me about running retarded? I would think if my quench is good, which I am sure it is because I copied my basic setup from a few others that run the same setup on this board, that it should be ok to run advanced. As for pinging i don't know what to listen for or what it sounds like. How do I tell if I am pinging? Listening to the engine the only sound that is strange to me is that of the valve train because I have never ran a solid cam before. Sounds mean if you ask me! :headbang:
 
Hard to not notice pinging. Kind of a tinny knock. Them aluminum heads are helping alot. I don't think them octane ratings are very accurate either. I go to one gas station in town and can run regular 87 octane and not ping. Fill up on other side of town ping on their super premium. My lawn mowers don't even like there gas. I've been reading alot of articles in mopar mag kicking out some serious horses on pump gas.
 
You would hear the knocking when you put a load on the engine. It could range from a little rattling sound to what might even sound like a rod knock. Your cam also plays a big role in how your engine will react to the higher compression. The actual running compression depends on your cam spec/design. A Ferrarri 360 Modena has 11:1 compression, makes 400hp, will rev to 8500 rpm without even try hard, and does it all on 92 octane pump gas. The valve and ignition timing plays a major role in getting it done.
 
Well that I think I will set the timing back to where it first was and tweak the carb a little bit than run it like that till I feel comfortable enough to take the motor to the track.

Speaking of cams how is redline figured? Right now I haven't rev the engine past 3,000rpm but I can tell there is going to be a big difference. The high end of the cams rpm range is 6500rpm does this become the new redline or is this where I want to rev it up to before I shift when racing?
 
Thats getting a lil out of my league for any advice. Hope to see you at the grove with it though. Even if you don't run the strip. I probably wouldn't until I knew it was broke in descent either. Had a good time at Mopar Happenings. The hemi under glass was there, and fired it up for us. Think I started drooooling! :drunken:
 
Sweet! I didn't end up going. Other than playing with my car a little and mowing the lawn I vegged out all day. I been working hard the last few days on the car and such so I didn't feel like doing much of anything.

Are you going to the Mopar show next sunday at the grove?
 
Hey. 40 degrees is to much the problem is your motor needs more initial timing to bring the vacume up to were the carb can be adjusted. with stock curve you set the total at 40 that allows the initial to be were the motor wants to be or close. Shortren up the total advance so you are in the 34 to 36 degree range. Some people will say that 40 degrees is ok but thats just covering a fat carb. If the timing and carb are adjusted corectly the 34 to 36 will be perfect no pinging and running good. Other people here have mentioned FBO Systems I cant begin to explain how much They have help me on the performance of my eng. Don there is sharp on tuning and can give you some good advise just have as much info as possible when you call . Cam specs gear ratio carb size. Your ride sounds fun good luck and get it tuned right.
 
racecarbob451 said:
Hey. 40 degrees is to much the problem is your motor needs more initial timing to bring the vacume up to were the carb can be adjusted. with stock curve you set the total at 40 that allows the initial to be were the motor wants to be or close. Shortren up the total advance so you are in the 34 to 36 degree range. Some people will say that 40 degrees is ok but thats just covering a fat carb. If the timing and carb are adjusted corectly the 34 to 36 will be perfect no pinging and running good. Other people here have mentioned FBO Systems I cant begin to explain how much They have help me on the performance of my eng. Don there is sharp on tuning and can give you some good advise just have as much info as possible when you call . Cam specs gear ratio carb size. Your ride sounds fun good luck and get it tuned right.
Click to expand...

Ok I will give that a try, it makes sense.
 
You must log in or register to reply here.
-

Back
Top