hi lift, hi compression tuning secrets!!!

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mbaird

mbaird

mbaird
FABO Gold Member
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Lets here from some of you running lots of lift and lots of compression on the street.
What timing do you run?
Do you run a vacuum Advance?
Do you think MSD helps smooth out the low RPMs?
How low can you get your idle?
etc... etc...

I know its not practical to run these on the street, but it sure is fun!! I love to rattle windows as I drive by.
The challenge of tuning for driveability is also fun.

So spill your guts guys!!!!!
 
Maybe I lost something..You mean pump gas, with high static compression tuning? I can run my car on pump fuel, but it's designed for VP C12. 12.5:1, closed chambers, flat tops. Total timing is 34*, 20* initial, no vaccum. Idles at 750-800. MSD 6AL. I run 4" pipes and 2 chamber race flowmasters. I can set off lights and alarms for about 100' to either side (side exit..like an AAR). It runs on pump fuel, but I dont run it hard on it. I suppose I could but I'd recurve the distributor a bit.
 
i run a 11:1 compresion 340 with a camduration of 270degres@ .050" and 630lift
i run a MSD probilet distributor with no vacumadvande and a MSD 6Abox and it idles lots better than it ever did with the mopar performance ignition.. initial timing is 10degres and a total of 38degres it idles as 800rpm but its not realy idling smooth at that rpm but it works and i like the sound it makes there... i have been working some with my ignition and used 20degres initial advance and that works lots better but its not tried and tested that it can handle it when there is a big cruising soo that is something i will try later on...
of course this is a real streetengine that i dont hesitate taking to work... and i dont hesitate slaming the pedal to the floor anytime on streetfuel ;)
and sure its fun when windows are rattling and car alarms set of when you roll past them ;)
 
I never considered running pump fuel in mine, at least 40% 110 sunuco or comparable fuel. What octane do they sell over there at the pump!!

I am running a 360 w/ comp roller .628/.638 302 dur.
and 12.5:1, ported W2's , M1 single plane ,MP ign.

I am curious about the difference in intial timing settings.
anywhere from 8 to 30 degrees.
 
mbaird said:
I never considered running pump fuel in mine, at least 40% 110 sunuco or comparable fuel. What octane do they sell over there at the pump!!

I am running a 360 w/ comp roller .628/.638 302 dur.
and 12.5:1, ported W2's , M1 single plane ,MP ign.

I am curious about the difference in intial timing settings.
anywhere from 8 to 30 degrees.
Click to expand...


shell have 99 octan gas called V-power over here and its pretty good my plugs looks lots better and the gasmilage goes down when i use it, the other gasstations sell 98 octan but i think the octan rating are calculated diferenltly compared to the american standard, my cam bleeds of lots of cylinderpreasure at low rpm so i realy wish i hade used even more compresion from the beginning..
the reason i dont feel safe using more initial advance is that i have a fealing that it will "trap" more heat in the engine during low rpm when there is a slow crusing and i dont like my engine boiling over beacuse of slow driving and low rpm waterpump rotation but its just a theory and i will try some more this summer to see if it will alove mee to use more initial igniton..
 
I just got off the phone with FBO up in portland and it sounds like
moper has the right combo for timing. He recomended those exact
timing settings (20 initial and 34 total, in by 2500-3000 rpms).
Thats without vaacum advance, which wouldnt work for us anyways since we have no vaacum below 2600 rpms.
 
A lot has to do with how the engien was put together too. Your W2 chambers are decent, and a good flat top psiston and thin gasket will go a long way to help curb detonation on lower octane fuels. (mine has a very small 516 chamber, and flaot tops...) The cam will bleed a bunch of pressure off at lower rpms too, so that will also help. But, the big deal is really the time it takes the flame to fully burn in the chamber, and where the piston is in it's stroke when that burn is making maximum "push" in the piston top. You may find, more initial helps the idle/low rpm, but too much advance means the cylinder is building max pressure before the piston is at the best position (7-12* after TDC) to get leverage on the crank. That's why a fast burn chamber likes less advance at the same rpm. Also, if your cam opens the exh valve early, you are loosing some of that pressure out the header, instead of using it to make the maximum effort on the crank. Incedently, my cam isnt that large (MP .528 solid w/1.5 rockers), and it doesnt have much of a detonation issue driving it around with pump fuel..I just choose to race on something less friendly to the environment. Race fuel burns slower, much slower than pump fuel. In my case, that means the max pressure during the burn cycle is over a longer period of time than pump fuel..So i can feel a difference in fuel type in idle, sound, and output, with no other changes other than fuel.
 
Mine 340 is 11:1 with a 260-165 @ .050" cam. Timing is 20 initial 38 total. It idles at a low 1200rpms. This is how it was set on the dyno, it hasnt made its way in to the car yet.
 
Mine has a comp 274 cam 37* total all in by around 2000rpm and idles lumpy at 850rpm
smooth idle @ 1050 rpm

10-1 compression
 

Do any of you remember an article in one of the Mopar rags about a
white '67 Valient post car on the east coast that was a notorious street sleeper?
The 1st article I saw was about 10-12 years ago and the 2nd was about 5 yrs back. The 2nd article was an overview of his new motor, a stroker
running W5's I think. The unknowing eye would look at that car and think of
grandma (until it started I'm sure!)

Any how, the 1st motor was near identical to my setup.
 
in a 3400lbs car, with 3.91s and 27" street tires, it's been 12.0s. The one listed in the "what is your combo" post..I'd lose a bunch of points if I said what I did to it. We'll just say it's one of those "parts bin/garage floor" type buildups that just seems to run well. It's not fully tuned, and I've had all kinds of experiments..cooling system, alignment, rear suspension, gearing, carb, timing over the course of 8 years or so. It's really not a street car..I just would rather have $2.70/gal fuel evaporate out of it than $7/gal..lol. So it get's pump fuel to run around on. If you got Hemmings Muscle Machines, they got a pic of her in the November '05 issue. The article about track rental. You can guess which one is me...lol.
 
mbaird , I remember that article. I belive it was a 397 stroker with Batten aluminum W2s not W5s.
 
I myself prefer to keep the comp in the 10.0 to 11.0 and run 93 pump on our street/strip cars. Actual comp depends on the cam and heads I use. My sons Dart with the .030 over 400 is at 10.2 comp and stock Eddy heads. It works great as all we use is 93 pump and it uses the MP .557 cam with 296 advertised duration. His timing is all in by 2000 rpm's and is set at 38 total. My 63 will be an iron headed 440 and with the same .557 cam I will use 10.1 comp and run 93 pump. It sure was fun to stop at the station outside the track and fill my sons Dart up with 93 pump and then drive in and run 11.50's ! Ron
 
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