Timing curves on a crate motor.

[DaveBauerSS6]

DYNO:
"The next biggest gain is geting your distributor built to the right timing curve to match the engines acceleration after you get the carb right. If you are firing too soon you bind up the engine if you fire too late you run too rich. Getting it right is as much as 10-15RWHP."

I run a Super Stock, 625 HP, iron head 4 bbl ; 4900 to 7600 on our average tracks. Are you saying it would be beneficial to run a timing curve ( not fixed) at that RPM range?? I run a tach recorder and am surprised at how long the rpms are in the lower part of that range.
Thanks, Dave

[dynoman14]

Do your run a fixed fuel curve on your engine???

Part of the reason engines don't accelerate properly is because the advance ignition of fuel is killing the momentum of the engine trying to accelerate

Lighting the spark plug when the piston is down in the hole does nothing but slow down the engine.

I have seen a couple of them engine run on the dyno at Jerry Hemmingsons and they accelerate pretty good on the dyno and at the track.

How does your Super Stocker run if you drag the brakes??? Same thing, just different forces acting on the car right. Why do you think an over advanced engine struggles to start when it is hot. It is fighting for its life against reverse cylinder pressure...

I guess people think I am bull$hitting when I tell them I run 20-22* timing on my fastest crate cars. Distributor spark timing is just one of about 5 factors that influence combustion timing. Once you figure that out you will have another world of engine tuning open up.

Most folks run 35* locked out because they were told that by some engine guru, they dial it in at the dyno and then tune the engine from there.

WHY??? Is it better? Does the engine accelerate fastest there?

Can you even measure how the engine accelerates?

Is it possible to measure engine acceleration with a pre-loaded water brake that controls the rate of engine acceleration???

I leave gaps to draw attention to these questions, when you find those answers you will understand how my results for the past 25 years are different than anybody elses, I have been inertia and acceleration testing all of my engines and parts development for 25 years.

That is why short rods run better than long rods, that is why low timing rich burn engines make more torque and have a higher acceleration rate than their lean burn high timing counterparts. That is also why engines that build and hold inertia for multi-lap testing outperform super-lite counterparts on the ChassisDYno and on the track.

There are reasons for just about everything we test you just have to find out why something works in order to make it better, and then keep working in that direction. I might be working in the wrong direction to some of you but it seems like the future of engine testing is just now coming around to my way of thinking.

I currently do 5-10 CalPak jobs a week, mostly for people on here. That is where I match the carb and ignition to the acceleration curve of the 602 and 604 engines on the fuel they run. Every single one is different and the pick-up a range of 14-32HP. Acceleration on the dyno from 2500-6500 can be as much as a full second and it show up on their dyno runs and at the track. They have all mailed me back amazed at the results.

That is only scratching the surface of what acceleration testing can improve. In the next 5 years you will start hearing about the new Inertia engine dynos that are REVOLUTION-izing engine testing. If I had any decent help I would buy one. I don't have time to do what I am doing now much less a new engine dyno. I have my own design I have been working on for about 10 years now since I saw one in use at Ferrari Racing in Maranello about 10 years ago. BTW they have a couple Serdi machines.

If I was to say I knew some of the folks at either place in the last paragraph that would be name dropping so I guess I won't because I know how it hurts some folks feelings out there.

I guess people would be thinking the world was still flat if it was not for Christopher Columbus???

[50j]

Magellan was the one that circumnavigated the earth.

[DaveBauerSS6]

No,,, I run a MSD out of the box. What ever curve that it came with. My IMCA stock Car I have is fixed, to improve the idle due to the small carb pulling fuel thru the boosters at idle with my engine combo.

So, is the answer yes that the curve be changed in that range? I assume (I used my worst word (WTF?)) the weights and springs can be tuned?

[dynoman14]

Dave,
Not to be smart but you have a carburetor problem that you are masking with advancing up your distributor. That would be like running 20psi in your right rear because your car is tight cause the rear end is mis-aligned tight.

Only reason fuel comes out of the boosters is because float level is too high.

If you have to idle your engine up that high to keep it running, you need a couple mods to that 2bbl to make it run on a late model engine. Is the carb built by someone that knows 2-BBLS or out of the box???

If you update your cooling system, your fuel system, and your ignition system you are one of the folks that would probably pick up 50RWHP if you did.

[dynoman14]

50j,
Never said he circumnavigated the globe.

Way back when I was in school Columbus was credited with finding the New World even though the Chinese did it 100 years before.

I guess you should be proud that you have a forum you can come on and criticize anything you want to whenever you want to, isn't that what makes America great ???

Bottom line:
If someone does not step out of the ordinary and do something different all of the race lemmings just walk in step and copy cat like they have for 100 years.

I take pride in working in directions and areas that are my own, giving credit to mentors and friends along the way.

My last set of custom crate headers, builder said they won't work and they will lose 25 # TQ and kill the power...guess what??? I just ordered 5 more sets. I love when that happens.

[stockcar5]

Only reason fuel comes out of the boosters is because float level is too high.

not even close to true. common problem on a 7448 with a high compression larger ci engine. they pull tons of vacuum at idle and cause pullover. all the good carb guys know about it and how to help fix it and float level isnt the fix. but you wouldnt know that would you?

[Matt49]

Only reason fuel comes out of the boosters is because float level is too high.

Not true at all. Plenty of ways that fuel can come out of the boosters at idle:
sunk float
debris stuck in needle valve
excessive fuel pressure
etc.

[DaveBauerSS6]

I have two 350 cfm carbs. One is a VDL, new out of the box. Not sure how popular VDL is east of the Rockys, but most racers run the VDL out here if they can afford it. The other is a Holley Keith Dorton model, new out of the box. I called Holley and VDL and both lead me on the normal setup checks. Both finally suggested locking the timing to allow the throttle to be closed enough to stop the pullover and for a good idle signal. They both admitted the 7448 is tough to tune to these IMCA motors. I don't like the lockout, but I have a clean idle now. And it worked for both carbs.

[sj valley dave]

We had a 4412 that we could not get to idle with a borrowed MSD that had weights and a curve...Had to idle at 1700 rpm to keep it going...Locked it out and problem went away.Idled it down to 1100...We haven't ran a curve in a distributor since the mid 90's...Both built engines (known national builders) we have had were locked out from the builder...

[dynoman14]

Like I said if it was not float level there are a couple other areas to work on.
As far as curves in dizzys I am sure 99% of engine builders don't know how to properly build a dizzy with a curve springs and weights. The ones people ship me daily are from race engines and they are junk.
I guess people should build fuel systems and carburetord with a flat fuel curve too.

Vanderley is a sharp carb guy as well as Keith Cotton. I am pretty sure neither 7448 was designers for your IMCA application.

My point was the 2 problems affect each other but are mutually.exclusive. if you fix your carburetor problems you can then unfixed the fixed timing curve and still make the engine idle.

That is as stupid as the folks on here that run off at the mouth about alternators robbing engine power and dirt cars can't run electric fans.

How does your engine start up after a race???

[DaveBauerSS6]

The car fires right off, hot or cold. I understand were you are going with the question. I must be lucky, because I flip on the ignition and it cranks only a short moment then fires. I know a lot of motors need to crank, then flip on the ignition to start. I have tuned many that require it. My starter system I would call average, no real tricks. I don't know why my fires easy??

As far as the application, yes both were for IMCA competition. The VDL was ordered for a IMCA Stock Car. VDL has serial numbers assigned to each carb, you call them and they discuss your carb. Holley/ Dorton according to Holley tech was for IMCA applications. Both agreed the application under IMCA can be varied. My motor is very much different than my competitors. I just put more effort in a clean idle; I believe a dirty spark plug never gets better.

[stockcar5]

Like I said if it was not float level there are a couple other areas to work on.

you never said anything of the sort...more lies.

Only reason fuel comes out of the boosters is because float level is too high.

notice the "only"...lol

Vanderley is a sharp carb guy as well as Keith Cotton. I am pretty sure neither 7448 was designers for your IMCA application.

my vdl 7448 was also built for imca. dripped out the boosters like most all of them do. nice try though..

[sj valley dave]

Dyno, sometimes you actually make me think hmmmm "maybe??", other times you just make me laugh

[stock car driver]

Dave, Jdr performance builds a very very good 7448, I put a whole lot of dyno time in helping him get even more out of them a few years ago... He says Vdl makes the only 4412 thats beat his. Locked dist is the way to go in my opinion whether you have carb issues or not.

As to your first original question, you can taylor the advance curve of a msd distributor.

One of my motors picks up 15 hp to the rear wheels at 38 degrees above 5200 below that it makes the most power at 36 degrees. My chassis dyno guy has a distributor machine and said he could curve my dist to have only that 2 degrees of advance and at that rpm etc. Im not sure how its done, Ive never had him do it.