Wideband Demon Tuning - Page 5 - Motorgen - Automotive Events, Meets, Cruises and Forums

Vettezuki · 07-26-2009, 12:48 AM

Quote:

Originally Posted by 94cobra69ss396

Yes, this was specifically for Adam who is the one tuning his car and asked. Now if he had posted that he just built an engine and wanted to know how he should go about tuning the carb my answer would have been different.

Alles Klar!

enkeivette · 07-26-2009, 01:08 AM

Damian, Zuki, you guys are arguing for an impossible method of tuning. You can't tune your cruise AFR without affecting your WOT AFR. You can tune your WOT AFR without affecting your cruise AFR, however.

And you can't just hit one then the other, ex: next time I get in there I will lean out the primary side which will drop the cruise AFR & the WOT AFR. Then, depending on how much it leaned out, I will need to guage the size I need to drill the PVCR out to, depending on that.

Stop thinking about it in terms of RPM vs AFR and think about it in terms of tuning this part of the carb first, then that part, then the other part, in that order.

And Adam did tune his carb when he first built the motor, then he changed the intake manifold, compression, cam lift did some port matching and added a blower.

Bird, MSD HEI.

CobraSS, I'm starting to wonder if my PV's blow out protection is working under boost and stopping the PV from functioning. I want to call BG Mon and get their opinion, might drill it out.

Vettezuki · 07-26-2009, 01:44 AM

Quote:

Originally Posted by enkeivette

Damian, Zuki, you guys are arguing for an impossible method of tuning.

Que? It's basically the method bird was talking about in the first place and what Ron would have recommended in principle.

Quote:

Originally Posted by Ron

Yes, this was specifically for Adam who is the one tuning his car and asked. Now if he had posted that he just built an engine and wanted to know how he should go about tuning the carb my answer would have been different.

. . . I'm not saying that you shouldn't tune the primaries first. . . That's how I tuned the 454 in the Chevelle. I drove it around at light throttle and got the drivability tuned for the first 500 miles or so and then tuned the secondaries for WOT.

Quote:

. . . You can't tune your cruise AFR without affecting your WOT AFR. You can tune your WOT AFR without affecting your cruise AFR, however.

Sure. Then go back and discover you need to reduce the size of your primaries for cruise and what happens to your WOT AFR?? Seems like a lot of inefficient tail chasing.

Quote:

And you can't just hit one then the other, ex: next time I get in there I will lean out the primary side which will drop the cruise AFR & the WOT AFR. Then, depending on how much it leaned out, I will need to guage the size I need to drill the PVCR out to, depending on that.

I don't know much about carbs in practice. But it's hard for me to believe it involves this much black magic. If it does, no wonder FI and computerized control took over.

Quote:

Stop thinking about it in terms of RPM vs AFR and think about it in terms of tuning this part of the carb first, then that part, then the other part, in that order.

What system is "this and that part" connected to? It isn't a carb in a "vaccuum"; it's part of an engine system functioning in a context. All references are made relative to throttle position which has at least something to do with rpm. Yes I know there is a lot more to do to this regarding engine load and vacuum, maybe I should only refer to throttle position and load. The idea is simply moving in a progressive manor bottom to top. Repeated cycles may be required to idealize all ranges for a given purpose, but the process must be systematic and logical.

I'll be investigating TB injection for RX-Snake. No Fing way I want to deal with these kind of issues at all.

big2bird · 07-26-2009, 05:08 AM

Ben,
There is a big difference between his induction system and the Snake. He pressurizes his carb. The Snake sucks. Big diff. Tuning a Holly, once finished, will hold it's tune well.
A carb is just a mechanical metering device that regulates the A/F mixture thru various air flows. Typically, on a N/A engine, once tuned, you can install it on another engine, and it will work fine.
Adam is pushing air into a carb that for 100 years has relied on differential pressure to operate properly.(Vaccum).

big2bird · 07-26-2009, 05:10 AM

Quote:

Originally Posted by enkeivette

Bird, MSD HEI.

Pull it out, and I'll install a 10* stop.

Damian · 07-26-2009, 10:32 AM

Quote:

Originally Posted by enkeivette

Damian, Zuki, you guys are arguing for an impossible method of tuning. You can't tune your cruise AFR without affecting your WOT AFR. You can tune your WOT AFR without affecting your cruise AFR, however.

Then I have to appologize then, my statements werent meant to argue, more of me wanting to understand why he chose that route to tune. The reason I was asking is because Im working on a guys Eclipse that turboed it. The shop that fabricated everything said the fuel system was a-ok for the setup, not even close. So Im going in and upgrading the fuel pump, fuel rail and injectors, among a full maintenence on the engine. Then Im going to tune for his bigger injectors. Then Ill tune his car for cruising and light boost, just enough to get him to a dyno shop of his choice to really dial in hit WOT a/f ratios. So thats how I do it, not saying its the only way, but my way.

I do see your reasoning now for the fail safe under WOT conditions. That is smart and thats exactly how Im going to tune this guys car, minus the WOT pull. But its a matter of finding a balance between the primaries and secondaries, and from the sounds of it, is going to take a lot of trial and error. Tuning EFI under boost is so much easier IMO.

enkeivette · 07-26-2009, 10:42 AM

Quote:

Originally Posted by Vettezuki

I don't know much about carbs in practice.

This is apparent.

I posted a thread awhile back with some Holley tuning basics. Review it. http://www.motorgen.com/forum/showthread.php?t=284

After all of that you move on to the jets. Not cruise AFR, not WOT AFR... the jets. Hopefully, after tuning the jets (both primary AND secondary at the same time, as they need to be 8-10 off) the idle, cruise, and WOT AFR will all work out perfectly.

...IF NOT! Then you can move on to f*cking with HSABs IABs and drilling out different parts of the metering block (PVCRs). You cannot, CANNOT, screw with all of that more sensitive stuff before you at least try to tune by jets (which is not cruise or WOT specific) otherwise you might (and will likely) cause irreversible damage to your carb. And THAT, is chasing your tail.

Like I said before, you move through the carb systematically, not RPM vs AFR.

As far as it being more difficult, cry about it. I've spent about 10 mins working on the carb since I hooked up the LM2, and after a few more quick changes it will be spot on. The rest of the time I've spent typing on this forum and waiting for it to be Monday so I can call Barry Grant about the PV check ball.

Quote:

Originally Posted by big2bird

Pull it out, and I'll install a 10* stop.

Bird, you are my hero. When can I bring it over? And how much are custom Bird bushings?

big2bird · 07-26-2009, 11:29 AM

Quote:

Originally Posted by enkeivette

Bird, you are my hero. When can I bring it over? And how much are custom Bird bushings?

Cheap. No one makes a 10* bushing. I am going to put a stop on the slot.
(Read as shorten the slot). Not to worry. It's reversable.

I think Weds might be good.

BRUTAL64 · 07-27-2009, 08:42 AM

I don't post on the week ends. So you guys have all your fun and I'm not around. I see how it is.

Vettezuki · 07-27-2009, 08:48 AM

Quote:

Originally Posted by BRUTAL64

I don't post on the week ends. So you guys have all your fun and I'm not around. I see how it is.

We're going to have to hold a bake sale or something to get you a computer for the shop.