MSefi.com read only forum (Jan.15,2018)

I have for some time wanted to install TPI on my 69 C-10 Pick-up. Well that plan has changed slightly over time and now I am getting to the point where I am really looking forward to learning efi and the tuning/configuration along with it. The original plan was to use a stock tpi intake with a factory ECM & stand alont harness, However now that I have been reading about the MS-II I am leaning towards changing that plan up some.
Here is what I have,
A 1980's 350 with 882 75cc chamber heads
a 275/280 cam that has a 108 lobe separation (from what I understand this can lead to trouble b/c I only have 10 to 11 inches of vacuum @ idle)
The doner parts I have right now are a throttle body from a 90 something lt1 intake.(tps sensor & IAC)
Ford 24# injectors @ 15.3 to 15.5 ohms
a stock (small cap) throttle body distributor with remote coil.
I plan on buying a Weiand stealth ram intake (wnd-7540) and fuel rail.
As far as the sensors go I want to use MS-II with map daddy for map, and stock IAT, CLT and hope to buy a wide band 02. Would like to install a factory knock sensor.
I know I have to deal with my fuel system. It will have to use and external pump, b/c I do not want to buy a new tank at this time. would appreciate any advice about pumps to use.

I have been reading about tuning from Matt Cramer and Jerry Hoffmann's book and it is helping understand allot. But I think I have a way to go.
At any rate I am sure I will be searching the forum and DIY's articles. It looks like they have done a nova that is similar to the setup I am planing. In the meantime I would appreciate any advice along the way.

Thank you,
Richard/Riche

Reading about FPR-ers. I can't find much info on the Holley FPR that comes with the fuel rail for the Stealth ram.
I If I am setting it to the correct static pressure, key on engine off. When the engine is started will the vacuum increase or decrease the pressure?

The regulator that came in our Stealth Ram kit wasn't adjustable.

Riche wrote:
Reading about FPR-ers. I can't find much info on the Holley FPR that comes with the fuel rail for the Stealth ram.
I If I am setting it to the correct static pressure, key on engine off. When the engine is started will the vacuum increase or decrease the pressure?

Engine vacuum makes the reg drop the fuel pressure - the idea being to counteract the 'suck' on the injectors caused by inlet vacuum.

Thanks for the reply's
I am trying to establish how this will affect me with the cam I have and if it is worth replacing my cam.
I was told by one friend that some FPR's require 14" of vacuum. If that is the case and my cam is only allowing my motor to pull 10 or 11 inches. That is going to affect my FPR. From what I understand so far my FPR will basically not reduce pressure at idle.
Is that a bad thing? considering my motor will probably want more fuel at idle anyway?

The FPR is intended to maintain a constant pressure difference from the fuel rail to the manifold. It does not "require" a certain amount of vacuum - the amount of vacuum in the manifold is what it is, and the regulator's job is to follow it.

So there is no magical vacuum # that the FPR is set to reduce the fuel pressure at?
If a stock small block pull 17 to 18 inches at idle and mine is pulling 10 to 11 inches, the bottom line is I will have "less" of a drop in pressure? Or less of a range in fuel pressure variation due to the limited vacuum?
ie. 0 to 18 inches stock vs 0 to 11 inches.
I am probably over thinking this, I appreciate your advice.

You don't have to worry about not having enough vacuum. When the engine is off, and also at WOT, there should be no vacuum. At this setting, let's just say we adjust the fuel pressure to 40psi. Think of the fuel pressure of being 40psi greater than ambient conditions. Now, when the engine is in a vacuum state, we have a negative pressure in the intake, so we need less than 40psi of fuel pressure at the rail to over come the atmosphere in the intake. So at a higher vacuum level, you should see less fuel pressure on your fuel rail.

If at 0 vacuum you set fuel pressure to 40psi, then at 5" vacuum you might see 35psi and at 10" vacuum you might see 30psi. I'm just using round numbers for the sake of the example, but the trend (higher vacuum, lower fuel pressure) is what is important. If your engine doesn't make much vacuum, it doesn't matter, it just means there the regulator won't be changing the pressure over as wide of a range as it would on an engine with higher vaccum..

Hope this help a little.

-Dave

Thanks Dave,
That does help, I understand.
With all that being said I have allot of reading and advice telling me to change the cam, but at the same time I am wondering if I am up to the challenge of getting this thing to idle.
From what I am reading I am sure it is not this easy as I am making it, b/c mainly I do not have a good understanding of the ve table yet, however why can't you just adjust the air fuel table in the idle range?
Is the problem with the intake not getting enough air? I am assuming I can throw as much gas as I want by adjusting the AFR table.
Will I be spending allot of time banging my head against the wall? Should I just go ahead and invest in a new cam?
Matt, I believe you addressed my concerns in an email.
I am sure I need to learn more before anyone answers these questions. Maybe we could just stick to the cam discussion.

I don't think you need to change the cam. What you have doesn't sound very radical. I'm assuming your 275/280 cam numbers are advertised duration. That should work fine. Please post all cam specs (or cam part number) if you want a more definitive answer. But, chances are your cam doesn't need to be changed.

I think you'll want to adjust the VE table by hand for the idle area. VE stands for Volumetric Efficiency. For a full understanding, read the MegaManual. The cliffs notes version is this: any given entry in the VE table provides a value for the fuel equation used by Megasquirt. Higher VE table value == more fuel. Lower VE table value == less fuel.

If you want to try and get it to idle even, here's a tip.. Imagine your first two RPM columns are 600 and 1100 RPM. Also, let's assume your idle is between 45-50kpa. See how the values are all different? Try to square-up the idle area. In the example, I'd try setting them all to 41. And then if you need to make an adjustment, adjust all 4 values the same -- move them all to 37 or 45, to lean or richen. As you get it tuned a little better, your kPa range might change a bit. Assuming it starts to idle better, you might end up in the 40-45 kPa range and you'll have to make a further fine adjustment. But this should help get you in the right direction.

I've seen it said over and over to not tune the idle by the A/F ratio. Listen to the engine. You'll be able to tell when it's idling nice or not. Tune for highest vacuum (lower kPa). Ignition timing can also have an impact on idle quality.

-Dave

ChevelleFan wrote:I don't think you need to change the cam. What you have doesn't sound very radical. I'm assuming your 275/280 cam numbers are advertised duration. That should work fine. Please post all cam specs (or cam part number) if you want a more definitive answer. But, chances are your cam doesn't need to be changed.

I must agree, emphatically, with Dave on this. I run a 383 sbc with a lot more cam than yours without issues. Proper tuning of idle ve (along with timing etc.) should do the trick.

Bottom line........ I would not change the cam!

Just my 2 cents (and experience).........

Ken

Wow, thanks for the advice. My gut was telling me it can work just had a lot of people saying otherwise. I really appreciate it and gives me a piece of mind. I am reading however I am not the type of person that retains very well unless I get my hands on something.

Here is my cam. It is a Howard's cam
Basic Operating RPM Range:1,800-5,800
Intake Duration at 050 inch Lift:221
Exhaust Duration at 050 inch Lift:231
Duration at 050 inch Lift:221 int./231 exh.
Advertised Intake Duration:275
Advertised Exhaust Duration:285
Advertised Duration:275 int./285 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.470 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.470 in.
Valve Lift with Factory Rocker Arm Ratio:0.470 int./0.470 exh.
Lobe sep: 108

I didn't really put a lot of thought into the performance of the cam when I bought it other than I was getting a 2200 stall and I wanted to get as much lope as I could without overpowering the stall. At the time TPI was not in my equation.
Thanks again

FWIW............

My first MS project was almost identical to your setup (heads, cam etc), with the exception of the fuel injection. In my case I used a stock 86 Corvette TPI with 24# injectors which worked very well with B&G code. It is now in my grandson's '68 Chevy stepside and is still performing just fine.

I am confident that your setup, as you described it, will work equally well.

Good luck!

Ken

BTW, just curious..... Is that a roller cam block? What ignition do you plan to use?

That is cool, and that was lingering in the back of my mind is the longevity of an ecm that "I" built. But to me this is about learning engine management and not just being a wench turner. I have had my truck for a long time... Right now it is flat black and I am just playing. I plan on rebuilding it again one day.
It is not a factory roller block. But I figured if I learn how tune this cam I was going to retro fit some roller lifters in it and put some good heads on it.
For the distributor I have a factory small cap 8 pin distributor with a remote coil from a throttle body engine that I want to run so I can learn how to adjust timing tables.
To get the project started I plan on using an old points distributor so I don't bite off more than I can chew like I have heard mentioned. That way I can work on learning the fuel first.

Stupid question, Just trying to understand the hierarchic. Is the AFR table more for closed loop corrections and the AE table is the basis for the fuel management?
If it is not an easy answer then just tell me which section of the book or megamanual I should "re-read"

Is the AFR table more for closed loop corrections

Yes

and the AE table is the basis for the fuel management?

No. The VE Table is for fuel management.

Ken

Thanks Ken,
The sad part is I probably read that somewhere, just gonna take a while for my brain to sort though all that stuff running through it. I spent some slow time at work today and re-read AE then looked at dave's post things started to make sense. Then I watched Matt's video he made for the nova start-up while I had tuner studio open looking at an AE table. I understand AE "better" now I just have to get a handle on how to tune it. I do feel more confident that I can make this cam idle.

Well,
I am playing around with the idea of doing this backwards...
Since I have the 8 pin distributor and have not bought the intake, fuel rail & fuel system(pump & lines).
What would be wrong with hooking up the ms-II to control the timing? Get everything wired and ready for the injection system, log data on my airfuel/map with my carb as I am learning ignition?

Riche wrote:What would be wrong with hooking up the ms-II to control the timing? Get everything wired and ready for the injection system, log data on my airfuel/map with my carb as I am learning ignition?

Nothing wrong with that idea at all, IMO.

I know of any number of users that have done that very thing. That is, they started with ignition, got it working and then went on to the fi portion of their installation.

Just one users opinion of course, but I do think it is perfectly viable.

Hope that helps.

Ken

Thanks Ken,

I figure this will get me into trouble but not to much at one time. I am eager to get get my hands dirty, and I figure this way let me learn as I go and give my wallet time to recover.