Author Topic: 2.3 mods (Read 20688 times)

slowride · « **on:** April 28, 2010, 09:35:17 PM »

I'm going to be playing with the wagon a bit, so I figured I'd start cheap and see what improvements I can make. I'll be adding a Hedman header in the near future, but I wanted to see what I could do with a stock intake. I picked one up from Fred and promptly disassembled it as soon as I got it home.
First, I'm keeping the stock Holley/Weber so the adapter plate will be staying. When you look at the adapter, you'll notice a couple things. The (for lack of a better name) flow plate on the backside of the adapter has a significant mismatch in the throttle bores. I figure it certainly can't help flow, so I'll start by smoothing the bores.

I've smoothed both bores, but have some finish work to do on it. Smoothing the bores more won't buy any more, but I have to have things a certain way. It'll be perfect. While I was at it, I tapped the EGR hole and plugged it, but if I ever want to put it back on I can.
In the plenum on the intake, the runners have very sharp edges as they enter the plenum. I know air doesn't like to turn corners, and it REALLY doesn't like sharp corners, so I've radiused the port edges to smooth flow into the runners. I'll be doing a quickie port match to the head when I replace the intake, but until then there's not a whole lot more I can do with this intake.
Hopefully these little changes will help not only smooth the flow for more rpm, but help atomization by keeping the air/fuel mixture from breaking down when going from the plenum into the runners. Will it wake it up more when I add the header? We'll see......

slowride · « **Reply #1 on:** April 29, 2010, 11:10:07 PM »

These pics should make the concept a little clearer.
This shot is with the adapter on the manifold. Looking in thru the throttle bores you can see the runner entrance to the plenum. As the air/fuel mixture goes down thru bores, it need to make a sharp turn into the runner.

There was actually a little casting flash at the edge of the runner making the turn even sharper than it appears. The yellow lines show where I radiused the edges to help smooth the transition to the runner.

This could all be academic, but in theory it should help atomization. When you stick your finger down thru the throttle bores you can feel how much smoother the flow should be. With my luck it'll give me another 50 rpm at 6k.

Wittsend · « **Reply #2 on:** April 29, 2010, 11:24:13 PM »

I have a lot of appreciation for guys who work hard to get the most out of existing parts. I can't pull a head/manifold without taking a grinder to it if even just to clean the sharp edges. I hope you gain a lot for all your hard work. All the best.
Tom

slowride · « **Reply #3 on:** April 30, 2010, 10:55:08 AM »

Thanks Wittsend. I am hand-fitting each piece to make sure I'm doing everything I can to eek out every bit of power. I fit the adapter onto a spare 5200 carb and checked how the throttle bores on the carb align with them on the adapter. I'll post a pic tonight. Not too shabby for production car stuff......

slowride · « **Reply #4 on:** April 30, 2010, 08:07:25 PM »

Here's the adapter bolted to the carb. The alignment isn't too bad. What DOES concern me is usually I see the thick spacer gaskets between the carb and adapter. This creates a big gap under the carb (between the bores) that may cause flow problems. I have both the spacer type and thin gasket so I'll test both to see if there's any difference performance-wise.

71pintoracer · « **Reply #5 on:** April 30, 2010, 10:51:50 PM »

When I was dirt-track racing and had to use the 5200 carb, I would spend about 8 hours modifying the carbs to increase flow. Every little bit helps, and anything in the way disrupts flow. I even cut the ends off of the screws that hold the throttle plates in! Hey, they were in the way! :lol:

dick1172762 · « **Reply #6 on:** May 01, 2010, 03:41:46 PM »

I talked to the Ford enginner in charge of their R&D dyno room in the late 70's about the 2.3 intake manifold, and how to improve it. He told me that it was a bean counter manifold , and made as cheap as possible. Thats why two of the runners are 1/2 the length of the other two. He said that on the dyno, it made no difference in HP reguardless of what carb was bolted on. He said it was the same HP with a stock cab as with a 500 Holley two barrel. He said the flow rate was so poor because of the two short runners, that two runners would run pig rich at all times even when the other two ran lean. LOL.

slowride · « **Reply #7 on:** May 02, 2010, 11:15:33 AM »

I've looked at a couple intakes and there's really no way to equalize the flow and fuel distribution to the cylinders (in a carbureted app) without raising the plenum and bringing the runners in at the bottom of the plenum (similar to the EFI intakes). Adding more plenum would help, but I would think you'd have to poke thru the hood to do it. It is what it is. It'd be hard to make it worse, eh?

dick1172762 · « **Reply #8 on:** May 02, 2010, 02:53:16 PM »

The 74/75 intakes are the ones all the mini-stock boys use when the rules require a 100% stock intake. Its the one with ribs in the bottom, inplace of the later ones with triangles on the bottom. They can be ported to work better, BUT never as good as an equal length manifold. Even Eslingers oval and d-port intakes are of unequal lengths. Only the Eslinger ARCA intake is close, and it wount fit a stock head.

slowride · « **Reply #9 on:** May 02, 2010, 04:29:13 PM »

I don't really see runner length as the biggest issue since runner size/shape can equalize it to a certain degree (if you wanted to spend that much time on a flow bench). My issue is with how to distribute the A/F mixture evenly considering the primary/secondary orientation. No matter how you change the carb position you are fattening some cylinders while leaning out others. That's why I said a tall plenum with runners at the bottom would provide the best distribution. Unfortunately that merely enhances something the 2.3 has no problem with.... a taller powerband. The manifold I'm playing with is a D5, but I don't know that at the power level I'm at the plenum floor would matter much.

slowride · « **Reply #10 on:** May 05, 2010, 01:40:56 PM »

Well, after having a few beers and staring at the plenum on this manifold, it looks like I need to find a mill and modify the plenum. The primary isn't the problem... it'll feed all 4 runners with little restriction (inefficiently, but relatively speaking). The orange arrows show the flow paths. The problem is the secondary. When the secondary opens, it can flow relatively unrestricted into #2 & 3, but for 1 & 4 it hits the "divider" creating a low pressure area behind it. My understanding of flow dynamics is that the flow hitting the divider will separate the fuel from the air/fuel mixture and create turbulence at the low pressure area behind the divider. So I'd have #2 and 3 richer that 1 & 4.
My plan is to mill the dividers out of the plenum and round all the runner edges to smooth the flow. In looking at it, it should flow smoother (and more equally) if the flow starts higher instead of moving horizontally in the plenum. This will require a spacer to lift the carb and extend the plenum higher. The downside is normally adding more plenum (like a tunnel ram) gives you more top end and not necessarily more torque down lower (where I need it).
There's only 1 way to find out...... :surprised:

slowride · « **Reply #11 on:** June 25, 2010, 02:53:47 PM »

Well, it's been a while but I'm back to trying out the mods. The header (Hedman 48030) will be here next week and will be the first thing I try. The spare intake manifold will be milled and tested after the header is installed and tested. Last will be the carb spacer to add more plenum. This should give me a good idea what the mods do and how they react to other changes.

78_starsky · « **Reply #12 on:** June 26, 2010, 02:26:15 AM »

Interesting read. what cam are you goin gto be running with this build? or do you have one in mind? I have a suggestion if you are doing the full build.

slowride · « **Reply #13 on:** June 26, 2010, 10:45:06 AM »

For the near future I'm running the stock cam. When I get this work done, I'll be pulling the head for machining and possibly make a cam change at that time. This is my daily driver so baby steps are just fine.

slowride · « **Reply #14 on:** June 30, 2010, 10:50:22 PM »

Fedex showed up today

We'll see if the muffler shop is open this Saturday to modify the exhaust

slowride · « **Reply #15 on:** July 02, 2010, 09:57:30 AM »

I made up the air injection port plugs yesterday, pulled the manifold back, and put them in. Went to the muffler shop and set it up for installation on Saturday

I'm hoping to pick a couple miles per gallon as most of my driving is freeway at 60-70 mph. A little extra power wouldn't hurt either....

slowride · « **Reply #16 on:** July 05, 2010, 09:14:55 PM »

The header was installed Saturday and it's already been off 2 times. First thing about the Hedman header..... it's a 2 piece with a slip-on collector. What does that mean? It'll leak.... if it's assembled as is. I pulled it off as soon as I got home from the shop to see if maybe they overlooked something.... they didn't. I spoke with a neighbor that works for Doug Thorley and he said they all leak unless you use some type of sealant on the slip joint. That brings me to the second time (this morning). I bought some ultra-copper which may seal it for a short period of time (maybe longer). A ceramic sealant was suggested, I just have to find it. Pulling the header really isn't hard or time consuming, but it HAS to be pulled and assembled in 2 pieces as it won't fit past the bellhousing in one piece. No big deal. Here it is after reassembling it with the ultra copper. I need to give it as much time to cure as possible, so I won't know how well it worked until I leave for work tomorrow morning.

Here's a pic of the slip joint at the collector

It is nice how well the header tucks up and doesn't reduce ground clearance

If you're contemplating this, keep a couple things in mind.
Remove the battery and spark plugs..... you'll appreciate the extra room.
Clean the slip joint VERY well. I sanded the surface rust and wiped it down with acetone before applying the ultra copper.
As far as any extra power or gas mileage? I don't have any mileage on it yet to test it.... I'll have a better idea tomorrow.

slowride · « **Reply #17 on:** July 06, 2010, 09:21:18 AM »

So after 13 miles of freeway, it looks like the collector is sealed and nice and quiet. A little more power at what is probably around 3000 rpm (I haven't installed a tach yet), but the gas gauge didn't move! Hopefully that means better mileage, not another project of replacing the sender..... :smile:

popbumper · « **Reply #18 on:** July 07, 2010, 01:53:40 PM »

Nice writeup and interesting topic. Thanks for sharing all of this.

Chris

slowride · « **Reply #19 on:** July 08, 2010, 09:59:37 AM »

My pleasure. After a few days driving it with the header I've become more accustomed to it's "feel". There IS more bottom end as I have a better launch from a stop. The powerband has moved down a bit as I have more pull lower in the powerband than I did before. Gas mileage appears better, but it's really too soon to tell.
Manifold and spacer mods are next and should be interesting.

slowride · « **Reply #20 on:** July 08, 2010, 03:01:35 PM »

After mocking up the carb on the intake, I chose to go with a 1/2" spacer. The flow plate under the carb is tapered.... a little less than 1/2" on the front, and a little more on the back). 1/2" will make adapting the throttle linkage easier, as well as (hopefully) keeping it under the hood. I ordered the Transdapt 2134 (open center) since I'll be milling the center so the flow plate just goes through the center. This will put the bottom of the flow plate right at the top of the plenum and provide a smoother bend into the runners.

slowride · « **Reply #21 on:** July 08, 2010, 11:14:24 PM »

This will give you an idea what the spacer will look like after milling (this is the bottom view). The flow plate will go down through the center of the spacer and be almost flush with the bottom. Below the plate will be open plenum.

slowride · « **Reply #22 on:** July 16, 2010, 11:30:05 AM »

Well, adding the spacer will be delayed as I bought the one Transdapt makes and it won't seal against the rear of the plenum. The sealing surface at the back of the plenum is MAYBE 1/8" wide, and it also doesn't leave much meat to mill out for the flow plate. Looks like I'll be buying some 1/2" thick billet and making my own.... $:-\$

slowride · « **Reply #23 on:** March 13, 2011, 09:56:43 AM »

After spending WAY too much time and money trying to modify a commercial carb spacer, It came down to making one. I bought a piece of 5"x12" .5" aluminum stock, cut it to 5"x6" and started drilling. A mill would have made this go MUCH quicker, but you do with what you have.
This shot shows the carb angle and how the spacer adds 1/2" of plenum and should make the transition into the ports smoother.

I tried to make the plenum hole as close to the flowplate's size as possible to keep the flow as smooth as possible. Theory is that a larger hole would disrupt the flow by creating a reversion (flow trying to go into the hole because of a low pressure area).

Next is to make a spacer to raise the linkage bracket 1/2" and hope the kickdown rod doesn't need to be modified.

slowride · « **Reply #24 on:** March 14, 2011, 10:33:46 AM »

Yesterday the spacer went on. It took about an hour total to install, and the throttle bracket did not need to be raised. everything fits under the hood easily too. I have about 15 miles on it so far and about the only obvious difference so far is the idle is considerably smoother than before. I need a little more time to calibrate the "seat-of-the-pants" dyno, but so far it seems to have helped a little in the higher RPM's. Most of my driving is freeway, so I need more time to see if it's stoplight manners are better. Gas mileage figures will be available in a week.

slowride · « **Reply #25 on:** March 14, 2011, 11:16:50 PM »

Well, the seat-of-the-pants dyno is getting dialed in, and a few things are becoming evident. First. let me acknowledge one thing..... I know I'm tempting fate doing this to a car with a C3 trans. Ever since I advanced the cam, I couldn't really jump on it from a stop for fear of scattering it. I dialed in the carb and it wants to holeshot a tad better, but the smoothness of the idle is amazing (for a 2.3). Before, it would pull well in the upper rpm's, but when the secondary opened it was less than spectacular. It didn't "bog", but I had to get the rpm up to really feel when the secondary came in. Now, it pulls a little lower and doesn't bog. Don't get me wrong, it still wants the rpm, but puts a smile on my face when I kick it down a gear, the rpm comes up, and the secondary comes in.
If anyone has some time to play around and make a spacer, I'd consider it time well spent. Granted I haven't seen the gas mileage yet (and playing with it this much may LOWER it), but it has definitely made a difference. I can't help but think it would REALLY wake up a manual trans car. If you have smaller tires than me (225/60-15 on the rear) and a manual trans, this mod should REALLY get your attention!

slowride · « **Reply #26 on:** March 16, 2011, 09:13:55 AM »

The next step will be milling the dividers between ports 1/2 and 3/4 to see if the flow on the end cylinders can be evened out a bit. The change in the engine now is just with the stock intake.

dyerjg · « **Reply #27 on:** April 10, 2011, 08:30:00 PM »

Good work, I like the play by play! Any thing on mpgs yet?

John

dave1987 · « **Reply #28 on:** April 11, 2011, 12:35:40 AM »

I would like to know! I am going to pull the carb spacer/EGR plate off the next Pinto I find so I can do some of the work you have done and just swap them out when I am done. I would love to try the spacer plate as well. The more get up and go and smooth acceleration I can get from my 78, the better! Granted my 78 is a 4spd and I can change gears when I like, it's always nice to know you have a car that is using all the resources it has to drive and perform well!

slowride · « **Reply #29 on:** May 18, 2011, 12:01:08 PM »

Sorry for the delay, but other vehicles demanded attention.
I am actually taking a step backwards and removing the header and putting the exhaust manifold back on. Without a more aggressive cam. there is no benefit to the header, and to be honest, the slip-on collector on a Thorley header leaks like a biotch and has annoyed me to no end.
The main advantage of the spacer has been a bit more power, and a smoother idle. Gas mileage has increased maybe 1 mpg, but I also suspect I need to re-jet this carb.

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Author Topic: 2.3 mods (Read 20688 times)