mobird

Haha I like that idea! Probably a little more complicated than I would go, but it's a really good thought!

I most likely will find some aluminum tubing of the same diameter as the STS baffles (I believe it is 1 1/4") so I can mess with it on the bench and fab up the cutout valve. Most likely the first iteration will be manual operation only (adjust it with a bolt head on the outside of the pipes) to test the theory a bit. Then if I can get that perfected, I'll start messing with a small servo motor to see how I could make it work.

First step is uncapping the baffles this weekend and doing some testing!

mobird

Wow that is very similar! Did you notice much difference going from the Vortecs to the Pro 1's? I'm assuming they have a bit better flow, same size combustion chamber? And any future plans for the car or just enjoy it as is now?

jim-81

No.... and that is what I am struggling with now. I was going to start a thread on what I might be missing. Car runs good but it seems like it should have more power with the good combo of parts I have. I figured I'd wait till I get to the track and have a quarter mile time for a baseline but last year I could only muster mid 14's. Anyhoo… For now I am enjoying it.

mobird

So I just did a quick google search, the Vortec heads and pro 1 heads flow very similarly up to .400 lift. At .500 lift the Pro 1 180's pull away a bit (257 Intake/172 Exhaust CFM vs 239 Intake/160 Exhaust for the vortecs). HOWEVER your XE 268 cam only has .477" Intake/.480" Exhaust lift (with 1.5 rockers) so you aren't able to take advantage of the extra flow at .500 valve lift. So you are probably only gained a couple horsepower from the swap from Vortecs to Pro 1's, but you definitely lost at least 40 pounds in weight switching to aluminum and got some better detonation resistance! Best bet if you want some more pep would be to go bigger camshaft, and if you are going through that effort I would say go Retro Roller to free up even more. Those Pro 1's have plenty of power potential (250 CFM flow at .500 can support roughly 500 hp), but it needs more camshaft to utilize it!

Also important, what insert do you have in your Doug's Sidepipes? Have you read some of the dyno tests on this forum? The insert makes a HUGE difference on the power potential of your car. I'm going to be doing some tests with the STS baffles in the near future so I'll let you know what I find.

jim-81

Good info on the heads - thanks. You're probably right, I just expected a big difference because they were better heads. And yeah a bigger cam and roller setup is in the cards but when I go there I am looking at a full rebuild, ya know, while I am at it. haha.

The insert I have is the 'medium loudness' one. Not sure of exact model but there are three ranges of restriction and I got the middle one. You could be right, there could be some power on the table by going with the louder ones. Might not be a bad idea, wonder how much louder they are... lol. That would be easy. And then there are the STS baffles as well. I DO like the sound of the pipes now, it is a very nice tone.

mobird

Yeah they are good heads! It's actually more that the Vortecs are really good as is. The Darts are definitely better, just not a HUGE amount better. If you wanted to, you could probably find a decent FT cam that has ~.530+ lift for around $200, that should definitely let you take a bit more advantage of your heads!

I wouldn't be surprised if it is your inserts killing power. I was doing some research on it this week. In one thread, there was a guy who had the STS baffles (undrilled) and they killed something like 70hp on his 500 hp motor. With them uncapped they did way better. There are a couple other threads that have dyno comparisons and besides the Hooker Max Flows, all the inserts killed quite a bit of power. Might be worth looking into!

What kind of mph were you getting in the quarter mile? And is your car roughly stock weight or have you done some weight loss? With those two numbers we can calculate a fairly accurate horsepower number for what your car is making and determine whether it is performing how it should with your combo!

BKbroiler

Just to throw some more data into the discussion - Way back when I first took my 77 to the track I had a 383 with XE262 cam, Vortec heads, stock exh. manifolds with 2.5 full duals, very mild converter (Auto trans), 3.08 rear and street tires. This setup ran 13.9 / 14.0 around 98 mph. Biggest improvements eventually came from headers & better mufflers, 3k stall converter, 3.73 gears, drag radials, head porting and other work and finally a hyd roller cam.

mobird

Thanks for the input!

What did it run after the new headers, stall, rear gear, tires, etc...?

mobird

Decided to chase my fuel bowl drain issue in the Quadrajet in the ongoing pursuit to make this car more daily driveable and less of a hassle. If I run the car everyday, you would not notice the issue, but if I let the car sit for more than about 2 days, the fuel bowl would be too low to start the car without cranking it over for 10 seconds or so. Inconvenient, and putting extra wear and tear on the battery and starter.

Originally I thought it was because the inlet filter I was using didn't have the little check ball to stop drain back, so I switched to a check-ball style filter. No luck, still drains the bowl after a few days.

Took the Quadrajet off for the millionth time and disassembled it. Filled the float bowl up with fuel and elevated the carb base on a couple 2x4s on my work bench. Came back in a couple hours, and sure enough, there is a TINY bit of wetness around the secondary well plugs. So I drilled out the solder plugs, and tapped the holes for a 7/16-20 thread. The perfect bolt for this would be a 7/16-20 1/4" allen plug, but I couldn't find one locally. So I just bought a 7/16-20 bolt and cut off two 1/4" sections. I then took my dremel and slotted the top of both the 1/4" sections so I could use a flathead screwdriver to screw them in. Coated the threads with JB weld and threaded them into my freshly tapped threads. I also put some JB weld around the top of the new plugs I had made after they were screwed in to make sure they were sealed. That was last night and I wanted to give them the full 24 hour cure time, so I will report back tomorrow to confirm that this fixed that issue!

Matt81

You are a better than I! My 78 behaved the same, I used it as an excuse to convert to fuel injection. Looking forward to hearing how the fix works!

mobird

That is what I WANT to do! But finances...

Bench tested and the fix worked, left gas in the carb over night with it on my workbench and there was ZERO moisture around the plugs in the morning. Carb is now put back together and back on the car, but it was late so I didn't get to drive it yesterday. I will do some tests this weekend!

mobird

So this weekend I decided to test out one of my ideas for the adjustable exhaust volume/flow on the STS baffles.

If you aren't familiar with the STS baffles, they look like this (pic taken from google):


Basically, the "Spiral" section is roughly 2 3/4" and the center section is 1 1/4". The center section is straight-thru, but capped on one end to keep the volume manageable. You can (and most do) drill some holes in the cap to give you a little more volume and flow, but obviously once you've drilled the holes there is no going back (other than to weld a plate over the hole or something). And it is time consuming and frustrating to take the side pipes off over and over. Plus (at least in my case) my car has to be two different animals: somewhat tame and "quiet" for just normal drives, late night or early morning startups, or when my wife drives it. But also, it is my hotrod and I want it to scream sometimes, plus I was curious whether the capped baffles were restricting any power on my motor (mathematically speaking it seems possible, as with the caps on you have a 2 3/4" flow area minus the area of the spirals and whatever restriction/turbulence they cause).

So my plan was to make a way to uncap/cap the center section of the baffles at will without removing the side pipes. I have future plans to make either an electronically controlled or cable operated butterfly valve to do this, but that will have to wait, too many other tasks that are more important! This is more just to test the theory.

I decided to go with the ultra-simple plan: weld on a threaded section of pipe and use an externally threaded pipe cap. I used 1 1/4" pipe adapter and caps in case anyone wants to do this themselves, total cost was under $10.

Here's the 1 1/4" pipe joiner/adapter and the two pipe caps:


And here is the pipe caps threaded into the adapter (just to show how it works). I cut that adapter down the middle (so one adapter was enough for both STS baffles).



Here is my sooty STS baffle (yeah car was running rich for a long time before I got the AEM Wideband and learned how to tune the Qjet):


I'm almost too embarrassed to show this picture, but here's the awful welding job to join the threaded pipe adapter with the STS baffle. I'll get my excuses out of the way: I'm a novice welder, with a really cheap gassless flux-core welder that splatters no matter what (you get what you pay for) and I was joining an iron pipe adapter to Stainless baffles with some harbor freight bought wire (yeah that is a BIG no no, but since this isn't in any way structural, I don't exactly have any worries about it from a safety perspective.) It actually ended up being a VERY strong weld, just looks ugly as all get out. I promise, my bench welds are at least a little cleaner looking haha.



And here is looking down the center of the baffle (obviously I cut the cap off the other end since my threaded cap is the new restriction).



All done! Put the baffles back in the sidepipes and the sidepipes back on the car.

First impressions: this worked out really well. It only takes about 10 seconds per side to remove or install the threaded pipe cap on the car, so really easy to choose if I want loud pipes or quiet pipes before I drive. At idle, the volume is about the same either way, the tone is different though. With the centers "uncapped" it is significantly deeper sounding. At WOT though... holy cow. It was decently loud with the capped STS baffles before, now it seems like a stock exhaust in comparison to the volume of the uncapped pipes! It is DEFINITELY too loud to go WOT in town, I am sure it could be heard a mile away. But the sound is intoxicating, I've always loved the sound of a small block revving up (I regularly run my motor to 6,000 RPM), but this is on another level. Don't worry, I plan to take some recordings of it with the baffles capped and uncapped, both at idle and at WOT and cruise to give you an idea of the difference. I'm also hoping to borrow one of those decibel-meters so I can record the actual volume difference between the two, and eventually I will be getting it on the dyno and running it capped and uncapped to see what the difference is in power.

All of that said, I drove it around a little with the pipes uncapped yesterday and you can definitely manage it in town. Just have to keep the RPMs low and be nice with the throttle till you find some fun roads. I didn't do much prolonged driving at highway speeds, but I'll report back on the volume when I do.

My wife hopped in for a quick pull and she ended up covering her ears (when the windows were down) because it was so loud at WOT haha. With the windows up it wasn't half bad, but my wife pointed out that my old rotting weatherstripping was probably not doing an amazing job of blocking out noise. And being the doll that she is, when we got home she took the T Tops upstairs and started doing the weatherstripping replacement for me (I've had a new weatherstripping kit for the car sitting in the garage for at least 2 years now and just haven't gotten around to it). So the T Tops have new weatherstripping, and I started removing the vertical door weatherstripping yesterday, but ran out of time. So yet again I was dumb enough to start a project without enough time to finish it, so the car is sitting for the moment until I can put new weatherstripping in and drive it some more!

Sorry for the wordy update, thought this one might actually be helpful for some people since the side pipes are an often talked about thing on the forums.

One thing I've started doing was keeping a word document on my computer of mods I plan/want to do in the future. I have a bit of a selective memory, so sometimes I forget some of my ideas, so I've just been opening that document and typing in my plans when I think of them. It is now up to 23 planned mods, not counting the eventual new motor, trans, and EFI. Most likely the next set of mods will be interior (I'm still rocking a two-tone interior at the moment, yikes!). I have some LED controllers and strips to play with for the speedo/tach backlighting as well as some nice sheet aluminum that I plan to make a custom switch panel, gauge surround, and possibly gated shifter with.

Stay tuned!

Priya

I think pipe fittings are cast iron which is quite difficult to weld. If it is cast iron you did a pretty impressive job of welding to get it joined with no leaks and without cracking the pipe fitting.

jim-81

That is an awesome idea and I might have to do that. As I stated in another thread, it is borderline too loud for normal driving around town. Having the ability to open and close the hole easily is great. Best of both worlds. thanks

mobird

Definitely Iron. Well It took ALOT more heat than normal steel welding to get solid weld penetration, and I wire brushed the crap out of both mating surfaces to make sure I had the best chance at it. Turned out fine, doesn't have to be pretty since no one will see it! Well besides anyone who looks at this thread now haha.

mobird

Thanks! I can only claim part of the idea, I read a post somewhere where a guy mentioned doing something like this, though I think he ended up just repeatedly threading the end cap into the STS baffle to kind of "tap" it for threads. I tried doing that first and it didn't work very well, I wouldn't have trusted it to hold for long. But that is where I got the idea for welding on a threaded piece! I guess if you didn't have access to a welder, you could probably make do with some of the steel reinforced JB weld (if it can withstand the heat).

Hopefully will have some vids up soon to compare the differences!

mobird

So kinda a cool development: scored a throttle body EFI setup (FAST EZ-EFI) from a forum member, so the C3 is getting fuel injected!

Which means that there will be a really nicely worked over Qjet for sale (with a bunch of jet sizes, Cliff's accelerator pump, Cliff's rods, electric choke, externally adjustable APT screw, drilled tapped and epoxied well plugs, etc...) And a 7104 Performer RPM Qjet intake manifold going up for sale once I get the EFI running good!

I'm super stoked about this because I thought I wouldn't get to start looking seriously at EFI until next year!

In the mean time, gonna try to finish up the weatherstripping install so that I'm ready to start installing EFI as soon as it gets here.

Matt81

You'll love having fuel injection. And with the setup you have, just needs a return fuel line and a few wires, right?

mobird

I'm really excited, my wife might be even more excited haha. Yeah pretty much! Still figuring out what to do for the return line. I may use the current feed line as the return line and then run a new feed line.

BKbroiler

To finally respond to your question - it has run 12.15 at 110, in good air. BTW - my exhaust is 1 5/8 headers, 2.5 inch pipes under the car and Magnaflow mufflers.