Poor life choices - C4 content

In reply to TED_fiestaHP:

Ok, good to know. I ordered a spring/weight kit for the distributor tonight too...hadn't got around to that yet.

I've been screwing around with the carb a bit this week. It bogs & sometimes backfires on tip-in, but is sort of/mostly running ok otherwise. Although it's very slow, definitely slower than our minivan.

I read something stating an SBC needs a 14"x4" air cleaner, so I picked up a 14" housing. Unfortunately there's just no room for a 4" filter though, so I'm limited to 2" until I find a drop-base I know will work/clear. It may have made a very slight improvement, but it's hard to tell.

The distributor kit arrived yesterday, so hopefully I can get the springs swapped this weekend. I rechecked base timing, and it's steady at 7-degrees BTDC, although with the vacuum advance connected it jumps to 23-degrees at idle...is that too much?

Lastly, it seems I have a coolant leak to track down. I noticed it was low before I started it last night, and after driving it ~2.5 miles I saw a trail of drip spots running up the driveway when I got home. Always something...then something else. Definitely not surprised though.

In reply to Pete Gossett:

I use a filter top on a 3 inch filter and have had no problems.

In reply to vwcorvette:

Do you have any pics? I had to dimple the air cleaner top so I could recess the nut, otherwise it hit the hood. Maybe my Weiand Stealth is taller than your intake?

I think I found my coolant leak. Let me clarify...I definitely found A coolant leak: I have two radiator caps - the stock one on the radiator, and another on the piece of Dodge upper radiator hose that's now the high point of the system. Both have 16psi caps, but for some reason the one in the Dodge hose is opening up early, and only when the system is at ~150-degrees, causing it to leak out the overflow hose, which is temporarily routed to the corner of the engine bay.

I'll see if I can pick up another one tonight that's a higher pressure and try it out.

pete that is a lot too much timing at Idle, 10 degrees and maybe 12 but you just got the sprng kit so 10 at idle. with the vacuum attached, so that means the vacuum hose is in the wrong place, so try the port in the body. ALWAYS put a new cap on in a coolant system you are not familer with

In reply to GTXVette:

Thanks John!

I didn't check timing today, but it's idling much smoother with the new springs installed.

Both radiatior caps are new, but they're both 16psi. I couldn't find a higher pressure one tonight, so I just shimmed up the spring in the upper one. Since I have 2 caps in the system I'm not worried about whether this one ever opens.

Reading all this is just more reinforcement for my general disdain for carbs. Allegedly they are simple, easy to work on, easy to tune. But my experience with them seems to be along the lines of what you're getting, temperamental, cantankerous, and just a headache.

I'm rooting for you though and hope you get it sorted.

I took the Vette to its first event today. Ok, it was just Cars & Coffee, and it was only 2-miles from home, but baby-steps...

Having never been to one of these I was expecting 50 or so cars. It was probably closer to 250 at any given time, not counting those who left & had their parking spot filled. Here are a few shots.

The Vette in all its glory.

An overview from opposite sides of the lot. I got there about 8:10 and didn't think I'd find a spot to park.

Twin turbos?

It's hard to tell, but the engine was about 10" above where the top of the hood should have been.

I've not seen window vents like this before.

An interesting VW 1.8t powered exothing.

Rusty-wrapped Mustang.

Overall there was an interesting mix of imports, exotics, hotrods, and other oddities. So it was at least a bit more interesting than your average car show. I also met some guys from an area Corvette club. They seem way more interested in "show" than "go", but I'm sure some of them have way more C4 knowledge & experience than I do.

Needs more triangulation, but I would like to learn more about this.

WOOOOHOOO!!! THE BRONZE BOMBER LIVES....WHAT CAN BROWN DO FOR YOU?

In reply to Woody:

It had a URL on it, but it must have been on the other side. He had just stopped momentarily when I took the pic.

You are right Pete, Vette Owners and Vette Racers are not The same, I look at Digital Corvette for Info because you can tell the Difference by the Post's they make.

Okay.... we've been seeing Snippets of your infamous Biloxi Brown C4. Now that you got it moving around how about a few artsy shots of the whole car? It's the least we are due having followed your most entertaining build/b]

In reply to Ovid_and_Flem:

Well I'm not much of a photographer(if you haven't noticed over these 69 pages ), but honestly other than the first drive to Advance Auto a couple months ago, Cars & Coffee today is the only "place" I've driven it to. The rest have been around the block & back home. Once I get the off-idle bog sorted out I'll be venturing out a bit more, and putting the car into more general use. I'll try to grab some artsy shots while I'm out!

You know, this -almost- makes me want to go out, get a C4 of my own, and try this myself. :) Although, I'm pretty sure I'd use some kind of fuel injection or go with a Q-jet. I've always preferred them to Holleys, personally.

A fantastic job, sir -- I admire your perseverance! Next time I'm on the MS Gulf coast, maybe I'll catch y'all out and about!

In reply to Mr_Merkur:

Let me know the next time you're heading this way & we'll find some time/place to meet up!

I made a bit more progress tuning the carb this afternoon. I found these instructions from Holley that states: " During acceleration tests, if you notice that the car first hesitates and then picks up, it’s a sure bet that the pump nozzle size should be increased." Ironically, these instructions are included in the Holley Trick Kit, of which I've bought 3 so far, but I never bothered to read their instructions since I'd already bought the book on rebuilding & tuning them.

I had a .028 accelerator pump nozzle on the carb, but in my stash of used parts found a .031. Installing it made a noticeable improvement, but didn't quite cure the off-idle stumble. I just ordered a .035 to try out next. Hopefully it's not too large.

Do keep in mind that you can also get a off idle bog/flat spot from insufficient timing advance at tip in (wrong vacuum source to distributor, broken or absent vacuum can, or insufficient base timing/mech advance would probably do it too) that can be kinda covered up by going big on the accelerator pump shot.

In reply to BrokenYugo:

Good to know, and that may also explain why it feels down on power from what I expected. Though honestly at this point I'm ok with getting it running well enough to use it, then deal with fine-tuning later. Even if it is an advance issue, wouldn't it need more fuel anyway once the advance was corrected?

No.

You of course need sufficiant fuel but Timing and advance rate is as Important. 750 to 800 rpm should be plenty at around 10 to 12 deg.advance. you will not need more than 35 to36 Total advance at 3500 RPM. It is not a race car, a race car does not run around at 2500 rpm, so 25 to 28 degrees at 2500 rpm is plenty.

Yes get the timing advance to adjusted, can use just the mechanical advance. But do check the advance curve, like GTX says, check idle and around 2500 RPM. If you have the timing light with the dial knob it is real easy. Just set the knob to about 28 deg, hold the RPM and see how close to zero the marks show.

If the accelerator pump is giving to little or if the jetting is to lean it can go flat as you give it more throttle. Make small changes and track how it responds. Also use a vacuum gauge to ensure you don't have a leak, that will foul up all the tuning.

All of this seems just as arcane to me as getting EFI working at this point.

In reply to Harvey:

It truly does to me to. And in the end I could have probably bought the FiTech ~$800 setup for not much more out of pocket, but I'm pretty deep down this rabbit hole now.

If nothing else, I figure this experience will give me a slight advantage when I do convert to aftermarket EFI - the concept, goals, and variables don't really change between the two, just the methods of adjustment and precision. It's still air/fuel/timing WRT RPM and load, EFI adds temperature into the parameters, and of course provides feedback signals.

If it is any consolation, there are a lot of frustrated Fitech owners who are struggling with the systems.

Vacuum leaks, exhaust leaks, low voltage and poor grounds lead the owner caused issues.

The "Fuel Command Center" , firmware that drops out on occasion, and cheap Chinesium sensors that are probably clones of the real GM sensors, is on Fitech.