I've been dreaming of Carbs (1 Viewer)

[pigmony]

Well. No real forward progress yet for me.

I attached a vacuum gauge on the manifold side of the carb. Vacuum bounces all around at idle (575 rpm). But smoothes out quickly when the rpm is increased. I'm hoping that the bouncing vacuum at idle is due to the Comp cam shaft I have. I'm gonna try to dig up the receipt to figure out what cam I put in there and research a bit. Hope it's not an indicator of valve problems.

Should I be reading baseline manifold vacuum at a higher rpm, say 800 or 900?

Later this week, I will be checking to see if the vacuum advance can is working (once I get another vacuum line adapter to hook up the gauge). And will pick up a compression tester to rule that out. O2 sensor should drop in this weekend.

If we do a club event at dyno night, or get our own dyno night, every one that participates should chip in an extra 5 or 10 bucks to go to the dude (dudette) with the lowest horsepower run.

It was my understanding that "idle" in the context of a vacuum test is 800-1200 rpm, but that's based on one repair manual for a different engine manufacturer and it was years ago, so I may be completely wrong.

 

[90WT]

So I finally found the receipt from my Comp Cam. Cam Lobe separation angle is 110, which explains the erratic vacuum at idle. As I understand, lobe angles of +/- 114 and higher will have a steady vacuum at low rpm. Lobe angles of +/-112 and lower will have poor vacuum as the intake/exhaust have a bit of overlap. This particular cam should give me a bit more torque in the mid rpm range, trading off some horsepower at high rpm. That's a good fit for me since I'm not driving in the high rpm range. And my setup doesn't have any vacuum needs for engine componets at idle. Maybe electronic ignition needs the vacuum at idle, idk, but mine is still mechanical points.

Installed (mostly) the O2 sensor and permanent vacuum gauges last night. Waiting for a chrome guage panel to show up from Napa this week to mount them into. Should finally get some data points this weekend and start adjusting stuff. It has been really hard not to fiddle with things before I can start it up and take some baseline numbers first.

 

[pigmony]

Is the plan to leave these diagnostic gauges as a permanent install? I could see that leading to lots of fiddling. You may inadvertently become a carburetor wizard.

 

[90WT]

Yeah, the gauges will be permanent. If I become a wizard after this, that's ok. But equal possibility of me going crazy if it doesn't work.

 

[pigmony]

The only thing that sets apart wizards from nutcases is that the wizard has proof of success. (Or at least they are enough of a salesperson that they can convince somebody else that they have been successful.)

 

[90WT]

Thought about doing a project update for a while. Well, I'm still not finished. But making progress.

I installed the o2 sensor, new tach, and new vacuum gauge. All turned out sweet. My idle was too rich. Also adjusted the cold idle speed down on the electric choke carb. Improvements.

While I was installing gauges, Mrs 90WT offered to recover and refoam my seat. So after some order and install time, seat is complete. Replaced some badly worn seatbelts. Then I find a leaky master brake cylinder. Brakes are super spongy. So pushing to do some brake work this weekend. Then, just maybe, I'll install the fuel pressure gauge and see if we've got a good steady pressure off the mechanical fuel pump. Still looking to play with the total timing and see what adjustments i can make before turning my attention to the secondary jets/needles. I can smell the burnouts already...

 

[90WT]

Me and the nice feller from Holley came to an agreement today.
The truck brakes were done in the Fall. Ended up making a lot of new brake lines, which is tedious but satisfying work. After sitting so long, the off-idle squirter is not functioning correctly. There's a big bog at any off-idle throttle engagement. I removed the carb and opened it up and can't find any reason why the squirter isn't working. Faced with troubleshooting a carb I completely despise, I'm throwing in the towel on this Edelbrock 1406. I just ordered up a 4bbl Holley. Old fashioned. 670 CFM. Manual choke. Vacuum secondaries.

 

[pigmony]

I like this. I'm going to limp my Edelbrock along until I either put in efi or the engine wears out and gets replaced with an ls.

 

[REZARF]

Why not go back to stock... just curious. Not like it's my money.

 

[JohnnyOshow22]

Not much to add to this as I only know toyota f/2f carbs really well but those interested in the Holley Snipers they work fantastic and I would highly recommend one for any toyota. They change the truck significantly for the better, every truck we've put one in we say "now this thing needs a 5 spd". I have a howell tbi kit in a box that came with my 40 and if I was keeping the 2F i'd likely sell the howell kit and get a sniper but the 2F is likely going bye bye after next summer. The install of the sniper is easy, the interface is simple and they "just work".

Although if you can get a carb dialed in they "just work" too

 

[ttFJC]

the squirter isn't working

 

[90WT]

It's still mostly stock. The major difference is the original 352ci engine had a 2bbl carb. The butterflys on that carb are so small. 427/428s would've come stock with a 4 bbl Holley. After my engine was rebuilt (bored over, new cam, rebuilt heads with new valves, etc) I bought a new 4bbl Edelbrock carb to go on a used 4bbl intake manifold I picked up at a junk yard.

I'm sure I was pressured into the Edelbrock from my family of Chevrolet lovers. (The 352 is a not a Chevy.)

I'm not interested in EFI for my truck. I see some advantages, but not all carbs are bad.

 

[90WT]

Carbs are sexy. Prove me wrong.

 

[REZARF]

Man Jewelry.

 

[ttFJC]

it will never ever be that shiny ever again

 

[elkun1]

it's the points i miss, i believe it was a conspiracy brought on by the anti smoking crowds to eliminate points! The real purpose of carbs was finally discovered when holley aligned their 2 barrel with 2 others, pure magic. 2 barrel or 6 barrel and nothing in between

 

[90WT]

Further carb adventures with 90WT:

40 starting running like cr@p randomly last Friday. (I still run the original 2bbl carb. I installed an Wideband 02 sensor and A/F gauge). As it's barely running, the gauge read really rich. Not normal. I shut off the motor and opened the hood and confirmed it's running rich by the gas soaked base of the carb. The next day I remove the carb and see all this gas pooled in the intake.

 

[mccracken]

Looks like water boarding for 2Fs

 

[90WT]

Luckily gas is "cheap" right now.

 

[90WT]

FWIW, I think the seat for the needle/seat at the float bowl had worked it's way loose enough to be overpowered by the fuel pump. I fiddled with the needle/seat and problem solved. Maybe cold and 4wheeling helped loosen it up? Anyway, I love a $0 fix.