dropstep said:
I'm a Holley fan boy pretty much, but it's what I learned on and had a bunch of parts for. It was also the best cold weather start I ever had. My 300hp crate engine came with a 600 cfm edelbrock recommended and i went with a 650 mechanical secondary Holley and had no issues. It was a street car that got drag raced. I also got a really good deal on a freshly rebuilt 750 vacuum secondary Holley that I used on a 302 then 351 with just spring changes in the secondary's it worked fantastic on both engines even being way oversized for the mostly stock 302.
True on the cold start. I use Holleys many times on boats. They have a great idle circuit that lets them idle nice and low on choke which is a high priority on a boat when your "transmission" is just a dog on a shaft and the "torque converter" is the water.
03Panther said:
What about this new Thermoquad copy that Demon has out (with their over advertising hype fancy name secondary) After throwing out the hype, they look promising. Most Thermoquads has been swapped for Hollys by the late 70's when I started playing, so I;ve never had my **** beaters on one.
I honestly haven't looked at them yet, but Demon does good stuff. I've worked on a few thermos but never really built one. I think most of the thermos got swapped for Holleys because the composite bowls didn't hold up well.
759NRNG said:
Why haven't you been hired as the 'INTERN' ????? yet... dude my eyes crossed and I have to come back to parargraph4-5 tomorrow to finish this dissertation for your graduation......
I'd be glad to write, but I can't imagine moving to Florida. Alligators and old people. Not sure which is more frightening.
Cotton said:
I like Quick Fuel carbs. Some nice features and easy to tune.
that's what I have a QFT 650 mechanical secondaries that I have no idea how to tune or maintain. Because carbs are voodoo and black magic and fUel injection makes sense.
Different minds... I'm the opposite. Mechanical things make sense. Electronics make me vomit.
I may or may not have used a band saw to shave cross sections of a Qjet just to see where all the passages go. After doing that, I felt confident adding staged vacuum ports in the venturi to tune ignition curves. I also drilled and tapped the air horn for adjustable primaries. It netted me 20mpg on a Caddy 500 in a 66 Bonnevile.
I understand nothing in a carb.
NOHOME
MegaDork
11/29/19 10:14 a.m.
In reply to bobzilla :
I understand both of them. The problem is the Fitech is not following the book and I am out of ideas and hence need to try something different to break the dead-end.
It may well come to be that the carb has the exact same issue but the observation leads me to an engine/install issue that was confounding the Fitech in the first place.
Quick Fuel carbs have incredible wizardry in their metering circuits. Crispest, cleanest-running carbs I have ever had the pleasure of working with. Never had to tune one, either, they always felt "right" out of the box.
This is for the old red anodized units. Never worked with their new cheaper line. You get what you pay for.
Metering is everything. Good atomization and metering will make a too-large carb work well. I was fighting a 289 that had a B*rry G*ant carb on it that ran absolutely awful, it could foul plugs and lean surge at the same time. In frustration, I stuck my old Holley 3310 (750 vacuum secondary) on it, and it idled and cruised perfectly, could rip the tires from a stop by tickling the throttle too hard, and the plugs stayed clean. WAY better atomization than the shiny CNC billet overmarketed junk, fuel doesn't burn when it enters the engine in big blobs!
The thing with CFM is the CFM rating of the carb is at a certain pressure drop. Pressure drop is another way to say restriction. That is why you generally want 30-50% more carb flow rating than the engine "requires". Also remember that the airflow into the engine is not steady state, it pulses, and so there are much higher instantaneous flow demands placed on the carb. But in a nutshell, if it idles and cruises well, the carb isn't too large.
Curtis said:
Different minds... I'm the opposite. Mechanical things make sense. Electronics make me vomit.
I'm similar to that. I understand carbs and mechanical things in part because I paid attention in Auto Shop. I also had an instructor who showed us what cars were all about (RIP Mr. Kyle). I learned on 60s Rochester 2bbl carbs which were pretty simple and made the transition to 4bbl and Webers easy. If you have mechanical skills you can learn carbs - if you want to.
I'm not as knowledgeable on electronics. But once I get the car I want to race I will need to and I will.
