For those of you that run or have run big block gassers in dump trucks, do you have a preference in carburetor that you think works the best and why? I have been looking for an old dump truck for a farm/home project, and I notice that most of the trucks came OE with Holley's on them, but many people switch them out to Carter/Edelbrock when the Holley's give them fits. Is that because Edelbrocks are easier to source locally, or do you think they make the engine run better than a Holley? Several years ago, I had a Ford F-800 with a 429, and the people I bought it from had put an Edelbrock on it. I never thought that engine ran quite up to its potential, and wondered if it wasn't getting enough fuel. I have always heard that Holley's gave the engine more fuel than other brands, and that these big block engines liked a lot of fuel. I would think that would be more of a jetting thing on how much fuel it was getting. Maybe its the how much fuel it and when it gives the fuel in the rpm band that is the issue. Any and all help is appreciated. Thanks,
The only big block truck engines that I've seen run all around well had fuel injection.
I had a Holley double pumper on a 401, Ford car. It ran well. I even drag raced with it. I think a lot of people don't understand how to set them up. Sooo many years ago I forgot all I ever knew about them.
I've always preferred a Holley...easier (for me) to adjust and tune. Just a matter of personal preference and what you know how to work on. I recall a Cutlass a friend had, mild build with a quadrajet, someone knew what they were doing with that carb as it ran like no other.... Ed
https://www.summitracing.com/parts/sum-m08750vs The carb above is a redesign of the Autolite 2100 from the 60's. It works well.
With some gravel trucks, there was only one speed, wide open throttle all day long. The primary throttle shafts on the holley carbs could be fairly loose and the engine would still run acceptably because they didn't idle other than loading time. 5 mpg average. Mind you, this was before the emissions era
The neat thing about the Holley's is that there was a threaded plug on the bowl that you removed and were then able to accurately set the float level.I do remember that.
Back in the day I had good luck with Q-Jets, easy to tune. One common mistake with Carbs is people over size, Dragster size not required for truck engine.
Does anyone know what cfm the stock Holley's were on the Chevy 366/427, and or Ford 370/428?
not sure of all but most were 600 rds.
I ran this old girl 14 years. It now has just shy of 60,000 miles on it. Towed a 9 ton trailer, and on a few occasions carried 25000 in stoneboat weights divided between truck & trailer for an antique tractor pull. I started with a big Holley, I don't know if it was factory original. It was bad for backfiring downhill. I changed to an Edlebrock 4 barrel. I've got the empty box, can't remember the model. It's rated 450CFM to 600CFM with different needles. Mine is set up for 450 CFM. It's quite a sports car empty, but Vermont hills are slow with the trailer & load. The engine is a recently rebuilt GM 427 tall block. This is NOT similar to pickup 427 engines. Big valves, big cam, heavy components, forged crank, BIG cooling system. I just switched the dump body to a newer truck. As a cab & chassis it's now for sale PTO hydraulics are intact. 5 speed Eaton with 2 speed Eaton rear. Drive it to MO.
These engines are happy all day long at 3000 RPM, with occasional uphills at 3600. They fall face down in hp below 2500. A four cycle engine flows its displacement in two revolutions. There are 1728 cubic inches in a cubic foot. 427 X 3600/2/1728=445 CFM. Running faster than 3600 RPM is something I'm reluctant to do. I figure these were used in generators in the 100 KW range starting cold at 3600 RPM they must be built to take that. I wouldn't feel comfortable doing that with a cast crank pickup engine, smaller bearings, with flatter pistons & fewer oil rings
Checked the numbers on the spare holley for the BILs old dump truck with the local parts house long ago, were only rated at 460cfm due to bore sizing, intake would not do more than that due to restricted runners and contorted pathways. May get a 500-750cfm to run on them but will not do any better than the OE unit that had the overspeed governors on them. Biggest issues we ever had on Holley was power valves popped when backfired, fuel bowl crosstube leaks, gumming up the inaccessible channels in the metering blocks and vacuum leaks from worn throttle shafts and or shaft bores. Motorcraps were almost as bad on the 429 Fords as to blowing power valves(adopted design) where always preferred the Carter AFB that Edelbrock is now clone copying. The old governed Holley had a operator problem when got impatient the herders would mash and release rapidly on the throttle trying to get more out of them, would trip the control linkage setting them back to about 1/3 capability.
I have always been reluctant to use Holley for the exact reason DMiller pointed out. Blown power valves. I have heard rumors of new and improved less susceptible to failure, haven't personally seen it. I like the AVS from what's now edelbrock. (Carter back in the day)
I bought an excellent book on Holley carbs. I loaned it, never got it back. There is a LOT to know about carbureton. I chose Edlebrock because a car builder was very well informed. He was very generous with information. I had bought a 1 ton Chevy crew cab with 454 intending to steal the engine. The 454 proved to be all wrong for my truck. He built a camper towing truck from it.
When you talk about a 366/427 truck engine and a 454 those are apples and oranges. The 366/427 truck engine is a tall block with smaller valves and intake runners. The Q-Jets were spread bore and on WFO 625 CFM. A square bore vacuum secondary 600/650 cfm will work just fine on the tall block. The primary's are 325 cfm. Plenty for pooping around. The carb below I installed cfm restrictors and cut it back from 625 cfm to 525 cfm and re-jetted. It was a original Carter AFB that I hung on to for years. The 454 below I installed a 850 CFM on jetted it down one size. But that engine is built to run strong to 5800. 500 cfm works well on anything from 289 to 327 cu. in with a small amount of jetting.
Nice Boat Motor! Tunnel Drive Inboard?
I never liked Holleys they never seem to work right very often. I have a buddy that worked at a GM truck dealer ship.He said they would replace the Holleys with edelbrocks on brand new trucks. I have replaced Holleys with diffrent carbs and never regreted it night and day diffrents but i also felt like i may have lost a little power. All of the swaps i have done were for other people or stuff that was being sold so i never got to change jets or try to make more power.
AFBs are the bomb, if you can read plugs or have an O2 wideband. Needles, jets and weight bias are not something everyone can grasp. The nice thing about them is, they'll run decent out of the box. A 650 will support almost anything steerable and give it decent manners. Unlike a similar Holley, you mash the throttle and it'll just bog out and dump fuel. A little off topic but, old mopars ran big blocks with 2 barrels. It was pretty common. All the power from down in the basement to middle of the road. Mother Mopar sure made power back then.
And if you looked in some of those big block mopars they were single plain manifolds. V-Drive.
daddyo never looked around
Tail Dragger!! Nice Tabs set. Brother was more into I/Os, had a 27' Formula, ASS Dragger, took over half throttle on twin 454s to get it on plane, then had to keep it there or settled back no matter how much tab was in the wake. Also nice touch padded fenders boat side!
Just ditch the carb and put one of these on with Methanol. http://www.ronsfuel.com/flying_toilet.cfm