On a more or less stock rebuilt 330 desoto hemi which cam would be better for overall efficiency? The s24 fireflight at 106degrees or the s25 adventurer at 112? I will likely get either blank ground to about .415 or so in a single pattern. I am more interested in mileage, torque, and driveablity. It will be loud and rumble anyway I slice it.
Here's a bump for ya. I'd think the answer to your question would be the final intended use of the engine. -Dave
I went a little different direction on my 330, bored it .40 over and used custom 10:1 pistons and re-ground the RV cam that came with it to match. I don't have the cam card handy to share the specs but will be happy to do so. We built this one to be a bit snotty but have an auto 518A and a 9" posi behind it. I haven't heard it run yet but hope to before winter. Single 4 bbl (sniper...shhh) on an aluminum dual plane. Mine is going in a 41 ford PU for light shop duty and cruising but I demand a lot out of my cruisers. Glad to meet another Desoto fan. What is yours going in @dumprat
My Desoto is going in a 34 ford truck. I am aiming for a gas conscious long distance cruiser. With the 833 od trans and 3.50 rear I should be turning about 1700rpm on the highway. I am running a 500 cam carb. The engine is a .030 over 330 with cast four barrel intake.
My suggestion, and worth every penny that you pay for it, is to stay away from the tight lsa. 'Economy' such as it is, would be even better at 122°. The 50s DeSoto used both 112 and 122 and the 122 was used in GrandMa's sedan. The 112 castings have shown up as tight as 106, probably what you have. The 112° is the 'standard' lsa for all Mopar v-8. .
Yeah........."snotty idle" and economy don't hardly go together when talking camshafts. Longer LSA (112 or more) and watch your duration numbers. Too much duration and long LSA numbers usually = pinging unless you turn the ignition wayyy back which = loss of power. Its a mad circle. IF you do all this and increase the lift a bunch that will = valve train issues. Can't win!! Besides....snotty idle with low vehicle weight and 3.20-ish gears should still = decent mileage + fun! 6sally6 My opinion, of course = every penny you paid for it!
If those were directed to me, the cam was new in a box when I found the hemi. The parts were purchased decades ago and the motor never assembled.
I actually don't want a snotty idle, it's not a race inspired car. I want smooth as glass. Think 1950's hillbilly "girl chasin" truck.
From personal experience I have found a stock or near stock cam installed with 6* advance performed excellent in a stock compression engine especially from a standing start. It’s also great when you will be cruising at 1700 and give it some throttle. Smaller valves also help torque too. Both items work well for quiet, quick performance. Good luck.
Smaller valves? This isn't a small block Chevy, I can't just go get some snogger heads. I didn't say anything about quiet. My post was related to efficiency! Huge overlap and blowing fuel out the tailpipes is fine for a racecar but not what I am looking for.
That sounds like a step backwards Gary. I want 25 mpg! Doesn't anyone understand how to make that happen?
^^^^ How heavy is the car? You'll need overdrive. 25 mpg might be possible. Had a '74 Plymouth with a 318 & automatic. All stock..., at 55 to 60 mph (remember the federally imposed speed limit?) it would pull in 22 mpg. Which I still think is good mileage for a non overdrive V8 in a full size sedan. You might be able to get there. -Dave edit: you can trust what 73RR tells you about these early mills.
The hemi is going in a 34 ford truck, so I am guessing about 2800lbs. And I am running an 833 overdrive trans. .71:1 in fourth. Most guys I have talked to only have one direction in mind, high rpm and lots of overlap for a rough idle.
Start with the wide LSA camshaft. Do what you can to keep the velocity up on the intake side. Stock cast iron 4bbl intake, duel exhaust and as much compression as you can afford the fuel for. -Dave
25 mpg..... put in a box stock GM LS or buy a Honda Civic....Honestly you can get the 25 you want with close to 10+ to 1 compression, using all the stock parts and driving smart. I had an uncle with a 65 Impala 327 powerglide and 3.08 gears what got 25 mpg driving between 60-65 mph. Your truck is not aerodynamic at all so your going to keep that thought when driving. My new 4500# truck with 3 overdrives will get 22 mpg at 70 mph and it's got every concievable device computor controled to do it. If your sticking with this idea a throttle body FI unit will need to be on the the top of the list if it were mine.. still good luck with your project..
Matt, it is doable with the correct pile-o-parts. I actually don't want a snotty idle, it's not a race inspired car. I want smooth as glass.Think 1950's hillbilly "girl chasin" truck. No 'snotty' idle at 122 lsa if you keep the duration 'moderate' for the displacement...imho, that would be 200° or so. Also, keep the overlap near '0' so you don't bleed off cylinder pressure. One of the old/early TV ads showed a guy sitting his coffee cup on the air filter housing of a running DeSoto...not so much as a ripple in the coffee. As town sedan notes, you will want a bit more than the oem c/r; for your build I would probably use 9:1. Afaik, most/all of the current cast pistons do not make advertised compression so a forging would be needed for 9:1. I do not recommend cutting heads/deck to get compression. With the .71 od you can use a 3.55 rear gear to keep the hi-way rpm down but if you use a tall tire a 3.91 may be better. I would shoot for hi-way rpm of 1900-2100. Around town you will likely never use od but either 3.5 or 3.9 is good for 3rd/direct gear. Stay away from multiple carbs; a small TBI would help you get the 25 number. Painless makes a wiring harness for use with the 80s-90s gm units that are compatible with your displacement. Just my thoughts, others will have theirs. .
I appreciate the input Gary, but I won't run fuel injection. That is just plain yucky on any real hot rod. I will let the LS knobs gush about how great it is. I will have to see what the compression is going to be, the block has been cleaned up on the decks and the gaskets are thin.
I've got a 330 Desoto in the shed for a some day project but even if I stick it in the 27 T body I have with the 2 something ratio Cad Seville (76) rear behind it and fine tune the two barrel I doubt I could pull 25 mpg. Still as been proven to in my own car when switching drivers on every tank on a road trip from FT Hood Tx to LA driving habits have a lot to do with gas mileage and a smoother driver can get better mileage than most of us who like to run though the gears.
Well the cam is on it's way back from the grinder. .425 lift. 109.5 lsa and [email protected] or there about. The blank was 106 but he opened it up a bit. I sent two blanks but this one had the best base circle. The other of the two was 112 lsa. We shall see how it turns out.
Interior cam supply in Salmon arm BC. I have used them before. They do nice work and have been in business for a long time. They measured the two blanks I sent, chose the best one based on what I wanted to do and called several times discussing the grind I wanted. They have thousands of masters and can do pretty much whatever you want based on what the core you have has room for. All for a price that is half of what it would have cost me to ship it to the states and have it done. $145 Canadian.
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