383 to 496

To throw some real world results here - the strokers use a shorter piston - that's primarily where the changes are to accommodate the longer stroke. Some use a shorter rod too, but honestly in the power ranges we're talking here, it's really easy to overthink the rod length. Truth is, in this one... " the rod has to connect the piston to the crank, and that's it." (taken from Smokey Yunick). Shorter pistons rock more at TDC, and that tends to mean accelerated wear. However, the 4.28-ish bore doesn't rock a lot, and my experience with the 496s is the ring seal has not gone south after 15K miles of hard use including some 1/4 mile passes. So it will wear out faster, but at 3-4K per summer's use it will last a long time.

As far as camshafts go - the engine I built uses a custom flat tappet because initially he wanted to stay with the stock manifolds. It's a 112* LSA, .540s lift, 250-ish duration at .050. It idled at 900rpm, had 16" of vacuum at idle, and pulled from idle to 6K. It's in an E body, with 3.23s, that the owner drivers to the track (2hours one way) in. the choice of cylinder head and camshaft will determine the power curve and manners. In my opinion, running any factory-type camshaft is a mistake. These engines need air to work. So great heads will work with less cam. Average heads need more camshaft and will have good manners.
 
The difference between a rebuild and a stroker kit isn’t the full cost of the stroker kit. It’s the stroker kit minus the cost of a piston rebuild kit (assuming you need to bore your 383 anyway). A quick search of summit says those cost about $750. Therefore the marginal cost is about $1500.

I’ll check my spreadsheet on rpms but even your numbers don’t say anything about running at 5800 rpm.

If he’s going to swap over to a 440 that’s more expense from his current 383 and a smaller difference. It’s onlu adding fifty cubes versus adding 110. That’s a huge difference. But he’s going to need to change out a lot more than just his engine.

If this has changed into a case of answering a question of what engine should a c body have if you’re starting from scratch, ok. But I think this guy has a 383 and is asking about options with this engine.
 
There is no replacement for displacement.

If you are planning a major rebuild on any engine, the only part of the short block you would reuse is the block and maybe the crank anyway. You could have the stock rods resized and new rod bolts installed for less than a new set of H-beams but you will still have a set of 50 year old heavy press fit pin rods with a quadrillion load cycles on them. Better to just spend $2-300 more on new lighter ones and be done.

All the other parts had to be replaced anyway and the machining is the same so for basically an extra $1000-$1200 you get another 113 cubes. You can't buy torque any cheaper than that.

Even if you ran the stock heads and camshaft it would still be a tire smoke generator that idled with 20" of vacuum at 600 RPM.

Kevin
 
Actually, there is. It's called cash in the wallet...lol
The differential is not a couple grand to do a non-factory stroke build. There's more in inspections (what if the block fails a sonic test?), assembly cost, more specialized parts, etc, etc etc. So it's a commitment of more than "might as well". Especially given the initial post was a 400hp goal in a C body and snappy performance. That's a good performance rebuild on a 383 with some bolt ons, and a set of 3 series gears. Much cheaper approach to meet the goal. Now if there's more goal like bragging rights or a desire to have the big power, that's fine, but not part of the initial desired results.
 
What if the block fails a sonic test on a stock stroke rebuild? Is assembly cost free on a stock stroke rebuild? Are the bolt-ons and gears free? Is the labor on rebuilding the rear-end free? How much more cost is there in inspections on a stroker than a "good performance rebuild?" Your comparison is taking into account all the costs that a 496 build would have, but not the costs that a professional stock-stroke rebuild would have.

Having re-read the OP's posts a few times, I do admit that I might have misinterpreted them. It looks like he doesn't want to pull the engine and does want to keep his bottom end intact, just swapping heads, cams, intakes and exhaust. But he's also seemed to indicate he wants to keep his rear-end the same. Will a revvier 383 be very "snappy" with 2.76 gears? A slab Fury isn't very heavy, but it's no E-body either.

I admit, I'm biased heavily towards torque, but that's because I have a 5,000 lb Imperial and not a 3800-lb Fury.

So, to reset as what I would do keeping the engine in the car, and the bottom-end intact, and willing to rebuild/port heads, upgrade cams and exhausts, I would go with 440-source or Edelbrock heads, mild cam (aftermarket under 200 degrees of duration at 0.050" at least 112 degree LSA), new aluminum intake, and maybe exhaust depending on what his dual exhaust is now. If we're talking about gears, I'd go with 3.23 and could live with more duration (like 225 degrees).
 
What if the block fails a sonic test on a stock stroke rebuild? Is assembly cost free on a stock stroke rebuild? Are the bolt-ons and gears free? Is the labor on rebuilding the rear-end free? How much more cost is there in inspections on a stroker than a "good performance rebuild?" Your comparison is taking into account all the costs that a 496 build would have, but not the costs that a professional stock-stroke rebuild would have.

Having re-read the OP's posts a few times, I do admit that I might have misinterpreted them. It looks like he doesn't want to pull the engine and does want to keep his bottom end intact, just swapping heads, cams, intakes and exhaust. But he's also seemed to indicate he wants to keep his rear-end the same. Will a revvier 383 be very "snappy" with 2.76 gears? A slab Fury isn't very heavy, but it's no E-body either.

I admit, I'm biased heavily towards torque, but that's because I have a 5,000 lb Imperial and not a 3800-lb Fury.

So, to reset as what I would do keeping the engine in the car, and the bottom-end intact, and willing to rebuild/port heads, upgrade cams and exhausts, I would go with 440-source or Edelbrock heads, mild cam (aftermarket under 200 degrees of duration at 0.050" at least 112 degree LSA), new aluminum intake, and maybe exhaust depending on what his dual exhaust is now. If we're talking about gears, I'd go with 3.23 and could live with more duration (like 225 degrees).


OK, new we are getting somewhere. :thumbsup: I did just talk with Dan. He is looking to make the car a dependable cruiser and have a little more pedal power. He would like to see 400HP, but this may be a little high for a street car & driver combo as it may fall more into the street/strip realm and no be so much a comfortable cruising car you can drive an hour away to a car show. I think 350-375HP would be a better goal?

Dan lives in Colorado which is at a higher elevation so certain components need to be taken into consideration, ie compression.

The block is .040" over, so it has indeed been rebuilt at some point. Flat top pistons. Heads are the "906" type - which I read are "open chamber" heads. Seems closed chamber are preferred by the race/HP guys, but open chamber heads have their advantage.

Dan is now looking at keeping the short block as is and making improvements to the "906" heads, but first will have a machine shop look them over. This would include Dan doing some basic port/gasket matching and cleaning up any casting lines or bumps in the intake ports to smooth them out -nothing more. A three angle valve job. His valves may be good enough to do this, but I would install new stainless steel valves, bronze bushings, new springs to match the cam. Hardened exhaust seats? I feel SS valves don't need them, but others will differ on this. This is option #1 on the heads.

Option #2 was possibly upgrading to the "Stealth" heads. Not a Mopar guy, I had to read up on these. The description states they are a reproduction of the stock "906" head. They can support up to 650-700 HP with work. Price looks to be good for an assembled head @ $499.95 each, or $1,000 for the pair. Says they can be painted and look lie factory. Stealth Aluminum Cylinder Head - COMPLETE - SINGLE HEAD-440 Source

Rebuilding the iron "906" heads may come in a little cheaper than the Stealth heads, BUT, what are your opinions on this, Iron "906" refurb or "Stealth" heads? Keep in mind that aluminum heads draw more heat and typically require another point in compression to compensate. Would Dan's flat tops work at his higher altitude along with the Stealth heads or would the iron heads actually be better in this situation?

Next is the intake. Dan likes the "stock" look and would like to keep the factory 4-Bbl piece. His carb is a 600CFM AFB. My suggestion is to go a bit bigger on the carb like a 750CFM which has the vacuum ( or weighted) secondary air valve. I actually recommended a GM Quadrajet in place of the Mopar version - the Thermoquad. Plymouth actually used the Q-jet on some of their police package cars. I like the small primary bores for better gas mileage and keeping up intake airflow and then the bigger vacuum operated secondaries for more flow/HP. They also have their own unique sound. Don't know if a 750 AFB/AVS would fit on his 4 Bbl manifold without opening up the rear holes larger to match the larger bores of the carb? It would require a spacer/adapter to use the Q-jet/Thermoquad and linkage adapter for the Q-jet, or might a 400CI which had the Thermoquad work and still have the "look" of his intake?

Car already has dual exhaust.

Cam selection. I recommended Hughes Engines for a cam. Reason is that they understand "cylinder pressure" which is very important in matching the cam to the compression ratio. You can get a great grind that will really work with low compression engines. Typically, iron headed engines should be kept in the 9.0 - 9.3 to 1 range if running pump gas & no additives. This changes when at altitude as more compression is needed, ie "cylinder pressure." You can find an article on this at Hughes, but here is their main page: Hughes Engines Here is another great write-up on cams and cylinder pressure. These guys have some great videos which I have purchased. Great info if you want to learn - its Chevy biased, but the principals are still the same: How do cams affect compression?

At this point, a torque converter upgrade will be made. I base this on my own '73 Fury with 360CI and factory 2500 stall converter and 2.76 gearing. It is a "loose" converter and takes a little pedal pressure to get the car rolling if easing into the throttle. Slap it down and it takes off rather fast for a big old boat. I installed a "tight" 2500 RPM converter in my brother's 360CI, modded 904 trans, and 3.55's out back. The gearing no doubt helps, but the converter does not slip like my factory converter. On light throttle, from applying the gas to letting off, it drops 200 RPM's. Nail it from a dead stop and it does as it should and lights the tires up. Here is where I got it and will get one for my car when the time comes. They have a from to fill out and I talked with the owner who personally took all my info: Mild Street Edge Converter for Chrysler 727 Transmissions [MSE727] - $345.00 : Edge Racing Converters, More Horsepower with More Torque Guaranteed!

A swap to a set of 3.23 gears may be done in the future, but the converter was going to be added and see how the car responded. I would also suggest a "shift improver kit" to firm up the shifts of the gears as this can aide in picking up a little more "free" performance.

That is where it stands right now. Could all change tomorrow, nothing is ever carved in stone when building an engine and it isn't over until you hit the key to fire it up.

So input is welcomed as Dan is still gathering info before committing to anything on his build.
 
First thanks guys for all the hard work put forth into someone who you've never met before. I spoke to Jim at length over the phone and he's correct on his statement. I'm so use to a small block chevy slapping heads, intake and cam and it just going.

I've realize that these Mopars are crazy creatures requiring so many different things and combos and I love that. I think I'll start with the basic, converter,shift kit and making sure the carb is tuned and correct for altitude and so on. I do have dual exhaust but in the firm of manifolds.

The heads are 506 iron and I really do love the look of a stock Mopar intake manifold. I do think the heads need to be investigated tho bc when I replaced the head gaskets this winter I could slide 0.003 feeler gauge under them (warpage).

If I do someday the heads or upgrade them possibly a little larger cam and possible intake upgrade. It I guess for now a few minor things and build up from there. I really want something that will blip the tires at the light downshift and out a smile on your face, but not at the cost of not being able to take a hour ride with my son;)

So I'm going to do so old reading on some Mopar builds from the past and start with a few basic and upgrade as I go;) if someone has a similar build ,at as I'm after please share;) last but not least thanks for all the hard work;)
 
:thumbsup:
The members knowledge of these cars here on this forum is quite something isn't it?
Keep us posted !
 
So I was speaking to somebody up at the local car show and told him I would like a little bit more horsepower out of my 383. He said and suggested the Stroker 496 kit for the 383. So what I'm wanting is a least be up in the 400HP range and just wasn't sure if doing a good set of heads,cam and intake would get me there or not.
I've done some research but haven't seen numbers for the 496, I get that it would be matched with a bigger cam and intake and so on. Has anyone done this 496 kit and if so where you happy?
Hello Dan,
I presume you're running that 383 in a '66 Fury. In that case, I agree with the car show guy; specifically, here's a recipe for a beautiful torquer for a C-body that won't break the budget, will last forever, and will look and sound stock as a rock:

383 with 4.25" stroker kit (Muscle Motors, 440 Source, others) makes 490-496ci depending on bore; reconditioned mildly ported or stock 906 heads; Mopar Street Hemi Purple shaft (0.484" lift, 284 duration), CR around 9.5:1, 750cfm carb (doesn't matter which), Edelbrock Performer RPM intake (can be filed and painted for the stock look. This WILL make about 470-490hp at 5300rpm, and about 600ftlbs at 4700rpm. The street hemi cam in a 496 has a smooth idle, and off-idle partial throttle take offs are breath-taking. Hundreds of these have been built, and that equates to hundreds of fellas with permanent smiles welded on! With a 2.76 rear, yer lookin' at flat 14s at about 4000lb; 3.23s will see this baby crack into the mid-13s. Up top, 140mph will come at ~5400 with 2.76s, and this engine WILL get there if you have the requisite intestinal fortitude.
I have built 2 of these over the years, and my opinion is that for your application this IS the answer.
All the best, fellow Moparphile.
 
All stock 66 383 with 506 heads. Bottom end has been bored 40 over and is running stock manifold with dual exhaust. She has been converted to a 4 barrel intake with a 1406 carb. Looking for just more HP then stock and when you just want to play around. Not looking for a track car but fun weekend Mopar

That is the biggest controversial statement I've seen in a while!
You can NOT have a stock motor that's been bored .40 over, they never came that way from the factory. The bearing have been changed, so you don't even know if your cranks been cut, do you? FACT! You have no idea what cam is in there now, cause it's not mentioned with what's in there now. FACT! It's also not stock when you convert to a 4bbl intake and a 1406! But it's your car so you know best right? Not! At any rate, bolting on a set of 440 source alloy heads will yield a 50HP increase right outta the box, more with some port & polishing! Whatever else you do to it is gravy. Good Luck
 
So after doing some more research and getting advice from many of you including PontiacJim=) I've spoke to a old time gear head by the name of Bob Karakashian. Bob AKA "Mr Six Pack", has been running and making his own camshaft for many years. He currently runs in Pure class at/around low 12's meanwhile keeping it as close to OEM as possible.

So after spending about a hour on the phone, the goal is a set of 906 heads changing up the valve sizes with harden seal with a few other things. I'll check the piston to deck height to make sure we have the required compression we spoke about for 92 octane gas. I'll be keeping the stock 4 barrel dual plane intake manifold and running a set of headers just not sure what header options are out there that fit? Next will be upping the carb from a 600CFM to a 800CFM

Out back he suggested keeping the stock converter because I'm planning on running one of his 4 cams. His custom grind cams usually run a 114LSA with a secret lift, but runs better with the stock converter. Out back I'll run a 3.23 gear or maybe I'll get brave and run a 3.55 lol. I feel this will give me the stock/OEM appearance i'm after but more performance that I want. If anyone has suggestion on header fitments that would be a great help because I've heard from the prior owner he had trouble getting them to fit.

Thanks again to everyone who's put forth time out of there day to help me out=)
-Dan
 
Thank Stubs you're correct when you look at the motor that away. Yes having the motor board .040 isn't stock and swapping out the 2 barrel out for a 4 barrel but considering what most have done it's stock lol. By the way how many more cubic inches is the car now since its now .040?
 
Hey Dan, great thread.. really enjoying it.. learning some things.
Good luck getting what you want out of your 383.
And thank you to all members who are contributing to the cause. I do not have any knowledge/expertise to offer on the subject.. but owning a bone stock 67 Fury/383HP 4bbl car, I can't help but take lots of notes here!
~Alex
 
GG I agree a lot of amazing members on here! I've gotten advice on going big and deep into the numbers or just cruising around town builds. I'll keep posting as I go a long;) once again thanks to all who have helped;)
Dan
 
So guys had time to do a cylinder compression test. All cylinders came back around or between 135-140. I'm not really sure what's good and what's bad?
Dan
 
It's low but that's expected for a plain rebuild on a 383. If they're not blueprinted they will not have compression over 9.5:1 no matter what shelf piston you use. So a stock cam or mild performance cam will get you shy of 150psi. As long as they are all within 10% of each other you're engine is in decent shape. Move on to the next step...
 
Moper if I heard and understood you correctly you're say that even with brand new pistons, rings and all the goodies if i rebuild stock, I'll still be sitting at a low cylinder compression and low overall low compression. Now changing from flat top pistons to a different style and cam upgrade with heads would increase my overall compression correct?
 
So guys had time to do a cylinder compression test. All cylinders came back around or between 135-140. I'm not really sure what's good and what's bad?
Dan
135-140 is pretty good, as moper said within 10% of each other is the key
 
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