383 build help one piece at a time

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Sully_PA

Sully_PA

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I have a 65' 2 barrel 383 with 516 heads that I'm dropping in a 76' dart ....Soon I'm taking the block to the machinist to have cleaned ,checked,and most likely bored 30 over as it has a pretty substantial lip at the top of the cylinders.
Any ideas on what piston to use for this build if I was to use the stock rods? I'm going to go with new cam/intake/4bbl carb/headers as well as put in a new rear. I don't have anything yet I'm just trying to come up with a build plan.
I'm on a tight budget so I'm looking to keep the milling at minimum.
My desire is for a nice street car... I'm just looking for a nice loping BB idle sound and the ability to light the tires up for fun :burnout:. I guess a street light to street light build. Any help as I plug along will be appreciated. It's my first build ....I'm somewhat mechanically inclined but this is my first real engine rebuild.
 
If you are keeping the 516's due to budget, have your machinist do some work to them. Have hardened seats installed so you can run unleaded without cracking them, and have them upsize the tiny (1.60) exhaust valves, you can get 1.74's pretty cheap. Also porting.
 
First, a 383 in an A body should be able to light them up any time. The trick with 383s is the piston and cam choices. The pistons - I like the KB hypereutectics. Close to zero deck, able to take some abuse, but you want to be careful when the guy hones the block to get the right (tighter) piston to wall clearance, and you want to make sure you set the ring gaps per KB specs and your worst intended behavior. On the cam, too small won't hurt. Too large will. Depending on the heads and deck height and resulting compression... It it's over 9.5:1 keep the cam smaller than 225° @ .050. If it's higher than 9.5:1 go with something larger than 230° @ .050. I'd also agree on the larger exhaust valve, and have the exh bowl blended to take advantage of the larger valve. This is very basic, but you get the idea.

Edit - Thanks to SG...
In order to get a 383 to 9.5 or above static compression with the KB pistons you MUST blue print the block, and MUST mill heads to reduce the chamber size. This also will mandate custom length pushrods and milling to fit the intake manifold properly.
 
Finding a used dp4b isnt that hard yet, and will keep it stock looking while saving weight and improving flow over a cast factory piece. Dont over cam this critter!
 
That's the thing ...my machinist wants the pistons before he starts boring.... So I'm starting from the bottom up and will match the cam....I was going to use the 516's with a light port stock but I'll do the bigger exhaust valve if you guys think it make a diff. .....so would this piston be what I'm looking for? I think it is as the 516 is like 78cc so i should be over 9.1 or better on compression ....

Do I just do the hardened seat on the exhaust valve or do you always do both? Thanks

http://www.jegs.com/i/KB-Performance-Pistons/648/KB162.030/10002/-1?parentProductId=755794
 
Sully_PA said:
That's the thing ...my machinist wants the pistons before he starts boring.... So I'm starting from the bottom up and will match the cam....I was going to use the 516's with a light port stock but I'll do the bigger exhaust valve if you guys think it make a diff. .....so would this piston be what I'm looking for? I think it is as the 516 is like 78cc so i should be over 9.1 or better on compression ....

Do I just do the hardened seat on the exhaust valve or do you always do both? Thanks
Click to expand...

When I had mine done I was told only the exhaust valves needed it.

IMO that tiny exhaust valve is going to limit the potential gains you would see with the other things you are doing. (cam, intake, headers, etc.)
 
I'll def. do the exhaust valve ....I've been reading that you may not need hardened seats with a SS valve too ...... is there a large diff in cost if you just enlarge the valve without hardened seats ?
 
Sully_PA said:
I'll def. do the exhaust valve ....I've been reading that you may not need hardened seats with a SS valve too ...... is there a large diff in cost if you just enlarge the valve without hardened seats ?
Click to expand...

The cost is going to depend on the machine shop, and I would likely do it anyway for peace of mind, I don't remember the cost breakdown on everything I had done, but I am one of the lucky few that can get a family discount at a local shop. I don't remember the hardened seats being a huge chunk of the cost though.

It's only a matter of time before the cost of adding lead substitute to your fuel equals the cost of having hardened seats installed.

One thing I can say for sure, if you don't get the hardened seats and end up down the road with compression loss from a cracked head you will be kicking yourself in the *** for not having done it.
 
1.6 is NOT a tiny exhaust valve and is more than enough for a mild 383 that will never see the happy side of six grand. Much better places to spend your limited money.
 
whitepunkonnitro said:
1.6 is NOT a tiny exhaust valve and is more than enough for a mild 383 that will never see the happy side of six grand. Much better places to spend your limited money.
Click to expand...

I don't want to get into a pissing match, using the word tiny may have been a little exaggeration. Just saying how I would spend the money if it was my engine.
 
moper said:
First, a 383 in an A body should be able to light them up any time. The trick with 383s is the piston and cam choices. The pistons - I like the KB hypereutectics. Close to zero deck, able to take some abuse, but you want to be careful when the guy hones the block to get the right (tighter) piston to wall clearance, and you want to make sure you set the ring gaps per KB specs and your worst intended behavior. On the cam, too small won't hurt. Too large will. Depending on the heads and deck height and resulting compression... It it's over 9.5:1 keep the cam smaller than 225° @ .050. If it's higher than 9.5:1 go with something larger than 230° @ .050. I'd also agree on the larger exhaust valve, and have the exh bowl blended to take advantage of the larger valve. This is very basic, but you get the idea.

Edit - Thanks to SG...
In order to get a 383 to 9.5 or above static compression with the KB pistons you MUST blue print the block, and MUST mill heads to reduce the chamber size. This also will mandate custom length pushrods and milling to fit the intake manifold properly.
Click to expand...

The only thing I will add to this is that with the 516 "closed chamber heads" you shouldn't have to mill much of anything to get the compression you want other than to true it up....
 
mguner said:
The only thing I will add to this is that with the 516 "closed chamber heads" you shouldn't have to mill much of anything to get the compression you want other than to true it up....
Click to expand...

All the information I have been able to find on these heads on the interwebs says they have a 73.5cc chamber. All the specs I can find on the interwebs show a 1965 383 having a stock compression ration of 9.2:1.

Also, FYI, I used a pair of the same heads from a '65 383 on my 440, when I took them to the machine shop there was hairline crack at one of the exhaust valve seats. The machine shop I deal with usually works on big diesel engines, my cousin had the head sent to their guy to have the crack welded (he assured me they do it all the time on the diesels and that it wouldn't be a problem) before installing the hardened seats. The engine now has probably 3 - 4 hours of run time on it, and so far so good.

Concerning the question of exhaust valve size for your application, I really would like to hear what IQ52 would have to say about it. While I consider myself to have a fair amount of engine knowledge, this dude is like an encyclopedia.
 
whitepunkonnitro said:
1.6 is NOT a tiny exhaust valve and is more than enough for a mild 383 that will never see the happy side of six grand. Much better places to spend your limited money.
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Save it. Why in the world would anybody listen to you anyway? Thirty plus years of building, racing and writing about cars just ain't enuff man.

Everybody wants big *** valves, 10:1 plus compression, cams with 250 plus @ .050 and single plane intakes.

You're just obsolete man. Time you realized it. lol
 
Like the guys said its a system not just one component.I was around when these things rolled off the trailer from Fenton and most were not slouches then.A stock 383 in an a body will roast a bunch of tires.You will have trouble hooking up if you can tune it at all.
 
First I want to say thanks for all the input...I appreciate it!

There is a lot of opinions and info out there which is kind of what makes it confusing on what exactly to do....
I want to get the most out of it but really just want a fun, quick car that looks and sounds impressive ...
I know my motor in almost torn down (got the pistons out tonight after work) and I should do everything I can afford while its apart but I really wasn't thinking I'd get into blue printing ,milling the heads and then getting custom push rods as well as milling to fit the intake .....
I mean I'm a rookie and a lot of this is a little over my head but my thought was to get a good bottom end that will serve me later as well,use my heads with a little porting and then add a cam/springs, intake ,carb and headers. I thought I could always take the heads off over another winter when the budget allows and get them worked . I would do the exhaust valve now if it makes that great an improvement at this time.

I was hoping to get a piston that would get me close but am I to believe there isn't one that will help the cause now and I should just get run of the mill flat tops until I'm ready to go all in?
 
Something more to think about.................

Years ago, Steve Dulich did a build up story in "Mopar Muscle" with a stock spec re-manufactured 383 Magnum, gave it a break in/base line run on the dyno. Magnums were rated from the factory at 335HP, he got real close to that, +/- 5, I think. He then started adding typical bolt on stuff, headers, carb, intake, showing on the Dyno what each piece added. Before the cam change he had just a lick over 400. I would think that should work out nicely for a fun, go any where driver "A" body.

Good luck
 
That was a good article, I saved it. Read it many times. Used headers should be easy to find for his a body so he doesnt have to use manifolds.
 
I ran 915's with the 1.60 valve. If the valves are good reuse them if they are iffy go 1.74, the heads are more like 80cc at least my 915 was, I would shoot for a zero deck piston with the felpro .039 gasket this way you have a nice quench even if the compresion falls around 10.25 or 10.5 the quench will still allow you to run 93 with a cam in the 220 to 226 @.050 duration. I would open up the bowls on both the intake and exhaust on those heads.
 
If you want to get into some serious quench, go with a replacement 68-70 383 HP Piston. Just slightly positive on deck height...if I remember correctly, a Felpro Composition gasket just barely makes it work with a closed chamber head. You might have to shave a few thousandths off the quench side of the piston...not a biggie.
The old saying goes, "If the pistons ain't hittin the heads, you're leaving power on the table"
 
A stock rebuild with slightly better than stock cam on this engine would probably get you what you are looking for. If you are planning on pulling the heads later for more work, freshen up the bottom end, drop in a little better cam, and run lead substitute for awhile if everything looks good on the heads. Do that and plenty of research in the meantime to decide what if anything you want to do to the heads. If you don't want to deal with lead substitute or if anything looks jacked up with the heads, the machine shop shouldn't charge you any more labor to swap the valves if you are having them do the seats or a grind anyway. Then you are just looking at the additional parts cost for the valves, and I don't think I paid more than $75 for the full set of new exhaust valves.

To clarify - This is my opinion, this is what I would do if I was looking at a 383 to build on a limited budget.

I do not know whitepunkonnitro or what experience he has, I wasn't trying to be insulting in any way, maybe he has gobs. I have gathered from lurking this forum that Moper and IQ52 both have a ton of knowledge and experience. Maybe try leeching some of theirs if you haven't bought parts or paid for machining yet. Get all the experienced opinions you can, and from there decide what you think will work the best for what you want your car to do.

For sure talk to the old guys, most of the info I got on what machining to have done and what parts to buy came from my old man who has built probably thirty some engines that worked well and made tons of power, half of them being mopars.

If you don't mind my asking, what kind of budget are you looking at to get your engine finished?
 
Build it like EL5DEMON340 said and it will run great. I ran 516 heads on my daily driver for years burning unleaded gas with the 1.6 exhaust valves and never had any cracking seats or abnormal valve wear at all, I never put any lead additive in either. I have that engine in another car now and it still runs good. Go conservative with the cam and use all your stock valvetrain parts and have fun.
 
Sorry, I have entirely avoided the piston question. If it were mine I would look at it like this: If you have to bore the block and can't reuse the original pistons, I would try to find a good name brand .030 over stock replacement or pistons that live slightly higher in the holes for a little higher compression. Lighter weight would be better. If there is a chance that you will ever want to run even a little boost or N2O, you will want forged pistons.

Don't know if you already know it or not, I don't see where anyone has mentioned it, if you swap pistons you will want to have the rotating assembly re-balanced, even if you don't it would be a good idea.

The 9.2:1 I have read these are rated at is pretty decent for street use. A cam spec'd at 225 degrees duration (@.050) should wake it up without being too much.
 
Here's where people get clouded. "I want it to sound good"

Throw that chit out the window. Any high performance engine will sound like one. Put sound completely out of the picture when choosing parts. That's how you tell bench racers from real car guys. Choose parts that will work well for your car's weight and its intended purpose. As long as you do that, It will flat out haul *** and be fun.
 
RustyRatRod said:
Here's where people get clouded. "I want it to sound good"

Throw that chit out the window. Any high performance engine will sound like one. Put sound completely out of the picture when choosing parts. That's how you tell bench racers from real car guys. Choose parts that will work well for your car's weight and its intended purpose. As long as you do that, It will flat out haul *** and be fun.
Click to expand...

Yep, you can cam the **** out of it and make it sound like a funny car without making any real usable performance gains. Build your engine to perform and it will sound just fine.
 
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