Budget 383 Build

roadrunnerh · Jul 15, 2019

Hello Folks! I'm rebuilding a 9-17-68 383 engine. It was originally installed in a 1969 Charger 383 2Bbl, so it's the advertised 9.2 to 1 compression ratio.
My Plan:
Disassemble, remove ridge, Flex hone, measure x 54 times and pray the bore measurements I get are lower than 4.2515!
I hope to thoroughly clean all pistons, install NOS Mopar rings, new Main and Rod bearings, new oil pump (standard pressure), fuel pump, 2806301 cast 4Bbl intake with Carter AVS, Aluminum Water pump and housing, new Cam and lifters, valve springs, and 1968 HP factory manifolds........... AND LET HER RIP!

* Pistons 1,5,7,and 6 have a number (casting?) 2863116 inside piston.

*Pistons 2,3,4, and 8 have number 2863115 inside piston.

I read in my 1968 parts book that there were .005" over pistons and standard size. (in addition to .020 and .040 over pistons available.
Do I have some cylinders which were .005" over from the assembly line? The part numbers in my book are 3004524 and 3004525 (.005 O/S).
Can anyone help out with a 1969 Parts book?
Also, Do any of you have experience with the Summit 6400 Camshaft?
I'm running a stoke 727, stock converter, and 3:23 gears.
Thanks for your help - it's much appreciated! (I'm sure I forgot something here)

roadrunnerh · Jul 15, 2019

Everybody likes pictures, right?

roadrunnerh · Jul 15, 2019

CompSyn · Jul 15, 2019

My 69 383 HP pistons have two numbers in them one digit off from the other. Not sure the reason for two numbers? Are you sure you only see the one number in yours?

Also, the HP piston with the flat top actually comes out to around 9.2:1 compression with stock 906 heads and stock block deck height. So your dished pistons will be south of that number. It would be interesting to know the CC's of the dish?

BTW, nice clean job on the pistons. What was your method for getting them cleaned up like that? I'd like to do the same with mine.

roadrunnerh · Jul 15, 2019

roadrunnerh · Jul 15, 2019

CompSyn said:
My 69 383 HP pistons have two numbers in them one digit off from the other. Not sure the reason for two numbers? Are you sure you only see the one number in yours?

Yes, I do have two different numbers.
* Pistons 1,5,7,and 6 have a number (casting?) 2863116 inside piston.

*Pistons 2,3,4, and 8 have number 2863115 inside piston.

.005 O/S and standard?

CompSyn · Jul 15, 2019

No, I mean each individual piston has two(2) part numbers behind the skirt, not one(1) part number per piston.

1 Wild R/T · Jul 15, 2019

What's going on with the rear main seal surface? Looks pitted....The rear main bearing surface doesn't look great either but that seal surface is sketchy..

383's are hard enough to build any C/R into, dished pistons & 906 heads aren't gonna make it any better...

Any chance of scrounging up some 516 heads.... They aren't the best flowing but they'll help the C/R enough to more than compensate...

If your staying std bore & totally on a budget I'd try to scrounge up some used 4 bbl pistons..

The Summit Cam your asking about is
214 224 @.050 so it should be a decent cam for a mild build

roadrunnerh · Jul 15, 2019

CompSyn said:
No, I mean each individual piston has two(2) part numbers behind the skirt, not one(1) part number per piston.

Even though I feel like a complete idiot, THANK YOU for clearing up that one! I went out to the garage just now and yes, both numbers are in each piston - one on each skirt.

CompSyn said:
BTW, nice clean job on the pistons. What was your method for getting them cleaned up like that? I'd like to do the same with mine.

Thanks man. Not the best method, but it worked ok for me - I soaked each one in large can of WD40 for a few days, Scotch brite pads, oil, old piston ring, and a ton of elbow grease!

roadrunnerh · Jul 15, 2019

The rear seal surface actually looks pretty good, still has factory XXXXXing.
This is the crank prior to polishing/cleaning.

CompSyn · Jul 15, 2019

Glad to help. I think the only reason Chrysler did that was to confuse people.

roadrunnerh · Jul 15, 2019

Sticking with the 906 heads. Incidentally, this was a Running Engine. #3 Main bearing below.

CompSyn · Jul 15, 2019

Cheers to the efforts. I'm working towards a budget 383 build with my 69. Crossing my fingers it works out...

1 Wild R/T · Jul 16, 2019

FWIW your dished piston & 906 head combo is going to give you a true measured compression ratio of about 7.8 to 1

Swapping to magnum pistons while still using the 906 heads will give you a true 8.75 to 1

Here's a set of 383 magnum type pistons with a 1.900 C/H
https://www.ebay.com/itm/383-CHRYSL...040374&hash=item48bd36ecd6:g:WxcAAOSwHSdcLSLp

I won't bother you any more, just trying to keep you from building a dog...

CompSyn · Jul 16, 2019

1 Wild R/T said:
FWIW your dished piston & 906 head combo is going to give you a true measured compression ratio of about 7.8 to 1

Swapping to magnum pistons while still using the 906 heads will give you a true 8.75 to 1

Here's a set of 383 magnum type pistons with a 1.900 C/H
https://www.ebay.com/itm/383-CHRYSL...040374&hash=item48bd36ecd6:g:WxcAAOSwHSdcLSLp

I won't bother you any more, just trying to keep you from building a dog...

The original 68/69 Magnum/Roadrunner high performance 383 pistons had a compression distance(CD) of 1.932". With stock 906 heads at around 90CCs, mine were 91, and pistons in the hole a couple thousands, a stock 383 HP would have been around 9.2:1, maybe 9.3 on a good day. The factory advertised 10:1 is the stuff folklore and fairy tales are made of. Given that, with a few day one bolt-ons, the 383 put down some legendary street performance that to this day, people talk about. The down side was adding a cam too big with the low-ish compression. Now you had a "dog", and in some cases, bent vales and push rods. This is where the 383 got some negative knocks against it no fault of it's own.

In the video, Tim Allen talks about the 383 Road Runner... "Fastest damn car" @ 02:19

So a piston with a CD of 1.900"? Without having the time really look into it; not really sure if it would be a big enough advantage over the factory dishes not knowing the CCs of them?

In this budget build, cam selection will be really critical, not going too big.

1 Wild R/T · Jul 16, 2019

FWIW I couldn't find the spec for the 1.932 C/H
I did find a spec for the dished piston, 12CC dish & 1.890 C/H
So the 1.932 C/H would gain another .5 of C/R over the 1.900
Which is good for nearly a full point over the dished piston...
But the 1.900 leaves a little clearance for valves....

66Satellite47 · Jul 16, 2019

As I recall, factory pistons had a left & a right with pin offset to minimize piston slap. Also, I think the compression height of the 2BBL piston was lower compared to the Magnum piston accounting for the CR difference. As I recall my 1970 383 low CR pistons were flat top not dished, could be wrong. Any good build needs the chamber volume, deck height & dome/dish MEASURED, NOT *** UMED. Head CC's vary a bit. The published CR's are fairly high compared to ACTUAL measured dimensions. If you have a non stock cam or have any milling on heads/block you must check piston to valve. BTW the minimum is not at max lobe lift, it's during overlap, piston chasing valve or valve chasing piston.

493 Mike · Jul 16, 2019

Use the OEM steel shim head gaskets to maximize the CR too.
Mike

roadrunnerh · Jul 16, 2019

Thank you all for the feedback and info! I should have been clearer with my goal and philosophy.
Although I have experience over the past 30 years working on my old Mopars, this is my first engine build.
This engine is replacing a Slant Six in my Plymouth Scamp. My expectations are lower than for a stout bracket car.
If this engine runs smoothly, produces 225 to 250 hp, and mid 14's on an infrequent 1320 run, I'll be very, very, happy.
If the bore measurements are way off, I won't be reusing the pistons. It will be bored and new slugs will go it.
I fully realize that the suggestions given here are aimed at optimal performance which is great, and I truly appreciate the input, not a "bother" at all. However, my main concern is not F'ing up the engine and producing a nice improvement over the Slant Six currently in the car. Will it run?
Will it idle smoothly and produce around 225-250 horsepower?
Anyone have experience with the Summit 6400 Cam?

Dajkzo · Jul 16, 2019

The parts don't look bad. How is the end gap on the new piston rings? You can use a new ring to get an idea of any significant taper in the cylinder bores. You just check the gap 1.00" below the deck and then an additional 3.00". And you can check the piston fit with a feeler strip. I just don't want you to get done and find there is too much blowby. I haven't used that Summitt cam. The numbers @.050" look fine.

Fresh rings and bearings are going to improve things. If it starts and runs and doesn't leak I'd call it a success.

Budget 383 Build

FBBO Gold Member

FBBO Gold Member

FBBO Gold Member

Well-Known Member

FBBO Gold Member

FBBO Gold Member

Well-Known Member

FBBO Gold Member

FBBO Gold Member

FBBO Gold Member

Well-Known Member

FBBO Gold Member

Well-Known Member

FBBO Gold Member

Well-Known Member

FBBO Gold Member

Well-Known Member

FBBO Gold Member

FBBO Gold Member

FBBO Gold Member

Similar threads