Mopar purple .528 for a 383?

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MOPARMAGA said:
Assuming it's a standard bore, assuming flat top no valve relief pistons, assuming true stroke 3.375 same for rod length, combustion chamber and other variables you'll be around 10.5-10.6
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I thought factory 383 HP pistons sat above deck at TDC, or is it just 340 pistons that do that?

I think it's time to do some measurements on where those pistons actually sit before going much farther...
 
MopaR&D said:
I thought factory 383 HP pistons sat above deck at TDC, or is it just 340 pistons that do that?

I think it's time to do some measurements on where those pistons actually sit before going much farther...
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Yeah the factory HP pistons were 1.932 and if the block is true 9.980 that would be.001 under.
I guess the factory model had pistons.020 over deck height but probably never made much into production engines.
Pistons available now I think 1.928 is the tallest.
But yeah midnight swinger get that thing tore apart and measure it.
 
MOPARMAGA said:
Yeah the factory HP pistons were 1.932 and if the block is true 9.980 that would be.001 under.
I guess the factory model had pistons.020 over deck height but probably never made much into production engines.
Pistons available now I think 1.928 is the tallest.
But yeah midnight swinger get that thing tore apart and measure it.
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Almost there, damn b body Hedmans fighting me to the last breath.

IMG_2947.jpeg
 
Why the change from the Hedmans to the Schumacher tri Ys? In my opinion that’s a step backwards.
 
MidnightSwinger said:
That’s exactly what I want. Im not going to daily drive, or long highway trips. I want something that starts to pull at 3k and pulls hard to 6k, and spin it to 6500k just for fun/sound.
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In a small block they're very daily drivable, mostly when you dial the cam about 5° advance...they become tire ripping.
Get it, start at 4 degree advance.
I think the intake closes around 60, cant remember though.
 
MidnightSwinger said:
Yeah I’m gonna run it. Everything is a compromise, so I’ll go with undercammed I guess. I hope you are right!
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I am. Undercammed is like undercarbureted. It's always better to err on the smaller side. You'll like it. Trust me. LOL
 
MidnightSwinger said:
What carb J?
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Since you have a 4-speed I'd probably go with like a std dbl pump 750 to a 830 annular dbl pump.
Auto, you could use a carter competition 625 cfm and it would pull hard and drive as good.
The .528 w/750carb, dual plane or single and a 4-speed daily Drive no problem
 
MidnightSwinger said:
Also, this is a victor copy with a shitty Chinese 1/2 angle valve job. I don’t think they flow like a real victor or max wedge. It will be fun to find out though and I’m still losing 50lbs off the nose of the motor.

A few changes to the build too, the Hedman b body headers are out and I was able to find some ceramic coated Schumacher tri y’s locally.

I sold the street demon, and im
On the hunt for a carb to work with this combo.
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Which head 265cc, 285cc or 325cc .
 
TT5.9mag said:
Why the change from the Hedmans to the Schumacher tri Ys? In my opinion that’s a step backwards.
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I got the ceramic coated Schumachers for $400. I also only have a 2.5” exhaust system, and the cam I picked is supposed to work well with a restricted exhaust.

For maximum performance, I agree the Tri-y’s are a step back. But I’ll be honest with you I’m damn tired of fighting the headers any time I want to do anything motor or trans related. The way they fit is like the way your foot fits in a shoe 1/2 size to small. It will work, but no room for movement.
 
MidnightSwinger said:
I’ve got an opportunity to pick up a new Mopar purple shaft .528 cam for a good deal and I wanted to ask opinions, everyone loves a cam thread.

‘74 swinger
1970 HP 383, standard rebuild (guessing at 9-9.5-1 comp but not verified)
The heads have mopar performance dual valve springs
Edelbrock dp4b intake
Street Demon 750 carb
Hedman b body 1 3/4 long tubes
2 1/2” mandrel bent exhaust ultra flo’s
A-833 4 speed non-od
3.91 gears and sure grip

Street car only, I’m building a burn out machine. Rowdy is ok, and I’m not looking for gobs of low end torque. I’d prefer it to scream up to 6500k.

I also have a trick flow track heat single plane intake that I want to run, so I may swap intakes at some point after the cam swap and see what happens.

View attachment 1716089325
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Not exactly the same, but the 0.509, 292 juicer purple I ran in a 383 was fantastic. My converter was way too tight, but once she hit 3k it was a Ninja rocket! Building a more scienced out 440 version of that engine for my '69 Dart GT, Torker, 2" to 2 1/8" Step Proparts style semi fender well, big valve plunge cut and blended, milled iron heads set for 0.035" quench, Total seal gapless top rings, hyperutectic prisons, h beam rods with bushed floating pins, single springs with damper, stock rockers... Anyway, should rip like what you are building.
 
Off topic, but I wouldn’t take a stock rod 383 to 6500 rpm.

the cam sounds like a winner for lumpy and rank. Do it!
 
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4mulas said:
Off topic, but I would t take a stock rod 383 to 6500 rpm.

the cam sounds like a winner for lumpy and rank. Do it!
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Really I turned my 383 6800 with ARP rod bolts many times with a MP 557.
Still have the block under the bench
 
MOPAROFFICIAL said:
Since you have a 4-speed I'd probably go with like a std dbl pump 750 to a 830 annular dbl pump.
Auto, you could use a carter competition 625 cfm and it would pull hard and drive as good.
The .528 w/750carb, dual plane or single and a 4-speed daily Drive no problem
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HP Street 750, just needs to be cleaned up.

IMG_2981.jpeg
 
MOPARMAGA said:
.030 of bore usually gets an additional point in compression or close so I'd run a .039 gasket.
Hopefully since the block has been machined it has been decked and is .000 deck and decent pistons were used. .039 gasket would put you at 10.2 if it were me I'd shoot for the higher but California probably has **** gas on purpose
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.00965” down in the hole and .030 over.
 
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I thought I would update this thread for anyone interested, motor is out and torn down to the short block. I remeasured the piston deck clearance incorrectly before. I’m actually at .0965 in the hole, whoever rebuilt the motor used standard 383 pistons. I would only get 8.71:1 with the 74 cc chambers and .027 head gasket.

I am definitely bummed out, but I’m glad I checked it because I would’ve been more bummed with that big cam and no compression. Starting the search for some pistons to bump me up closer to 10 to 1.
 
MidnightSwinger said:
I got the ceramic coated Schumachers for $400. I also only have a 2.5” exhaust system, and the cam I picked is supposed to work well with a restricted exhaust.

For maximum performance, I agree the Tri-y’s are a step back. But I’ll be honest with you I’m damn tired of fighting the headers any time I want to do anything motor or trans related. The way they fit is like the way your foot fits in a shoe 1/2 size to small. It will work, but no room for movement.
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With a 112 LSA it won’t care what exhaust you use.
 
MidnightSwinger said:
HP Street 750, just needs to be cleaned up.

View attachment 1716092458
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If you got that fuel line with it, SCORE!
I bought a 850 brawler recently from Speedway, as a "kit". (Kit was $50 more than just the carb.) Came with a drop base ac, liquid fuel pressure guage, and a fuel line similar to that. For giggles, looked up the price for the fuel line....$130!
That 750 freshened up should be perfect on your 383.
 
33IMP said:
If you got that fuel line with it, SCORE!
I bought a 850 brawler recently from Speedway, as a "kit". (Kit was $50 more than just the carb.) Came with a drop base ac, liquid fuel pressure guage, and a fuel line similar to that. For giggles, looked up the price for the fuel line....$130!
That 750 freshened up should be perfect on your 383.
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And the air filter too! I love a good deal!

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