.557" purple shaft 318?

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benmopar318

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I am wondering if any one has run a .557" purple shaft in a hot 318 set up?
Will it have enough vacuum for power brakes? I'm thinking of installing a booster tank under the guard to help.

I want to try the .557" in my std bore 318 that has .040"off deck and the four valve relief pistons which are .020" taller.
Out of the box Eddy heads with bushed Speed Pro (273) rockers.
Holley Strip Dominator intake with modded 600 AFB (secondary initial discharge ports enabled and dual fuel inlet -6)
Accel billet dissy with Mallory coil
Extractors tri-y with large port header flange, twin 2 1/2" short exhaust.
4000 stall full manual 904 and 4.11 gears in light weight Aussie A Body




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I don't think it'll have enough compression for that cam, but it'll SOUND mean as hell. lol Can we see more pics of that Valiant "Regal"? I like it.
 
with its 110 LSA...it idles pretty docile in a 340....
 
Then I bet the idle in a 318 would be about the same since the stroke is the same.
 
.................u wont have enough valve to piston clearance, or guide clearance without shortrning the guide..........as mentioned, not enough compression.....the idle will be pretty crappy in a 318....kim....
 
had it in a bracket 340 for several years...did not like it with the 110 lsa....just my opinion...
 
Man, that is one NEATO car you have.
 
Thanks, it has had a mild hyd 276 @ .420"cam with 1.6 stainless rollers and made 224 hp at the wheels
Just like to cam it to see what power it might make, but if it wont work i'll have to wait longer until funds let me finish it off with a built bottom end.
 
I think it will physically fit and work without piston to valve interference. Of course, you'll want to make sure of that......and really, the only way is to remove the heads and use clay to measure by. However, I think you'd be much better off with a different grind strictly from a power standpoint. I believe that cam will bleed off too much cylinder pressure and give nowhere near the results you're looking for. I think this would be a great choice for a step up in cam.

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=640&sb=2

Those are Mopar specific lobes, not chebbie lobes. There's more area under the curve. It's essentially a revamped version of the 474 MP cam. I think it would work well for you.
 
sweet as man!!!! do you know what pushrod length is for 1.6?
I'm going to use my 1.5 adjustable rockers, they're near new Speed Pro on grooved shafts, as i have the pushrods to suit, but later it would be nice to have the option to go with the 1.6's.
 
benmopar318 said:
sweet as man!!!! do you know what pushrod length is for 1.6?
I'm going to use my 1.5 adjustable rockers, they're near new Speed Pro on grooved shafts, as i have the pushrods to suit, but later it would be nice to have the option to go with the 1.6's.
Click to expand...
7.5". ball and cup. the stroker has ally heads and 11.7 comp, so it uses the cam. its not just there for the sound. 1.6 rockers makes it around .590 lift
 
If you stuff it in you'll realy, realy want to check piston to valve clearance! I think it's gonna hit! You stated that you've taken .040 off the deck, and the pistons have pin height .020 higher; over the years pin heights ranged from 1.74 to 1.76 according to "How to Hot rod Small Block Mopars". The actual measured pin height would be very helpful.

I crunched some numbers, was optimistic figuring .020 on top of the 1.76 PH, that put your piston .002 down in the hole.

What head gasket are you using? Go thinner if you can. How much do the pistons rock in the bore's? Less rock, tighter quench, alittle more compression.

Cylinder head chamber volume is killing compression, OTB Eddy's run about 65 cc, which puts you around 9.2 compression ratio, shave the head down to 60cc and you are around 9.7, alittle weak for a .557 cam.

More gear, that cam in a teen, I guess 4.56's to 4.88's.


I run that cam in my 65 Barracuda; 360, Eddy heads, M1 intake, 750DP Holley, 4.56 Gears, 28 inch tall tire, a best so far of 11.10 at 120.48MPH; I've run it with 4.88's and gone 11.14 at 118mph.


Your results may vary.

Good luck.
 
pistons are definitely further than .002" down from the deck maybe .030" but a lot closer than the '78 318 i have on the shed floor that one is .030 over and real low comp but i ran a CCH-302 grind with 273 heads and LD340 in a Duster it wouldn't turn the tires with a 3000 stall but ran 13.9 @ 102. Later swapped in a
4000 stall and fitted Eddy heads mine are 63cc too and and she really got going along just nice and would smoke 255-60-15's with 3.7 gears.
i was just comparing the crown height to these other std flat tops i have laying around and they are taller so this one's got more comp for sure but not enough to be a great combo yet until the KB399's go in.
 
I think instead of the 557 you might want to try the 528 solid. Of the two, the 528 is my hands down favorite and would work better. Not sure about the power brakes tho. There are much better choices than any MP if you are really concerned with making power.
 
moper said:
I think instead of the 557 you might want to try the 528 solid. Of the two, the 528 is my hands down favorite and would work better. Not sure about the power brakes tho. There are much better choices than any MP if you are really concerned with making power.
Click to expand...

The 528 is a dang good one.
 
the .528 is safe and and with 1.6's would be great, most of the combos i found ran 12's, i'd like to progress to 11's but no faster, that will cost enough time and effort.
going fast with a 318 isn't common but here in Adelaide, guys have run 11.2 -10.8 in full street stock stroke 318's, there must be more like this in the States?
researching times for the purple shaft i found the .557 has been used to run 11.00 in 3.31 stroke 318 down to 10.3 with 340's
does this mean the cam would prefer 5000 stall and 4.56 gears for such a small motor?
i know that there is better modern grinds but a purple shaft is true tried and tested and has 70's cool like Zepplin.
 
Everyone's definition of streetable is unique. My impression is if they are running that hard they are not what I'd consider streetable. In the US we build bigger engines. They are the same money and we can get more power from them.
Do you really think the cam is what makes them run that well? And no, it's not like Zepplin. Zepplin's art, which is timeless. Purpleshafts are technological, and as such are way behind the times. Yes, they work, but there's much better around now.
 
Streetable is any car that can drive further than a 1/4 mile! Duhhh!!...I have decided its safer to ram ( less risk of being unhappy) the .528" in at the moment with the std bore donk and see how close to 375+hp it might make.... and install the .557" in another block ( i have 6 318s) that is bored .040" with the KB399 pistons and H-beams and then we can spin the ***** up with High comp and a Super Victor intake or tunnel ram and run that motor HARD or throw it on the bottle if it can't pull the skin off a rice custard!!!
and yes old profiles for old motors by people who know better MOPAR ALL THE WAY!!!!!!!!!!! MOPAR! MOPAR! MOPAR!
 
**** my .566 is going to hit on my zero deck 318 with valve relief's(eddy heads)...stupid of me torqued my heads down...waiting for push rods and ill know for sure..................
 
wanting just to throw the cam in i went for the safer option of 284/528

[ame="http://www.youtube.com/watch?v=FEjAaBpVkxg&list=UUk8YjfNAdokNHAhR8IkY-Vg&index=3"]318 284 .528 cam - YouTube[/ame]
 
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