273 blower cam

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65TerrorCuda

65TerrorCuda

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Hey y'all,

Currently got a isky E4 260 adv, 108 lsa solid cam. Want to try a hydro, what do you think of this one:
JEGS 200160: Hydraulic Flat Tappet Camshaft & Lifters for Chrysler: 1964-Up 273-340-360 and 1967-Up 318 - JEGS High Performance

Has same overlap but 12* more exhaust duration, .050 numbers are lower vs the isky. Price is right. Let me hear your thoughts,

cam specs:
jegs cam.png
 
I'll second that motion, lol! Is that a 4-71 on the 273 in your photo garage? Do you have 360 heads on it?
 
Very cool build! Would there be any clearance issues with the 2.02 intake valves and the small bore with the speedmaster heads?
 
65TerrorCuda said:
Yeah, 4-71 with 302 heads on it off an 85 318. I've got speedmaster heads planned along with maybe this cam.

And pushrods! There's something I'll have to figure out, going from mech to hydro
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And probably different pushrods for Speedmaster heads. Bore notching to make the big valves work as well like Garrett mentioned above.
 
Garrett Ellison said:
Very cool build! Would there be any clearance issues with the 2.02 intake valves and the small bore with the speedmaster heads?
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Thanks Garrett,
I believe notching for the intake valves like TMM mentioned is mandatory. Definitely wouldn't do the 2.02's without a blower, it might still be lazy down low, I guess I'll find out. The speedmasters are soo nice, can't wait to drop the 50(?) pounds and spice up the underhood a bit.

toolmanmike said:
And probably different pushrods for Speedmaster heads. Bore notching to make the big valves work as well like Garrett mentioned above.
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My understanding is hydro lifters oil the rockers though the pushrods and mech though the head, am I right to think I can use any pushrods that fit? I sure don't want to ruin stuff by oil starving it

Thanks for the replies yall!
 
65TerrorCuda said:
Thanks Garrett,


My understanding is hydro lifters oil the rockers though the pushrods and mech though the head, am I right to think I can use any pushrods that fit? I sure don't want to ruin stuff by oil starving it

Thanks for the replies yall!
Click to expand...
Nope. LA's oil up through the heads and into the rocker shafts. Magnums oil through the pushrods. Check your Speedmasters to make sure they oil through the head. @pittsburghracer knows for sure.
 
toolmanmike said:
Nope. LA's oil up through the heads and into the rocker shafts. Magnums oil through the pushrods. Check your Speedmasters to make sure they oil through the head. @pittsburghracer knows for sure.
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I never ran a magnum block but from reading here and Moparts some years oiled just like an LA block. But most were pushrod oiling. I don’t know what years this was offered. Every Mopar Speedmaster head that I have touched oils like an LA engine. Through the block to the shaft.
 
I thought the 1st year or 2 magnum had the block drilled for shaft oiling.

that’s what I’m looking to do actually. A magnum with LA heads, using the first year of production block.
 
mopardude318 said:
I thought the 1st year or 2 magnum had the block drilled for shaft oiling.

that’s what I’m looking to do actually. A magnum with LA heads, using the first year of production block.
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Sure anything goes in transition years.
 
pittsburghracer said:
I never ran a magnum block but from reading here and Moparts some years oiled just like an LA block. But most were pushrod oiling. I don’t know what years this was offered. Every Mopar Speedmaster head that I have touched oils like an LA engine. Through the block to the shaft.
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I knew I was confusing some facts in my head. Thank you! My speedmasters are oil through block LA style so that's a relief
 
65TerrorCuda said:
Thanks Definitely wouldn't do the 2.02's without a blower, it might still be lazy down low, I guess I'll find out. The speedmasters are soo nice, can't wait to drop the 50(?) pounds and spice up the underhood a bit.
Thanks for the replies yall!
Click to expand...
I can’t imagine that 2.02s would decrease the low end with a blower. But, your going to have a phenomenally more efficient intake for boost with the heads. And your still going to have efficient chambers, too. So you’ll probably find out that you’ll see a drop in PSI of boost because part of your current boost is overcoming the smaller intake port. It will probably change the tune requirement up some. Boost that was used to overcome the smaller intake ports and valves is going to equate to more cylinder charge, especially at low RPM where there is increased charge time for the cylinder to fill. The more efficient the heads, the better the blower will work due to the increase of adiabatic efficiency (less heat in the intake charge generated by boost). Just curious, what kind of static compression, how much boost, and what fuel do you run this on? Are you running locked out timing with a boost retard? Going by the current trends in forced induction with good cylinder heads, the cam with extra exhaust duration, equal overlap, and 112 LSA would be good with the speedmaster heads. There’s going to be more charge in via boost, which makes more volume of exhaust gas for the pistons to push out.
 
Garrett Ellison said:
I can’t imagine that 2.02s would decrease the low end with a blower. But, your going to have a phenomenally more efficient intake for boost with the heads. And your still going to have efficient chambers, too. So you’ll probably find out that you’ll see a drop in PSI of boost because part of your current boost is overcoming the smaller intake port. It will probably change the tune requirement up some. Boost that was used to overcome the smaller intake ports and valves is going to equate to more cylinder charge, especially at low RPM where there is increased charge time for the cylinder to fill. The more efficient the heads, the better the blower will work due to the increase of adiabatic efficiency (less heat in the intake charge generated by boost). Just curious, what kind of static compression, how much boost, and what fuel do you run this on? Are you running locked out timing with a boost retard? Going by the current trends in forced induction with good cylinder heads, the cam with extra exhaust duration, equal overlap, and 112 LSA would be good with the speedmaster heads. There’s going to be more charge in via boost, which makes more volume of exhaust gas for the pistons to push out.
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Well I like the sound of that!
The 302 intake ports I can't even stick my index finger straight through, the pushrod pinch is so extreme. Unported, just upgraded valves and springs.

CR is 8.55:1 at 5000 foot elevation, 91 octane with a recurved mech advance only dizzy, 20 initial 32 total. No boost retard. 5 psi at 10% underdriven blower. Shorty tri-y headers, eddy 750 carb. eddy 500 gave 4 psi. Runs really well.

Dyer's recommends keeping rpms under 5k with cast pistons and the car is plenty fast for me. Just seems wrong to have these aluminum heads sitting on a shelf
 
Ooommmppphhh!!! Yeah, I definitely wouldn’t turn up the tune on that with the cast pistons. I would go as far to use some VP octanium booster on the first tank, probably a half a can to 10 gallons for a little extra margin of safety. I appreciate the kink factor of the 273, but if I had to tear it down to notch the bores, then I would consider an industrial / truck type 318 with good bores to run some of these pistons.
They’re notched for both Poly and LA engines, and are made to run at generous clearances.
Sealed Power 2268P Forged Pistons Set For 1963-68 DODGE 318, 318LA STANDARD SIZE | eBay
 
Those and that '85 roller 318 I got the heads off would be awesome.

So that's what the unusual cutouts on the face of the piston are about! I was wondering until I reread your post. Poly pistons, cool.

It's already a handful with the 273, I really have to watch myself. A 318 might just wrap me around a pole
 
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Garrett Ellison said:
Ooommmppphhh!!! Yeah, I definitely wouldn’t turn up the tune on that with the cast pistons. I would go as far to use some VP octanium booster on the first tank, probably a half a can to 10 gallons for a little extra margin of safety. I appreciate the kink factor of the 273, but if I had to tear it down to notch the bores, then I would consider an industrial / truck type 318 with good bores to run some of these pistons.
They’re notched for both Poly and LA engines, and are made to run at generous clearances.
Sealed Power 2268P Forged Pistons Set For 1963-68 DODGE 318, 318LA STANDARD SIZE | eBay
Click to expand...
Those are Poly pistons.
 
mopardude318 said:
I thought the 1st year or 2 magnum had the block drilled for shaft oiling.

that’s what I’m looking to do actually. A magnum with LA heads, using the first year of production block.
Click to expand...
I have a late 91 and a 94 magnum, both have the oil passage
 
What are the current valve sizes? 1.88 intake? IMO with a blower, you'll likely never see the difference with 2.02s.
 
65TerrorCuda said:
It's already a handful with the 273, I really have to watch myself. A 318 might just wrap me around a pole
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I bet it is, aint nothing like roots blower torque! A 318 would probably require 1:1 or overdrive blower ratio with a 4-71 to generate the same 5PSI of boost as the 273.
 
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RustyRatRod said:
What are the current valve sizes? 1.88 intake? IMO with a blower, you'll likely never see the difference with 2.02s.
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1.78 and 1.5, stock sizes. I ran it on desktop dyno on my old pc and it showed a substantial gain with the bigger valves. 20 year old computer program but it's all just fun in my head right now anyway.

The speedmasters are jeweled chunks of aluminum that are fun to stare at and a weight savings. And right now paper weights sitting on a shelf

Garrett Ellison said:
I bet it is, aint nothing like roots blower torque! A 318 would probably require 1:1 or overdrive blower ratio with a 4-71 to generate the same 5PSI of boost as the 273.
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With the same pulleys I could run it at 10% over, and like you said probably be around 5. And then the back tires wouldn't stand a chance. I live across the street from the police academy and they can find me lol
 
Oh so you have the big valve heads already? Well notch away and run the piss outta them. LOL
 
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