Will this bore clean up, magnum head content too.

-
ok, anyone know of an LA cam that has .461/.456 lift int/exh

edit: remeasured and i think this is more accurate. still not seeing many cams with more lift on the int vs. the exh...
 
Last edited:
cookietruck said:
ok, anyone know of an LA cam that has .464/.447 lift Int/Exh ???
that's a weird one. maybe i should measure a few more lobes. I measured off the lobes through the hole right above the cam.

I found an Elgin cam, 936PK that .444/.466 lifts but the Int and Exh are reversed to what I measured. I double checked the lobes i measured.
Click to expand...

Are you 100% SURE you got the intake and exhaust lobes oriented right? I've made that mistake a few times myself. It's easy to do. I cannot think of a single flat tappet that's a reverse grind off the shelf. That would be very strange. Did you try another pair of lobes to duplicate it?
 
RustyRatRod said:
Are you 100% SURE you got the intake and exhaust lobes oriented right? I've made that mistake a few times myself. It's easy to do. I cannot think of a single flat tappet that's a reverse grind off the shelf. That would be very strange. Did you try another pair of lobes to duplicate it?
Click to expand...

yeah i went and dbl checked. i think i got a more accurate measurement this time. still have more lift on the intake...
The cam has orange and pink paint dabs on the rear (still in the car).

Lobe lift:
.3075/.304
multiplying by 1.5 to get .461/.456

this time i measured cyl 3., for sure got the int and exh right this time.
I know there should be some taper on the cam but only .002 or something like that right?
 
cookietruck said:
yeah i went and dbl checked. i think i got a more accurate measurement this time. still have more lift on the intake...
The cam has orange and pink paint dabs on the rear (still in the car).

Lobe lift:
.3075/.304
multiplying by 1.5 to get .461/.456

this time i measured cyl 3., for sure got the int and exh right this time.
I know there should be some taper on the cam but only .002 or something like that right?
Click to expand...

Yup, generally, .002"-.003" is what's used across the board, I believe.
 
cookietruck said:
OH!!! i got an exh lobe that was .309"
I think the cam is measuring all over coz it's worn a bit and measuring a bit different. My measurements were repeating though.

pistons are .006" below deck.
Click to expand...

Time for another camshaft.
 
cookietruck said:
I bet this is the cam, a 268 magnum..
DODGE COMP Cams 20-309-4 COMP Cams Magnum Muscle Camshafts | Summit Racing
Click to expand...

Finally pulled the motor and tearing into it.
That IS the cam.
I got the degree wheel out. Its a comp high energy intake lobe and magnum exhaust lobe.

Cam looks ok but I think I’m gonna send it to bullet to get a hyd .875 lobe a size or two larger and maybe get the lsa to 111.

Left the motor in teh garage with the heads off for a few years so def going to have to flex hone all the cylinders.

Have a virgin bore block and mahle pistons but I hate to just trash this one.

IMG_4468.jpeg
 
Sheeeyit. Heard from bullet.
Cam is 215.5 at .050
.303 lobe lift.

Went to emails from wayyyy back with previous owner. Summit 454 lift cam.

Its the summit 1789.

So its a 272 cam…if i grind it to a 280 ultradyne lobe.
Seat duration is about the same but duration at .050 is 230 instead of 215.

Get roughly the same operating range?
 
Oh that wasn’t too bad. Std bearings on both mains and rods, i can get some king stdx to add .001 clearance. Will just use some plastigauge to get a rough idea where its at to make sure that’s a good move.

IMG_4503.jpeg
 
Here is what the bores looked like after sitting in the garage a few years with heads off. The surface rust from sitting cleaned up from the rings just rotating trying to figure out timing events.

IMG_4528.png


And 30 mins with a flex hone and some atf mixed with mineral spirits.

IMG_4527.jpeg
 
The bad bore isn’t perfect, what will this be? 5% less pressure? I think this cylinder pumped 180psi on a compression test. The others 185-190.

A little pitting.

IMG_4522.jpeg


And the worst, circled in green some more pitting from a weeping gasket. You can. Feel it with a fingertip but whatever. Should be good for a hot rod right?

IMG_4524.jpeg
 
Think i’m gonna try to polish up these bores a bit with some wet/dry sandpaper on a three prong hone and a little water. Forget where i saw that but seems worth a shot. Rings seated just from degreeing the cam supposedly.
 
cookietruck said:
Think i’m gonna try to polish up these bores a bit with some wet/dry sandpaper on a three prong hone and a little water. Forget where i saw that but seems worth a shot. Rings seated just from degreeing the cam supposedly.
Click to expand...
That’s more likely to bell the bore than help anything. A proper rigid hone is the only thing that will correct geometry. Have you measured for diameter and bore taper with a proper bore gage?
 
You must log in or register to reply here.
-

Back
Top