Cam swap without pulling motor

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KB107's seems to be a popular choice to gain something in the realm of 9:1 on a stock 360. i've used them in the past and depending on previous work done and head CC (and head gasket) i've wound up with everything between 8.5~9.8

the thing is, you won't know unless you actually pull it down and measure. everything else is just a guess.

the only one i know that's out of the hole (off the top of my head) is one of the speed pros.

anyway, if the bore is good i don't see why you couldn't just run a hone and pop some fresh slugs in and call it soup.
 
Earlie A said:
If I used the Summit compression calculator correctly, CR is 7.63:1. 4.030 bore, 0.051 gasket, 9.1 cc dish, 0.106 in the hole, assuming a 71 cc chamber.

Now, what to do about it.
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Put pistons in it.
 
As much as I would like to pull the motor and put in better pistons, that’s just not an option right now. Too many other life priorities. I am going to use the Lunati Voodoo 258/265, 213/220, 0.454/0.475 112 LSA cam that I have sitting around.

Here’s my question. Does it make sense to use 1.6 rockers? I have a set of the Speedmasters from Black Friday. I know I want to keep the duration down because of the sub-8 compression ratio, but would the additional lift be beneficial? I think the Voodoo cams are fairly fast opening anyway.

Truck is 1979 D150 with 360, 727 trans and 3.55 gears, factory exhaust manifolds and iron heads. Heads are currently getting 1.88 valve job and some mild porting. Might do a Performer or an RPM intake.
 
If it's a hydraulic cam, just use stock rockers. Just pull the end plugs out of the shafts and clean them really good with solvent and a long brush. You can buy new plugs to replace the ones you remove. They will work fine on a cam that mild.
 
Is this a juice not worth the squeeze situation with the other valvetrain problems that 1.6 rockers can cause? Or more of an issue of the iron head flow? These nose over at 0.375". Huge guide bosses in these heads.
 
I don’t love fast rate Hyd cams used with higher RR in general…….. so for me, that’s reason enough.

That being said, that cam is short enough to where I could see the 1.6’s making a little more power.
But I still wouldn’t use them.

I’d apply whatever $$$ the 1.6 changeover would cost towards bumping up the CR(head milling, thinner gaskets, etc).
 
PRH said:
I’d apply whatever $$$ the 1.6 changeover would cost towards bumping up the CR(head milling, thinner gaskets, etc).
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this. this right here.

you've got bigger fish to fry than to be faffing about with rockers. that good money only spends once so throw it where you can maximize the return.
 
PRH said:
I don’t love fast rate Hyd cams used with higher RR in general..
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Even when the advertised duration is just 258?

The head milling and thin gasket might just happen. I think I can get that done quickly and get the truck back together. I just really can't drag this one out right now.
 
Earlie A said:
Changing cams in 1979 Dodge truck with 360 engine. Hoping I do not have to pull the motor. Radiator, water pump and all auxiliaries are removed or out of the way. Is draining the radiator and removing the water pump sufficient to get coolant level low enough to remove intake and heads, or do I need to drain the block as well?
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I would drain the block at the block drains to prevent as much coolant as possible from getting in the oil pan or on the floor.
 
I ended up not taking out the block drains just because I'm not as young as I once was. A wet/dry shop vac can suck most of the remaining coolant out. I got it down to a couple of inches below the deck.
 
Here's a few flow tests that show how an old turd can be polished. The butt dyno should feel the difference.

These heads are 1.88 valve smog heads and do not peak very high. A 1.88 valve 587 head (or a 1.88 J head) from the early seventies would be very similar down low but peak at 195 cfm at 0.500 lift. I think the guide boss is larger in the smog heads.

IMG_2993.jpg


IMG_2994.jpg
 
200 and a nice flat curve. Like you and PBR say - it's about the apex and the short turn on these Mopar heads. Almost there.

Pistons are in the hole 0.106. If I do get the heads surfaced, the quench dimension might be 0.150ish. Isn't that right in a danger zone of creating detonation? Or is the gain in compression (might be able to get to 9:1) worth having to possible adjust the timing?

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IMG_2995.jpg
 
I’d calculate how much milling would be required to get it to 9:1.
Personally, I wouldn’t go nuts with that.
I wouldn’t want to end up in a situation where I’m limited to what I can do with the timing curve because of the quench distance.

If you added a full point of CR, and as much shorter as that cam is……..it should be a big difference.

I forget, did you do a cranking pressure test before tearing it apart?

The one I revamped years ago that was 7.7:1 pumped barely over 100psi.
 
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