I'll try and make this short and get to the point. I recently purchased a pair of HP420 engines that were supposed to be fresh rebuilds with only around 10-15 hours on them. After I brought them home I started tearing down the first engine to check things out and I discovered that one of the cam lobes was wiped. It was the factory HP420 cam as expected so after looking over the rest of the engine real good I installed new cam and lifters and re-assembled the engine.

Fast forward to today as I was tearing down the second engine I discovered it had a completely different cam installed. similar specs but definitely different. So here comes the question. Which cam will be better or does it not matter much since the spec's are so similar? Cam & engine specs are below. I would love to upgrade both to roller setups but unfortunately that just isn't in the budget at the moment. Just need to decide which cam will be best and swap the other over to match.

Cam #1 Crane 132561 (factory 420 cam)
Duration at 050 inch Lift:228 int./236 exh.
Intake/Exhaust Lift - .530/.551
Advertised Duration:298 int./306 exh.
RPM range - 1800-5800

Cam #2 - Comp XM270H
Duration at 050 inch Lift:226 int./236 exh.
Intake/Exhaust Lift -.544/.547
Advertised Duration: - 270 int./ 286 exh
RPM Range - 1600-5800

Engine Specs:
454 .060 over
9.3:1 compression
GM Rectangle port Heads - 2.19 valves
Forged bottom ends
Single plane intake
EMI Manifolds w/ long stainless risers (water enters about 6" from the transom

The Crane has a 114lsa vs the 112lsa of the Comp Cam. I barely know the difference between a cam button and belly button, but that’s the direction that I’d lean in.

Crane $231
Comp $154... sold, sold, sold!
I also like Comp cams.

I love cam threads, never can have too many.

Which motor rpm’s higher ?
I’ll put $20 on the Comp Cams, but only $20.Lolol. We can’t see the .100” and .200” lobe lift duration #’s so, that aside, The 112 LSAshould accelerate a smidge better.

Thats the way I was leaning as well.

I haven't ran the engines yet so no idea. I'm sure the engine with the comp ran better though since it had all 16 lobes being functional haha

Now on to the next hurdle. Apparently one of the heads is a gen6 502 (casting 12562934) and the other an 088. All kinds of conflicting info on running newer heads on older blocks. Looking at the water passages everything seems to line up fine..

I’ve never learned more about engines than cam threads. Bring it on.

My opinion, if they measured the seat timing the same way, the Comp cam would have a better idle and a little more bottom end torque.

They don’t.
comp measures seat at .004” like most cam companies. Comp at .006”, so Comp will always appear to have shorter seat.

If you do some digging here, i have provided many crane hr’s with both .004” and .006”. This will give a good idea on the difference.

can't believe the 3/4 race cam was not on that list,,it will make hhhhhuuuuggggeeee power.