590 cam is gone and a comp XR286 roller goes in with Howards lifters and cam advanced 4* as per degree and running K800 springs. Car is a DOG. Running out of ideas of why?
Comp test 190-195, leak down 4-8%

Gonna need a little more info on exactly how it runs different than before.

Isnt that roller a street grind and way smaller than the 590 you took out?
Think the roller is on a 110, the 590 is on a 106. Different animals for sure.

The 590 i believe is 271 degrees at .050,
Much more duration and overlap. It is bound
To hurt power a bunch if the combo worked well with the 590.

If that’s the 286 solid roller that is not nearly enough spring. I ran 11.00@122 with that cam in a all steel duster with a 408- 10.5, and indybroks. Only 3k converter and 4.10s. That was through full exhaust and @3350 race weight.

What is the performance difference? What are the track times by comparison, or is this by the butt meter? Two very different cams for sure.

The roller looks much smaller in duration 23' less on the intake and 17' on the exhaust side, a little less lift and ground on a 110 instead of the 104.

Noticed on a history search that FlyFish ran this cam in a 408 Barracuda and had good results. I thought my converter was going as the car slowed each pass by .020
Changed the converter and rechecked the cam degree and advanced it 4* to have the 110.
Last year it ran 11.00@120 with wore out slicks and this year with new slicks was 11.36@118 11.49@117 then the next day was 11.63@115 11.87@112
I'm looking at pulling the motor and put it on a engine dyno and see WTH is going on

I would be looking at the cam going flat.. unless
you have a bad bearing or so

Cam is good as I just did the advance of 4* on it and took it to the track. Flat tappet cams yes I'd be at that right away but this change to a roller was to keep from ever going through that again.

What’s the motor combo?

That cam is 106 ICL, so now you have it @ 102 ? , what ICL is the cam installed ? you said is was at 110 in one of your post,, 110 is the LSA

Looking at those et’s, I’d be cutting the oil filter open for a look see.
Leak down all the cyls, etc.

If you don’t find anything in the motor, it’s probably the converter.

I'm surprised after reading the on going loss of performance that the rods aren't in the pan or some similar catrstophy hasn't struck. Time for a total disection to see whats going on.

I ran the .590 and loved it! It was faster than the Crane .625 solid roller it replaced. I've read multiple posts about the .590 and it's dated technology. However, I've also read a few posts similar to yours about new cams that don't run as well. I think the .590 purple shaft and the .650 comp are tried and true combinations. Good luck buddy!

The 590 cam works really well with the old cast iron heads but might not be such a good choice with something newer like Trick Flow heads. All depends on the combo. No idea on the OP's problem since I don't see enough details to even hazard a guess. Could be anything.

Looking at it from another perspective, if the 590 cam was correct for the motor/car combo, then the XR286R really would really be “too small” to be optimum.

Looking at the OP’s sig says a best of 10.76, I assume that’s the old cam.
Then reports of 11.00 with bald slicks and running the much smaller and milder street roller cam...... which to me bodes well for the XR286R.

And, that’s not even taking into account that it appears “something” in the motor/car is going away.

The .590 cam ran well in my 440 with MCH ported edelbrocks.

Yes, that cam worked unexpectedly well with my 410 combo years ago. Had a best of 10.5 @126mph, but usually ran in the 10.7's.

Sounds like you have other issues unrelated to the cam with it losing mph on every pass...not good. Check the trans, see if you are burning it up (smell the fluid, see if it stinks).

My 408 combo is
Scat forged stroker kit, KB744 pistons,Scat forged I beam rods and forged crank
Eddy RPM heads ported and no flow numbers with K800 springs and 1.6 ratio PRW roller rockers
Comp XR286R cam with Howards lifters (no need for oiling mods)
Super Victor Intake and Holley Ultra 850hp
TTI headers
MSD digital 6 and locked dizzy
904 trans,low gear, 4800 J&K converter
4.30 gear with 9" Hoosiers
3420# with driver

When I first built this motor with the 590 cam and had the engine on the dyno it pulled 537hp 540 tq with 750hp carb and TTI headers
We tried a 830hp carb and 1 7/8 headers and it pulled 550/550
The more I think about it the more I think the issue may be in the trans?

Okay, so what was the motivation for the cam change?

Those cams are quite a bit different than each other.

Like I said earlier....... cut the oil filter open and see what’s inside.
As much as your car slowed down, if it’s engine related...... it should show up in the filter.

I assume you checked the basic stuff...... timing hasn’t moved.....still getting full throttle, etc.

I’d do a compression and leak down test as well, and if it all looks good..... time to pull the trans pan.

Dont forget to check battery and alt.
Bad battery can kill ET
I found that out a few years years back