ZZ502 110 LSA in 454 Reversion issues?
 

Found a low time ZZ502 take-oit with lifters.

It fits right in the speet spot for my cam needs, but has the 110LSA.

I have Stainless Marine exhaust to thru-hull 3" risers.

Gen VI 454 with worked over Peanut Port heads or Gen VI Vortec heads...have not made a firm decision. Mostly comes down to if my 0.095" forged domes will fit the Vortec chamber fin.

The ZZ502 cam swap was very popular...what has the long term experience been for reversion?

I don't want to run dry..and be louder than comfortable for the family.

What IS The exh Valve closing point with factory icl?

In My opinnion IT might Be fine If you advance IT 6 degrees, 104icl. Exhaust valve closing IS then Similar compared to Crane 731.
https://cimg6.ibsrv.net/gimg/www.off...4a363ff077.jpg

Crane 731
https://cimg4.ibsrv.net/gimg/www.off...5c0ebb541d.jpg

I ran a ZZ502 cam for 10 years and over 600 hours in a Gen 6 454 with rectangle heads, domed 9.32:1 pistons, Mag EFI intake, and Gil headers. Never a problem for me. It made for great motor. I recall the new owner talking about supercharging it too.

What's a good way to check and see if you do have reversion?

couple of ways,,listen for a skip at idle,,listen for a skipping getting on plane.run engine in neutral up to about 15-1800rpm shut it down,look in exhaust pipe,look up by the joint,separate the pipes,or pull the back spark plugs and look for water drop lets.and the classic,,a ton of milky oil and its really bad.

Good question.

Probably pulling a riser off and using an inspection camera...have a look in the exh ports etc.

Cold exh manifolds can condense inside in warmer humid weather.

ZZ502 cam exh valve vlose at 7° ATDC.

Piston is 0.020" down the bore.

ZZ502 cam 2° adv @ 5° ATDC... piston is 0.010" down.

731 cam has far better lift than the ZZ502, but I don't need it for the 450hp goal...and easier springs on the valvetrain.

My plan was to go custom cam from Jones. But this this cam came available...and maybe worth just running it.

Older GM lifters with low time are more reliable than the 'new' stock.

Just advance IT 6dg and Run it. What kind of exhaust? GM lifters Are good with mild springs, 150/400lbs. i used gm lifters on My Old Combo, 230/236 @050 cam