cam timing mod on 96+

[dohcfiend]

on the 96+ has ne1 tried the 13* mod on these, or will it cause problems? being how it is an interference motor.

[ez112]

nice post. This is something I would consider if it's safe to do.

I heard from a source that it's a no no though....

[dykz34]

The timing in stock form is different. Compare the #s on the site here.

I would you use the 91-95 cams if I were you--no one has the tuning done for the 96 cams.

[dohcfiend]

fair enough, i won't mess wit them then.

[grandprixgtp_91]

i just helped someone out that blew the timing belt on there 96 GTP and they didnt bend the valves. i told them how to change the belt and it worked good. no bent valves.

Jake

[ez112]

I guess you can consider that person you helped pretty lucky. Though this isn't the first time I've heard of this.

People (including myself) are just a little cautious of doing such a mod, knowing what the consequences can be. Especially with this particular engine. Unless it's written in stone that your eingine will be ok, don't be surprised if this isn't attempted any time soon.

[SappySE107]

Just adjust for the difference in the cam timing stock and go from there. The valve reliefs are still cut in 96 heads and I haven't seen any GM specs saying 96 are interference. I have just heard it being said....along with other bullshit info I have read. Not saying its not true but its not verified and its not tested. From measuring the depth of the valve vs the deck, the 96 actually sit further into the head (not much, just some) and the valve reliefs in the piston are deeper in the 96 pistons, its just the dome which is not in the path of the valve. From this, I am of the opinion that they are not interference, its only on worn engines at high RPM that go bad...or modified engines with decked heads or different type pistons (obviously). As far as just testing cam timing goes, its not gonna hit the valves under normal operating conditions unless you go really far off. I just found out today someone tried 24 degrees retarded on the exhaust and 24 advanced on the intake...and although it didnt run, it also didnt bend or hit anything. Thats 91-95.

[pontiacjeff]

Wasn't the Smith Fiero a 96 engine? He ran -18 ex./-8int.

[SappySE107]

Yeah, but it didnt have most of the runner length either.