cam timing speculation

[dohcfiend]

well i will begin my quest for either another longblock or shortblock. and since i have to set the timing, i will probably do an ex cam retard.

but i don't want to be as aggressive as the 6.5 degree retard. can some of the cam guru's chime in and lmk what u guys think of maybe a 3.5 or 4 degree retard instead?

i may go as high as 5 if u guys think the benefits will be worth it.

[SappySE107]

RE: cam timing speculation

I wouldn't even bother. Going below 10 (5) makes very little difference in performance. I would try a variation of 13 degrees difference and do intake advancing and less exhaust retard if you don't want to do it all on the exhaust.

[dohcfiend]

RE: cam timing speculation

hmm perhaps 5 retard on exhaust and 1-2 advance on intake? will intake advance hurt peak power? also will changes need to be made to the spark table?

EDIT: will advancing intake help vacuum?

[SappySE107]

RE: cam timing speculation

Who knows what the best timing for your application is. All i can say is try something and see how it works. I will be trying 6 retard on exhaust and 7 advanced on the intake (crank degrees). Advancing the intake will lower the powerband. Vacuum...i didnt have any issues with just exhaust so i dunno if advancing the intake will help vacuum any. Spark advance, im sure you could play with it some but I haven't found a need to drastically change anything spark wise on my car.

[dohcfiend]

RE: cam timing speculation

how much would 2-4 crank degrees of intake advance would lower the powerband if at all? just off the top of your head? also lmk what the ass dyno says on the 6/7 split u are doing.

i see myself doing 10e retard and 2-4i advance split.
lastly, what about a 10e retard and 2i retard? thoughts?

[SappySE107]

RE: cam timing speculation

I couldn't tell you what the powerband would be. Until someone gets a dyno of before and after, no one could tell you this info.

[dohcfiend]

RE: cam timing speculation

hey, just looked at the timing tool. very nice. i may have to get one.

while i am on the subject, this just popped into my mind. i have to go check and see if it is actually applicable but has any1 ever thought of modifying the rear valve cover so you could say remove the end piece to get to the cams without having to pull the intake to remove the entire valve cover? perhaps a 2 piece design?

it might not even be possible id have to check the engine to see if i could actually get to the cams with the intake on and the valve cover off. i am thinking it may be a possibility on the 96 intakes but maybe not the 91-95 b/c of the egr mount being right there. i will check later and see.

if it can clear, i think it could be made somewhat easliy. this is just what i came up with in about 5 minutes. and it would dramatically speed tuning time at the dyno.

[your_I.D.]

Cant get to it with intake on.

[dohcfiend]

oh well. i read the 96-97 are already retarded. so what are the specs compared to the 91-95?

[your_I.D.]

oh well. i read the 96-97 are already retarded. so what are the specs compared to the 91-95?

News to me. Did someone degree both cams and compare? Could you PM me that link. thx

[SappySE107]

It may be only 97 that is retarded exh and adv intake compared to 91-95(96). I think the info we have is from 91 and 97, though I don't remember if someone deleted the 91 or 97 parts off this site for some reason.

[dohcfiend]

that's kewl. b/c the longblock i have coming is a 97. give me a guestimation then on how much ex retard and in advance. if the ex is already 3 degrees retarded i will only add 7 to it then?

[your_I.D.]

Is cam retard casted in the cam itself? Or is it set by cam timing flat being retarded like we do.

[SappySE107]

The cam itself is retarded when you have the flat facing the same position as the older cams.

[dohcfiend]

very interesting. are both of them retarded or just the exhaust cam?