highway21

ok that makes sense....so does duration hav anything to do with ptv isues...an u hav a 290 duration cam with .600 lift intake and exhaust and hav no problems?

OnyxCobra

I'd drop the $210 on the Steeda 19 and use the summit gift cards to buy more supporting mods. It's not really special but it's nice because the lift is low so you can run it with 1.7 rockers with no PTV clearance problems and also has pretty good duration (220/226 @ 050).

Also that cam example of high lift with no PTV issues, I think that's more towards a custom grind and cam degreeing than a benchmark, usually cams with lift as high as the one you're looking at with 1.7 rockers will give you PTV clearance issues, I think usually the limit is .530 lift but you should always clay the pistons to find out for sure.

Mustangkiler

+1 on the steeda, only option id throw in a 94-95, i got one in mine, and only cam i ever heard of that wont give you any problems after the install since its has a 115 angle on it which gives a lot more vaccuum at idle which our computers need.

tooslow5.0

wow, thanks for all the info guys! so the steeda 19 is a great cam, which should make it even greater with 1.7s. what kind of gains could one expect on an otherwise stock cobra engine, just for example?

Joel5.0

Negative........ could you explain how a big lift cam (BTW....full lift happens anywhere 100°+ after or from TDC, or when the piston is > 1.7" AWAY from the head) could cause PtV problems?......

Check my sig...... X-303 with 1.72 rockers = .583" lift...... been running it for 15 yrs.... no problems whatsoever. I've also installed (and checked/clayed) other X303, Stg1, Stg2, Schneider, Crane, and other cam/rockers setups with .542"+ lift numbers...... and no piston notching was required.

Again.....total lift (which happens when the piston is >1.7" away from the deck, or head) has nothing to do with possible PtV problems...... it's during the overlap cycle that PtV needs to be checked for...... always, and regardless of my, or anybody else's setup experience. All engines are different........ just a thought.

OnyxCobra

I was just going by a general rule of thumb, none of that was my idea. AFR says with stock pistons anything over .530 lift is pushing it and could cause PTV issues, I didn't just dream that up one night. Since all cams are different then it's quite possible that some will work and some wont with similar specs. Pistons are notched because the valves and pistons are both near eachother at the same time, there is not a lot of space to work with.

What heads are you running? What are the valve sizes?

dimebag

joel good info

now... i did know that but also THOUGHT(well <-- theres the problem, i thought) that total lift had SOMETHING to do with it... i realize its not going to be at .5xx at TDC, well i sure hope to hell its not, lol... but did think that they were related

whenever looking at cams( and im in NO WAY good w. this whole cam picking deal) i would look at lift numbers, then duration to get an idea if it would smack or not... grant you if i had the cam card in front of me(like on comps site) ill pay some attention to when valves open/close deg wise, and come up w. an idea of if its safe or not..

none the less, thanks for the info, helped me some, and i know it helped others alot...

thanks forbringin some "sbf tech" over here!! i go on that site often, but most of these guys dont

tooslow5.0

im running genuine cobra gt40s that were milled only enough for cleanup, maybe .010". the valve are stock size, but the heads are going backin for a three angle job and mild port work. is the steeda #19 smog legal in cali?

Joel5.0

That's the point....... how can you use a general rule for PtV using a specification that has no relation to the possibility? When the piston is near TDC during the overlap ..... the valves are off of their seats anywhere from .016" to .167", but this is dependent on the exhaust closing + intake opening events at the end of the exhaust stroke. This is when PtV problems could occur......