OnyxCobra

Take a look at the Steeda #18 cam, .480 lift (.510 with 1.7s) and 220/226 duration @ .050

Maxwelhse

The more I look at the #18 with some good 1.7 ratio rockers the more I like the setup. Basically the first cam listed with a ton more duration. With 3:73s and 6000 RPM powerband I think it would work pretty well. Think the stock lifters would live for long at 6k (street/strip use)?

my77stang

stock lifters are fine, cause its not like your gonna be holding em @ 6k while going around a track.

aode08

its hard to get to 6k rpms and stay there for long .

I find camshafts with an operating range of 1800-2000 starting, with 5,000-5500 rpm ending and valve float at 6,200 rpm is the way to go for 302 displacement factor.

Any duration over 224 with those heads will dissapoint you.

Any lift exceeding .550 int/exh factoring in .030 lift increase with 1.7 rollers will hit the pistons. Even if you are lucky , the first time a lifter acts up, smack.

Just going from stock to a trickflow cam , I noticed my car kinda bog, but when operating range kicks in,

Maxwelhse

Thanks, aode06... That's exactly the kind of info I was looking for. Even with your recommendations, it sounds like the #18 isn't too far out of wack. It it were installed a few degrees advanced it would be just about exactly what you're talking about.

But... By the time you consider advancing the cam and the need for 1.7 rockers, a custom grind isn't sounding so overkill.

aode08

to compensate for my lag at the bottom, I bumped my timing up, and now you have the general idea, and will be ok with whatever.

But if you had some aftermarket heads (maybe later or future HCI etc), that 302 would be get sick , 270-280 rwhp , if you hold a feeler guage, of .010 and one of .030 in your hand , you will say, (these look just alike).

thats how much precision you are dealing with here

Joel5.0

Could someone please explain how total valve lift could cause PtV problems?....... lift increase due to rocker ratio increase is not a fixed value....between 1.6 and 1.7 rockers, there's a 6.25% increase of the lift figure with 1.6s ...... and why anything over 224° with GT40p heads would be a disappointment?

my77stang

i'll chime in and say with a .500/.500 lift and 300/300 advertised duration hyd. flat tappet cam i wasnt dissapointed with 351 heads, and it would snap up to 7k and wanna go faster. yeah, it wouldnt melt the tires as easily as some of the smaller cams - but it worked out well because i could romp on it from a stop and have little to no wheel spin, but it only needed to get to about 1500 before it started waking up and by 2k it was really starting to pull. if i was cruising at 2500 or 3000 and nailed the gas it would just about break your neck.

long duration can compensate for lower lift, and in the end you get something less radical with gentler ramp rates which equals less wear on the cam/lifters and a higher rpm ceiling

aode08

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Could someone please explain how total valve lift could cause PtV problems?....... lift increase due to rocker ratio increase is not a fixed value....between 1.6 and 1.7 rockers, there's a 6.25% increase of the lift figure with 1.6s ...... and why anything over 224° with GT40p heads would be a disappointment?
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his vlave springs, would have to support past .550 of a lift without binding, the ones on there now may even have to be changed if not already.

2nd those heads can only pull so much air and staying open longer from lift or duration, streetabilty and power loss will come into play

Joel5.0

Valve springs is one item he needs to match to the cam anyway........not due to lift and coil bind limitations, but with the correct spring rate for the cam. I was referring to the valve lift and PtV relation........

Here's another area to think about......the heads are limited in flow, but matching peak numbers between camshaft and heads = leaving power on the table...IMHO. Why?.......you have heads that are OK to .500", if you "match" them with a .500" lift cam......for how long will those heads flow at its peak?.....or, for how long will that valve stay open at its peak value with the engine turning 5500 rpms?....wouldn't you want that peak flow earlier, and for a longer period of time to better fill those cylinders?.......just a thought.