I have a 77 impala coupe.350 rebuilt with 1.52 roller rockers.Flamethrower distributor and flowmaster exhaust.I recently added the full rollers.Stock is 1.50.I was wondering would the 1.52 cause any problems when time to smog.The flamethrower hei distributor is sappose to help with emissions too.Engine guru's chime in.Last smog with stock distributor and stock rockers passed with room to spare.Thanks.  

I'll run through the math to show how negligible that difference is...

Let's say our cam card reads .500" gross lift with a 1.5:1 rocker ratio. This means that the lifter rises roughly .333" from the base circle at maximum lift (.500"/1.5). Another term for this value is lobe lift, so now take the lobe lift (.333") and multiply it by the new rocker ratio (1.52) and we have .5067 lift (with a little rounding). So, the net increase in lift is approximately 7 thousandths of an inch. Which isn't a lot!

Coincidentally, this is very near the value of which most hydraulic lifters are said to collapse during every valve cycle. For example, Comp Cams measures their advertised duration when the lifter has risen .006" from the base circle.

So, it won't make any difference to your smog testing, it actually gives some peace of mind that the valve is receiving all of the lift that is stated on the cam card.

Improving the spark will most likely improve emission testing. If there was a significant improvement in the spark quality it will improve the burn characteristics and there will be less unburnt fuel leftover, reducing hydrocarbon (HC) emissions. It may increase NOx emissions, but this difference should be slight.  

Right on!!!!Seems you know whats the deal with cams/ rockers.I would truly enjoy the sound of a slight lope.You know of any cams that has lope for sbc that will pass smog?I checked out the voodoo.But no info if it will pass calif smog.  

Lope is something that isn't measured very easily. It's not very scientific and I guess from as much as I hear about it, it's pretty sexy to all the teenagers cruising the town streets...

I can't determine what you want with a lope, all I can do is explain what it is and how it's a problem with your smog-testing limitations...

Lope is a low-speed misfire of the engine caused by excessive overlap and valve duration for the available gas velocities the engine is dealing with. Since overlap is a condition where the valves are both open at the same time a lot of charge coming in through the intake tract can either find its way out the exhaust valve or by reversing up the intake tract since exhaust scavenging at the low engine speeds we're discussing is non-existant. Exhaust gases can make the same trip and re-enter the combustion chamber at low speeds contaminating the burn and causing the misfire associated with 'lopiness.'

The problem is that if an engine is mis-firing there is a ton of unburned fuel that is going to increase HC emissions greatly, since the combustion is so poor CO emissions will most likely go up as well. If the engine is past the rpm's where the misfire isn't as noticeable the added camshaft duration will contribute to adding in more charge to the cylinders than necessary at these speeds and still increasing emissions.

I can't decide how much lope you want and I can't say how much overlap will cause a given amount of lope, all I can say if you get excessive with camshaft duration you won't pass your smog test.  

116+ lobe seperation is very common with the 3rd gen LS engines,they have evolved to having roller cams with .500" lift 200 intake duration and wide lobe spread all because 15 and 12 degree high flow heads.Less cam- high flow heads is slowly changing the trend for street rides.You might wonder why I'm drifting off the subject, it just felt right.   WIEDER  

Slightly off-topic but still very applicable...

Wide lobe separation angles can be used in old GenI engines, it will definitely cost more peak power than in the case of GenIII but it will still do its job. That job being increasing manifold vacuum, decreasing overlap, and improving emissions.  

Thanks on the info guys.I do appreciate the help.Things got crossed up and had to change my user name.Seems that I have done all I can do with this car and pass smog.Might just lean towards a little juice.But I must say.The full roller rockers made a very noticeable diff in performance.  

Hopefully, your foot can't tell the difference in 5-6 horsepower! If it can your foot could be an effective weatherman....

Maybe you had a weak coil and the ignition system made a more significant difference than usual.  

Pedal responce has improved.Engine revs smoother.Through out all rpm's.A few more r's up top.(Performance).I can tell the diff in performance.I dont think you would need a dyno to notice these changes from stock rockers to full rollers.the distr was on before the rockers.Did not notice much diff at all until the full rollers were mounted.  

Why don't you tell me how big of gain you think those roller rockers created.  

I see where this is going.I did not join this site to bump heads with other users.I posted what I noticed with the rockers.All in all I am happy I went full rollers.  

I'm just trying to make a point...

Roller rockers are not per dollar the best modification to improve power, don't believe what market tries to make you believe! At 4500-5000 rpm  valvetrain friction is really not a drastic problem and if you didn't go to a 1.6-1.65:1 rocker ratio you did not significantly affect the lift to the valve.

Headers and a cam & lifters would cost about the same as a set of pretty aluminum "full roller" rockers and would gain 30-35 peak horsepower, whereas I would guess the rockers only pick up 5-6 at the relatively low-speeds your engine is running at. Besides, if you didn't get rid of the stock valve springs and pushrods the valvetrain system is not very rigid and not very efficient in its current state so the addition of fancy rockers would be limited by other inefficiencies 'inline' with them.

We don't need to bicker unless you continue to give me ammunition...  

Wysco 1.52 3/8 stud full rollers.$125.00 to my door.I was not trying to get more lift.My goal was to free up some power by less friction.Give you ammunition?SWEET!!!!!  

Yeah, there's a ton of friction in those steel rockers! I bet you picked up 50 horsepower just by reducing friction, even at 2,000 RPM!

That's enough of this, go tell you stories to someone dumb enough to believe them.

PS: Those are some dirt-cheap roller rockers, they must be the highest-quality Chinese pieces available.  

dude you have a problem and your funny too..they may be cheap but they work and has not failed as of yet.When and if they do.no problem for me to replace with a better product.I have a life and no need to tell lies to anyone.I have no need to type or write stories.I"ts been a while sense I have met a new ass hole know it all.I guess it was time.Dude people like you should not have access to a pc.Big mouth Billy Bad Ass behind your key board.You did not have to even reply to my thread.Fuckin Jerk.