slickfx3

lift or ramp rates?
my xfi 280 comp cam on my AFR 195 street eliminators, may have worn out my 8019 upgraded springs, i have 17,000 street miles on them, should they last longer?

what is the remedy, instead of buying new springs? they are still good for a smaller cam right?

smaller cam?

rhoads lifters?

or should I put a rev kit in there all call it a day, and then do I need to frequently replace those or the valve springs?

http://www.summitracing.com/parts/CCA-08-305-8/

1.5 roller rockers? I have 1.6 crane golds now.

don't drive it past 5,000 rpm, what? please comment....

AlkyIROC

Somewhat but neither really. Valve float is from weak spring pressures but really aggressive cam grinds can easier hammer out the springs.

The cam lobe lifts the lifter and pushrod to push the rocker arm which opens the valve. As the lifter goes over the peak of the cam lobe, the valve spring closes the valve and pushes everything back down. At high rpm, this happens very fast.

Valve float is when the cam lobe allows the valve to slam closed against the seat so hard that it bounces on the seat which bleeds off cylinder pressure. Valve springs matched to the camshaft provide enough pressure that when the valve is slammed closed, it stays closed.

You can have valve float with a stock cam if the valve springs are worn out. Very aggressive camshafts need higher spring pressures with double or even triple springs. I use triple springs in my engine that have around 300 pounds of pressure on the seat and over 800 pounds when open. Basic factory SBC valve springs have around 80 pounds on the seat and a couple of hundred open.

Valve float is normally detected at higher rpms. An engine may run fine at lower rpms but can hit a wall above 3000, 5000 etc where it just won't make any more rpm. As those valves are bouncing off the seats and the pressure is bleeding off, the engine just won't make any more power.

Install the proper springs recommended for the camshaft and set them up for the recommended install height. Check clearances to make sure the heads can handle them and you shouldn't get any valve float.

The only way to know if your springs are bad is to test their pressures. Any good machine shop can do that if you don't have the proper tools. Once they're worn out, they're scrap metal.

slickfx3

afr says if they test XXX, they could still be good for a smaller cam, I'm trying to minimize expenses to tackle this issue, since I can not do this at my complex where I live, nor do I have the tools, or the guts to do it.

I want the next set up to go 75 k mile before I have to mess with it again. going back to my list of remedies, are any of them viable?

btw my wall i think is around 4600 rpm, my stock tach on the atari dash vette i don't know how accurate it is, i think it is way slow but...

lastly you say machine shop? you mean I should have them taken out and then to a machine shop? can my mechanic check 1 or 2? or 3 or them?

AlkyIROC

It's unlikely a machine shop will have an on engine tester. They normally put the springs into what looks like an arbor press that measures how much spring pressure there is at specific compressed heights.

If your springs were to have 120 pounds at 1.800 install height, they would set the press to 1.800 then quickly go through all the springs to see if the gauge is close to the 120 pound pressure. If they're weak on the seat pressure, they'll be weak on the open pressure also.

It's possible to have a few weak springs in an entire batch and just the weak ones need replacing.

If in doubt, replace them all and see if that "wall" goes away. If it does then you know the springs were worn out. If it doesn't then you have a set of spare springs.

I hate seeing heads sold fully assembled. The springs will rarely be the proper pressures for the cam you want to use. Even my triple springs are slightly low. I think I need to upgrade the springs to something with about 50 more pounds on the seat but I'll see how they work first with the new camshaft.

slickfx3

they were NOT off the shelves springs, afr heads talked me into the 8019's, supposedly they are good for the 280 xfi, I have been warned by my shop that even not running the valve are kept opened and weaken the springs and their life span is 2 seasons, and it is around that....how about's I just go to 1.5 rocker, will that ease things up for the poor springs to do their thing at 6000 rpm?

AlkyIROC

Are you sure the 1.6 rockers didn't put them into spring bind?

Orr89RocZ

iTrader: (20)

Those springs should be more than enough spring for the XFI .570" lift. I had those springs to .613" with room to spare and they were shimmed up.

17K miles is a good number of miles, especially if you beat on the car. The lobes are pretty aggressive and they hammer on springs. 1.5 rockers will help some but you will give up alittle bit of power. Its not uncommon for springs to be worn out with an aggressive cam by 15-20K miles. I remember talking to a cam grinder for an LT1 setup and he said some of his more race grinds would need replacement springs after 7-8K miles of hard running!

To verify spring condition, you need to pop them off and test them in a spring tester to verify pressures. A mild cam may like 120lbs on the seat but XFI stuff should use 150+. I'd like to see closer to 160lbs on the seat, around 400 open.

If you want a cam that wont eat springs and last a long time, get a custom grind on a lazier lobe profile. You can try the old Comp Magnum lobes, fairly lazy if you use the non high lift versions. My cam used the high lift version and are still aggressive but offer better valvetrain stability.

slickfx3

I hammered on it the first 8 k miles, and eased off quite a bit.

some boys over at CF is using this and cams close to these, for strokers of all sizes...396, 4oh whatever...

http://www.summitracing.com/parts/CCA-08-305-8/

i like it, when you say lazier, you mean ramp rates not so much lift right?

after having the car for 24 months with that engine configuration and the price of gas the way it is, my 11 mpg is getting old for my daily driver., this may be my chance to get a teenie cam to up the mileage. since I will loose power going down, should I try the 1.5 rollers first or go straight to a smaller cam.

how small can I go,if I decide to go that route? otoh, i would like to avoid such a big hassle/job, but I can't eat springs either, i need to go 75k miles....I need to stop fooling with the car, and concentrate on business.

how ridicules would this be or even smaller?

210/220

http://www.compcams.com/Company/CC/c...?csid=212&sb=2

will my 10.7 compression have a problem with to high dynamic compression with a smaller cam?

how about AFR's rev kit? any good? will it stop having to change springs?

or how about rhoads lifters? put them in and forget about it...

Orr89RocZ

iTrader: (20)

You only getting 11 mpg? Seems low. I'd figured mid teens easily and closer to 18-20mpg highway for sure.

Lazier lobe as in rate of lift and amount of lift. High lift really does hammer springs but mid 500's isnt really that high. Its just the rate of valve opening and closing that also hammer the springs. Aggressive cam lobes have that sewing machine sound while a mild lobe will be smoother and quieter.

I wouldnt go any smaller than 220's deg on that setup. I think the cam you have now is good it just needs fresh springs every once in awhile. To avoid that try a custom grind around similar duration but on a lower lift cam lobe and alittle softer opening/closing rate. Will be down on power but last longer

slickfx3

11-12 mpg if i baby it, been like that forever, wide band reads very nice...it does sound like a sewing machine, i thought it was the roller rockers.

1.5 rockers would slow down the rate wouldn't it?

yeah some people still have the LPE 219/219 in something like mine and still goes good.

i was told the cam change will not affect things too much, loose perhaps ~35 hp. for a ~220 cam.

can you recommend a spring that will fit the heads? or is the 8019 optimal?

Orr89RocZ

iTrader: (20)

8019 springs fit well. they should have good valve life. If you are concerned with the AFR spring (as i dont know where they get the spring) then go with a similar spec'd PAC spring. They have an identical one, same spring pressures. Thats what i'd use.

1.5's would help slow the rate down abit since its not lifting the valve as much but a good 220's cam on a softer lobe will be a better choice. LPE is a good example. Their zz409 aint bad either.

305sbc

iTrader: (3)

What lifters are you running in your vette?

You may find that you have a lifter collapsing or defective, or that you have just one damaged spring.
I would run through a thorough visual inspection of your valvetrain, then test the cylinders for leakage that could indicate a bent valve. It only takes one defective part to drop your RPM limit.

slickfx3

http://www.jegs.com/i/Comp-Cams/249/850-16/10002/-1

now you are scaring me, the car runs perfect in every way, up until the higher rpm's,

idle, cruise, cold start, wide band, acceleration, taking to the shop tomorrow, the shop want's to test drive it, and didn't go with my hunch, he wants to go with his apparently...

Orr89RocZ

iTrader: (20)

Put it on a dyno and watch the power output at higher rpms. it will flatline or be wavy. In a superram 383 however, its likely that the power will peak in the 5800 range anyway and just hold power till 6200. Thats not really high rpm but still can have float issues.

If the shop can pull a spring and test it with a spring tester, that will give an idea of whats going on.