[N0DIH]

Anyone know if I can put 1.6 Rollers on my LT1 w/o changing springs?

Thanks!

 

[BCs71]

Anyone know if I can put 1.6 Rollers on my LT1 w/o changing springs?

Thanks!

I would NEVER consider any rocker change without swapping the valve springs on an LT1 engine. The stock springs are really crappy, these are the same springs on B-bodies (the iron-headed LT1) are are widely regarded as POS.

When the rockers are off, it's really easy to throw on springs (except for cylinder #8, which is sorta under the firewall and the spring compressor tool fits tightly). Basically if you bring the engine to TDC then you can remove the intake/exhaust springs for cyl#1. The valves will only drop a half inch before resting on top of the piston, and then you can install the new spring and insert the keepers.
Then turn the engine over by hand (5/8" socket on the crank bolt on the front of the engine) 90 degrees and do the next cylinder in the firing order, which is 18436572
Crank engine over 90 degrees for each cylinder in firing order and you'll be at TDC for that cylinder so the valve won't drop.

Check out www.cmotorsports.com out of Las Vegas, they have a great spring that is only $100 and in the B-body world have been proven to be a quality part (made by EX COmponents). I run these on my FW.

 

[BCs71]

Oh yeah, in regards to roller rockers, let me throw out my two cents. I run roller rockers and if I had to do it again I would opt for a new set of stamped non-rollers from an aftermarket company. The reason being is that I don't want a race car that squeezes out ever single HP possible; my goal is to gain performance and have a nice street cruiser and occasional strip car just for fun.
The roller tips under the factory steel rocker covers are quite noisy. In fact, kinda annoying. The Corvette composite valve covers are an option to throw on there, they help insulate against rocker noise (GM put these on the vette with an LT4 since it came with factory roller-rockers) but unfortunately are quite expensive (like $150+).
The other downside is the fact that the noise they make can be picked up by the knock sensors as knock (false) and actually pull some timing, essentially affecting power and mileage.
So that can be resolved by another factory GM piece, the LT4 knock module ($35) that is less sensitive to picking up knock. IMO this is an essential piece if running RR. Until I got an LT4 KM, I verified with scanning software via my laptop that I did indeed have knock retard.

Add to that the fact that decent true roller rockers (fulcrum and tip) are about $250-280, much more than your typical stamped rockers that don't have any of the above mentioned noise related issues. The rockers I use are Comp Cams Pro Magnum rollers, a great quality piece. But they'll cost you..... gotta pay to play sometimes.

 

[N0DIH]

Is there that much performance gain with the 1.6's vs 1.5's on the stock cam?

Or is it really best to go with a cam like the HT383 cam or a custom grind?

My thoughts on a new cam, I would go for a .470/.470 lift, with a LC of 107, duration of 201 intake, 206 exhaust @ 0.050".

Maybe a little more duration if I felt the top end of the rpm range could tolerate it. I think if anything it needs more breathing, but how much to not sacrifice low end.

Shoot me an email at V4P_Fleetwood_LT1 (a t) hotmail.com

 

[BCs71]

Is there that much performance gain with the 1.6's vs 1.5's on the stock cam?

Or is it really best to go with a cam like the HT383 cam or a custom grind?

My thoughts on a new cam, I would go for a .470/.470 lift, with a LC of 107, duration of 201 intake, 206 exhaust @ 0.050".

Maybe a little more duration if I felt the top end of the rpm range could tolerate it. I think if anything it needs more breathing, but how much to not sacrifice low end.

Check this link for other cam data.
http://www.fierolt1.com/lt1_camdata.htm
As you can see, the stock LT1 cam with 1.5 rockers pushes .447/.459 and .477/.490 with 1.6 rockers. That's a significant gain IMO to switch to 1.6 rockers.

I run the 845 cam with 1.5 rockers, it's listed in the link I posted. Lift is .488/.509 with the 1.5s. I could have easily got more lift out of the setup (putting me at .521/.543) but there are two things to consider here:

#1.) With stock heads, will they actually flow enough to take advantage of the extra lift? Possibly - but borderline most likely on the exhaust side without any headwork (porting).
#2.) On the cast iron heads, they utilize pressed-in rocker arm studs (as opposed to screw-in studs) which have limitations on how much lift they can handle before snapping or being pulled out. I kept my heads stock, so decided that .543" lift on the exhaust side made me uncomfortable with pressed-in studs. So in order to not risk a disaster like stud breakage, I opted for .509 lift with the 1.5 rockers.

As far as your cam selection, it is NOT worth the money and time to swap cams if all you're going with is .470/.470. You can gain that or better just by throwing on 1.6 rockers and the stock cam. And for duration, the stock cam is greater than 201/206.......
And LSA at 107 is weird...... for emssions testing 112 and 114 LSA usually are safe I believe.
You may want to rethink that choice!

Honestly, the stock cam is really a great cam for low end torque. The F-body has many more choices than we do for cams since weight is not such a factor - they don't require the torque we do in 4000+ pound cars.
Matching the right bolt-ons to stock internal engines can produce awesome results..... there are stock-internal Caprice/Impalas in the 12 second quarter mile time bracket with just bolt-ons and no nitrous, believe it or not. :stirpot:

I'll drop you an email so you contact me off-site.

 

[N0DIH]

The reason for 107 is low end torque. I don't have to worry about emissions, just driveability (my big thing...).

I don't want to stuff in a cam that is huge and will kill off bottom end like the HOT cam.

If I was going to go big cams, .470/.470, 308/320 adv duration, 231/240 @ 0.050".... On a 112.... You Pontiac fans may be familliar with it.... ".it will tear your head off up to 6400 rpm..." That it will..... It was a factory grind. First computerized grind in GM.