Hey guys. Let me preface by saying that I do not own an L03 F-body. I have an L03 caprice with running a wet plate 135 bhp nitrous setup. I have been looking into 1.6 rocker/spring/valveguide replacement. The guys at impalassforum.com pretty much only know the LT1, so I'm coming here in hopes that some of you have done it and know the details(maybe even recommend the right parts). Any suggestions would be greatly appreciated.

 

I would check this thread out. It was just posted a day or so ago. Any extra umph that you can give the cam in these motors is a worthwile mod. Unless you have a serious amount of miles I would not worry about replacing the springs yet. You can get away with the stockers and 1.6 RR on the stock cam.

https://www.thirdgen.org/techbb2/sho...hreadid=235071

 

Does the L03 have enough compression to use the "turn the piston to TDC and let the valves drop" method?

 

the L03 is not a low compression engine, it is rated at 9.3:1 just like the LB9 and L98

 

This is just an issue the LT1 guys brought up, because they are used to 10.5:1.

 

What is involved in the installation if I am replacing the rockers only?

 

My neighbor has a 91 LTZ Caprice with an LO3 (305). He's using the Federal Mogul stamped steel self-aligning (or rail) 1.6 rockers (pn 1023R, where R=rail) along with new springs (unknown which ones... I think they are low-mileage Bcar LT1 springs leftover from a cam/spring swap in his SS).

I believe Elgin also sells the same item under their own pn, which can be found by searching on the SS forums using the keyword Elgin. The Federal Mogul parts info has been posted here on TGO in a different forum, as well as on the NAISSO Bcar forums. There are a number of Bcar owners using them, besides the Fcar owners that have them.

IIRC the other mods done are the AIR pump delete (using the export pulley), 65 #/hr injectors from a LO5 9C1, ECM tweak to delete the speed limiter and adjust the injector constant, complete N10 duals + exh manifolds from a 96 SS, 94-96 trans crossmember, 94-96 tailshaft housing from a 4L60E used on his factory 4L60/700R4, EGR delete, ported & rewelded factory aluminum intake manifold, Caddy elbow above TBI + sewerpipe + cone filter.

He might install a leftover 3.73 gear (replacing the GU5 3.23 he has now) and add a leftover higher-stall converter. He really doesn't plan to spend any real money on the car/engine because of his other cars/projects.... so his goal was to spend no real dollars on the car but see how far into the 15s he could go.

He hasn't had the car at the track but I have ridden in it, and we agree that it feels almost like a stock Bcar LT1. It sounds like a stock LT1. He also hasn't been able to get a decent GTech run in because the trans still shifts way too soon. There is no way to say how much of the performance gain is due to any one part (incl the rocker arms), but the rocker arms definitely helped because the LO3 in the Caprice uses the same puny "peanut cam" that Fcar owners complain about. So the LO3 needs all the help it can get, and the 1.6 rockers go a long (cheap) way to help that.

HTH.

 

My other mods are as follows:

KYB gas-a-justs
15x7 alloys from a '95 silverado
a flowmaster single exhaust system
ghetto dual snorkel cold air induction (looking to change that)

I ran a 7.1 0-60 on a somewhat lousy launch with the gtech on the juice. Because I do not have posi, I have horrendous traction issues. Regardless, I beleive that my car is faster on nitrous than an LT1 car. But I'm tired of this dam truck cam! So this seems like a cheap way to give it a little more pull at high revs (and maybe take some torque away from my launch LoL). Rockers combined with PCMforless should improve things a bit.

 

You just need the rockers and new locking nuts. It may be a good time to replace the valve seals and locks since they are cheap.

 

vjo, I noticed that you mentioned the vortec RR's from enginekits.com on another thread. How good of a match are they for the L03?

 

they will fit perfectly on the L03 because both the vortec motors and L03s use self-realigning, narrow bodied (centerbolt heads/valve covers) rocker arms. These will increase your lift to .373/.410. I would go with the roller tipped $90 rockers, i dont think roller rockers are necessary on our engines, i hear you dont take advantage of them until high RPMs.

 

Sounds great. Since I'm leaving the springs in, is it just a matter of unbolting the original rockers and bolting down the new ones to a specific torque?

Another question: I'm running 4 degrees of timing retard on account of the nitrous, should this pose a problem with the new lift/duration?

 

No. You have to set the valve lash. There are like three different ways to do this. This is covered all the time in the general engine tech board. A quick search should tell you how to set them.

 

I'm going to reiterate my question about timing retard here. I have 2 more questions. How do I change the shift points on the 700R-4 to better accomodate the new powerband? Do I need to move to bigger injectors? I know that this is getting old but your help is greatly appreciated.

 

You do not need to change injectors. I would still only use 4* to 6* advanced as your base timing. Try a search in the drivetrain board to help you with shift points. These trannys are not computer controlled (only the lockout is) so you will have to shift the car manually to get your desired points. A shift kit will only firm up the shifts.

 

the rocker arms will not change your power band, you are just going to get alittle more power across the board. You are only gaining .023/.026 lift and maybe a degree or two duration at .050 lift.

 

I'm saying I NEED to keep it 4* retarded because of the nitrous, I'm wondering if this will pose a problem with the rockers.

 

I gottcha. I would not worry about it. Everything should be fine since the amount of lift you are changing is almost negligable.

 

LoL thanks. Should be a fun project for early summer. Looking at the specs it will only be about as "cammed" as the LU5.

 

From looking at a few dyno graphs from people who have switched to 1.6's, your power band will increase significantly. IIRC, there was a board member who went from peaking at like 4200-4300 to peaking close to 4800 rpm, verified on a chassi dyno.

 

Are you saying that you are running -4deg as base timing or just taking out 4 degs at WOT? If at WOT then you should have no problem, if it's base timing then you'll loose a lot of low end torque and gas mileage during your daily driving.

Steve

 

I'm pretty sure it's base timing =/. Bleh too many issues here. Is there a way I can change shift points on the th700r4? I think I'll try to figure out a way to retard timing only when running the juice. Another point on the issue of timing: I have shrunk the spark gap to on the big side of .025, so would this possibly counteract the problem?