asilomar244

I posted last week regarding a stripped spark plug thread on my '94 LT1 motor. After getting some input and doing some reading up, it seems I should remove the heads to not only ream and thread insert the #8 plug that I know is trashed but carefully check all other plug ports in both heads. I can get free machine work from the shop at work which same me money on a Time Sert kit. However, since the heads are coming off and I need to reseal the top of the motor, I think now it the time to do a mild cam upgrade and I would like to get some input on how to do this right but on a budget.

The Gen II LT1 is a great motor and I have it paired to a T56 in an engine conversion. Good low end, decent power but it always seems to run out of oomph heading into the upper rev range. The stock cam is just so mild. However, another factor is that due to CA smog and limited space in the engine bay, I am using '86 TBI ramhorn style exhaust manifolds which does provide some exhaust restriction. Then to 2" Y-pipe to single cat and 2.5" exhaust. For intake I have the stock plenum to MAF but with a K&N cone filter. I am going to fabricate a straight plenum and build a cold air box for the K&N filter. So that is an overview of the intake/exhaust setup. What I want to do is figure out a good street cam for better pull into upper rev range and slight bump in peak power/torque (30-50 HP?). The heads were rebuilt about 4k miles ago by a local machine shop. Springs and valve guides were replaced, valve seats turned and ports de-shrouded which may be relevant to selecting a good cam kit.

So that is the main question- what do folks think this type of setup call for in terms of a cam kit that will be smog legal and provide good street performance and all around driveability?

Looks like PCM tuning will be required, would PCMforless.com be the best option?

Looks like this is the best option for a top end gasket kit... Also picked out ARP head and intake manifold bolt sets.

Any input/guidance is welcome. Thank you for going over this.

Chimera96

The GM "hot cam" will give you more higher RPM power than stock and is often a low $. Since you note your valve springs are new they should be good assuming they are not "stock" replacement springs. Motor falling on its face at 5k rpm generally means valve springs are weak. The GM LT4 Hot Cam "kit" springs are not good for LT1 valves as they are solid heavier valves

Given the work it takes to do a cam I would not cheap out. Check out Elliott Portworks site. His stuff is the best for LT1

You need to remove timing cover to do cam swap which means front oil pan needs to drop some...so you should replace pan gasket also which is not a easy job with motor in car (read you need to lift up motor). You may get away with using RTV on your old gasket and cross your fingers it does not leak

Injuneer

That exhaust is limiting. The typical 4th Gen owner can realize 10-15 HP by moving up from the stock 2.75” crimp-bent intermediate pipe to a 3” mandrel-bent pipe and low-restriction muffler. Would CA allow you to use shortie or mid-length headers that are CARB-EO certified for the single-cat configuration? I ran CARB-EO JBA 1-5/8” shorties for a while. But they didn’t seem much better than the factory manifolds over 5,000 RPM. But they might be an improvement over the ram's-horn. And 1-3/4” step headers might yield better results at higher RPM, if there are any CARB-EO still being manufactured.

I'll second looking at what Lloyd Elliot has to offer. He does have recommendations based on emissions compliance. Since you'll have the heads off, he can work wonders on LT1 heads.

LT1 LE1 «

asilomar244

Thank you both, I'll give Elliott a ring this week. Injuneer, the engine is definitely not breathing well enough and I do want to find a blockhugger header solution sometime next year. But I will need to run the current exhaust configuration for at least another 6 months. At that point, I will consider your advice on improving the exhaust once I figure out CARB legal headers that fit...