L81 Factory Cam Spec or P/N

[GerryLP]

Vader,

I noticed on your pics that you also removed the heads. Was that intentional? The pistons look ok. Were the cylinder walls ok? How was your #8 cylinder? I am curious, for I found some water signs on the #8 cylinder (Actually my mechanic did and informed me). He says that the #8 is common for having signs of water if a vehicle is used during short drives and long rest periods. Condensation settles on acount of valves being open at the #8 when turned-off...not sure about this.

I'm afraind that even 1.7:1 FMS rockers wouldn't help that thing.

Well...maybe some of our L81'ers would find it usefull to enhance the L81. A 1.6 rocker ratio with some good stamped rockers from CompCam or Crane would yield close to 0.026" more lift. A 1.7 ratio would yield approximately 0.052" additional lift. The short duration helps keep whatever compression is there (8.2???). The bigest advantage would be from the more accurate lift multiplication thorughout the rpm band.

Will it help make 14-second et's by itself? NO, but it would help along the L81's in stock configuration. Remember that plenty of our members prefer their Corvette as close to stock as possible. Some components or systems may have been upgraded or improved since the 1980's, and if the parts are in need of replacement, then a replacement part could bring added reliability. Case in point the stamped-steel rockers.

What did I win anyways???....(I cheated...I looked it up in the shop manual)...:L

 

[Tom Bryant]

Vader,
Were the cylinder walls ok? How was your #8 cylinder? I am curious, for I found some water signs on the #8 cylinder (Actually my mechanic did and informed me). He says that the #8 is common for having signs of water if a vehicle is used during short drives and long rest periods. Condensation settles on acount of valves being open at the #8 when turned-off...not sure about this.

I really doubt this Gerry. That doesn't even make any sense. What are the chances that an engine would stop in the same position every time? There is nothing mechanical in an engine that would cause it to stop with one valve open as opposed to another every time or even most of the time. Sounds like a Las Vegas gamble to me.

I would say that if there was signs of water in #8 it would be due to a bad intake gasket or possibly head gasket. Of course if it sat for a very long time in a damp storage area the oil film in that cylinder with an open valve could break down eventually to the point of allowing rust to start forming. This isn't going to happen just by not driving in for a few weeks or a few months even, unless the car is setting out in the open with no hood. The engine I took out of my project was stopped with valves open in #2 and #3 and they had the very rusty cylinders walls to prove it. The rust line indicated water (rain probably) from sitting out at some time during the previouse owners work.

See the attachments in the first couple of post in this thread.

Tom

 

[Vader]

Gerry,

Yes. Removing the heads was intentional. They are now wheel chocks, as the factory intended. I installed '416 castings that have been worked over. Valves were sized to 1.94/1.50 (just like the '624s), but the bowls were enlarged, short side radii cleaned up, valve guide bosses trimmed, ports were enlarged from a measured average of 151/56cc to an average of 177/64cc. Rocker stud bosses cut 0.400" and screwed ARP stude installed. Ovate wire springs and titanium retainers finished the top side. The chambers of the '416s are designed at 58cc, but measured 57cc when I first got them. With the addition of the 1.94" intakes and the unshrouding, the chamber volume was 58cc when completed. Valves are undercut stem stainless. Even with the 13cc dished pistons, net static compression is now 9.39:1.

That was the original intent of the project, but once I measured the cam lobes, it was not going back together with that profile. The new cam specs at 0.443" /0.465" - 214°/224° - 112° LSA. I can always change rocker ratios later, since the guide slots were elongated and the springs will handle 0.540" lifts (guide tops were cut down for the new seals).

As for the pistons and bores, I cleaned the pistons and checked the deck while the heads were off. The specs I've read on this site quote 0.030" deck height, but the VIN and assembly stamps hadn't been machined off (so the block was probably never milled) and the measurements I took were more like the conventional SBC 0.020" deck height. I don't know where the specs on this site were generated, but for this engine at least, they were wrong. At least the cited "0.021" head gasket compressed thickness was correct. Actually, mine measured 0.020", but, close enough. I also checked the bores (with the piston in) from top to bottom and had a worst bore of 4.0026". I feel comfortable with leaving it at that for now. I saw no signs of water/coolant contamination in any cylinder nor chamber. Coolant leaks or water ingestion usually results in a cleaner chamber and valve, and all were equally deposited.

I've been around one or two SBCs over the last few decades, and I've also never heard of the described problem with a particular cylinder. Your description sounds more like a gasket problem or engine that was improperly stored for an extended period of time.

 

[Vader]

O.K. It took a little longer than I had planned (we always run into those little nuisance issues that need more attention, don't we?). After repairing A.I.R. tubes on the factory SS exhausts, replacing seized studs on the intake, air duct repair, and rewiring some of the melted harnesses, yada, yada, it's back together and running. The cam is run in, and the lash has been reset hot and running after break in. It still needs a little "Quadrajet Magic" secondary tuning and shift point / TV adjustment, but the cheap heads and cam added plenty of "pop" to the previously lame little 'Y' car. A few test drives around the farm roads after fluid changes provided more kick in the pants than before. Even with the secondaries not opening as they should, and the timing at stock base on 89 octane, there was no disputing the increase in torque at higher RPM, and no noticable loss of torque at lower RPM. For less than $350, the gains were well worth it. For some old heads, springs, and studs that were just lying around, and a $130 cheapo cam kit, it turns out to be a pretty respectable little package. Getting sideways at a stop sign from something other than braking is a little foreign to this car.

 

[GerryLP]

Tom,

I thought that the story sounded fishy as well. The cylinder was scored though.

Vader,

Great pictures.

Sorry for the late reply guys. I was out and about Northern and Southern California bringing back a 71 Camaro for my drag project that my sister-in-law just gave me. I'll be busy a while with this one. ...:L

 

[Vader]

O.K. Who do I have to marry to get a sister-in-law like that? Mine just bring me broken Saturns and Tahoes, and the occasional Cavalier with the stuck convertible top...

That should be a fun project. Got some nice, heavy SFCs selected, or building your own tube frame?

 

[GerryLP]

Vader,

I am first going to research the numbers on this car to see if it is anything that should be restored. It has a "small" block 396 or 400 in it. And the seats that it has were an option IAW my Chevrolet High Performance Book. I have already taken the car to the car wash and washed the engine bay completely (it had been sitting sitting since 1996). The engine will come out. It has a posi rear end that was available as option then.

I would hate to make it a racer and turns out to be a restoration candidate. I'll let youguys know which way it will turn-out. I have never repaired rusting on body panels before, and this one will need some new pieces of steel welded in place, so I am looking forward to that.


p.s. It took my sister-in-law about of 2 and 1/2 years of storage fees (at $60 per month) to give it away. I would have searched a storage place far away from the San Francisco Bay Area to store this car, and then would have been about $10 - $15 per month.

 

[Vader]

OUCH! Storage in a seaside location probably didn't do the body any favors. There are restoration panels available for that body, http://www.rustrepair.com/Camaro_parts.htm and probably other places. If it's a good candidate for resto, it would be a lot more valuable as a 70½-71 Camaro than a drag car. Try searching for repair parts and advice at www.fbody.com

 

[GerryLP]

Vader,

Thanks for the info. I'll surely take a look at that. Yes! It has some corroded panels and the paint must be stripped and brought down to the bare metal.

Thanks again!