I'm usually on the C3 side, but I am putting a 1986 l98 into my '78 S/A. It's an early '86 TPI, aluminum heads, 1 pc rear seal and flat tappet lifters. I got the engine for almost nothing and it is sound. Block and heads have just been gone over and I am looking for a cam, maybe one notch above stock. My goal is a daily driver with decent MPG. No high HP or racing ( can you tell I'm OLD!). I have come across a few cams that are COMPUTER CONTROLLED. Specifically a Comp Cam12-388-4. I have never heard of a compter controlled cam so could one of you explain it to me. I have an idea of what that means, but I don't understand how it works. Or if it is different than a regular cam. I will be getting my computer/wiring harness etc after I get the engine together and in the car. And this is a budget project, as in LOW BUDGET, so any experiences will also be apprectiaed. Thanks.

 

The term computer controlled cam is misleading. The cam is not controlled by the computer. The cams that are used in engines have different lobe separations and duration. The computer samples all the sensors such as the 02 sensor and others to control the fuel going thru the injectors to control the fuel running thru the engine. The computer is able to maximize the miles per gallon, control emissions, combines air/fuel and others. A carburetor can't come close to these parameters and basically dumps fuel. That is okay if your going in a straight line down the 1/4 mile. But you will not get a engine that will get 25-30 MPG, easily run in the 14's or better and meet today's emissions.

You should consider that the stock cam in the 86 has a stock tune in the computer. If you change cams, you can get more HP....but you will have to change the parameter in the computer to handle this change. Before changing the cam you need to look in your area for a shop than can re-program you computer for the new cam. If there is not one in your area, you will be limited to a mail order tune. You will have to capture data generated by your computer and feed that to your tuner to get them to make the changes. This may have to be done several times until it is finally correct or your cam/engine configuration.

I am old like you....in our days, if you had spark and fuel thru the carb...the engine would run. With the computer, there are so many areas that are tested and the results going to the computer it is difficult to figure out what is going on. It is not like changing jets or moving from a two barrel to a four barrel carb. Vacuum in the intake would draw fuel thru the carb. The cams used for fuel injected cars like our Corvettes do not generate the vacuum.

My stock 85 with automatic transmission would get 26.6 miles on the freeway and 16-18 around town. You will not get that with a carb. When I installed the ZZ4 with the Lingenfelter cam and other mods with a custom tune for the cam I could get 30 MPG on the freeway and around town to 18-22. And the fun factor was fantastic.....from mid 14's through the quarter to 13.2. And I was able to run Regular gas without a problem.

Hope this helps.

 

Computer controlled cams are typically ground on a wider lobe spread to help keep intake reversion low and idle vacuum higher than a “typical” cam. The cam you listed is quite small for a 350 – that’s more like something you would want to run in a 305. The 86 TPI uses a MAF system and they’re a little more forgiving on the cam size and whether or not custom programming is a must. I ran a 218/228 -110 cam in my 86 IROC with a 355 and it ran pretty good with the stock chip. However, idle was a little hairy and if you’re looking for something to give you a little more power with a relatively smooth idle, go with the fast rate of rise cams like the Comp Xtreme Energy (212/218-112), Comp 4x4 (210/218-111), or Lunati VooDoo (213/219-112). All of these will idle smoothly, would run “OK” on the stock chip, pull similar vacuum, and generate similar power curves. Obviously a good custom tune would dial in driveability as well as increase performance and fuel economy, but if it’s not going to be a daily driver you could get by without having to “tune it”.

 

Thanks to both of you for explaining the computer control thing. Makes sense to me. I had been planning on a mail order tune, but I recently came across a local guy that does this, and has some good recommendations. I had an 85 a long time ago and the torque and mpg were what made me go for this set up. So if I understand, the computer controlled cam will get me better performance as long as I can get the proper tune, better than a NON computer controlled cam. I am limited in that I have flat tappets instead of rollers. I have to get up to speed on the numbers you guys mentioned above and look for one in that range. Thanks for the help.

 

Assuming your keeping the same block, you could retro fit hydraulic roller lifters into the current block.

The heads on the 86 are a big step above the cast iron heads that were on the 85. If you consider that there have been huge increases in the technology in today heads that are on the market compared to what was produced in 86. The new heads right out of the box would put the stock 86 heads to shame. Heads, cam and a little exhaust work and your rolling .

 

keeping the heads and block. From what I know the tradeoff for the roller change isn't cost effective. I am trying not to get too carried away with this. I don't want to go down the hole of beefier trans, stronger rear, bigger u joints...it took a lot to talk my son out of the 500 hp stroker! Right now i am looking at a Voodoo 10120701 non computer controlled or 10120638 computer controlled. This is a whole new learning experience, but now at least I know there are no wires from my computer to the cam!https://www.corvetteforum.com/forums...es/cheers2.gif

 

Just a thought here. I have an 86 convertible so I have the aluminum head 350 as you described. From your description, sounds like you plan to drive it, that's pretty much it. If that's the case, why not try it for a while as it is, it's already set up and see if it's what you're looking for?

Mines stock, it's a cruiser and for that it's perfect. Decent mileage and handling and I don't have anything exotic with it so if it should need help away from home I don't have to worry or wonder if it can be fixed.

Just a thought.

 

The cam had some issues from the PO who didn't like to change oil. SOme of the lobes looked bad. Same with the crank journals. That's what started me on making some minor changes, " while I have it apart"! And we all know how that works out.
And as for exotic, remember I am putting this into a '78 S/A C3, so starting with the fuel pump in the tank and moving forward from there, Mr. Goodwrench won't be much help.
Thanks.

 

If you want decent gas mileage then you are going to need an overdrive transmission like a 700R4, 200R4, or a 5 speed manual. A TPI want do it alone. Back in 1991 I considered switching out the 4 barrel carb on my C3 76 to a 85 Camaro TPI. Came to my senses and bought a C4. Keep the 78 SA for what it is and enjoy it.

 

The 10120701 (256/262, 213/219 - 112) would actually be more computer friendly - it should idle smoother (shorter seat duration) and there wouldn't be much difference at all in the power output. However, if you have someone that you can trust to do a good tune, the 215/225 - 112 should be "tunable" and would make fractionally better power. Still,, I think I'd go with the 213/219-112 for the smoother idle,,, although you might want it to show a little more bump. Another factor, if you're running a converter stall speed of less than 2200rpm, that would sway me towards the smaller of the two as well.

 

I actually already have a 200R4 transmission sitting here out of a Buick. It is a direct bolt in to a C3, no changes in crossmembers of driveshaft. Haven't gotten to the stall speed learning curve yet. And I'm not really concerned about a bumpy idle. I am going to have side pipes on this thing, ( at least until my wife says she won't ride in it!). Can't thank you all enough for walking me thru this. I have done my fair share of wrenching but the computer controlled idea is all new to me. Not just the cam, but as said above, the metering of the fuel and air to get optimum efficiency and power. I guess you can teach an old dog new tricks. Or you can at least try!