Hey Guys

Some of you may have read some posts I made about upgrades for my '86 TPI.

The cam is coming down to be the biggest headache for me. I'm going to try to spec my car as best as possible, and need opinions on what cam to go with. Any real world information would be greatly greatly appreciated.

Car:

1980 Camaro 3600lbs

Drivetrain:

-Stock 1986 Corvette Torque Converter (I have read this is around 2000rpm stall for the '86 Corvette. Others say its around 1500 or so?)
-700-R4
-GM "Corporate" 10 Bolt 8.5" rear, 3.73 gears (posi, of course )

Engine:
-Stock Bottom End
-Ported lower intake and plenum
-Reprogrammed PROM
-Stock cast iron heads
-Stock flat tappet cam
-Custom CAI
-MAF Sensor

Exhaust:
-Full length heddman headers (The size escapes me right now)
-High Flow Cats (Will be punched out soon)
-2.5" Dual Exhaust to Dynomax Mufflers.
-No "H" or "X" pipe.

Future Mods:

From what I read, I will most likely go with AFR 180 heads.

I am looking for a cam that will provide great bottom end torque, and it does not need to rev high, however, I do want it to take advantage of the intake porting.

I do not really want to change the torque converter, but I will need to if necessary.

What are some cams that everyone ran, and were happy with.

Remember: My engine is a flat tappet. I can convert over to roller, but for costs sake, I'd rather stick to flat tappet.

I'm open to any opinions that everyone has!

Thanks in advance

 

With my experience building my 383 it really takes a lot of research and thinking as what a person should do, you don't want to re-invent the wheel because someone has something that is working well.

First off, your cam needs to match or excide the flow rate of your intake and heads, where is the weak link of flow.

I'm not sure what your budget is, but I would talk to the fellows at TPIS in Chaska MN, they will give you a proven set-up for your needs.

 

If you're running on the street I would go with maybe the zz9. I run the zz409 but I don't drive on the street.

 

I think if you are keeping the TPI or a using a mid range RPM intake, then a cam close to my recommendation would work very well. I see you chose to use the Hedman headers, which I believe are 1 5/8". That is good for low and mid range RPMs. Also, the heads you chose will be really good for this application too!

I would recommend a cam around 218/218 duration @ 0.050", around 112-114 LSA, and as much lift as you can get up to 0.600" as that's the max stock AFR 180 heads can use.

This should be a real torque monster, especially with those gears.

I think you will be very satisfied and it will definitely rip panties off.

 

this Lunati flat tappet is a good choice with your mods and future mods in mind.
you can run it with 1.5 rockers and if you upgrade your heads go to 1.6 to get some more lift.
http://www.summitracing.com/int/part...make/chevrolet

 

The posts above give you the right idea. When using a long-tube intake, having more duration on the input side helps. I posted in a recent thread that short-runner intakes create less "resistance" in the runner and, therefore, tend to provide better off-throttle response. (Until runner pressure takes over for mid-range "boost".)

With more duration you have to be careful about LSA to make sure you retain good low-end (street) responsiveness. You can also advance the cam to favor street performance.

With stock alum heads, something in the .500" - ".525 range of lift must be considered. Stock heads have limitations w/o modification/machining. The conversion to AFR heads will provide better opportunity for lift.

One this to consider is 195's have better mid-range flow -- enabling you to move more air with less valve opening. So, you MIGHT consider conversion to 195's because the result could be more satisfying with the (lift of) cam necessary to function with stock heads. OTOH, you MIGHT be the only person running AFR heads with a ported stock intake. (Will you at least increase runner size?)

In general, picking a single pattern cam (same/similar intake/exhaust duration) is a good idea for a long-runner TPI upgrade. If the overlap is modest, you won't need any (or as much) mechanical cam advance. If you opt for more overlap (for a bit better mid-range bump in performance), rotating it 4-degrees would be a good way to retain low-end too.

"Modern cams" use more lift and less overlap to build power. But, that's because roller cams make life "safer". That zz9 cam is a milder lobe and easier on flat-tappets. But, I'm not sure the intake duration is best suited to build an intake "charge". The zz409 cam provides that single-pattern design and more intake duration. That makes it a good option especially when mounted advanced to favor low-mid performance in a long-runner setup. Some might consider it a hair big for the build in question though having something to favor intake "restriction" isn't going to hurt. And, it's not so big to have idle/emissions nightmares. FWIW, overlap builds in some natural EGR dilution of intake charge to eliminate the need for that circuit. So, that's another reason it might be a good choice.

Finally, to ease your confusion, know that lift/duration changes aren't HUGE factors in overall performance. In the range of cams you'll be shopping, you'll probably gain/lose a mere 10lbs in TQ/HP based on the rpms you favor. So, pick something in the mid 21x to mid 22x range (duration) and build that motor!

 

GREGGPENN! You are the man! This is exactly the type of information I was looking for. Its alot to take in, and just adds more depth to my decision, but it makes understanding it a whole lot easier. I will definately be going with larger runners. I just wanted to get the lower intake and plenum finished first.

If I remember correctly, the lower intake went from 1.4" diameter, to 1.7"? Something of that sort? I know on a size scale, it isnt that big, but for airflow, it should breathe a bit easier. I'm going to try and get pictures to verify this.

I know that the original tubes can be stretched, but I can go for a set of high flow runners. I'm not sure what to go with. I like the SLP's, but i believe they are no longer made. I DO NOT like the look of the Edelbrocks. I want to keep it stock looking, I love the look of the intake.

 

Stock is 1.45". Stretching (with *****) gets you to 1.55ish. TPIS, ACCEL, and AS&M runners can be mistaken for stock. So, look for a set of those (possibly used). Out of the box, they are in the 1.65"-1.7" range. FWIW, even ported SLPs seem to be outdone by these oversized, aftermarket tubes. That's because SLPs start out around 1.55" inside. Life is easier not having to spend HOURS porting tubes. Edelbrock/Accel makes a good base or you can hone (just as expensive) or learn to port your azz off. (I think the Edelbrock runners with don't look bad either. But, I also think they are a hair smaller...in the 1.6" range.)

The jump from 1.45" to 1.7" really is a good increase. It's something like 20-25% IIRC.

Matching the plenum to the runners is good while some also remove the humps behind the TB openings. Mostly, TBs feed what any 350 needs so concentrate on the runners (and base).

There are a handful of people that have built HP TPI with the stock intake. The bubble of power gets more pronounced and in a smaller RPM range. You'll be happier with the power in 3rd gear but may wish the rpms would run out a bit more.

 

I am using this cam in my 86, no complaints.

http://www.summitracing.com/int/part...make/chevrolet

 

This looks like a pretty decent option. I was gonna suggest an LPE 219, but then I realized you needed flat tappet.

As others have suggested TPI cars can be made to be cent runners. My build wasn't too different than yours. Mine has ported 113s, an LPE 219 cam, an Accel base, AS&M runners and a ported plenum on a 383 bottom end. With these relatively mods, my car normally goes high 11s in the 1/4.