I am in the process of installing a ZZ4 cam and the mechanic who is helping me said with that cam I'll need a performance torque converter. He said with that cam my car will have no power at low RPMs. I just wanted to know if the 700R4 tranney will compinsate for this, what I mean is it has such a low first gear that it the cam shouldn't hurt low RPM performance and launching from a stop. I also have 3.73 rear end. One last question what exactly does a performance converter do? Thanks for your help.

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88 Formula 350
Upper and Lower SuperRam, 1000 CFM Accel Throttle Body, 24# Motorsport Injectors, Custom Burned PROM, Larger Gutted Mass Sensor, MSD 6a box, Flowmaster Muffler, Homemade Cold Air induction, TB Bypass, B&M shift Kit, 160* Thermostat, ZZ4 cam

 

If it's just a ZZ4 cam (208/221) and not the LT4 HOT cam (218/228), then I wouldn't worry about the loss of low end. I still have plenty of torque from 1200 rpm on up with my LT4 HOT-cam'd 355. With the TCC locked up, the engine pulls quite strong, and by 2000 rpm it feels like the car's being pushed by a train. Yes, the low 1st gear helps, but only when starting from a stand-still.

A performance torque converter is one with a higher stall speed. The stock stall is about 1500 rpm for the TPI engines, although that'll increase a little with a stronger engine behind it. A good stall converter (like one from Precision Industries) will help tremendously in launching the car at the drag strip, will bring/keep the revs up sooner to help mask any loss of low end you might have, but won't compromise it's around-town driving manners, and going with a lock-up TCC will keep the highway RPM's the same as before.

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Greg Westphal
'87 IROC 355TPI/A4

 

Greg, talk to me about the HOT cam. I'm deciding between the lpe 211/219, lpe 219/219, and the HOT cam. I'm going to throw it in my 355, and in a few months, a 400 I'm building. What made you choose the hot cam, what kind of intake are you using, and what kind of results are you getting?

 

I chose it since I know other guys getting great results from it, plus it's only $180, not that the difference between that and a $250 CompCams cam is gonna break the bank. I'm running a ported Edelbrock intake but the stock runners. My SLP runners should arrive early next week, at which point I'll be porting them out and port-matching the plenum to them. My best run was a 13.58 @ 99.8 mph, but I had quite a few problems like detonation, a slipping tranny, and the DS getting slapped by the DS loop. For a better example, a friend just ran a 12.18 @ 109.6 mph with this cam in a ZZ4 engine, SLP headers, siamesed Edelbrock intake, AS&M LTR's, 58mm TB, 2800-stall Vig converter, and 3.73 gears. For a 406 engine, I'd get at least a 224/230 cam, which would also work in the 355 with some decent PROM tuning.

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Greg Westphal
'87 IROC 355TPI/A4

 

224/230 is a big cam. I have a 224/224 lunati in my car now with a performer RPM, a 3.42 rear and a 2.41 (Super t-10) 1st. My car has nothing down low. How's the low end with the HOT cam. I know you've got a 3.06 1st, what's your rear gear ratio? Do HOT girls like the HOT cam, because that might be the determining factor. I just don't want to go slower than my mph now. Did you install your cam straight up? Did you degree it?

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355 c.i.
Dart 180 Heads
Lunati 224/224 cam
Harland Sharp 1.5 rockers
Performer RPM Manifold
Holley 600 cfm double pumper
Hooker Super Competition Headers
Flowmaster Exhaust
Competition Engineering Sub-frame connectors
Super T-10
GM posi 3.42 rear
Hurst Roll Control
13.9@102

 

The 224/230 cam is definitely not too big for a 406, or even a 350 (I know some 4th-gen guys with that cam and some even bigger) if one is able to do their own tuning (burn chips or re-program the computer). Carb'd cars lose all of that bottom-end torque because of the loss of vacuum (and hence the vacuum signal to the jets). EFI cars don't usually have that problem, and can still make tons of low-end torque since you have much-better control over the timing and the fuel.

My low-end is quite strong with the LT4 HOT cam from 1200 rpm on up. I have 3.42 gears, so I'm turning ~2000 rpm at 60 mph, at which point I can almost floor it (TCC locked up, still in OD) and the engine pulls the car along like a freight train. The cam was installed straight up and degreed by the guy that rebuilt and assembled the short-block. I verified that it was installed correctly when I finished assembling the engine before I swapped it with the original but tired 305.

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Greg Westphal
'87 IROC 355TPI/A4

 

greg westphal,
do you have the opening and closing specs
for the hotcam?
what lobe centerline does it have?
i already have the general lift/duration/lsa
specs, but gm has somehow miss placed the
cam cards.... hummm
weve done an lt1-lt4 conversion on an impala
ss and found that being a much heavier car
a 2500 stall and 3.73 gears woke up the torque
on the car.
airdeano

 

Greg, what kind of torque converter do you have with that hot cam. You said that it had plenty of low end torque when you had the computer programmed properly. Does this mean that you would not need as high of a stall to get the car to be more drivable. Thanks for your input.

Ben

 

Sorry, don't have the cam specs since GM doesn't supply a cam card with it.

I have a Precision Industries high-stall 12" converter that is stalling at 2600 rpm. I burn my own chips, so that's how I have it running so well. I prefer the higher stall for better launches when drag-racing, and am contemplating a Vigilante converter (also made by P.I.) for next spring once I'm finished my induction mods (heavily ported SLP runners and plenum). A higher-stall converter does make a car more drivable since it doesn't get lugged down in the low revs, but my engine still has plenty of torque from 1200 rpm on up.

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Greg Westphal
'87 IROC 355TPI/A4

 

The HOT cam is rated 218/228 with 1.6 rockers. With 1.5 rockers, the duration at .050'' changes. It will be something on the order of 1-2 degrees less duration. Anybody know? Greg, are you running speed density? How did the engine idle respond to the HOT cam?

 

The lift with 1.5 rockers would be .492" each side. I think the duration would only change by 1 degree, maybe 2 at the most, so it's be like a 217/227 cam or 216/226. I'm running MAF with the $6E code. It idled rough until I bumped the idle timing (in the main spark advance table) up to 30 degrees. I tried it in 2 degree increments from 18 up 30 degrees and found the best vacuum and it ran the smoothest at 30. I have it idling at 700 rpm in Drive for now, but I may turn it back up to 725 or 750 rpm since it's even smoother there.

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Greg Westphal
'87 IROC 355TPI/A4