A bone-stock ZZ4, when installed in a C3, will crank out a minimum of 290 RWHP - no fuss, just pop it in and get the good numbers. Yes, you lose the chance to scrape some knuckles and swear up a storm, but you're guaranteed to get results.

 

Very true............., but where is the fun in that. For many people this is easy solution, but for others like me, it takes away from the very thing that makes this hobby so much fun. Anyone can go down the the local Chevy dealer and write a check. That is not to say that there is anything wrong with that, but it sure takes the fun out of bench racing if every body is running the same combo. On the other hand, building your own unique engine that is carefully pieced together using gathered info to match components as well as you can is where the challenge and enjoyment is. In my case, I enjoy changing my combination from year to year in a never ending process to try and equal or better the power produced by some of the more modern engines available over the counter. It is by no means easy and often disappointing, but when I have success, it is so much more rewarding than having simply opened a crate. :chevy

Tom

 

I couldn't agree with you more, Tom! Is that why you're so eager to help me with this engine of mine?
Anyone can install a ZZ4, or something someone else built. I'm so damn excited to build this engine of mine! I've never heard of anyone running the XR264 cam. Guess I'll just have to be the first, no? I can't wait to put the general in his place. I hope we can do this, good buddy. I also hope that you can get to the bottom of your problems. As said, I'm willing to help as long as you give me a bit of warning!
-Steve

 

tom
for the same effort shimming the springs, you might as well change them. Speedway has a 125# set for $40. Designed for a SOLID cam. :yesnod:
part # 577-810107

 

I didn't mean to say that no one should ever give it a go; Lord knows I have - once from scratch with a friend and the second time had the short block done professionally, then a neighbor and I finished up the rest. Both times were very satisfying, but both required alot of time and effort. The third time a rebuild was considered (due to emission requirements), I asked a well-known Corvette specialist what the cost would be to change the cam. He asked me if I wanted some guaranteed tire-spinning power, no tinkering, and a very clean (no worries with smog test) engine. I said "Heck yeah!" and he recommended the ZZ3 (many years ago). I couldn't have beed happier, since shortly thereafter, most of my time was spent driving, not tinkering.

Recently, Corvette Fever magazine decided to build-up a 350 that would pump-out 400 horses (net) and stick it in a C3. After much tweaking and fine-tuning the carb, distributer, etc, they found that the setup failed smog. Their solution? They tacked-on some catalytic converters. Yes, their engine pumped out a bit more HP than the ZZ4, but it had to be saddled with those darn converters.

So, give it your best shot (as I did); it's a great experience. The next time, though, you want to free up some of your leisure time to enjoy that car of yours.

Good luck!

Dave

 

Tom,
i agree w/ drives61 on this- if your gonna go to the trouble of pulling springs you might as well put fresh(better) ones in and, just possibly, solve your problem. Also, if that fails to help I had another thought- I apologize if it was mentioned above but I missed it. Have you checked your fuel pressure to make sure it's up to par? Just a thought....

 

I read through the whole thread quickly and didn't see anything about airflow...

The first thing that came to my mind when you mentioned that actually driving the car felt better, but the dyno pull showed worse was that maybe you're pulling cooler air into the intake at speed than on the dyno. It would be nasty for power if really hot engine compartment air were being sucked in while doing the pulls.

Some years ago when I did some dyno runs they brought out the biggest damned squirrel cage fan I ever saw and practically blew my car off the platform.

-Noel

 

I just finish doing my ZZ4 swap and there was alot of fun involved in it. I got more then my fair share of cuts and scraps. I feel the zz4 is an excellent motor and does take some of the work out of it. I personally like building motors, but hate dealing with piston ring filing. That just sucks. I am still working on my big block, but that will have to wait until I finish college. Money is the main issue. I want to do that project right and make a minimum of 500 horses. The zz4 is effecient and great, but the only way I think someone loses out is when they pay someone else to do the job.

Mark B.

 

Well, I performed a leakdown test using a makeshift setup and at the very least found all cylinders to be consitent with %10 leakdown on luke warm forged pistons. This number should drop significantly when at operating temperature and pistons expand.

drives61, After looking over the dyno printout closely with Chuck Harmon earlier today, It may very well be that this valvetrain is functioning fairly well, but could use a bit tighter lash and better mufflers to bring it to life. As I reported earlier, I am now getting 12v at upper RPM, but have not had a chance to do any test drives. I don't think the dyno printout shows any valve float, but very subtle fluctuations indicating that the ignition was not at it's best. Regardless, I think I will just go ahead and throw on those springs you recommended for the sake of "doing it right". Besides, I've been wrong before, so I may just be pleasantly surprised with a burst of unleashed HP. I sure hope so.

Steve, You asked if that is why I'm so eager to help with your upcoming engine project. Ummm.....not exactly "eager", but willing. ;) :jester

Dave68, I can't argue with that. The ZZ4 is a damn good motor, however, if I'm gonna get crazy with my credit card at a Chevy dealer, it would be the ZZ502 that would be inside the crate :D Now that sounds like fun, huh? If you're gonna be a bear.....be a grizzly!!!

Les, The A/F readout looks pretty good, so I doubt that there is any fuel starvation issues. In fact, it seem to richen up a bit at the end, which could go along with the ignition and restrictive muffler theory.
Also, I completely agree with you and drives61. If I'm going that far into the motor, I might as well just replace the springs and be done with it. BTW, do you happen to have a 9/16" I can borrow ;) :jester :jester

Noel, They did not use a fan for any of the cars(except for the turbo RX-7). I did my runs with the hood up, so I don't know exactly what impact that would have made for me compared to others.
I believe the flatter torque curve of this solid cam over the old hyd is why this thing seems so much stronger now. I can't really say that it pulls much harder up top, but the revs just keep climbing past 6+, whereas the old hyd ran out of steam around 5200 and then dropped off significantly.

Thanks for the input everyone. I will be doing more work to the motor as time allows and will post my results. Stay tuned :cheers: