Need some ZZ4 input...
Drifting
Joined: Jul 1999
Posts: 1,541
Likes: 43
From: Plano TX
I put a ZZ4 in my 80 vette several years ago and have been very pleased with the power. Remember the ZZ4 is a torque motor and yes HP helps but it's torque that spins the tires.
Mine makes 290 HP at the rear wheels with a stock rochester. I was down on HP at first and found the secondaries weren't opening all the way. My car will spin the tires no problem so I suspect carb, ignition or major exhaust restriction
Mine makes 290 HP at the rear wheels with a stock rochester. I was down on HP at first and found the secondaries weren't opening all the way. My car will spin the tires no problem so I suspect carb, ignition or major exhaust restriction
Last edited by DaveL82; Dec 14, 2009 at 08:18 PM.
Drifting
Joined: Apr 2002
Posts: 1,736
Likes: 37
From: Stockton Ca
Dyno Time?
I thought my 74 was not too bad, until the dyno tech found 80 hp!
I agree that you need to make sure you are getting proper ign and carb is opening properly. After that you can think about what to do next!
Are you running fresh wires, cap, rotor? These things together can make a big difference.
The ZZ4 is a little over rated, but it can be made to do whatever you want done. JMHO
R
I agree that you need to make sure you are getting proper ign and carb is opening properly. After that you can think about what to do next!
Are you running fresh wires, cap, rotor? These things together can make a big difference.
The ZZ4 is a little over rated, but it can be made to do whatever you want done. JMHO
R
Melting Slicks
Joined: Dec 1999
Posts: 2,116
Likes: 156
From: Mid West
Cruise-In III Veteran
Check to see if your getting full throttle. If they used the Q-jet throttle cable bracket with the Edelbrock, your probably not ever at full throttle. Have someone push the throttle pedal all the way down, and look at where your secondaries are at. I had that problem at first and I was down a good 60Hp.
I also recommend that your recurve the HEI like someone else suggested. It made a world of a difference to the throttle response.
With GM's hot cam and a home port job of the L98 heads, I'm running consistent low 13's, with a best of 12.8 sec 1/4 miles. This is with the car setup for road courses, so it's not even optimized for the strip.
Here's my dyno sheet at the rear wheels.
I also recommend that your recurve the HEI like someone else suggested. It made a world of a difference to the throttle response.
With GM's hot cam and a home port job of the L98 heads, I'm running consistent low 13's, with a best of 12.8 sec 1/4 miles. This is with the car setup for road courses, so it's not even optimized for the strip.
Here's my dyno sheet at the rear wheels.
Thread Starter
Advanced
Joined: Dec 2005
Posts: 70
Likes: 0
From: Martin TN
After driving it the last couple of days, I had to reset the timing tonight. Previously, I had to set the initial to 18deg to get the total to 34deg or so. It ran ok but it pinged on light acceleration. MPG decreased drastically also. I reset the initial back to 12 deg. I think the total now is 26-28deg @3000 rpm. When I had the idle set at 3000 rpm to set the total, I noticed a slight popping noise from the tail pipe, and I've noticed a slight rocker rattle noise when driving. Could the valves need to be readjusted? The car seems to run really strong at WOT and just off idle, but it feels flat and almost feels like it is missing under half throttle acceleration. It seems to go away if I increase throttle to WOT. I'm a little confused about that part. I'll see if the local parts store has a recurve kit for the dist tomorrow. I have a stall converter left over from another project I'm planning on installing over the holidays. It's a TCI Sizzler. It's not much but I've already got it so it's worth a try I guess.
Drifting
Joined: May 2005
Posts: 1,629
Likes: 4
From: Somers CT
After driving it the last couple of days, I had to reset the timing tonight. Previously, I had to set the initial to 18deg to get the total to 34deg or so. It ran ok but it pinged on light acceleration. MPG decreased drastically also. I reset the initial back to 12 deg. I think the total now is 26-28deg @3000 rpm. When I had the idle set at 3000 rpm to set the total, I noticed a slight popping noise from the tail pipe, and I've noticed a slight rocker rattle noise when driving. Could the valves need to be readjusted? The car seems to run really strong at WOT and just off idle, but it feels flat and almost feels like it is missing under half throttle acceleration. It seems to go away if I increase throttle to WOT. I'm a little confused about that part. I'll see if the local parts store has a recurve kit for the dist tomorrow. I have a stall converter left over from another project I'm planning on installing over the holidays. It's a TCI Sizzler. It's not much but I've already got it so it's worth a try I guess.
If you're hearing a popping noise combined with rocker noise, you could have a valve train issue. Those are hydraulic lifters, once properly set they should not need adjusting and should be very quiet. Has someone changed the rockers to roller tips by any chance? Those sometimes are noisy.
Make certain your rotor, distributer cap, wires and plugs are in order. Pull the valve covers, look at the rockers verify they are stamped and original and adjust them properly for a hydraulic roller lifter.
Also, some good advice given above about checking the throttle linkage to make sure the throttle plates are opening 100%.
Pro
Joined: Oct 2002
Posts: 733
Likes: 15
From: Clarksburg NJ
Check to see if your getting full throttle. If they used the Q-jet throttle cable bracket with the Edelbrock, your probably not ever at full throttle. Have someone push the throttle pedal all the way down, and look at where your secondaries are at. I had that problem at first and I was down a good 60Hp.
I also recommend that your recurve the HEI like someone else suggested. It made a world of a difference to the throttle response.
With GM's hot cam and a home port job of the L98 heads, I'm running consistent low 13's, with a best of 12.8 sec 1/4 miles. This is with the car setup for road courses, so it's not even optimized for the strip.
Here's my dyno sheet at the rear wheels.
I also recommend that your recurve the HEI like someone else suggested. It made a world of a difference to the throttle response.
With GM's hot cam and a home port job of the L98 heads, I'm running consistent low 13's, with a best of 12.8 sec 1/4 miles. This is with the car setup for road courses, so it's not even optimized for the strip.
Here's my dyno sheet at the rear wheels.
My ZZ4 is fuel injected, but my best ET to date is 12.85 @106. (3:55 gears)
Drifting
Joined: Jul 1999
Posts: 1,541
Likes: 43
From: Plano TX
You must set up the initial timing correct and then work on the advance issue. Do not let the motor ping as the hypereutectic pistons don't like it at all!
Your best money spent is not on new HP parts but a dyno run so you see if the carb is working right and if there is a mixture or timing issue. Make sure you find a place that knows carbs.
You've got some good parts there to make a fun ride so I think it just needs a bit of tuning.
Your best money spent is not on new HP parts but a dyno run so you see if the carb is working right and if there is a mixture or timing issue. Make sure you find a place that knows carbs.
You've got some good parts there to make a fun ride so I think it just needs a bit of tuning.
Thread Starter
Advanced
Joined: Dec 2005
Posts: 70
Likes: 0
From: Martin TN
I got the recurve kit tonight but didn't have time to mess with it. I've noticed, at part throttle, acceleration it is very flat and it seems to miss at upper rpms but as soon as I go to WOT the miss goes away, and it pulls very hard. I know the timing needs some attention to get to 36deg total while maintaining 12deg initial but I don't see how this would cause the miss. I have replaced the cap/rotor/ wires and the plugs look new. I would love to take it to a dyno but the closest one is probably 300 miles away. As a side note, I found some old receipts where the PO had the car to a couple of different shops with lack of power being the complaint. Not repairs were ever made according to the receipts.
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Thread Starter
Advanced
Joined: Dec 2005
Posts: 70
Likes: 0
From: Martin TN
Well I got the dist. recurved and the timing is where it should be. Still no power. Runs ok a WOT but anything less than WOT and it is a DOG. Still can't even break the tires loose from a dead stop.
Safety Car
Joined: May 2003
Posts: 3,814
Likes: 105
From: Dearborn Heights Michigan
When I went up 5 jet sizes on my Holley 670 Street Avenger,primary & secondaries, the motor went from night to day in terms of performance. Also, when installing the carb, I initally didn't realize there were 2 fuel inlets on the carb and quickly found out it would run good at steady state , but, a dog otherwise.
Last edited by FKING1; Dec 21, 2009 at 04:27 PM.
