Hello all, new to the board as a member but ive used this site as a great research tool but im at the point that I need to seek reliable members advice.

I own a 81 Vette 4 speed that was upgraded with a ZZ4 motor and 650CFM speed Demon carb. Recently I had a shop undertake a number of upgrades to the motor and after I did a lot of research on the Vette forum and asking around with the best setup, in the end the shop I had perform the work took their own liberty to order and install what they thought was best for the car and not what I wanted nor told me ahead of time. Ill describe what I had asked for versus what was installed and maybe im wrong about it all, but the boards opinions and thoughts are better than what I have in my limited knowledge and repertoire.

My build request was:
Lunati Voodoo cam 20120712
ProMag Push Rods 7.3"
Pro Mag Rocker arms 1.6" (int) 1.52" (exh)
Comp beehive valve springs & retainers

What was installed was:
MThumpr cam OE Roller 08-601-8
ProMag Push Rods 7.3"
Comp High energy 1.5" rockers 17001-16
Howards spring - 98212

When I picked up my car I wasn't even aware they hadn't ordered or installed any of what I wanted until I asked and saw my bill and their excuse was based on lengthy shipping times and accessibility, so they made an executive decision on what they installed as they had told me was common with alot of other vettes similar to mine they've worked on in the past. Now im only an enthusiast and took the shops word, as they're a very well known and reputable shop where I live and are mainly servicing and restoring corvettes and other older hot rods. Here's where my problem is, prior to the install I had fairly decent low end torque and modest mid level power and now I have nothing until at least 3,000rpm (Prius's accelerate fast than I do from a dig), and where I used to be able to chirp my tires, now im lucky to try and get the thing off the line but once it goes....it goes mid to high end is very fast. What I was aiming for was good power throughout and now im honestly having remorse with how my car performs, can anyone tell me if its in my head or if my build as I requested would make a difference than what im currently experiencing relative to my expectations.

Thank you in advance for your advice.

 

Does your car meet the requirements for this cam, stall speed if automatic, rear gears, intake, etc.?
https://www.compcams.com/*****-thump...oller-sbc.html

 

yes sir 10:1 and it’s a 4speed so no converter. The ZZ4 intake I researched suggests it’s more than sufficient.

 

What rear end gears?
Did you check the ignition timing?

 

that’s a good question, no I don’t know the rear end or have I checked timing, I don’t have a timing light.

 

Standard rear ratio for 81 four speed was 2.72 which is the wrong gearing for that cam.

 

🤦🏻‍♂️ I’m not sure what the trans ratio is, I’ll look for the serial # tomorrow to confirm.

thank you MelWff

 

Not transmission, rear end gears.

 

Well unfortunately they blew the cam selection.
I can't believe they made that kind of change without telling you!
They blew it so I think it is on them.
A ***** thumper cam will not run nearly as well as that voodoo would have.
Those are all about a tough sounding idle, but do not run very well. 235/249 is huge!

The cam changes:

• Extra 10 degrees advertised intake duration
• Extra 20 degrees advertised exhaust duration
• Extra 4 degrees .050 intake duration
• Extra 10 degrees .050 exhaust duration
• 3 degree tighter lobe center from 110* to 107*

Each one of those changes kills low end TQ, and pushes an all ready maxed-out street-marginal 231/239 cam further over the edge, and all of them together, basically destroys it's streetability.
What in the world made them think those 2 cams are even remotely similar????

I understand parts lead times, but I would ask for some compensation to change the cam back to something closer to what you wanted.
They should not have picked one that far off.

The ZZ4 was pretty mild. 208/221 dur @ .050.
You may not even want one as wild as that 231 Voodoo, if you are just cruising.
224 would be much safer. Things go downhill in a hurry past 230. (Like low end TQ.)
Do you want to race it?
Do you have at least 3.5 rear gears?

 

Too late now but would have changed the rear end gearing before messing with that ZZ4. It is/was rated at 355 horsepower. I had one in my 78 but it had 3:55 gears. Excellent grunt around town and smooth idle. I pulled it out to put the car back to original. Still have that ZZ4 tucked away in the corner.

 

I'm with Leigh on this one. The cam they installed was one of those Knuckle dragger cams. Makes it idle like, thump, thump, thump. So as to impress pre teen boys I guess.
Absolutely not even close to what you asked for. DEMAND they fix it! It's not what you hired them to do!
And then for god's sake learn to work on your own car! No one loves your car as much as you do!

 

Strange situation. The shop needs to fix it right.

That said...GM makes a "hot cam" for that engine. That would have been my first choice. Not my car, I know.

 

It seems they built the engine they wanted. Make them eat it!

Shoot the moon option: Get your money back, plus the value of the ZZ4 ($1-$2K?). They keep the engine, you find a better shop to install a crate engine built to your spec. Or DIY!

 

Talk to them and ask them to make it right. Explain you are not happy and the cam THEY selected because it does not perform like the one you wanted.
If they give you the run around or refuse to make it right then be prepared to go to court. This could be a bait and switch type case. How much did the total job cost?
Do you have some type of documentation of your requested parts that you wanted?
In the future, if you want a specific part or parts installed then make sure there is some type of paper trail with your request and their acceptance of the job. Also, when dropping the car off for the work, reiterate the parts list and ask to see the actual parts.

 

I have a ZZ4 in my '71. Before I installed it I was going to upgrade it the ZZ430 specs (the Chevy dealer I bought my crate ZZ4 didn't have any ZZ430's in stock or I'd just bought one already assembled) but ran out of $$$. I still plan on doing it but haven't looked at it in a long time since my ZZ4 runs great and made my car fun to drive. I'm not out to win drag races or anything. I just want some good street performance and fun. The ZZ4 does just that over the stock 270 horse engine that it came with originally.
Here are the specs. Not sure if they still sell the "hot cam" or not. This engine at the time was the LS of it's era.

• Power: 430 hp at 6,000 rpm, 430 lbs/ft of torque at 4,200 rpm
• Displacement: 350 cid, 5.7L
• Bore x Stroke: 4.00-inch x 3.48-inch
• Compression Ratio: 9.6:1
• Block: Cast Iron, 1 piece rear seal, 4-bolt main caps
• Camshaft: steel hydraulic roller tappet
• Cam Lift: .525-inch Intake / .525-inch Exhaust
• Cam Duration at .050-inch: 218 degree Intake / 228 degree Exhaust
• Lobe Separation: 112 degree
• Cylinder Heads: Aluminum, 3/8-inch screw-in rocker studs
• Combustion Chamber: 62cc
• Maximum GM Recommended rpm: 5,800

As far as the shop is concerned. I'd be pissed if they did that to me. In this day and age of cell phones anyone can be reached at any time. Just to go ahead and make the decision to put parts in without your consent is just bad business. I could see it if it were a part bolted on the exterior of the engine and could be easily replaced but internals? That's just insane to me.

 

Calgary,

So, as you were writing the check on your final payment to the shop, you must have been thinking:
Can't wait to burn the hides off the beast from the shop to three blocks away.
In reality, it felt like a dog, and you knew somethings was not right.
This is unacceptable.

I think I would make a copy of this entire forum post and show the shop about our opinions and of their craftsmanship & poor decision making.

Just my 2 cents worth, the Beehive springs? Meh. Just use strong std diameter.
A set of 16 Comps 1.52 rocker is an excellent choice without straining the valve guides.

 

That’s a really odd cam choice based on what you wanted. They could have substituted a comp xe282hr and been close, but that thumper is a different animal. I’ll bet they had that cam laying around.

Parts availability can always be a issue, but they could have come close.

 

Put a gear in it. Nothing will be right without a gear change.

 

Calgary.....I grew up there, and My family is still there....Welcome to the forum.

I can't believe they put one of those cams in....it's got to be the worst grind in the catalog. Not only that, but they chose to put in a cam that was quite different than what you wanted.
I even think the grind you wanted was even to big for a 350 on the street....it would be lazy until 2500 RPM.....I agree with the others that something around 220 intake duration with a 110 LSA would give you the lope and the performance to back it up, as well as loads more torque.

Time for you to make an executive decision.....tell them to take it out!

 

Thanks all for your input, I really appreciate the advice and input you've all confirmed just what I thought, the CAM needs to come out!.