zz383/425hp in a 66 Corvette

[Dennis B.]

Has anybody tried or have any advice on putting a zz383/425hp Chevy crate motor in a 66 Corvette with 3:55 gearing?

[Ed Jennings]

Re: zz383/425hp in a 66 Corvette

Due to the increased height of the Vortec heads, you might have a hood clearance issue. A big block hood would probably solve the problm.

[Joe R.]

Re: zz383/425hp in a 66 Corvette

Dennis,

I have never done that but it should be a piece of cake. Please, Please keep us informed when you want to accomplish this task. I'm gettin excited just thinking about a 383/425 in a 66. Makes me want to jerk the BB out of my 66 roadster and order me that neat little package.

Don't forget to keep us informed.

Regards,

JR

[Michael H.]

Re: What is it?

Joe,

Ok, I give, what's a ZZ383/425?

[Joe L.]

Re: What is it?

Michael------

It's a GM Performance Parts crate engine. It is 383 cubic inches and, as configured, generates 425 hp and 449 lb/ft of torque. Basically, it uses a 350 cid standard bore (4.00") and 400 stroke (3.80"; original 400 cid was 3.75")to yield 383 cubic inches. This engine is, essentially, a 383 cid version of the ZZ-4. It uses "fast burn" aluminum cylinder heads, 4 bolt main block, forged steel 1 piece rear main seal crank, hypereutectic cast aluminum pistons, 9.1:1 compression ratio, and a special high performance, hydraulic roller camshaft (not the same as ZZ-4). The engine is not supplied with an intake manifold. The heads will accept either a Vortec or conventional intake manifold. It is available from GM under p/n 12498772.

[Michael H.]

Re: What is it?

Thanks Joe, looks like I need to get current on all these new toys coming out of GM. Sounds like that would make an excellent street motor for my 63. Would be nice to just park the original motor in the corner and put in something that I could have fun with.

Are you saying this motor could be fitted with a conventional old style intake manifold? Interesting! I could install the old Rochester FI unit?

Michael

[Joe R.]

Re: What is it?

Michael,

Yes, get with the program. Check out your local Chevy performance dealer for the latest fire breathing monsters Chevy makes. That 383 won't make close to 425hp with that old FI but with a good aluminum manifold and a Holley it will.

That old 66 roadster I have has a Chevy LS-7 crate motor in it. After Reher-Morrison did the heads it will pull stumps. Old technology but it will stripe the street.

JR

[Joe L.]

Re: What is it?

Michael------

I posted confusing information regarding the intake manifold options for this engine. It can be used with Vortec or RAISED RUNNER style conventional manifolds. It cannot be used with original configuration 55-82 Corvette small block intake manifolds. When used with Vortec manifold GM #12496820, it will fit under the hood of most C2 and C3 Corvettes. With high rise Vortec manifold GM #12366573 it may or may not fit under C2-C3 hoods.

[Michael H.]

Re: OLD Rochester???

Joe,

I'm going to have to investigate but I think we need to discuss something you said about not makin much power with "that ol Rochester FI unit". (oh, here we go!)

In 1989, I put a Rochester unit on a 63 Vintage race car that was running consistant lap times of 2:40. at Road America with a curent Holley and intake. The engine was a "today" 355" with all the good stuff in it. I installed the Rochester unit that I built for it and with no other changes, the car was running consistant lap times of 2:37/2:28. That first weekend, it beat a Cobra for the win and a GT40 that wasn't even in my class. After the checkered, a lot of people came over to see the car and were absolutely shocked to see the old Rochester unit on it. "That's inpossible", those things never worked that well... did they?? Well, I guess it all depends on who builds it! Actually, the unit was surprisingly close to stock with only a few modifications.

I've never road raced a car that I liked better than that one when it was injected. I drove well with the carb but it was so much better coming off corners with the Rochester unit.

Guess I'm totally off the original subject now, sorry. I'll send ya a few pic's of the car and the FI unit in place.

I'd love to have that new 383 in my coupe with the FI on top. Bet the old Corvette valve covers wouldn't fit tho....

Michael

[Jim Klug]

Re: zz383/425hp in a 66 Corvette

It's a 350CC Stroker the 383CC crate motor is a great match I am thinking of puting one in my 66 Coupe with a 700R trans and FI ! Keep me up on your change.

[Michael H.]

Re: What is it?

Thanks Joe. Was just my luck, too good to be true that the FI would just "bolt on". I'd probably be better off building an older motor with pre raised runner heads anyway.

[Mike M.]

Re: OLD Rochester???

mike: did you add an extra air meter to the rochester? the 585 cfm an ole rochester allows in probably not enough air for a 355 ci engine to perform efficiently. Frank scibiaca told me to space the diffuser cone out away from its mounting plate and he felt the cfm might approach 600. your thoughts? mike

[Michael H.]

Re: OLD Rochester???

Mike,

No, I've seen that done many times in the old days and it never worked. I remember when Ralph Salyer tried that on his new 63 A/P Corvette and it was quite a bit slower. He was back to a single A/M thenext day at the track.

Nickey Chevrolet in Chicago used to sell a complete kit to install the dual A/M setup and several people tried with the same negative results. The second A/M would have been near 1200 CFM and that just killed the slight signal needed for the main control diaphram.

The runners and the manifold in general was a wonderful design and was quite sufficent for 327" or 331" motors but after that they dropped off pretty bad. The restriction was the air meter and specifically, the pizo ring and cone. The easiest way to increase air volume was to increase that area so I started installing spacers between the cone and the pizo ring. Because the cone is taperes, the total area of air inlet was increased quite a bit for every .030" of shim I installed. When I first ran the car in practice on Friday, I had zero spacers and the motor ran out of breath about 600 or 6500 RPM. Over the next several test sessions, I wound up adding about .060" of spacer plus recalib after every change. At the final dimension, the car pulled incredibly strong at high RPM and probably would have been well suited for 9000 if I wanted to push it but I kept it under 7000 most of the time. It didn't take much in the way of spacers to duplicate the 750 CFM of the Holley carb that was on it.

The low speed operation was affected slightly after the spacers were installed and drivibility would have been a bit tricky on the street but I never had time to really finish the project.

I'm sure you know, Road America is definitely a horsepower track, being four miles long and if things aren't right, you know it immediately. Slight incorrect something and you can drop five seconds off your lap times.

I had a video camera mounted on the roll bar just behind and to the right of my head and it shows every moment of the entire battle with the GT40. It took four laps but I finally got him coming down the long hill and into corner 5. Later, I was told there was an incredible round of applause when I finally got by him. The Corvette people were happy!

Michael

[Clem Z.]

Re: zz383/425hp in a 66 Corvette

a friend has this engine in a C-4 with the edelbrock FI setup

[Jerry S.]

Re: OLD Rochester???

You beat a Cobra? Come on who are you kidding? Are you sure this is not the touring class? 2.37 in your dreams.