[FONT=Times New Roman]I'm selling some vehicles and am interested in building a C4 Corvette with a 572/620 crate motor in it. Here is what I've gleaned from web surfing:

One post said Hot Rod magazine did an article on this swap several years ago (1997?). Gist of it was:[/FONT]

- use stock small block engine mounts/brackets

- use GM oil pan 14091356 with Mark IV big block

- use as-delivered pan with Gen 5 crate engines, they come with pan 10240721. No mention of Gen 6.

- use '65-'70 big block Vette short water pump and corresponding accessory brackets (factory serpentine system won't fit), modify as required

- clearance is especially tight between crank pulley and steering rack

- use a '91-'95 LT5 heater core case (passenger side valve cover hits stock heater core case)

- driver's side valve cover hits firewall inboard throttle cable pass
through, modify VC as required

- use small distributor cap

- use '70-'74 big-block Vette exhaust manifolds or custom headers.

Then I found this on the BBC - C4 swap:

I have worked on several of these swaps now and I’m in the process of getting ready to do another one, here’s what’s needed:

Steering rack mounts cut and rewelded 3/4"-1" farther forward (that of course means the power steering pump lines/steering shaft, need to be extended 3/4" also);

Small notch (starting at rear and going 3" forward from rear edge X 3/4"deep X 5" wide works well in rear top surface of (K) frame cross member to clear damper and pulley) (if you use an internally balanced big block with the 6.75" dia. damper you can most likely skip the notch but with the 8" dia. damper its necessary, and some oil pans will also require the back 1 1/2 of the (K) frame to be notched at an angle sloping to the rear to clear them so you’ll probably need the notch of some kind anyway)

(and yes before you ask you could shim/modify the motor mounts up to get the clearance, but that would slightly raise the weight center and slightly affect the handling, and that also makes the windshield motor and distributor clearance a bigger problem, a 1985 blazer wiper motor can be modified for greater clearance on the valve cover and swapped in to gain valve cover clearance)

Air conditioner shrouding fiberglass on passenger side footwell around the air conditioning on the firewall needs to be modified for clearance, (the fiberglass cover from an LT5 makes this easy--evaporator housing cover)

1971 bbc Vette exhaust manifolds (or custom headers) and all brackets/pulleys (mods needed here) (see the post on building your own headers). Oil pan needs to be only 7.5" deep max.

3" hood scoop unless you run a low rise intake and carb or a low height efi system.

For a step by step instructions with pictures get a copy of the August 1998 Vette magazine article (starts on page 34) it helped quite a bit the first time.

Otherwise it’s almost a drop in deal, but keep in mind that you’ll need a bigger radiator, the trans will not last too long with that amount of torque, and it may not pass emission testing.

A small size starter is needed, and your windshield wiper motor needs to be replaced with a much smaller one, I don’t remember where we got them, but a little measuring and a trip to the salvage yard took care of that problem, and no, tall valve covers don’t work well!

BTW install the short block then add the heads with it in the car its FAR EASIER THAT WAY than trying to install the long block. Is this true? Even with the clamshell hood removed?

BTW the earlier cars like the 1984-86 (I’m not sure what years exactly) don’t have the heavier forward frame bracing above the steering rack that makes this swap more difficult to do! I have worked on this swap on the 84, 85, and 86 cars so I know they work fine, the later cars like the 1992 with the heavier forward frame braces above the steering rack look like they will be more difficult but still do-able with some extra work, btw there’s a guy at ARIZONA SPEED AND MARINE that has one you might want to talk to.

Anyone have any experience here? Did Hot Rod do an article? Does anyone have the Vette 8/98 issue? The company only goes back 12 months on back issues. I know GM did the "Big Doggie" but have little details.

Don't have the car yet--am thinking '90-'91 to get the big brakes, 17" wheels, nice dash, but not pay for the LT-1 of the '92-and later cars. Maybe I can find an auto trans car at auction with a rod knock or something.

This will not be a drag car, I just like torque on the street. Had a '96 Viper coupe with which I was Eastern Region champion in the Supermodified class of the Michelin Challege (Viper Roadracing Series) in 1999. Sold it after my stroke and divorce, but things have improved much since then and I thought this might be a fun project.

Intend to use a 4LE80 or Art Carr-modded stock automatic. Will the bigger auto pose major clearance problems?

I intend to have to put a hood scoop over a hole in the hood.

Does anyone make BB "shorty" or block-hugger headers with primaries bigger than 1 7/8"?

Any real experience on BBC-C4 appreciated.

JR

 

John,

First of all, welcome to Corvette Forum. I'm surprised nobody has chimed in here on this one yet, but then again, your plans are *really* extreme! I can't say that I know of anyone (off hand) with a Big Block C4. Now that's not to say that it can't be done...I saw a Viper V10 in a PT Cruiser once, so I know anything's possible...but you just might be the first to do it at that level.

As for the tranny, I can maybe chip in a little on that one, but only to an extent. At the shop where I recently had some work done, they were doing a ground-up rebuild on a 64-67 Coupe (though I have no idea what year...it was pretty much just bare fiberglass). They put a 502CI motor in, and mated it up to a 700R4 tranny. Now I know that's not as big as what you're talking, but at least it's one example of something that is being done - even if not in a C4 shell...

Best of luck to ya', and again, welcome!

 

The 572 is a big block with a higher deck height.

Sure, it will fit, and, there are some here on the forum that have done it.

Is it practical? hell, no. but who cares.

I read an article in one of the vette mags, can't remember if it was Vette or Corvette Fever about a guy who has done this.

 

Leon from the Frederick CC did his own conversion, making all the brackets and pulleys from billet aluminum himself. He used block-hugger headers from Edelbrock (I think I remember). He fabricated his own plenum to go over an Edelbrock (Holley?) injection setup with DFI. It is a sweet looking installation all told.

He won a celebrity pick at Carlisle and was invited to the museum to show his ZR2 with the original Chevy museum car.

He runs a machine shop so he was able to fabricate everything himself. Really a sweet car!!

Here's a shot of his motor.


Here's a shot of his car at Manassas cruise in: