572 in a C4?

[John Ross]

[font=Times New Roman,Times,Serif]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:[/font]

[font=Times New Roman,Times,Serif]One post said Hot Rod magazine did an article on this swap several years ago (1997?). Gist of it was: [/font]

[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]- use stock small block engine mounts/brackets [/font]

[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]- use GM oil pan 14091356 with Mark IV big block [/font]

[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]- use as-delivered pan with Gen 5 crate engines, they come with pan 10240721. [font=Times New Roman,Times,Serif]No mention of Gen 6.[/font][/font]

[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]- use '65-'70 big block Vette short water pump and corresponding accessory brackets (factory serpentine system won't fit), modify as required [/font]

[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]- clearance is especially tight between crank pulley and steering rack [/font]

[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]- use a '91-'95 LT5 heater core case (passenger side valve cover hits stock heater core case) [/font]

[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]- driver's side valve cover hits firewall inboard throttle cable pass [/font]
[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]through, modify VC as required [/font]

[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]- use small distributor cap [/font]

[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]- use '70-'74 big-block Vette exhaust manifolds or custom headers.[/font]

[font=Times New Roman,Times,Serif]Then I found this on the BBC - C4 swap:[/font]

[size=+0][font=Times New Roman,Times,Serif][font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]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:[/font][/font][/size]

[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]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);[/font]

[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]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)[/font]

[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif](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.[/font]

[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]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.[/font]

[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]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![/font]
[font=Verdana,Geneva,Arial,Helvetica,Sans-Serif]
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.[/font]

[font=Times New Roman,Times,Serif]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.[/font]

[font=Times New Roman,Times,Serif]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.[/font]

[font=Times New Roman,Times,Serif]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.[/font]

[font=Times New Roman,Times,Serif]Intend to use a 4LE80 or Art Carr-modded stock automatic. Will the bigger auto pose major clearance problems?[/font]

[font=Times New Roman,Times,Serif]I intend to have to put a hood scoop over a hole in the hood. [/font]

[font=Times New Roman,Times,Serif]Does anyone make BB "shorty" or block-hugger headers with primaries bigger than 1 7/8"?[/font]

[font=Times New Roman,Times,Serif]Any real experience on BBC-C4 appreciated.[/font]

[font=Times New Roman,Times,Serif]JR[/font]

 

[redc4corvette]

If you want that much power go all the way click below.



http://www.sdpc2000.com/cart.asp?action=prod_detail&catid=1579&pid=14349

 

[corvette66]

Looks like you are in for a big project. I have been working on the same thing. I am installing a 502 in a C4. I have not yet finished building the motor yet but I did start to research the swap. I found the same info you found, The major problems I have come across so far were.: the steering rack has to be modified, motor mounts probably have to be altered. Other than that I have not come across much else. I have had the motor out of my car and did all the measuring, looks like it will slid in pretty easy. If you come about some other info let me know. And i'l do the same. I also have looked for the 1998 magazine, but have not been able to get ahold of it

good luck

 

[redc4corvette]

You will be out $30,000 and the rear end will still not be strong enough for the car.just my 02 worth.

 

[jpanek]

OK, don't laugh please - anyone thought of dropping a Northstar V8 in there? I know they don't have torque and power like the big blocks, but they might have these advantages: less expensive, 32 valves breathing, OBDII for diagnostic help, etc. I'll go check the web to see what people have done to them for more power.

 

[Aurora40]

If you want 32-valve breathing, why not just get a ZR-1? The 300hp Northstar is a lot weaker on <5000 rpm torque than the 275hp motor. Now, toss on twin turbos like some sand cars have, then you're talking Northstar power!

In regards to the big block, there was a ZR-2 big block concept car that I think GM did, but maybe it was not GM. This was in the 1990 time frame with a 454. I recall a Road & Track article on it. Might be worth a trip to the library?

 

[Mad-Mic]

If you want that much power go all the way click below.



http://www.sdpc2000.com/cart.asp?action=prod_detail&catid=1579&pid=14349

not streetable at Compression ratio is 14.4 to 1. if you want something alittle more streetable in BB application check out http://www.shafiroff.com/598_755_engine.asp and if you want a race motor with 14.1 to 1. compression then check out http://www.shafiroff.com/632_bigduke.asp and call it a day and IF thats not enough then get the http://www.shafiroff.com/706_bigchief.asp !

if you want BB performance with alot less modifying then check out http://www.shafiroff.com/472_675_engine.asp drop it in, bolt it up, and drive it all day

 

[Mad-Mic]

OK, don't laugh please - anyone thought of dropping a Northstar V8 in there? I know they don't have torque and power like the big blocks, but they might have these advantages: less expensive, 32 valves breathing, OBDII for diagnostic help, etc. I'll go check the web to see what people have done to them for more power.

why would you want to do this? good luck trying to find parts for this motor since it is setup for a FWD application. when you do have fun modding the existing engine cradle. alot of these guys that do it build the car around the NorthStar motor like T-Buckets and such. very hard and financially draining to try and modify everything else to fit the motor in. same with a big block. you'll spend a small fortune easily.

like what i posted earlier 472 cu sbc pumping out 675 hp and if thats not enough Juice it or Blow it and your looking at 1200 hp easily!

yeah it's cool to say you got a Big Block in a C4 but i would think it would be even more cool to say I got a Big Inch Stroked Small Block with an F4 ATI Blower pushing 1000 hp on pump gas!

 

[Aurora40]

why would you want to do this? good luck trying to find parts for this motor since it is setup for a FWD application. when you do have fun modding the existing engine cradle. alot of these guys that do it build the car around the NorthStar motor like T-Buckets and such. very hard and financially draining to try and modify everything else to fit the motor in. same with a big block. you'll spend a small fortune easily.

Just FYI: http://www.chrfab.com/Engines.htm Plenty of RWD'd Northstars for sale at varying power levels.