Ive gotten alot of help from Grumpy on this, and I actually have a slow moving build thread over on his website centering around me swapping a 1999 gen vi 454 into a 1986 corvette.

for those of you BBC guys who have performed the swap, were any of you able to accomplish a serpentine belt accessory drive without relocating the steering rack? I was olanning on doing it yesterday, but it looks like no small task. Also, I know a few folks have accomplished the swap without it.

Does anyone have any pictures of pulley to rack clearance?

 

A few here have done them, sure youll get an answer. Would love to have a bg block in a C4 esp with a manual...Id use a 396 just for its unique exhaust note
That will be a monster even with a mild 454

 

a 396 sounds different then a 454?

 

..... Yeah ... it sounds like fewer cubits .....

 

..... Show us a pic of your pulley to rack clearance .....

 

Right now its enormous since the motor is on a stand, and the engine bay is empty.

 

..... Have you done a test fit ? .....

 

Not yet, but because of the clearances, time constraints and difficulty procuring volunteer labor, I’m trying to just out it in once.

 

For what it's worth, make sure you figure out what flex plate/torque converter you are going to use, if you have the automatic 700r4. GM never bolted a BBC to the 700r4 and I believe there will be balancing/bolt hole location issues between the two (flex plate/torque converter)! What I mean is, if you get the externally balanced flex plate that your BBC has to have, the bolt pattern/location will not line up with the 700r4 lock-up torque converter bolt hole pattern/location! I'm sure someone out there has solved this problem, but I am unaware of where to get the right flex plate. Of course if you have a manual transmission this is irrelevant (unless the externally balanced flywheel for the BBC is different from what the 4+3 tranny uses, if it's unique in anyway). Short of drilling/grinding out the existing holes, I'd find one that is correct! Thought I would mention it before you get it all installed and go to put the torque converter bolts in and then realize the problem and the transmission has to come back out! Good luck 👍

 

Good advice!

https://www.summitracing.com/parts/pqx-1845401

 

454 is externally balanced I believe. The 454 will fit its been done before. Somebody
put a 540 in his on this forum awhile back. What are your build plans?
Get a DeWitts or Cold Case radiator and a real good set of fans.
That would be fun...esp wtih turbo style mufflers and stock wheels. Stealthy!

 

Hastings moly rings, clevite 77 bearings, stock bottom end, stone honed cylinder walls, comp cams XM284HR .547/.547 230/236, L29 heads ski jump smoothed, short turn radius work, valve seats are in good shape, so lapped valves, comp .300 rotator eliminators, pac-1220 valvesprings with 10 degree titanium retainers and locks, and new hardened stock length pushrods with the stock non adjustable valvetrain, Holley oval port efi single plane intake, 300 lph in tank pump, Siemens Deka 80 lb. injectors, Edelbrock 4150 throttlebody, pro-comp reverse flow aluminum short water pump, stock c4 corvette accessory brackets.

thats what is being built currently. After I recover from that financially, I would like to put a single summit racing s475 on it and run 10 lbs of boost (hence the reason for the 80 lb. injectors)


Intake mocked up on my kitchen counter. My wife was a big fan of this maneuver.

Me (in the green) and my buddy yanking the subject 454 out of my 84 SS (its getting a 468 all forged main and head studded edelbrock headed .612 lift Firebreather)

On the stand getting ready for the rebuild

The Corvette is a fiberglass Vessel, now with a mercruiser 7.4 in it, its only fitting the cam be a marine cam.

Cam specs

Hastings rings

Mocked up

Teardown begins

Teardown continues

Head stripped bare

Dirty piston before

Dirty piston after

Dirty heads before


Ew

Barf

Yaaaaaaay

 

That's a baby cam for a 454. Though the marine grind comps work really well for whatever reason... nice fat powerband... I have a marine grind in mine. I like.

 

Its bigger than the cam that comes with the Zz454/502, and its right at the limit of ptv clearance, guide/seal to retainer clearance, and the stock heads really wouldn’t benefit from more cam.

I picked this cam for longevity, the ability to use the factory valvetrain, and it will work pretty well with low boost (under 14 psi)

pre turbo, with a good tune, this combination should be good for a very honest 425 horsepower and 510 ft lbs of torque at the crank.

I am hoping for c4 zr1 levels of performance out of the gate

 

I need to keep an eye on this build. Always loved C4's and love the idea of a big block in one. I'm west of you about 2 hours so maybe I can see this bad boy on the road some day!

 

👆. This is what Id do vs. an LS swap

put a lightweight hood on and you’ve mAde up the weight penalty

 

At first I was like only 425hp... then I remembered how terrible those stock heads are lol. With a decent head that's a well over 500 cam all day imo. The 425 is reasonable given the combination imo. I like comps marine grinds if I haven't said it already. They all favor average power ove peak from. What I've seen.

 

do you weld lol.

does anybody in here live in central florida and want to help me relocate the rack? It seems to be the last piece of the fitment puzzle.

 

That looks like a lot of fun! I have many memories of building my 427. Big Blocks are fun but a bit more expensive than their smaller brethren. When I rebuilt my 427 the parts for a BB were about 50% more expensive than for a small block.

If you are trying to squeeze one between the frame rails I would have started with a Plastic 454 and made everything fit while working around the plastic block. Makes it MUCH easier in the long run. They sell them at Summit and Jegs.

I bumped my compression up a bit to the L88 levels and that "really" woke up my engine. I use Water/Methanol injection system when the weather is warmer but can run on Pump gas in the cooler weather even with 12.25-1 Compression.

Get the very best heads you can that avoid detonation, in the old days when I built my 427 the aluminum heads were too expensive so I chose to use a GM cast Iron head with "Closed Chambers". After doing lots of research I learned that the "Closed Chamber" was preferred over an "Open Chamber" head as the open chambers got better emissions but had problems with detonation. These heads fit the pockets in the L88 pistons. The closed chamber heads were used on earlier engines but used up to 1970 on Big Block applications. The newer cylinder head designs and shapes are probably better than my old heads for Detonation prevention.

I like your fuel injection system! Why did you choose to mix components? I had a tough time deciding but finally bought a Holley EFI System which simply replaces the carburetor as opposed to a system with 8 injectors and fuel rails. Your system should be more efficient. I struggled at the choices out there but using a hood that connects to the carburetor reduced my choices. I am using a Holley Sniper Stealth 4150 and a Holley EFI Fuel Tank Module. It is simple and works. Best of all is you can't tell that the car is fuel injected unless you look hard with the L88 wedding cake assembly on the engine

 

For now, I’m using slightly touched up 1996-2000 Vortec heads, they have closed chambers, and a “ski jump” to promote tumbling. I’ll keep my eye out for some decent heads, but I want to try to do this as cheaply as possible for the sake of argument.

when I originally installed this setup in my monte carlo, the stock L29 intake is really just a marine intake, and it uses the mercruiser/ramjet common rail fuel injector, which is a huge pita. I think I spent a month having to drive around with a tool box, and had to stop in numerous parking lots, remove the upper intake and mess with the fuel rail because it kept alternating between having a massive vacuum leak because one of the injectors wasn’t seated all the way, and having a massive fuel leak because the fuel rail divorced itself from the injector.

the Edelbrock 4150 throttlebody plugs right in to all of the stock gm harness plugs, so thats a plus, it has an onboard map sensor that can be swapped out for a higher bar map sensor.

i actually consider the fuel system to be more conventional because it uses a standard multi point port per cylinder layout with one fuel rail per bank. Ultimately this motor will see boost, so I wanted something easily serviceable and tuneable.

according to my research, that setup will also clear a stock c4 hood, although I am still working out a filter method for it. I suspect it will be breathing directly through a x&n round air filter lid that is fastened directly to the top of it. Its not ideal but I bet it would work.