drop top roc

I have had a number of 3rd Gen F-bodies over the years with everything from TPI to TBI and carb motors. I've had 305's,355's,and even a 1970 400 sbc in these kind of cars but one thing i never had in one was a BB chevy. I've only seen ones on the internet and I think even on here but anyway, I know have to remove the heat, smog etc. But Im worried about motor mounts, and issues I will have with headers and power steering. Has anyone done something like this? I have my Eyes on a 1991 chevy 454 TBI out of a 3500 dually and want to put in a 1990 convertible RS which has a 305 TBI.

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drop top roc

My mistake I started reading more forums and found some of the info i was looking for but if anybody wants to offer more insight i will be checking back.

Air_Adam

Since I am in the middle of the BBC conversion as well, the best, most accurate advice I can offer is this - the more money you have to spend, the less headaches you'll have. If you are cheap, just off yourself now

The biggest headache with the BBC is the exhaust - spend the money on headers meant to put a BBC into that car, don't buy the cheap headers that 'look' like they will work... the odds are against you. As for accessories, just use whatever the big block had. You can adapt the chassis-side of most/all of those accessories to work with the big block stuff just fine. Most of it is the same anyway.

Stephen 87 IROC

Although the swap is no different, I'd shy away from the 91 454. It's a Gen V block and has no real performance potential without a lot of work when compared to the older Mark IV engines. The swap can be done but an older block would be a better and easier choice.

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jstoltz

or use a gen VI engine if you can find one for a decent price. 96-2000 454

ZONES89RS

My worst problem right now getting my stuff together is the damn heads. I am being picky because i want to make plenty of power and just buying a set of stock ovals is not enough. You need to replace the valves since the stainless valves can handle a beating. I want to get some nicer top end, so i am using square ports, but everyone bitches about less torque, guess what, it is a big block with 4.30 gears, it is not going to hurt me to lose some bottom end.

As for everything else, i just need more money for the cam and lifters, headers and a good radiator. Other than that, i have been getting the parts to make the 6 speed work, a 400$ flywheel fit the bill, so not i am just trying to get everything else together with money i dont have.

Once i have enough to get te car started in the process, i will probably do a full thread just for guys like us that want to know what is involved with the BBC swap and using a T56.

I am a budget guy, but i can tell you, budget and big block are loosely used in the same sentence when you want to make power.

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Built Not Bought

www.fquick.com/zones89rs

jwscab

yeah, 2 big things when it comes to big blocks in thirdgen's, and 1 'less' important thing.

exhaust-like said above, find something that is known to fit, and don't be suprised if you have to modify the firewall/floor to get it to fit.

hood clearance-any kind of decent manifold is going to bump into the hood. I THINK, but not sure, a minimum of a 2" hood scoop will give you the clearance you need.

third thing, little less important, and also depends on how you build the engine, be aware of the added weight to the nose, some spring rate change may be in order.

ZONES89RS

Well, as far as weight, if you are ditching all the factory stuff like manifolds, AC compressor and smog pump as well as any other junk that is not needed, you nearly break even with a fiberglass hood.

So it isnt that big of a deal

Stephen 87 IROC

Aluminum heads are cheap. Putting them onto a BBC will drop the weight down close to a production SBC weight. An aluminum intake brings it even closer. Aluminum heads on a BBC will shave off roughly 70 pounds.

Even with iron heads, the increased weight is easily offset by the increased torque that the engine produces.

Air_Adam

This. Don't worry about a few extra lbs. The added torque will more than make up for that.

ZONES89RS

From what i have seen, a aluminum headed BBC is the same as a all cast SBC. So yea, works out great.

JUNKYTRANSAM

headers, weight, i dont know how everyone one else is gettin by, but i had to run coil overs, stock v8 springs, my oil pan nearly touched the ground!! a kick out sump out pan is def. in need! the shallowest you can find! i got a milidon 8" sump, still to low... I run 210* all the time, big rad. big fans, ive tried it all... and you've got to do something with the rear end, the stocker may get you by for a while.. short water pump is a neccessity, then try to find an alternator to work with a short pump and still clear the hood.. i ended up installing a tubular k memeber, man what room that gives you for the big block!! other wise, fits pretty dang good!!!
motor mounts, stock v8 mounts work fine, moroso steel mounts work even better.

ZONES89RS

Well, i am hoping dial fans on the engine side and a single pusher on the other side of the pullers will keep my engine tamp about 190ish, but 210 is no biggie unless it wont stay there when you dog it.

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Built Not Bought

www.fquick.com/zones89rs

Stephen 87 IROC

Back when my car was still relatively stock and I dropped a BBC in, I never had many problems. I ran V6 springs for a few years and my deep 7 quart oil pan never had a clearance issue. The Hooker Supercomp headers are always a pain especially if you run any kind of aftermarket head with raised exhaust ports.

Although mine has never been a street car, I've never had a cooling problem even when I was running on pump gas but I also installed a big aluminum rad. A short water pump isn't necessary but it does help to clear the dual fans I was still using. I was using a Moroso water pump drive kit to run the short aluminum water pump and used a factory style crank pulley to drive an alternator just like a long water pump setup except the belt doesn't drive the water pump. You could run a more streetable style electric water pump and do the same thing. My cooling requirements have changed since I started running alcohol. I now use a rad from a Firefly and still have trouble building heat.

I didn't install a tubular k-member until I dropped in the 540 with the large tube headers a few years ago. The K-member allowed me some clearance for the header tubes and using a front motor plate, allowed me to drop the engine down and back slightly. I still need to drop the center link to pull the oil pan off but the k-member allows me to pull the oil pan without lifting the engine.

drop top roc

The reason i wanted a 91 motor was it was rated higher in horsepower copared to the 96 and later vortec motors. They compared it to the LS6 in 1970 its supposed to be over 350 horses 400+ tq in bone stock form.I read that when i typed in 454 in google search and went to wincyclopedia

drop top roc

I believe it said the 3500 models

Stephen 87 IROC

The 91 is only rated at around 250-260 hp. NHRA stock eliminator rates it as high as 310 but that would also be in Stock Eliminator trim.

The HP of any engine can be changed by changing cam, intake heads etc. The Gen V engine is just a bad design engine. GM only used them from 91 to 95 or 96 before introducing the Mark VI engine.

About the only good things about the Gen V is the steel crank, one piece rear main seal and 4 bolt mains. Bad things include non adjustable valve train, peanut port heads, coolant passages in the deck that don't line up perfectly to passages in Mark IV heads, no fuel pump boss for a mechanical pump.

drop top roc

Thanks maybe I misread but is it true Im hurting myself as far as performance if I buy a tall deck block?

Stephen 87 IROC

Tall deck block have performance potential (except the 366 engines) however in their stock form, they have little high HP performance. Installing a tall deck block adds more clearance issues when putting one in a third gen.

The talldeck block has a deck height of 10.2" compared to a normal short deck block of 9.8". That extra .400" is because the talldeck blocks have a longer piston to accommodate a third compression ring. The extra deck height in a performance build allows for a longer stroke without having to put the wrist pin up into the oil control rings.