ratsun.com

[shortbed454]

i dont know if this is where i need to post this but, has ratsun.com moved or changed. i cant seem to access the site. it gives me a blank screen.i want to do the bbc swap and i need all the info i can get.

[wpnmkr]

I know what you mean. I can't find them either.

[Michael]

The Ratsun.com forum hasn’t seen much activity in over a year. It was a good idea initially, but somehow never gained momentum. Maybe because with the advent of the LS1, the big-block community is shrinking? Hopefully Brad and Mel are still doing well, and still racing their Z. They still get mentioned from time to time on the web site of their home drag strip.

 

Are you interested in the BBC swap for the 240-280Z? If so, I might have some suggestions. We get “will a 454 fit into the Z engine bay without cutting†and “will it require back-halving†posts about once every month or two. From what I recall, there was a pretty thorough discussion on this subject in August. Try a search for posts in the past 3 months under “big blockâ€, in the Chevy forum.

 

Successful BBC swaps are those where the owner is already thoroughly familiar with the engine (and it sounds like you’ve got this covered), with why he wants a BBC instead of a 400-based SBC, and with some welding skills. Other would-be BBC swaps tend to morph into small blocks or end up as perpetual projects.

 

My 280Z received a 454 BBC in the spring of 2000. Then the cam got wiped. I’ve been tinkering with the car and rebuilding the engine ever since – and might get the thing streetable again by next summer.

[shortbed454]

i would say im familiar with the bbc. i have grown up around chevys all my life and i have built a couple. though every big block i have swapped has always been in full size chevy cars and trucks. the only reason that i'm considering the bb swap is because i love the torque that you get with just a stock bb (and for the wow factor). but like i said in a previous post i have 2 bb and a 400 sitting on a stand and i'm just trying to decide witch one i want to go with.

[Michael]

I would recommend against doing a BBC swap with a stock or relatively stock engine. The work necessary for the swap would be better spent building-up a 400-based SBC. The reason to the BBC swap is, as you said, to get high hp without sacrificing the low-end torque – and this essentially implies doing a stout BBC buildup; aluminum heads, healthy mechanical roller cam, and so forth.

 

For a non-Z audience, there’s enough of a “wow†factor in just a regular SBC swap. For a HybridZ audience, people wouldn’t be too impressed by a stock engine, even if it’s a big block – especially if it’s a big block from a 1970’s truck, with 236 peanut-port heads and 7.5:1 compression, making a whopping 215 hp at the crank.

 

Of course, if you’re planning on using a stock BBC just to engineer the swap, check parts-fit, and so forth – that’s an entirely reasonable plan. Just don’t stop there.

 

I started with an engine from a 1978 Suburban, with the idea of first getting the swap to work, then buying a Gen VI GM ZZ502 crate engine. At the time, aftermarket support for Gen VI BBC’s was nil – and I would have been stuck from the outset, as I wanted a manual transmission, and there was no flywheel available to replace the ZZ502 flexplate. Meanwhile, “while I’m at it†struck, and I bought a Comp Cams “K-kit†to upgrade the engine’s valvetrain. Said engine ran for all of maybe 30 minutes before wiping the cam. 5 years and $5000 later, I have a long-block nearly assembled in my garage – all based on that original 1978 Mark IV 454. I retained the block, rods (mistake), crank (big mistake) and damper. The rest is aftermarket.

 

If and when I ever build another BBC, I’ll use an aftermarket siamesed-bore block (4.600†bore sounds about right!), 4.25†forged crank, and 6.535†billet rods with 7/16†bolts. Then use some nitrous.

 

My current engine should be good to 6000 rpm (but probably no higher), can’t use nitrous, and is neither “budget†nor high-end. It will cost about as much as a high-end GM crate engine or a low-end aftermarket crate engine, and will make comparable power. However, it will have some very nice components that the comparable crate engines won’t have (Isky Red-Zone mechanical roller lifters, SA gear adjustable billet timing set, Hamburger 8†oil pan, Brodix Race-Rite oval-port heads), and I’ll have the piece of mind knowing what’s inside… that is, assuming that I correctly set the ring gap (it’s around 0.016†on both top rings – I still have no idea whether that’s what it should be), set the bearing clearances correctly (I have neither the tools to reliably measure down to fractions of 0.001â€, nor the skill to use them!), got the rod bolts installed correctly (have no stretch gauge, used nominal torque values from manufacturer’s web site), and so forth. In other words, there are plenty of places where I could have screwed up.

 

Had I gone the SBC route the urge to one-up myself would have been less. I’d have installed a $1500 Goodwrench engine and used that as my test mule. This approach doesn’t make sense for big blocks, as the comparable big block is about $4000.

 

Brad Barkley and Ron Jones did the BBC swap because they love big blocks, and the custom fabrication didn’t faze them. If this sounds like you, then by all means, go for it!

[spork]

They were pullin wheelies at the strip this last weekend when I took my car out. I didn't get a chance to talk to them this time, and probably won't till next year as I'm done racing for the year. I didn't realize thier site was even down...

[Michael]

Spork, would you happen to have Brad's e-mail address?

[RPMS]

i have 2 bb and a 400 sitting on a stand and i'm just trying to decide witch one i want to go with.

 

What you want to do is build up the big block, and sell the 400 to me so I can use it in MY car!

 

Scott

[Scottie-GNZ]

Unless you got your hands on a hi-performance rat, I would think building a big mouse based on the 400ci block would be the better way to go for a street car. Like Michael said, not all V-8s are born equal and just because you have a BBC does not mean you have a hi-performance engine. The incredible weight of a big block in the nose of an early Z, already frail with marginal suspension and brakes in stock form is a scary thought. (Dont flame me, I said "in stock form").

 

Unless you just want the WOW factor of seeing that thing stuffed in a Z, I would think a massaged 400ci would provide equal performance and make for a much better balanced car for the street.

[spork]

I looked in my e-mail for an old message but don't seem to be able to find one...If I come up with his address, I'll post it.

[shortbed454]

well like i said, i do have 2 on the stand and both i have built. on is a stock 95 454 the other is a high performance 402 i.e. no stock peanut ports and no dish pistons and definitely no stock cam. the 402 pushed my 79 1/2 tun truck to low 14 sec. times i think it should motivate a 280z just fine and definitely more so then my .030 400 sbc

 

and if you are interested in the 400, RPMS drop me a line.

[Michael]

Shortbed, have you converged toward a decision?....

 

To follow-up on Scotty’s post…

 

The difference in weight between all cast-iron Mark IV BBC and all cast-iron Gen I SBC is on the order of 150 lbs. The exact numbers vary depending on specimen, and will incessantly be a point of debate. Replacement of cast-iron components on a BBC with aluminum results in more weight savings than a comparable move on a SBC. To introduce some “hard†numbers, my 0.030â€-over 454 assembled short-block (minus the cam and timing chain) weighs 380 lbs together with the engine stand. Subtract maybe 25 lbs for the engine stand. The pair of Brodix aluminum heads weighs 90 lbs.

 

Personally I would consider the tipping point between SBC and BBC swap the threshold of 500 ft-lbs torque at 2500 rpm. If your BBC build can achieve that, do the swap. A stock-stroke 400 SBC would have a very difficult time making those numbers, without nitrous or forced induction.

 

Also keep in mind that every BBC car on HybridZ has some form of altered frame/unibody. Ron Jones had essentially an all-tube car with a 9†on a 4-link. Brad Barkley had something similar. I retained the unibody and R200-based rear end, but the firewall was set back 6â€, the unibody was cut into pieces, then welded back together around the frame. None of these mods are strictly necessary, but become increasingly advisable when dealing with the mass and the torque potential of a BBC.

 

That said, some modern heads and a roller valvetrain on your 454 ought to be a very satisfying combo in the Z....

[pparaska]

Point of interest in the BBC vs SBC weight issue.

 

If you decide to forget about using an old (or new) GM 400 block, and go for the iron Dart (or World) block, realize that you're adding 50-60lbs to the engine. The dart block weighs about 200 lbs.

 

I'm not sure of the weight of the GM BBC block, but this is what Dart advertises for the weight of their Big M block:

Weight: 4.250†bore - 280 lb / 4.500†bore - 260 lb / 4.600†bore - 250 lb

 

Food for thought.