Big Block Chevy guys! I have some questions??

Im not a chevy guy but lately Ive been trying to brush up on big block chevys, as one of these days I might have the opportunity/reason to build one. So I have some questions for yall.

What is the difference between "peanut port" and "oval port" ?

What is the deal with the different generation blocks?

What is a good way to get 400+ hp and 500+ lbs torque that is really good on the street (something that the wife could drive)??

Im all ears!!!

 

The difference between the two is the shape of the ports and also the combustion chamber size. If you want a good streetable big block the oval port heads with roughly a 10:1 compression with a cam in the range of 550 to 579 lift with 280 lobe seperation should easily give you those power number.
This is basically what my 402 was that I had run for 13 years. Good power band and runs on pump gas.

 

A 454 with a moderate cam (like he said, around 230 degrees at .050" lift) works good, 9:1 compression should be fine, you'd want a bit of gearing and stall to make it run strong. Oval port heads would be good, or put some with the big rectangular ports on it if you can find them reasonable. Add headers, a 750+ cfm carb (vacuum secondary holley or Q jet would be fine).

Without knowing your wife, it's hard to say whether she'd like to drive it or not. Mine wouldn't have a problem with it.

 

The peanut ports were the truck heads, and the oval port heads were the p***enger car heads. Peanuts work OK if you're not going to spin the engine past 5000 rpm, but your best bet is to go with either a -049 or -781 oval port head to get to the horsepower number you're looking for.

The early big blocks (396, 402, 427, early 454) were Mark IV engines. The Mark V is kind of an orphan, and lots of stuff won't interchange. The Mark VI is a little more user friendly and more stuff will interchange between the versions. For me, I have found that the Mark IV versions are the best, and nowadays you can buy 454 cores dirt cheap.

A good reliable, inexpensive (by big block standards) 400 horsepower build: Mark IV 454, use the -049 or -781 heads, decent compression (9.5-1), Edelbrock RPM Air Gap intake, 850 Holley. Match the cam/converter to the weight of the car, the transmission, and the rear gear ratio. You won't need much cam to get 400 horsepower and 500 lb/ft of torque.

 

She loves cars with lots of power and knows how to use it, but I dont want to hear about how hard it is to drive in and around town because it has such a monster lopey idle.

 

in what years can I find good 454's in

Is the difference in blocks due to deck height?

 

I've got a 502 Mk VI that is available. It is an Iron Head 502 that is fresh. It is over 450HP and 550 Ft. Lbs. It has about 6 miles on it. It was in a 34 that we bought but the guy wanted a SBF in it. It does not have a water pump or intake manifold (those were sold when we thought it was going in an injected nostalgia car), does have a Milodon pan, Flex plate for automatic. Stick a manifold, carb and water pump on it and you're good to go. Asking $5,200.00 for it, the current version from GM is over $7,000.00!

 

There has been a lot of good info here already...but to answer your question directly...the difference between so called "peanut" and oval ports is the size of the port. The earlier oval port from about 1965 till the mid 70s or so were a similar size...pretty good size really for street performance and torque. When the 454 was just being used in trucks, high rpm horsepower wasnt as important so they focused on low end torque they made the port about 2/3rds the size of the old oval port...those became known as the peanut port. The peanut ports are still oval in shape, and I have seen many buildsup in mags using the peanut port head..they make a lot of torque because of the small port setup maintains high port velocities...where bigger ported heads like square port only really start to show their worth in the upper rpm ranges..

 

There use to be a book called "How to Hot Rod your Big Block Chevy". Great book with lots of good info and pictures. Also check out www.speedomotive.com for their crate engines. Prices have gone up but when I was looking for a BBC, an ***emble long block from them was cheaper than buying an un***embled engine from P.A.W.. They tell you what parts they used to get their HP along with a dyno sheet.

 

My BBC is a really good compromise.

454 with a 282 comp cam 9-1 compression ratio, edelbrock performer rpm manifold and holley 830 dp carb and ported oval port heads.

Put out 470hp@5500 540ish bhp at the same rpm with over 400 from 3000rpm and runs very low 12's with a DNE 4+1 and a 3.25 rear end.

Went to the Hot Rod drags in September, a round trip of about 300 miles, 10 p***es on the strip and still pulled back over 18 mpg.

This is the most docile engine ever, you wife will love it and would probably be a second faster with an auto.

Build the right combo and you can have the best of both worlds.

P.

 

Lots of them on that famous auction site
And it is a great book ...

.

 

I'd highly endorse buying Bill Fisher and Bob Waar's book also! It's is the gospel for anything big block Chevy, and it will keep you frombuilding something you or your wife don't like. It will also keep you from wasting a ton of money!
The small chamber, oval port heads are by far the best heads around for mostly street and some strip use. Steer clear of the big rectangle port heads, or any open chamber heads unless you're planning on buidling a high compression big block.
Also steer clear of long duration cams. Get the highest lift possible while not going over around 284 duration. I'm running a 284/284 with .528"/.530" lift on my 427 broed .040" over and it's a joy to drive, yet anyone can easily cruise it too.
The 750 Holley with vacuum secondaries is the perfect carb, and will make a good big block come alive.

 

everything you need to know is in this book

 

Thanks for all the info. I was looking at books the other day on line and found 2 that looked like they were worth getting. I went to a few book stores this past weekend but found nothing. Ill order some after the holidays (maybe Ill get some gift cards ). So it sounds here like finding an early 70's 454 with some closed chamber oval port heads would be a good place to start.

 

Here uyou go; under $16:
http://www.amazon.com/How-Hotrod-Big-Block-Chevys-HP42/dp/0912656042

 

You might even get lucky and find an early '70s 454 with the open chamber heads (-049 or -781) already on it. There's tons of info online about those part numbers, and they outperform any of the other factory oval port heads. If you're buying pistons anyway, just get a set that gets you the compression you're looking for with the 119cc combustion chambers (open chamber). The open chamber design unshrouds the intake valve better and gives you a better flame travel across the top of the piston. The open chamber design was one of the few features of the smog-era designs that worked better than the non-smog versions. But, if you're freshening up a low-compression engine and you want to pick up the compression without buying new pistons, a closed chamber design is a good choice.


Just look at the aftermarket BBC aluminum heads and look at the chambers. They are all the open chamber design.

 

You're gettin lots of good advice here. The book especially with lots of tech and dos and don'ts. BBCs are like tattoos. They make you want more. I started out to build a hydraulic cammed oval port high compression 468. I ended up with a roller cammed Dominator topped 477 with iron Merlins. Went 10.30s in a 3500# car with no juice and 10.5 tires! One of the best build cores would be an early 70s "smog motor" (as we used to call em) out of a Suburban or truck. That was a decent head and compression was easy to build in em (they were 8.5:1). That chamber had the extra quench deal near the exhaust but with some home port clean up and matching coupled with a mild dome on the piston it has the potential to tuck yer gonads up yer hiney! If you remember Racing Head Service, they had a 468 pkg that was 10:1, smog heads like I was describing with bigger valves, a 280 hydraulic cam and a low rise single plane intake. The things would take nitrous like nobody's buisness and I knew of 1 for certain that went 11.teens in the 1/4 in an all steel Chevelle with slicks and a 2500 stall convertor through a 3.73 gear. He juiced it with a 150 shot launch and another 100 shot 2nd and 3rd. To that end I built a similar pkg for a guy. Same engine, 125 shot, all steel 69 Camaro with *******s and 9" slicks, 3.73 gears and a 2400 stall. 12.70s on motor and juiced it went 11.46. I bracket raced it one night and it went 12.71, 12.70, 12.71, 12.69, and 12.68 (I broke out with the .68). Like I said, they're addicting.

 

Interesting...way back when, I was racing my pickup truck every weekend, it had a warmed over 325 hp 396. I had the closed chamber oval ports, and swapped a pair of open chambers onto it...ran the same ET.

I think theres a trade off between the added quench and the higher compression vs the unshrouding. so it all works out about the same.

Bottom line, if I found an oval port 454 to build and the heads are in good condition, I wouldn't worry too much about which ones they are. Seems the most helpful thing to do to any of them is a nice clean up port job in the bowl area.

 

The closed chamber design does not seem to be as much of an issue with the 396's 4.094" stock bore diameter. As you move to the 427/454 4.250" bore size, the open chamber shape found on most Mk IV iron heads works much better with the 2.19" intake valves than the CC heads, and even more so with the 2.25" intakes (***uming of course that the valve angles & throat are worked accordingly).

The CC heads are helpful in another way with the 396/402 engines; they have very limited off-t******lf piston choices, with most pistons giving way too little or way too much actual (true) compression with most open chamber heads. There are a few open castings that can be safely milled down to work, but most are 115-118cc and are just too big (or you buy $550+ TRWs with a huge obstructive dome, or $800+ custom pistons from Diamond, Ross, etc.)

To the OP: one safe route to what you want is to build a larger engine. Given the power you want, a relatively smooth idle, etc., I would build either a 454 (or if the budget permits a 496) similar to what flat-n-low outlined (though I would use either a Holley 750 vac. secondary, or possibly even aftermarket fuel injection, depending on your lady's tolerance for cold starts). I probably would not even bother with anything smaller. You haven't outlined the vehicle, so it's hard to say much about cam choices, gearing, trans choices, & so forth.

 

Jim-
I speculating, but the swap to open chamber heads should have dropped your compression ratio a little, possibly being the reason why the ET didn't change.

 

Im thinking a retrofit roller cam with an intake duration of +/- 220 duration, 108-110 LSA with good (over .500) lift. Hood clearance is important so probably have to stick with a performer intake over the performer RPM, Air gap is out of the question because the heat crossover is important. Maybe 4 speed with 3.55 gears? If not a 4 speed then a automatic with overdrive and 3.70 gears. Im looking for something a tad hotter than a stock 450hp 454 chevelle motor (sorry I dont know the "L" number yet). Oh and headers of course.

 

roller is a good idea, it's getting hard to keep a flat tappet cam over 500 lift alive in a bbc.

 

There has been a ton of good information posted. I had a early 80's 454 in a 65' chevy c10, th350 with 2200stall, dual plane intake, 750cfm edelbrock, full length headers into lake pipes (no mufflers), and 3.43 rear. The motor came out of a dually and had about 70k miles on it. All I did was add the parts mentioned. The truck ran hard! I am not sure on any hp numbers but by far it had plenty of power and torque. Also I was still getting about 13mpg too! Unless your totally fixed on having a dyno monster or track beast I say find a good motor and just freshen it up and enjoy it. BBC's can get pretty costly if the only thing your "power numbers" are for is bragging rights.

 

Back in '86 or so, I had a '70 LS-5 Chevelle, .030 over, stock crank and rods. It had forged popup TRWs (11.5-1) and rec. port heads. I sold off the big heads but kept the pistons, ran open chambers that knocked it down to around 10.2-1, Crane hyd cam (525/550, 290/295), Rhoads lifters, orig. Torker int, 3310 Holley and headers. Trans was an M-21 and it had 3.31 gears. I drove the **** out of it and it ran hard, but the best part was when I drove sensibly and skip ****ed, etc., I pulled down 23 mpg! I've always wanted to build a copy to see if it was a fkuke.

 

I dont suppose the 1.7 rocker ratio has anything to do with that

 

I bought that book when it first came out... Damn, I feel old...

 

Just curious, why is this? Bad lifters, soft cams, type of oil or what? I always ran cams way over .500 lift in my big blocks back in the late 60's without any problems. I have an old Baldwin ZL-X 427 it has a GM can am cam .6oo in and ex that I plan to finally put back together. Squirrel seems like you know what your talking about so your opinion or advice is appreciated.

 

I'm curious too? My 427 in my car has been using a flat tappet cam for all it's life. Original cam was in the car from 1971 to 1999 with no problems. The present cam (a .528" lift) has been in the car since 1999. Never had a bit of trouble with flat tappets in a BBC.

 

I dont want to get into a flat cam discussion here but all you guys had broken in your cams years agao with the old oils. once broken in they work fine. I have a cam in my pickup that I installed in 2002 and it has worked great and still does.

 

I guess I don't know what I'm doing, I can't seem to get more than about 20k miles out of one.