[81camaro400]

ok. I do understand the need for more specs on the car. First here is a list of near future mods. Subframe connectors, cage, fuel cell, 12 bolt, ladder bars(eventually 4 link), front suspension and steering upgrade. Back to the 600 hp. I guess i was shooting too high. I wouldn't mind the bbc. Eventually i will get there. To those of you who are familiar with this block, what would you say would be a reasonable hp goal without spending a fortune? Or am i just truely better off selling mine and getting a big block?

[Leoman]

I've had a 400 block; they can be problematic. The 2-bolt is stronger than the 4-bolt, and the footprint of the caps on the 2-bolt is huge, so you'd want that for starters. But even then, the siamesed cylinders are a traffic-jam overheat waiting to happen. That's one reason why 383s are so popular --- normal water jackets.

600 naturally aspirated gross hp in a small block with pump gas would call, I'd think, for something like an aftermarket block with a 454 stroker crank (maybe a 434 would do it), a set of good 220cc heads, and an aggressive hydraulic roller. It could get you somewhat close at least, and it would be fairly streetable but not exactly even-tempered.

With 400 cubes or so, you'd need a power adder. In theory, tossing 7psi at a motor ought to give you a 50% hp increase (since atmospheric pressure is about 14.7psi), but in reality it's usually more like 35%. If you use aluminum heads and hold the cr down to around 8:1, you could probably toss 10psi in with a blow-thru charger like an ATI. With that type of blower, the carb becomes a pretty good intercooler! That ought to get a 380hp natural up to over 600.

But again, 600hp is 600hp and I don't think a normal 400 block is up to that. The 400 smallblock was never intended for high-performance as a casting, just as a station-wagon puller.

[lmsport]

The last stock block 400 oval track racing engine I built had Track 1 heads, 250@.050 roller, high compression, and made about 580-600hp with a 850 carb on gasoline. After about 100 laps, it blew the two rear cylinders out, which then killed the crank and caused the car to wreck. I still have a piece of the cylinder on my toolbox, it was only .040 thick with a .030 overbore. Leoman is right, get an aftermarket block. If you go big block I would go to 600hp on a stocker.

[cobalt327]

Originally Posted by 81camaro400

ok. I do understand the need for more specs on the car. First here is a list of near future mods. Subframe connectors, cage, fuel cell, 12 bolt, ladder bars(eventually 4 link), front suspension and steering upgrade. Back to the 600 hp. I guess i was shooting too high. I wouldn't mind the bbc. Eventually i will get there. To those of you who are familiar with this block, what would you say would be a reasonable hp goal without spending a fortune? Or am i just truely better off selling mine and getting a big block?

IMO, Imsport said it right back @ Post #10- you're deep into BBC territory, or a aftermarket SBC block and all the fixin's and/or forced induction. IMO it would be easier and less expensive to build a bad-A BBC w/as much cam and compression that the fuel you plan to use will let you get away with and let the HP numbers fall where ever they may.

FWIW, I had a torqey 455 Pontiac in an '81 Camaro. Even w/connectors, it broke the windshield on a foot brake pass made at Orlando Speedworld from so much body flex. This was a 100% rust free car, w/NO structural damage to it from collisions or repairs/modifications. It was a tight car, even had new suspension bushings and body and mounts. So the engine is just one part, as you've indicated that you realize from reading the shopping list of mods you have planned.

[81camaro400]

I already have the stock 305 and the 400 and do not want to buy another engine. I believe the 400 was a mild build before i got it. I have been reluctant to crack it open and see exactly what it is. Now is the time. It has a nice lope to it and pulls hard with the stock 2.56 rear gear (which is the first thing to fix). I would say it's a good 350 horses. I am really looking to get the most out of what i have without spending a small fortune or buying a third engine. I was originally misinformed in the beginning and set my goal too high. I just need to get the right cam, carb, and head setup and rethink my plans for the next stage and just do a potent rebuild for now. I'm on a shoe string budget with a nice tax return.

[Custom10]

Anyhow now U know,,,Spend that $ on heads,,,no mention of them so far and that is the key to your HP, 450 is a much better target cause you can get there on a Stout bottom end with the money on top. AFR maybe...now were talk'n,,,thank uncle sam for his generous rebate.

[Leoman]

Since it's a stock 400 block, if you are getting heads don't forget to make sure they have steam holes for a 400 already tapped. You don't want to get stuck drilling holes in new heads and hoping you did it right. Gaskets can be tapped easily enough with a template, though 400-style gaskets with the steam holes are available too. Ten years ago or so, I couldn't find 400-type gaskets made for aluminum heads (at least from FelPro) so I had to drill my own steam holes in the gaskets I got with a 1/8" drill (I think).

[cobalt327]

There are several 400 gaskets w/o holes. I suppose they're for Brodix (and any other heads) which don't require the heads to be drilled. Drag race only engines don't necessarily need the holes either, the idea being they don't spend enough time idling to cause a problem. The OEM iron heads sure need the holes, though.

According to AFR, "Fel Pro #1034 should used for 4.100 or larger bore. Applications requiring steam holes should use Fel Pro #1014."

They go on to say, "AFR has removed the cooling passage between cylinders 1 & 3 and 5 & 7 to increase strength of the casting, do not drill these areas out in an attempt to find water jacketing."

Just something to keep in mind if good aluminum heads are in your future.

[Leoman]

Originally Posted by cobalt327

There are several 400 gaskets w/o holes. I suppose they're for Brodix (and any other heads) which don't require the heads to be drilled. Drag race only engines don't necessarily need the holes either, the idea being they don't spend enough time idling to cause a problem. The OEM iron heads sure need the holes, though.

According to AFR, "Fel Pro #1034 should used for 4.100 or larger bore. Applications requiring steam holes should use Fel Pro #1014."

They go on to say, "AFR has removed the cooling passage between cylinders 1 & 3 and 5 & 7 to increase strength of the casting, do not drill these areas out in an attempt to find water jacketing."

Just something to keep in mind if good aluminum heads are in your future.

That's interesting. Does AFR recommend these heads for 400 street use?

I noticed that the 1014s have a flattened steel ring, so they will brinell the aluminum heads... that's of interest if you intend to ever reuse the heads. Think I used 1010s. They're a close call with a 4.155 bore 406, but they worked and had a copper ring for aluminum heads. I did have to drill the steam holes in the 1010s. This was with Trick Flow aluminum heads.

[81camaro400]

i would like to possibly use a pair of stock heads to keep cost down but i'm afraid that the machine work will raise the cost to the point where i would be better off getting aluminum heads. I was looking into a .525 lift cam or possibly larger with a 250 duration with 1.6 roller rockers. I think i will have to mill the heads to accept bigger springs. Is this a good cam for my engine? If so is there a decent set of stock heads to use because the ones i have are not really that great. Or will i just be better off getting a new set? Also if someone has a setup that you have used in the past that worked good please let me know.

[cobalt327]

Originally Posted by Leoman

That's interesting. Does AFR recommend these heads for 400 street use?

The cooling passages in the heads are revised from the OEM design. It is misleading for me to have said the heads do not require holes, period, w/o going on to say that this needs to be verified by application- both usage and block and head type.

On the AFR site I linked to above, they also say:

"14) 400 Blocks:
Steam holes are recommended for all 400 block applications. Use a 400 gasket as a template and drill the three holes nearest the spark plug side of the head straight down, the other three which are very near the head bolt holes should be drilled at a 30 degree angle away from the bolt hole. The center hole will intersect water about 1" down and the two outboard holes to a depth of 2 1/4". Use a 1/8 drill."

[Leoman]

Originally Posted by cobalt327

The cooling passages in the heads are revised from the OEM design. It is misleading for me to have said the heads do not require holes, period, w/o going on to say that this needs to be verified by application- both usage and block and head type.

On the AFR site I linked to above, they also say:

"14) 400 Blocks:
Steam holes are recommended for all 400 block applications. Use a 400 gasket as a template and drill the three holes nearest the spark plug side of the head straight down, the other three which are very near the head bolt holes should be drilled at a 30 degree angle away from the bolt hole. The center hole will intersect water about 1" down and the two outboard holes to a depth of 2 1/4". Use a 1/8 drill."

Ugh... none for me thanks! Sounds like the usual drilling instructions. My CNC machine is in the shop