<puts on flame suit just to be ready>
Alright this year I'm going to be running 882 heads. I've gathered that, on this board at least, they are one of the most hated sbc heads ever made. I've attached some dd screen shots in order to show the comparisons between 416 and 882 heads on MY motor, not saying this is the way its always going to be. I know that DD2k doesn't give real accurate numbers and tends to run high, but i should work for a comparison right? I've tried to compensate some for dd being generous by giving myself 500cfm of air flow, and not adding any air flow for the very mild port and polish i did on these heads, or the swirl polished valves.

Another thing I'd like to address is that I've seen a lot of people on here refer to the 882 heads as lightweight castings and the 416's as heavy. My 2 sets are exactly the opposite, the ridge under the exhaust ports of the 416's is "bumpy" and the 882 is the straight design, showing the heavywieght casting.

Here is a link to the screen shots... sorry for the blurryness.

Cylinder Head Comparison

Thanks for taking a look at this... I'd like to make discussion out of this, as long as it doesn't turn into a bash-fest.

 

The increase from the 416 combustion chamber size (58cc) to the 882 size (76cc) will yeild a far larger drop in compression than .25. More like 1-2 full points. Without knowing pistons and what not, for reference, it would drop a 10:1 with 58cc's down to 8.3:1.

In stock for, 305 castings aren't that great, either. They are hindered by valve sizes. Start doing upgrades to the 305 heads and they will belittle the 882's.

The fact that 882's are considered "lightweight" is because they are thin castings in critical areas and are prone to cracking (center wall between the exhaust ports namely, IIRC). Though, I think there was a heavier casting version of the 882...but am not certain.

 

Ok, I was kinda wondering about that. The pistons are stock for this block, which originally had 76cc heads and 8.2 compression I think. The 882's have been milled down some (.050, I believe) to take a nick outta the surface. So maybe 8.5:1 then for compression.

I still am pretty excited to have what looks like quite a jump in power with these heads.

 

Work over the 305 heads and see an even better increase.

cc the 882's. Until then, compression is guess work.

 

There is infact 2 different "882" castings the old heavy 333882 and the more recent 882 thats like a 624 casting
Its a lightweight casting. And tends to crack.

Both have 76cc chambers and don;t flow worth a........

A stock 305 head like the 416 doesn't flow any better till ya port them and install larger valves and deshroud the chamber a bit. But the beauty is the small chamber and the fact that they are a dime a dozen.

You can carve and machine it. to what ever size you want. I've finished them to 62cc, 52cc and 65cc before.

I've had 882's , fully ported and modified 416's and vortecs all on the same 350ci short block, in my car. I can tell ya the 882's suck, the vortecs work nice and the ported 416's are right there with the vortecs both flow wise and performance wise "in the car." Lot of bang for the buck.

 

everyone talks and talks about this... but I never see any before and after track numbers, I guess i'll be the guinea pig here in like 1.5 months. I want to see others numbers, not just talk.

Last years best 1/4 with the 416's was 13.36@100.5
best 1/8 was 8.34@83.88

The car is staying basicly the same, we'll see what there is for a difference!

 

I clicked on the "Cylinder head Comparision" link.
i see a chart for stock SBC "041" heads , not 416's

Not the same. But the flow will be simular.

The flow chart for the 882's is excadurated. If you read the fine print in the Hot rod magizine article where these flow tests came from, it states the some of the heads were not exactly true stock heads as delivered from GM.
The 882's were "warmed over" with bowl hogging and a 3 angle valve job. makes a big difference. Thats why they seem to out flow stock 441's. "stock" 882's don;t flow that much. They are one of the worst of the open chamber smog heads. They have a particularly restrictive exhaust port. Yes they can be improved with porting.
You're going to see a big drop in compresion ratio on your motor going from 58cc's to about 70cc (shaved .050")

 

I already had the flow data from the 041s on my comp and saw it was pretty identicle to what i had seen for 416's, which is why i used it.

Well the 882s i'll be running just came from the machine shop with a new valve job for the 2.02 1.60 valves. They have also recieved some porting around the bowls and the exhaust. I guess I'll just have to wait and see.

 

Let us know how many seconds they cost you.

I think you're in for an unpleasant surprise. I'm guessing it'll take you no more than 10 minutes from the time you crank it up, to head back to the parts store for another set of head gaskets, to undo the mistake you just realized you made.

416s and 041s, with the same size valves and the same chamber relief and the same port work (which is minimal on 041s and massive on 416s to bring them to the same state), flow similarly. Stock 416s are pitiful compared to stock 041s. It is meaningless to try to substitute the numbers from the one, for numbers for the other, without carefully verifying that they are in exactly the same state.

882s are WAY behind either of the others. DD cannot be believed in that particular detail.

 

I'm not trying to be disrespectful here but:

How can cylinder heads with 2.02 1.60 valves and some porting and polishing, and new swirl/undercut valves, flow worse than bone stock heads with 1.84 1.5 valves? I know I will loose compression with this set-up, it is no suprise to me at all. I did some more figuring and I should be at 8.5:1 compression.

I've talked to 3 shops in this area who build race motors and they all told me the same thing, that these 882 heads will make more power than the 416's. For what its worth (which, I admit, probably isn't much) a CHP article i read seems to agree.

Once again, I'm trying to keep this perfectly civil and respect everyones input! If I go out to the track april 2nd and run like ****, I will report back and eat a flock of crows! 50 days away... we'll see..

 

In the 882 to 416 comparison that the shop was making, they were probably referring to unmodified 416s.
My own opinion of 76cc factory heads is, if you have a set and can't afford something else, they're an acceptable substitute til something else comes along.
If you have a 350 +.030 with a zero decked block the combination of the overbore and the tighter quench clearance will raise the CR about 1/2 point, from 8.5:1 to 9:1. Which isn't too bad for a 350, especially if you want to burn 87 octane.
I wouldn't deliberately set out to purchace a set of 882s though.

 

I was running stock heads, so yes, thats the comparison they were making.

The motor is already together, so further machine work is not possible before the start of the season. I also did not have to pay for these heads, just the valve job, guides, and planing.

 

If your block hasn't been decked, then in your case it couldn't possibly do any harm to use a thinner head gasket. Maybe even a .015 copper gasket.
I've noticed that some of the guys here have used those even though they aren't recommended for the street.
Hey... I have a set of 882s too, I wouldn't throw them away, they can be okay heads for a truck or if you want to use a pretty small cam with a high axle ratio and burn 87 octane.
But I wouldn't endorse the idea of investing a lot of money into a set of those either.

 

Not sure if it helps, but on my old 85 Z28, I swapped out a set of stock 624 heads (similar to 882s) to a set of worked, large valve 416's. I picked up .5 with the 416s. I went from a consistant 14.2~14.3 to a consistant 13.7~13.8 car. My motor and car setup was very similar to yours in your sig.

 

It's kind of the opposite of what i'm doin. But I'm keeping the 416s around this summer and probably going to port them when I get bored.