Big Block Head Comparison

[BigBlockMonte]

Hey All.

 

I have a set of the 6272992's heads on my monte carlo. Has comp springs and roller rockers, I seen a set of 6272990 heads for sale and read the HP rating for these heads were 425HP from the factory. My current heads are 270HP from factory. I'm going to runing a 3.73 gear with a 700r4 trans. Cam is a mild .510 lift 270 duration I believe. Would these heads and different camshaft really get this car moving or would I be waisting my time. Car is a street car that I like to spirit drive. . Thanks for your help

[wallaby]

I don't know the casting numbers, but given the HP numbers, I'd think the 990 heads are rectangular port heads?

I just checked, and yes the 990 heads are listed as a rectangle port head. The 992's are oval port. Other than that, the heads seem the same. Same chamber size, same compression. You would have to get a different intake manifold to make rectangle heads work, and in my opinion, the oval port heads are better for big car/street driving.

[Sam (Bones)]

stick with the ovals and put bigger valves in them (2.19") if you plan on a bigger cam, stock size valves with that cam. the 990's will kill the bottom end, I think the 990's have a 325cc intake runner, my 468 has 310cc's and pumping 12:1 and a very large solid roller cam. I wish I would have went with a smaller intake runners, less compression, and less cam, I street drive it some, not nearly as fun as some of my more moderate 454's that I have built.

 

my favorite 454 that I built was with ovals and stock size valves, great street combo in my book, tons of torque

[BigBlockMonte]

3.73:1 with the low first gear of a TH700R4 is a recipe for spinning tires. You will be out of first gear before you get moving.

 

I think that gear is a bit steep for a 700R4 but that is me and not what you were asking about.

 

 

I have heard that also. I'm running a 28" tall tire currently, I don't really shift it down to first to start out. I normally just mash the pedal getting on the highway or while on the highway mash it down and let the trany kick itself down. Maybe I went a little to much on gear. Once they are in I'll see if I like it or not. I still have the 3.31's if I can't get used to it. I'm hoping that 28" tall tire will tame it down a little. But who knows. It may be right up my alley and I love it, or want more. In that case I'll just go to a 27" tall tire.

 

Thanks for the input on the heads, It sounds like it better to stick with what I got for now. I got excited about the HP ratings on the 990's. That and I have a buddy that runs them in his 65 impala doing 10.20's. He's pretty much the reason I was considering them, but if it's going to kill my torque, I'm going to have to sway away from them. Without torque how else will I get this ol girl moving. .

[680HPStroker]

I read all these posts and agree for the most part, but let's all remember one thing "it's a big block". It will have a ton of torque no matter which heads you use. 325cc runners are big for a street car, but if you are planning on making runs down the track once in a while with the right combo it will still perform well on the street. With a big heavy car, tall rear gears and a 3.06 first gear in the tranny more torque vs HP is just as bad, or worse than not as much. The right torque converter can manage most of the issues you will encounter with either heads. BB Chevy's are more forgiving than small blocks, so don't get so caught up in the numbers game.

[71monteme]

I read all these posts and agree for the most part, but let's all remember one thing "it's a big block". It will have a ton of torque no matter which heads you use. 325cc runners are big for a street car, but if you are planning on making runs down the track once in a while with the right combo it will still perform well on the street. With a big heavy car, tall rear gears and a 3.06 first gear in the tranny more torque vs HP is just as bad, or worse than not as much. The right torque converter can manage most of the issues you will encounter with either heads. BB Chevy's are more forgiving than small blocks, so don't get so caught up in the numbers game.

 

X2

ANY BB that is thought out and put together correctly will make lots of torque, if it can't move the monte then you really have issues.

[Heckeng]

I agree, but I have never had oval ports to compare to. I have 325cc rectangular port heads that seem very streetable, but I have a little stall helping them out. Also, my 60' time is not the greatest which I think would be helped by smaller runners.

 

I also ran the car with these heads and a smaller stall with 2.73 gears and a smaller HR cam for several years with no problems.

 

I guess what I am trying to say is that ovals would be a better choice for street, but don't be afraid of using rectangular port heads if you have a good deal on them too!

[mc71454]

Originally Posted By: 680HPStroker

I read all these posts and agree for the most part, but let's all remember one thing "it's a big block". It will have a ton of torque no matter which heads you use. 325cc runners are big for a street car, but if you are planning on making runs down the track once in a while with the right combo it will still perform well on the street. With a big heavy car, tall rear gears and a 3.06 first gear in the tranny more torque vs HP is just as bad, or worse than not as much. The right torque converter can manage most of the issues you will encounter with either heads. BB Chevy's are more forgiving than small blocks, so don't get so caught up in the numbers game.

 

X2

ANY BB that is thought out and put together correctly will make lots of torque, if it can't move the monte then you really have issues.

 

Hi Thanh

 

Looking Real Good ! How have you been ?

 

Tom

[BigBlockMonte]

very cool pic. I just put it on my desktop. Okay back to the heads. So the heads would be okay on the car ( get it moving a little more) with the current set-up. Basically I was thinking of swapping my components over to the 990's, getting a different camshaft (possibly) and calling it a day. If that would make an big improvement, then cool. I'll get them, but If theres more than that involved to make these run right, then the 992's on there will stay. Have a baby on the way, (1st one) and can't completely tear down this motor and redo it again. Trying to prepare. ya know. Thanks for the input on the subject, I was thinking I could make a few ponies just by adding these heads on the car.

[71monteme]

Originally Posted By: 71monteme

Originally Posted By: 680HPStroker

I read all these posts and agree for the most part, but let's all remember one thing "it's a big block". It will have a ton of torque no matter which heads you use. 325cc runners are big for a street car, but if you are planning on making runs down the track once in a while with the right combo it will still perform well on the street. With a big heavy car, tall rear gears and a 3.06 first gear in the tranny more torque vs HP is just as bad, or worse than not as much. The right torque converter can manage most of the issues you will encounter with either heads. BB Chevy's are more forgiving than small blocks, so don't get so caught up in the numbers game.

 

X2

ANY BB that is thought out and put together correctly will make lots of torque, if it can't move the monte then you really have issues.

 

Hi Thanh

 

Looking Real Good ! How have you been ?

 

Tom

 

Tom.

doing great, how about you?

are you racing this year? we'll be doing the NHRA and the IHRA this year. so we'll be racing alot more this year. still trying to get into the 10's. might do it with the nitrous.

see you @ LVD.

Thanh

[mc71454]

Yes,

 

I will be racing this year..Monte on Sundays in the early Fall my '70 Chevelle on Wed nights starting in May.

 

Monte is getting bars run to the engine compartment and across the dash. Suspension update with an Anti-Roll Bar and then to the paint shop June 1, and then a new vinyl top.

 

Still recovering from my accident with back troubles, just taking it slow.