I'm thinking about the 325CFM Aluminum heads for my Big Block.

http://www.airflowresearch.com

Anyone ever runs these? :confused:

Thanks graemlins/beers.gif

What is the rest of the combo? Lot of head for even a mild race only 427.

Originally posted by Mike Feudo:
What is the rest of the combo? Lot of head for even a mild race only 427. 468ci 4bolt main
forged rotating asembly
10:5:1 compression
Demon 850DP
Holley Strip Dominator
GM iron 325cfm rect. heads 2.19/1.88 valves
300 duration solid cam .600 lift
2 1/8 Hooker sidemount headers
4speed (soon to be T56 6 speed)

The AFR heads are only slightly larger than what I have now, but flow better and are a lot lighter.

I have a set of the BBC 305CC non cnc version heads on my 468 that is a similar build, i really don' think you need the 335's. AFR heads are very nice, and I don't have any regrets in buying them. The Canfields are very nice also and a bit cheaper, that would be the only other route that i would of gone. A lot of guys are going to tell you to use cast iron oval ports, but that might not be right for you. I would definetly use the CNC 315 heads or if you cant afford those go with the heads i got the non cnc 305's. You definetly couldn't go wrong with either. here is some pics of my heads;
http://www.geocities.com/codybouc/headpage.html
email me if you want any suggestions or info on ordering the heads, otherwise guys are just going to want to argue that rectangle port heads are just way to big for your engine tongue.gif
codybouc@yahoo.com

Cody, thanks for the info. smile.gif

If I had a 3800lbs+ Chevelle, no doubt I'd go w/ the Ovals, but my 3,200lbs Corvette LOVES rectangle ports.

I SO want the CNC 315's, but doubt I can swing the extra $1,000 for them

Thanks again. graemlins/thumbsup.gif

We have used & sold a few sets of the AFR's & they are an excellent head. I think the 335 is a little big for your combo. It sounds like the 305 or 315 would be much better & the 305 would be the best bang for the buck. If you want a larger head the 325 would work but is still pretty large unless you are planning a roller & some RPM.
Here is a link to an engine we built a while back with AFR 315's & some flow numbers on the heads.
http://www.chevelles.com/cgi-bin/forum/ultimatebb.cgi?ubb=get_topic;f=4;t=015077;p=2

You can email me if you are interested in a set. ;)

If I were building the engine I would either save for the 315 heads or buy the 305's and later down the road send them back and get them cnc'd which makes them 315. with only 10:5 on a 454 I don't think the 325's would really be the best. Not saying that they wouldn't work but I think the advantage with the 325's would be in the top end, I hope you have a bullet proof blueprinted motor if you are going to rev it so high to take advantage of the bigger ports. I have heard arguments before that made sense, saying that a somewhat bigger port IF it flows very well(since it would flow so good velocity will still be high) will bring the same hp numbers in a similar torque curve and leave you room for growth. So the 325's might be the way to go if you plan on going with a nasty solid roller, or if you plan on builing a bigger motor in the future. Right now you are using the GM rectangle ports which probalby don't flow that great, if you used a 305 CC port from AFR you would have MORE flow and much higher Velocity!!! also what cam do you have? 300 duration and only 600 lift doesn't sound all that great. My ultradyne solid 288/296 has over 625 lift. Its up to you, I don't think you could go wrong either way, besides the 2 1/8 headers the 305's match your combo better, but the 325's will definetly kill some of that half shaft breaking torque! Its up to you! I would definetly stick with the rectangles for your build, I still think that sometimes bigger can still be better!! :eek:

Since you want rect port aluminum heads, and dont want to pay a ton, I recommend you check out the Canfield 310s. Awesome head, not quiet as good as the AFR's, but definatly cheaper. I havent seen a bad result from them yet.

Cody, I'm running the CC 294S 294/294 duration 248/248 @ .050 and .595/.595 lift. I plan to step up to a more aggresive solid roller in the near future.

My rotaing assembly consists of:
4bolt main block
Forged TRW dome pistons
Forged GM rods 7/16 rode bolts
Forged GM 4.0 Crank
All bolts are ARP

-SS454-

I would go w/ the Canfields but they have a rather large exhaust pot that will not work with my headers. :(

That is a decent bottom end but definetly not bulletproof, but should definetly do for what you want. I don't understand how the exhaust port on the canfields are "too large" is this hearsay that you heard from one person, or is this a know fact? Doesn't seem logical? That cam works well for people and was the cam i was going to buy, I think the ultradyne would work much better though so i went with that. I would research the canfield's some more. The AFR's are nice but are a tad expensive unless you have the money to spend and want the bragging rights!

Cody, the raised exhaust ports do allow the Hooker side mount headers to line up without hacking them up. I spend $1,200 for these chrome headers and I'm not about to take a torch to them. :D

On a sidenote how do you like your D&D T-56, I have an eye on that piece? smile.gif

So if the headers DO fit with raised exhaust ports then how come they work with your stock GM heads? also The canfields and AFR's I believe both use a raised exhaust port. I am a little confused? also I like the tranny but it will be awhile before it is installed So i don't really know yet, seems like the best way to convert to the T56, and it is really strong, however you have to run a low gear like 3:73/4:11 to use it

Originally posted by cody:
So if the headers DO fit with raised exhaust ports then how come they work with your stock GM heads? also The canfields and AFR's I believe both use a raised exhaust port. I am a little confused? also I like the tranny but it will be awhile before it is installed So i don't really know yet, seems like the best way to convert to the T56, and it is really strong, however you have to run a low gear like 3:73/4:11 to use it Let me explain, the GM heads have a raised exhaust port, but it's milimal. The Canfirlds is wuite extensive. I know two people who tried and failed making them fit.

As far as the tranny, why such low gears? 5th is 1:1 and 6th is like .70 right? I know several Richmond 6 speed/ F-body T-56 owners using 3.08 and 3.33 and 3.55 gears with their Big Blocks. And the one with the 3.08 is a L88 clone? :confused:

Is the Viper box geared that much differently than the F-body T-56??

the Canfields and AFR's both used .600" raised runner exhaust ports over stock GM heads. So your headers will have just as many problems with either head.

From what I've seen the Camaro T56 used the 2.66 first gear, .74 5th, and .50 6th. The same ratio's as the Viper T56. I am not 100% sure about these ratios in the Fbody trans, but thats what I've seen. Either way, 4th gear is 1:1, and 2 OD gears.

There is one more option to consider. AFR offers a CNC chamber for around $300 extra. When you spend $900 for a CNC head it includes the CNC chamber. Tony from AFR claimed 1/2 of the power increase is from the chamber upgrade. Dollar per hp increase it is a good deal.

Originally posted by 68chevelle533:
There is one more option to consider. AFR offers a CNC chamber for around $300 extra. When you spend $900 for a CNC head it includes the CNC chamber. Tony from AFR claimed 1/2 of the power increase is from the chamber upgrade. Dollar per hp increase it is a good deal. Hey Cody, how's the project coming??

That's correct, the 305 with the cnc chamber option will flow very close to the 315 except at higher lift so unless you are planning on a .700+ lift cam you will not see a bunch from the full cnc option over the 305 with the cnc chamber option.
The 305 has some cnc bowl work standard & it also comes with the tulip exhaust valve now.
The new flow figures are posted on the AFR site.
Also I believe Tony told me the AFR's exhaust port is raised .375 not .600 like the Canfields.

I must have misread or misunderstood about the .600" raise exhaust ports for the AFRs. Sorry if I misinformed anyone.

Well I'm bummed! I don't think my heads came with the tulip valve when i bought them :( . I also don't see that CNC chamber worth all that they are claiming. I was considering it but i really dont think i would of made that much more power. an then my heads bill woulda been like $2500!!!. Wolfplace- my project got kinda outta hand! Engine has been finished for awhile now, and it came out pretty nice;
http://www.geocities.com/codybouc/enginepage1.html
also to see what i meant by "outta hand"
http://www.geocities.com/codybouc/restopage.html
enough trying to show off redface.gif back to the subject! I wasn't familiar that GM made cast iron rectangle port heads with a raised exhaust? Sounds like you know what you are talking about though. The F bodies with the 1.1 5th gear is the LT1 f bodies with the old T56's. The LS1' Corvettes and VIpers use the ratios like SS454 said. So you can't be using 3:08s!!!! This is what i had with my doug nash five speed and you are right you wouldn't want to go much steeper.

Stingray. Unless you are going to run a pretty radical solid roller (250 + at .050) at higher rpms (6500 +) I would take a serious look at the new Brodix Race Rite oval port heads. They have very high flow numbers and a small port, great for the street. These heads would have tremendous throttle responce and give very good hp numbers, perhaps the best part for you is the fact the exhaust ports are in the stock location.

No complaints here. I ordered a pair of the “as cast”, and they send me a set of 100% cnc’ed. :D :D :D Of course I didn’t want to argue.

Originally posted by cody:
The F bodies with the 1.1 5th gear is the LT1 f bodies with the old T56's. The LS1' Corvettes and VIpers use the ratios like SS454 said. So you can't be using 3:08s!!!! This is what i had with my doug nash five speed and you are right you wouldn't want to go much steeper. What trans are you talking about? The LT1 F-body T56s had two overdrives, 5th was .75 and 6th was .50 from 94-97. The 93s were close to that also but slightly different.
Ron