i have a 302 with 12.5/1 pistons. i was wondering what set of heads and cam i should get for this. I was thinking about getting a set of dart 180cc heads, but i haven't decided on a camshaft. It will be mostly a weekend driver. Do you all think this is the best setup or do you know of another one that will provide me with better power. thanks for the help

 

The Edelbrock heads did really well in this test: http://chevyhiperformance.com/tech/e...est/index.html

The Comp Xtreme 274 they used for the test would work with your high compression, but would peak ~ 6,500. Not much low end torque. But the factory 302 cam had ~ 250* @ .050, and they used it with 3.73 gears standard. Solids behave ~ 10* smaller than a hyd cam, so the Comp with 230* @ .050 would have less duration than the factory cam, and a much more modern design.

 

It should be noted that the tests in that article were done with a 383, and though you can certainly turn higher RPM with a 302 and probably make the same HP numbers (or close) the torque just won't be there. I'm not saying that it's a bad thing necessarily, just a sacrifice that i'm sure you realize will most likely be made.

Also realize that your "12:1" pistons may not be 12:1 with a different set of heads, just something to think about.

Jeremy

 

yea pistons are pistons, figure out the dome volume, and run a compression calculation, that includes compressed head gasket thickness, deck height, and head cc, then cc your heads they arent all that consistent, most vary a cube or two in production.

however, your main issues are going to be torque and heat, get a nice dual plane intake, like the new weiands that keep stock dual plane torque but still allow you to rev high. and you'll want monster exhaust runners (huge cc length doesnt really matter) and headers to help with power

for heat, too high of compression and bored cylinder walls can cause issues, pretty much if you run too high a compression with too small a cc chamber on your heads, be prepared to spend a lot on a radiator and electric fans. so buy your heads accordingly if you find that 64 cc is going to yield like 10-1 dynamic compression ratio... go 76cc

but with compression comes torque and the smaller engine will need some torque assistance, so... alluminum heads cool better and flow better than anything iron. so look at alluminum, and to boost up torque the last bit, consider rear end gears, like 3.73s and a stall converter if your cam comes in too high.

but for cam, make sure you get a reasonable cam, for a cruiser you want torque, since that's what you feel, and seriously how often will it see 6000rpm for hp? lol

so if you get Dart 180cc aluminum heads with like 1.94-2.02 valves I'd go with like what angel71rs is saying, high rpm power is cool, but realize you'll need a new torque converter and gears to use that high rpm power, a smaller cam keeps your torque, but... eh.. it depends on what you want

 

I'm already running a set of 76cc heads on the 302.(882 casting) I have an edelbrock performer rpm dual plane on it. I also have richmond 3.92 gears in it along with a borg warner 4 spd. This car is going to be street/strip and it will only see driving on the weekends. Im still kinda worried about going to aluminum. If they get cracked how hard are they to fix? Is there any other problems with them? thanks for all the help so far

 

IMHO
You'll see significant gains with even a 180cc runner over the smogger 882 heads. (even if they've been touched up) That small displacement will have no issues cooling with simply good condition cooling system. (unless you mess the pulley size up or don't use a shroud) Therefore you have no reason to expect issues with aluminum heads. Inparticular the aftermarket heads with quality engineered metalergy. I won't get into an aluminum/steel debate, they are both good. I am fond of weight savings and easier portwork on aluminum. I am fond of the availability of used affordable cast iron. For example I have 3 sets of 200+cc heads for sale right now. Because, I went aluminum.
As for your ideal combo, if I assume you have 26" tall tires, 3.92:1 gears, 1:1 4th gear and raceweight is 3200 lbs(with driver and cage?) you need:
510HP, 6500 RPM at the lights
That will net you a low 11 second pass with a moderate driver. The gears are what is determining this. obviously with less hp you'll still be pretty quick, but your RPM through the lights will be lower.
Good questions, I hope at least one thing I've stated helps raise more ideas.

 

You also want to consider the fact that your combustion chambers are rather large. If you went with a 64 cc chamber you might end up with 15:1 compression, which would be great if you always used race gas, lots of power!

And I wouldn't worry too much about cracking aluminum heads, chances are if you were running that hot with iron heads you would have detonation problems destroy your engine anyway.

Just my opinion though,

Jeremy

 

sry, to take long in response, long work week, but you better not be crackin heads... unless they're the kind that have skulls and mouths that talk too much crap about your car

882's are a very good head, high flow numbers for cast iron, but the 180 cc runners are bigger, and better engineered, and all around cooler to have lol, just dont crack em. now for repair, an aluminum welder that'll fix aluminum is gonna cost ya, like aluminum radiators are cheaper to buy new than fix usually. and cracked cast iron is usually not gonna get fixed either, but it like aluminum, is done, you have to look for an experienced welder to keep the head flat, or have it resurfaced...

EDIT: oh yea aluminum is going to withstand more than iron will as far as ^detonation^ and cooling them... all around, except spark plug holes... they still might strip, but torque em to spec and you wont have problems

 

.....I believe aluminum is easier to repair than steel.... If you want a rough idea on your compression go to campbellenterprises.com they have a compression calculator there. The cam you've chosen is HUGE for a 302 street car. I'm having my 413 small block rebuilt and that's the cam I'm using. The XE-274H-10, the only difference is it's a 4/7 cam. 230/236 duration @ 1/2", .523/.523 lift w/ 1.6 rockers......
Bill

 

....I ran your combo on my Desk Top dyno. I didn't have the flow numbers for the Dart 180 heads so I used AFR 190's w/ 2.02 intake, 1.6 exhaust, 74 CC heads. I went .030 on the bore, used a 660 carb, dual plane intake, the XE274 cam, large headers, & 11 to 1 compression. It put out 489 HP @ 8000 & 374 TQ @ 5500. When I switched to a single plane manafold it put out 561 HP @ 8000 & 420 Tq @ 5500. The dual plane manafold doesn't match the rest of your set up.....
If you get me the flow numbers on the dart heads & the piston spec's I'll run it again.... hope this helps ya, Bill

 

thanks for the info, i sure hope my engine makes that much power with just a heads/cam change. How accurate is desktop dyno anyway? I've heard some people say its pretty close and then ive heard its pretty far off. Anyway, thanks for the info.

 

Your welcome, I ran it again with a smaller cam {224/236 @ 1/2" .552/.552 lift} and it was a much more streetable package. 445 HP @ 6500 & 408 Tq @ 4500. With the bigger cam {230/236) If you have an Auto Trans {someone mentioned that you did?} you'll need a 5000 stall which is VERY un-streetable. Before you buy parts I'd get some feedback from some of the engine guru's on this board. I'm not that knowledgable on the 302 motors. You ABSOLUTELY want to have a combination of engine parts that work together..... bill