do I need to change the pistons ? the short block has Mahle flat tops with 2 valve reliefs,5.7 rods and cast crank the current heads (brodix track 1) needs new valves and valve guides so I was thinking why not going with 18 degree heads instead of 23 I heard that 18 degree heads require special pistons for clearance or something ! I need more info on this

 

yes you will need pistons for those heads

 

To my knowledge, the pistons and most of the valvetrain, as well as the intake manifold, will need to be purchased in order to fit with 18 degree heads. Not sure about the block. It's not as easy as swapping pistons and bolting them on though that's for sure. Also, unless you're building a pretty high end street/strip and/or race motor it's not really worth the money for the power gain in my opinion.

 

this time I will buy full CNC heads and I was thinking of the 18 degree heads they got very nice flow numbers

 

I got two options right now buy a fully CNC'd heads with recommended intake or save up and buy a compelet Scott Shafiroff real street 427ci and sell my 383ci

 

well you'll make more power with a 427, but with AFR 195 Comp Eliminators you could make great power with that 383. I can't imagine the costs would be at all comparable unless you bought the 383 pre-built...and can get near a similar amount for it now.

 

Cost vs. performance for a street car I can't see it being worth it now. 23 degree heads flow so well now, AFR eliminators or Trick Flow heads, you would have to build your entire engine around the heads. Not worth it IMO but that's just me.

 

i just built a drag specific 383 motor and i ended up going with afr 235 heads 23* i was going to go with an 18* setup but the heads are almost double the cost new pistons most of the 18*heads you need shaft rockers which are about 1000 for a set it wasnt worth it all for the horsepower difference i would have had. btw on my motor i should make around 700 havent seen dyno yet. hope this helps -tony-

 

I just decided to go with these heads http://www.airflowresearch.com/index.php?cPath=24_115

 

The 220 race head is a great head. But what are your goals for this motor? Are you using nitrous? A 220 runner is a big head. Flow #s are not every thing. You also have to look at velocity. What is the compression ratio? What size cam? Carb? Stall? Plan out your whole combo don't just piece it together because you think it will work better. There is a guy here in Michigan going bottom 8s with a 388ci and 23 degree heads and a ton of nitrous. And at 3100 pounds. So I would call afr and ask them what to use.

 

I wont go with 18 degree heads

what are your goals for this motor? hitting 10s
Are you using nitrous? I might in the future
What is the compression ratio? currently with 64cc heads its around 11.3
What size cam? will go with solid roller if I bought those heads
Carb? currently 750 double pump I will go with quick fuel if 750 is not enough
Stall? now I got 2400 but will change it as soon as I choose the cam it might be 3500
3.73 gears

the car is 92 Z28 I removed some stuff for reducing weight and Im still on it I will try to get it around 3100-3000,I know a guy that has full suspension,K member and 9" rear end I might buy it from him if necessary

 

I would call afr about the heads. Then call comp cams and get a cam. Then call prosystems about a carb. Then you should be able to get in the 10s on motor. Of coarse toy will need a new stall. But all this and you will still get out cheaper then switching to 18 degree.

 

23 degree heads are very proven in todays time compared to older heads. Their flow numbers rival some 18 degree heads on the market today.

The heads you chose from AFR are good set of heads and will make plenty of power for you. You already have you bottom half so it would be in the right of mind to get a good set of 23 degree heads to back on the motor.

Don't ever count out the 18 degree heads these days though. Just because the flow numbers from 18 to 23* heads are about comparable don't mean they will make the same power. It is how the air gets to the chamber in the intake port is what makes the difference.

Check out this article on Trickflow and read the paragraph on the 18* they put on a 406 and tell me you are able to duplicate that with a 23* with the same compression and cubes.

http://www.chevyhiperformance.com/te...lt1_heads.html

As far as the heads in price you are correct that 18* is expensive but if you are building a motor anyway the 18* specific piston are not that much more. A good set of AFR's are going to cost between 2000-2200 so alittle bit more is not going to hurt for the power that is to be had.
Here are some prices from Summit for the Trickflow 18* heads and the Brodix heads which are a lil more.
http://www.summitracing.com/compare.aspx


http://www.summitracing.com/search/P...e+brodix+heads

By the way Brodix also makes an 18* head that accepts 23* valvetrain so all you would have to swap is the pistons.

http://brodix.com/heads/-18x.html

 

I will just stick with 23 degree heads and go with AFR 220

 

Good choice.

 

18* > 23*

 

Not when you look at the prices

 

yeah the prices is just crazy

 

I agree 18 degree heads are money. They are used for high RPM aplications. I remember this past fall when I was looking for a set of heads. I was going to go with a set of AFR eliminators but I found a set on edelbrock's website that really interested me because they were on clearance. I was going to go with an 18 degree head because it was the same price as the 23 degree head. I have pistons that accept an 18 or 23 degree head, but I would need the expensive 18 degree intake and I would need exotic valvetrain. I ended up getting the 23 degree edelbrock/chapman 243cc heads for $1000 for the set fully CNC without valves come to find out I need shaft mount rockers, but for around $2300 total I have a sick topend and capability to make 700hp N/A and 250 shot on top of that. AFR makes some nice heads. That 220cc should be perfect for your set up just don't go too big on the cam.

 

If you already have a set of Brodix heads that just need some work why don't you send those to a professional porter to get the most out of those heads along with new valves, springs etc... then you would come out much cheaper and make good HP. I am using GM LT1 castings in my 383 and it runs 10.80's@127mph on motor setup to run n2o. It doesn't matter which head you use as long as you have a good head porter.

Vortec355 what is your engine setup b/c we have very similar et's and mph? I am in the process of ditching my GM LT1 intake for a much improved Victor E that is fully ported and should put me in the 10.50's-60's after a LITLE fine tuning. LMK Later Clint