I am in the process of building a 302 for my 67 coupe. I have 71 mexican block bored 30 over flat top forged pistons with valve reliefs. A voodoo cam that comes inat 1500 and stops at 5800 wienand stealth intake roller rockers. My question is with my heads. I have a set of 65 289 heads that have been ported big and have 2 inch intake valves and 1.75 exhaust screw in studs and good dual spring valve springs. I was talking with one engine builder and he said the heads will not match up well with my cam and intake? He thought a stock set of 289 heads would be better for the power range I was looking at. I have an aod with 2400 to 2600 stall. The motor is still apart but getting ready to put together as soon as it comes back from the machine shop. what do you guys think also what is the advantages and disadvantages of aluminium heads verses iron?
Attention SBF engine guys
- Thread starter Bdharn
- Start date
66P51GT
New Member
To me it sounds about right. Was the guy specific about why he didn't think the heads would work? The small chamber of the early heads will keep the compression up and the larger valves will help it breath better.
One of the largest advantages of an aftermarket head (iron or aluminum) is better flow characteristics. Aluminum heads also allow you to run at higher compression without detonation. There are other advantages/disadvanteges of each but I don't know the details off the top of my head.
It doesn't sound like you have an extreme build. Persionally, I would try the setup with what you have. If you decide to upgrade your heads, you will probably want to re-think the cam, stall, ignition, gears, etc.
Also consider, the guy could have just been trying to sell you a set of heads.
One of the largest advantages of an aftermarket head (iron or aluminum) is better flow characteristics. Aluminum heads also allow you to run at higher compression without detonation. There are other advantages/disadvanteges of each but I don't know the details off the top of my head.
It doesn't sound like you have an extreme build. Persionally, I would try the setup with what you have. If you decide to upgrade your heads, you will probably want to re-think the cam, stall, ignition, gears, etc.
Also consider, the guy could have just been trying to sell you a set of heads.
shotsy
New Member
Check the following link, looks like stock 302(gt40) heads will flow more than tricked out ported 289 heads? 
do your home work first at any rate you'll be happier in the long run!!
http://www.jason.fletcher.net/tech/flowdata/castiron.htm
do your home work first at any rate you'll be happier in the long run!!
http://www.jason.fletcher.net/tech/flowdata/castiron.htm
SoCalCruising
Founding Member
That is a huge exhaust valve. I'm surprised those valves fit in the 289 chambers. I don't know what your flow, but I haven't seen those heads flow over 215-220 on the intake side after porting. Don't recall the exhaust side. TW or AFR 165s would be my recommendation for your engine. If you have right around .500 lift with that cam (flat tappet), woul dbe very tempted to go with TWs as they flow so well at that lift. Billgear (on this board) made 333rwhp using 165s and a stealth intake, but custom roller cam.
iskwezm
10 Year Member
Thats what im thinking,I remember 2.02 and 1.60's almost touch in the chamber.SoCalCruising said:
SoCalCruising
Founding Member
Thanks Guys I just want to get her back on the road really. I will give it a shot and if I come up with the money change to some afr's or TW. The exhaust valve is a 160 not sure what I was thinking. you guys are correct. 58cc chambers at the face the intake does measure 2 inch so may be a 190 not real sure how they measure the valves to be honest. I have 380 gears in a 9 inch with the aod and the tourque convertor is a lockup. once the trans goes (I got it for free and the convertor for 150 bucks so not out much ) i am saving for a lentech as we speak. will go non lockup and I should have a better idea of how the motor will run when I get the funds. I think the guys was just trying to make a buck he was going to trade me and I was going to have to put new valves and springs in the stock heads I just didn't feel good about the whole thing you guys just confirmed that I did the right thing by walking away.
shotsy said:Check the following link, looks like stock 302(gt40) heads will flow more than tricked out ported 289 heads?
do your home work first at any rate you'll be happier in the long run!!
http://www.jason.fletcher.net/tech/flowdata/castiron.htm
They may flow more but won't you lose power from the loss in compression jumping up to a 64cc chamber on the GT40s?
I've currently got a set of D0OE heads with new valves and springs. I was looking at going with a set of GT40 cast irons but didn't want to lose the compression and power.
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