I'm having a problem tring to find how much power i'm making & what to change to benefit the most. I don't have a horsepower rating program. Talked to a couple of shops & they told me different things. "347 stroker will make more power than a 302" or "just have your heads ported" or "throw the iron heads away & get aftermarket heads with larger valves. It all cost about the same but I can only do one for now. New heads & rockers $1300. Stroker kit $1300. They also said that more cubes will make the cam act like its smaller or something like that. This is my choices: 302 ci. Holley 600 Edelbrock Air Gap GT40 Iron heads with 1.84 intake & 1.54 exhaust, 155cc runners, & 62cc chambers Comp Cam hyd flat tappet: Duration at .006 is 268 intake 276 exhaust, Valve lift is .531 & .531, Duration at .05 is 222 intake & 226 exhaust, Lobe separation is 108. Internals are the same but with .30 over pistons Compression is 9.5:1 Rockers are full roller 1.7’s All the same as the originals but with a Holley HP 750 & a 347 ci stroker kit All the same as the original but with Edelbrock RPM heads with 2.02 intake & 1.60 exhaust , 170cc runners, 60cc chambers What would you do or what would you do 1st?
There's much more cost in stroking the 302 to a 347 than just the cost of the kit. The block has to prepped for rod clearance (mo $). You already have .030 over - you would probably want to go .040 while you have it apart (mo $). IMO, it would be difficult to stroke the 302 to a 347 for only $1300. You're using a pretty nice 'streetable' cam as is. If you want to keep the price down, I'd opt for aftermarket aluminum heads and be done with it (no removing the engine to have it machined and ground for rod clearance, etc.,). You could do the head swap for the $1300 (assuming you're doing the work yourself). Sell the existing heads to offset some of the cost. You wouldn't want to put the existing heads OR the 600 on the 347 either (mo $). My
Thanks Rick, Do the block needs to be prepped to a 331 kit? What would your guess be with this set up in horsepower numbers & if I changed my heads & rockers, how much do you think I will gain. I have read were companies post numbers but I don't trust them. Like AFR's web page with 420 or 450 hp but the cam is way big or Trick Flow with a 70 hp gain. I asked around & the shops here says no way maybe 30 or 40hp.
I dunno about the clearance issue on the 331. BTW, here's a good article on the 331 (which is stated to be originated because of the people who were gunshy of the 347 and it's early oiling problems). http://www.mustangandfords.com/techarticles/5197/ You won't go wrong with either head. Personally, I prefer the AFR's just because I know a lot of buddies who run them and I could tell one whale of a difference (over my ported Victor Jr's) when I put the 185's on. I never had the car dyno'd before or after the headswap but if I had to guess, I'd say the H.P. gain was closer to 70-80 (that's over the VJ's - I don't know how they flow compared to your GT40's). It would be difficult (for me) to estimate your current horsepower without quarter-mile numbers or the amount of gain with either set of heads. There are guys on here who are much more qualified than me to give you a 'close' estimate. The bottom line is: it doesn't matter that you know how much h.p. you will gain. What is a fact is that you WILL gain h.p. over your current setup. Swapping for aftermarket heads is among the first mods any engine builder (or shadetree mechanic) is going to do to increase power by any substantial amount. Of course there's always the option to not change a thing to what you have now and add a nitrous system - for a lot less money (in the short run). It all depends on what YOU want yourself.
I like Rick's basic plan... Sell the heads you have. They are decent for someone wanting a little power boost over stock heads. Make sure the heads you get are aluminum, have the same cc or smaller chamber, and use a thinner gasket if possible. You want to bump your compression up some, that is the main reason for using aluminum heads (other than weight loss). Aluminum heads can run 1:0 more compression than identical iron heads, and still use the same octane fuel without detonation. Then the weight loss adds effective RWHP. 100 lbs lost weight is equal to 10 RWHP! So, if you changed nothing else... flow, valve size, compression, anything at all, you would still get about 8 RWHP from aluminum. The other stuff is then the gravy. Now, my .02: Sell the intake and get a mild single plane. Make sure you have at least 3.40 gears out back. Look into losing even more weight... easy RWHP! You didn't say if you run a mild stall converter... These are all things that will either add effective RWHP without going into the engine much, or will make the car quicker with what it already has. I like your combo pretty good. It wouldn't even hurt much to work on what I listed above, and just dissassemble your current heads and put a good port and polish. That would work wonders. Good luck Dave
2.02 intakes with a stock piston? Are the eyebrows deep enough? My flat top TRWs wern't. Might check first
Speaking of porting Dave, I'm so lost on that. I have talked my ears off to many different places & all have different answers. The only company that said keep them were Power House Heads. They said a port job would flow just as well if not better than getting aftermarket heads. What is a mild single plain & can I run this on the street too? I do have a 2500 stall & 3.55 rearend gears. Just would like to have a little more.
heads vs stroker Here is a hotrod article I posted a while back demonstrating the potential of the switch from stock iron E7TEs to aluminum AFR 185s. They saw a 100hp gain but that included a better set of headers as well. I'm not sure your gain would be as much due to the fact that the GT40s flow better than E7TEs. http://www.carcraft.com/techarticles/116_0307_ford// Also, you can compare flow numbers here http://www.jason.fletcher.net/tech/flowdata/castiron.htm Keep an eye on valve size as the larger 2.02 intake valves will not clear the stock valve reliefs in the pistons, so I've been told! The idea of bolting on a set of heads and headers and gaining 100hp is very appealing. They ended up with an additional 20hp by switching to 1.7 rockers on the stock GT roller cam. You have the cam to make the 185s breathe, so the aluminum heads and headers make sense. Good luck.
They are not the stock pistons so they do clear. They also have 2 notches in them for some reason I think.
Thanks, I need to save this link. I didn't think gt40's flowed that well maybe 175 cfm on the intake. The article said the AFR 165 would flow 245 but a pro ported GT40 would flow 210-220. That does not sound like a big increase for $1300 & I will have to get new rockers also.
Axially, the 185's are 267/185 @ .500 lift. Also, the cost to have a set of iron heads "professionaly" ported is not pocket change. They could easily spend 8 hours a head @ a shop rate of ?/hour. It adds up quick. You might've save a couple hundred after it's all said and done - and you still have a set of heavy iron heads that will not flow as good as the lighter AFR's. Save yourself super headaches and heartaches and put on a set of 185's (or equivalent) and be done with it. When you DO decide to go 331 (or 347) those heads will still perform well. I've seen used AFR 185's for around $1100. Good luck.
Streetrod, I agree with Rick. GT40s are very weak on the exhaust side in stock form. It would probably cost you more in the long run to get the iron GT40s to flow like the AFR185s. It is hard to argue with 400FWHP on a stock GT shortblock/cam with AFR heads, headers, a decent intake and a new carb! These are impressive for iron heads but a bit pricey! http://www.powerheads.com/SB50.html
I was going to mention the whole 2.02" valve thing... but I didn't want to cloud things too much. The Trick Flow TWs are supposed to be the only 2.02" head that will work without cutting the pistons. At least not until the valve lift gets pretty tall. With the stall and the gears, IMO you would see improvement just by going with a slightly more aggressive intake. If you think about it, with the 2500 stall, you are losing half the power band of that intake before you transmit power to the 3.55s. I am confident in saying you would be happier with a Torker 289, Offy Port o Sonic, or Wieand Xcellerator. These intakes are seriously springing to life when your tranny stalls, and they rap up the RPMs really fast, as opposed to a dual plane which RPMs slower and slower as the Rs rise. Not a good match with decent gears. Dave
I will agree with ratio on the intake (even though it is just barely part of the original question...but...) I noticed that the acceleration was much quicker after swapping out the Performer 289 dual-plane (with an open 2" spacer) with a non-spacered Torker 289--the old one, not the new Torker II. Before I even drove the car, just revving from under the hood, I could clearly tell that it revved quicker. On the street, there was no comparison. Of course, I also just swapped out my stock heads for mildly home-ported GT40Ps and headers. I would not be amazed if someone told me I picked up near 100 HP on the swap. Feels like it
Thanks for the link EFIMAV. I talk to them today & good news I think. The gut there said that a GT40 ported with 1.90 intake & 1.60 exhaust valve flows the same as a AFR165. It might evan bet the AFR because of something it had to do with iron heads versus alum. heads but I didn't seem to understand well. Maybe something like iron keeps the heat in or something dunno. If I send a bare head to be ported would be $500 or a little more $ for new valves, a hundred or two. I'm keeping the rockers & springs because it all matches the cam. Thanks Again.
