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302cc heads

5K views 21 replies 9 participants last post by  ziggs 
#1 ·
hey guys has any1 here spent a bit of time getting a bit out of their 2v cc heads?
wat sort of flow have they managed and wat sort of hp numbers could they produce?
 
#2 ·
ziggs said:
hey guys has any1 here spent a bit of time getting a bit out of their 2v cc heads?
wat sort of flow have they managed and wat sort of hp numbers could they produce?
I have spent a fair bit of time porting my own 2v,s. Properly done they can flow around 275 cfm which ,by theory is enough to support over 550hp.Last time i had mine on the flowbench they were at aound the 240 cfm mark with a standard size 2v valve but since then the throat has been opened up considerably to suit a larger valve of around 2.1 inches. Going to a 4v size valve on the intake is not recommended but 4v exhausts are ok.
Given the amount of time it would take to achieve such results ( time = dollars),my advice is go with a set of alloys,that is of course if you can,t do it yourself.
 
#4 ·
ziggs said:
i reackon u'd be able to put biger exhaust valves, porting, cc ing the chambers and rollers for less than the price of bare heads and it'd will be at 450hp to 500hp mark and wif an extra 800bucks in the wallet.
unless your doing the work yourself. I'd advise you to do your sums first. I advised another FF member who was a bit warey of the $. He found the 302 CC head worked out a few hundred cheaper max. This was last year.

I've been there and done it unfortunately. $3700 and 2 years later. I sold the heads 100% bare for $600. The were prepared for screw in studs etc. All that was needed to complete them was roller rockers/screw in studs/valves/pushrod guides, springs, retainers and collets.
 
#5 ·
I can't remember what CFM mine flowed but i worked out that they flowed an average of about 470hp. Will have to have a look at my flow sheets. They are 2V CC heads. I would like to upgrade to some alloys now though. I would recommend going and getting alloys, they are great out of they box. Will save a lot of hassle and should make more power than most irons, while being more compression friendly.
 
#6 ·
XFFAIRMONT said:
I can't remember what CFM mine flowed but i worked out that they flowed an average of about 470hp. Will have to have a look at my flow sheets. They are 2V CC heads. I would like to upgrade to some alloys now though. I would recommend going and getting alloys, they are great out of they box. Will save a lot of hassle and should make more power than most irons, while being more compression friendly.
ives seen afd's out of the box and they needed a lot of work to bring them up to scratch, sure u could have used them but the chambers werent finshed properrly and the porting still needed a bit more work i dunno wat the chis r like out of the box but then u hav to buy his mainfold thats another 500-700 i think on top of the heads, and if the stock heads can flow it i cant see how the the alloys can be worth it on a street car where i'm not chasing tenths.
 
#7 ·
I should rephrase that. I have heard that they are great out of the box. I have not seen a set which are not already on a car. I am very happy with my 2V's though and can't really see myself forking out 3grand to replace something that works well. I think that the alloys would be that bit better and also weight saving. As brenx has said somewhere, just by sticking on his CHI's and changing nothing else he gained a considerable amount of rwhp. And by the sounds of it he had spent a fair bit on the 2V's which he replaced with the CHI's.
 
#8 ·
You don't have to buy the specialised manifold for the CHI's. I ran a weiand xcelerator on mine. Took a little bit of work but not that hard. CHI have now realised that people don't always want a high rise manifold. They now have heads available that accept any aftermarket or stock cleveland manifold.
 
#9 ·
XFFAIRMONT said:
I can't remember what CFM mine flowed but i worked out that they flowed an average of about 470hp. Will have to have a look at my flow sheets. They are 2V CC heads.

wats the flow sheets say?? i've heard it'd be had to get
420-450hp out of em. wat sort of work did u do to them bigger valves and porting??
 
#10 ·
ziggs, the CHI 3V's (185 or 218cc inlet ports) come with free spacers to fit a normal manifold. Extra $500 not required.

CHI have just released their alloy 2V. All stock 2V parts fit like a normal iron head. These flow 300cfm at 0.600 valve lift and will support 600hp. You can buy a fully assembled set for only $2650. Remember hardened valve seats, pedestal machining for studs, bronze guides, port/polish, CC chambers, etc etc plus....SS valves, teflon seals, quality springs, retainers & locks - and labour to set them up. Price all that up and tell me what you get ;)

There's no way you'd be able to get 2V irons ported and polished to flow that much or cost that cheap!! You then have all the other advantages of light weight, better thermal qualities, run more comp, better CC's etc etc. They also make a much larger torque curve too.
 
#11 ·
ziggs said:
XFFAIRMONT said:
I can't remember what CFM mine flowed but i worked out that they flowed an average of about 470hp. Will have to have a look at my flow sheets. They are 2V CC heads.

wats the flow sheets say?? i've heard it'd be had to get
420-450hp out of em. wat sort of work did u do to them bigger valves and porting??
I bought the car with the heads on already. But i have the flow sheet at home which was done by the engine builder (Paul Norman). I'm pretty shure he done the heads along with Mario Torrisi in Mackay as thats were the car is from. From memory they have what Paul called a semi race port which in his case is probably pretty good as he's had some wicked cars over the years. I know they have 4v exhaust and probably 2v intake not really up on all this kinda stuff though. I know people are scepticle of iron 2V's getting close to or over 500hp flow, but thats what my flow sheets has stated and i know its the correct one. Mine actually flow about 480hp max but i figured out the average of the top 5 or so figures. I think a set of 3V CHI's would really open the old girl up a bit though as it has a rather large cam(624lift), and has been taken out slightly to 366cubes.
 
#12 ·
thanks for the different views and stuff but i think i'm gonna follow the the normal way of doing things by spending the $$ on the old cast heads and build the combo to its maxumum on thse heads and in a few yrs i mite go big enough for 4v's which with some hope will be a little more affordable as later on i'll prolly be chasing the bigger numbers, hell my engine bloke reackons he can get 450hp outta them that'll do 4 now. sure i'm spending money now and then later but it's only money hehe and its only natural to do it this way, lol. thanks again.
 
#14 ·
xw383 said:
My 302cc were ported by ourselves, they flowed 440hp. Then i went to 4vex valves with port tidy up on flow bench, they then made 513hp. this was done by a engine builder in Brisbane.
thats a fantasic result, unbelievable a stock head has that potential, with a lil bit of work it gives me a big smile to hear that. thats the good old 70's for ya!!
 
#15 ·
ziggs said:
thats a fantasic result, unbelievable a stock head has that potential, with a lil bit of work it gives me a big smile to hear that. thats the good old 70's for ya!!
The 351 openchamber heads i have have flow potential of 490hp. If you want much more, but heads that are designed for it. :hy:
 
#17 ·
ziggs said:
obviously wif the open chamber design u can sqeeze in the bigger valves wif hardened seats but apart from that is there any other avantage to run them?? wat was the point of offering 2 chamber sizes??
I think this is what you are asking............different CC sizes are a function of 2 different engines.

The 302 has a shorter stroke than a 351 crank. So when the 302 smaller cylinder volume is compressed, a smaller chamber allows you to keep a decent comp ratio. When the larger 351 volume is compressed into a 302 closed chamber the comp ratio increases - a little too high for your average daily driver requirements.....hence why they use an open chamber. The factory comp ratio if I remember right is about 8.9:1
 
#18 ·
TruBlu351 said:
I think this is what you are asking............different CC sizes are a function of 2 different engines.

The 302 has a shorter stroke than a 351 crank. So when the 302 smaller cylinder volume is compressed, a smaller chamber allows you to keep a decent comp ratio. When the larger 351 volume is compressed into a 302 closed chamber the comp ratio increases - a little too high for your average daily driver requirements.....hence why they use an open chamber. The factory comp ratio if I remember right is about 8.9:1
thanks dude for a sec there i was thinkin that 351's came out wif closed chamber heads, dunno wat came ova me, lol. prolly just that u hear of so many 351's runnin closed chamber heads, another quik ques just for my personal knowledge did the 4v heads come out in 2 chamber sizes like the 2v's??
 
#19 ·
ziggs said:
thanks dude for a sec there i was thinkin that 351's came out wif closed chamber heads, dunno wat came ova me, lol. prolly just that u hear of so many 351's runnin closed chamber heads, another quik ques just for my personal knowledge did the 4v heads come out in 2 chamber sizes like the 2v's??
yes ziggs, 4v heads are available in open and closed styles.Some even come with 2v size valves but these are a rarity.
 
#21 ·
ziggs said:
obviously wif the open chamber design u can sqeeze in the bigger valves wif hardened seats but apart from that is there any other avantage to run them?? wat was the point of offering 2 chamber sizes??
You can also fit 4v valves in 302 c/c heads.

However, most people recommend that only the exhaust valve needs upsizing
 
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