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302 heads on a 351


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#1 xfpv8

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Posted 08 June 2012 - 10:06 PM

What needs to be done to 302 Clevo heads to use them on a 351 Clevo? I'm guessing the combustion chambers will need to be machined out to keep the CR down but will the inlet and exhaust valves need to be changed for larger ones? Any help will be appreciated.

#2 FREE.51

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Posted 08 June 2012 - 10:20 PM

Just bolt em on

#3 jeffb5.8

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Posted 09 June 2012 - 11:06 AM

If you are going down this path there is a few things I have been told by the clevo guys to make it reliable.

Have the heads cc for size as well as
Get your block height to piston top check to work out you comp, if your block has been deck to zero you need to know to work out the comp

Then get the heads relived to the desired comp you want for your combination, eg cam, stall, diff ratio and what you want from the car street or strip (be honest most want the idea of a drag car. When really it will do the 1/4 once a yea and never rev over 6,000rpm

Also do a search on here there should be heaps of info,
if you just bolt them on you may have detonation issues, I would get the valves replaced at the same time to stainless single piece ones and guides done for unleaded.

Edited by jeffb5.8, 09 June 2012 - 11:09 AM.


#4 russxr67

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Posted 09 June 2012 - 07:52 PM

Just bolt em on


That's bad advice. To get the best out of them you need to have the piston within 10 thou or closer to the deck. In most stock applications the piston will be way down the hole and the lack of "squish" can lead to detonation issues especially with small cams. That goes with any performance application.

You'll need to check the chamber volume and work out what compression you end up with as well. Typical volumes are in the 57cc range as compared to the open heads which are 70+ cc's.

Now, there are two ways to approach the chamber volume issues. One is to rework the chamber to the desired volume and the other involves using a piston with the appropritely sized dish.

#5 xfpv8

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Posted 09 June 2012 - 09:21 PM

Thanks guys for the advice. I think I'll leave all the math to the machinist who's doing all the block work for me. The cam I'm going for is the Comp Cams Magnum 282 S :- anyone on here running one of theses cams? Any feed back would be appreciated.

#6 XCSEDAN

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Posted 09 June 2012 - 11:21 PM

i can tell you stock 2v heads will hold you back, a lot, with that cam.
by the time you reco them, it'll cost you a grand... then you will need to spend money on porting... only 1800 for new AFD 2vs, my advice would be to do that. they will well outperform dollar for dollar the money you will spend on cast 2vs
how hard are you going to rev it? be honest too, i rev my xc to max revs all the time (5000rpm, cause its farked, if it went to 7500rpm i'd push it there all the time), as in 4-5 times a day, just because its how i drive, but not everyone's like that (in fact most are not), so how do you actually drive? if you're never going to see much over 6000rpm, and want a solid tappet, crane f238 is a solid well known performer. with the afd 2vs you should see plenty of punch, round 440hp. it'll pull to 6500 of you want it to.
linky
http://www.cranecams..._detail&p=24495
by the way, have you taken in the maintence factor of running a solid cam?

Edited by XCSEDAN, 10 June 2012 - 12:05 PM.

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#7 russxr67

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Posted 10 June 2012 - 11:20 AM

I second with what XC has to say on the choice of heads. Spending money on 2V's is a waste of $$$$. For the price they are these days the alloys are hard to beat and can be ordered in the chamber volume you desire.

#8 FREE.51

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Posted 12 June 2012 - 04:55 PM

I must have my info wrong, Aussie cleveland 351s had 2v & 4v heads from factory so I just assumed that you could put 2v heads from a 302 on a 351 no probs. I didn't take into account that the 2v heads from factory have been "worked" to suit the 351s extra stroke my mistake I was drunk when I posted the "just bolt em on" reply.

#9 Tweaker351

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Posted 12 June 2012 - 05:51 PM

I didn't take into account that the 2v heads from factory have been "worked" to suit the 351s extra stroke


They havnt been "worked" as such, they just have different chambers, hence closed chamber and open chamber. 302's had closed chamber to keep the compression where it should be, if they had the open chamber heads with the shorter stroke of the 302 crank there wouldnt be enough compression...
2v and 4v is a totally different conversation lol

#10 grease monkey

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Posted 12 June 2012 - 06:52 PM

That's bad advice. To get the best out of them you need to have the piston within 10 thou or closer to the deck. In most stock applications the piston will be way down the hole and the lack of "squish" can lead to detonation issues especially with small cams. That goes with any performance application.

You'll need to check the chamber volume and work out what compression you end up with as well. Typical volumes are in the 57cc range as compared to the open heads which are 70+ cc's.

Now, there are two ways to approach the chamber volume issues. One is to rework the chamber to the desired volume and the other involves using a piston with the appropritely sized dish.



this is true ,also the thing thats going to happen is your going to increase compression to about 13,1, this is bad ,on pump fuel and you will never stop it from pinging, get the heads cc,d ,and the combustion chambers layed back a little ,,unless your running straight LPG ,and it will still ping alittle

#11 FREE.51

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Posted 12 June 2012 - 07:18 PM

Check out this web site www.aus ford-uk.co.uk then click on Engines, it explains all about 302s & 351s in Aussie falcs it's a good read & has photos.

#12 xyturboute

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Posted 19 July 2014 - 08:48 PM

hey looking for a bit of advice here, fitting some closed chamber 302c heads onto my 351c. am aware that I will have to open up the chamber to drop compression, question is were should I be removing this material from? have a set of CHI 185cc heads here that I have traced the combustion chamber onto some paper and marked this shape onto the iron heads. that area is marked In black. plan to run on 98 octane so what is the max ratio I should run? engine has flat tops with relief for valves, cam is :231/235@.050" .554 lift, has studs top and bottom, zero deck. know all about working out for comp ratio etc., just thought before I go hacking into these heads I would ask, the chi heads are for something else. 



#13 xyturboute

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Posted 19 July 2014 - 08:57 PM

<p>trying to get some pics from photo bucket,&nbsp; which link do I copy?&nbsp; copied the img &nbsp;&nbsp;then tried to paste onto the page and no go??</p>

#14 russxr67

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Posted 20 July 2014 - 10:53 AM

Click on the third link down then paste it in here.

#15 russxr67

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Posted 20 July 2014 - 10:54 AM

hey looking for a bit of advice here, fitting some closed chamber 302c heads onto my 351c. am aware that I will have to open up the chamber to drop compression, question is were should I be removing this material from? have a set of CHI 185cc heads here that I have traced the combustion chamber onto some paper and marked this shape onto the iron heads. that area is marked In black. plan to run on 98 octane so what is the max ratio I should run? engine has flat tops with relief for valves, cam is :231/235@.050" .554 lift, has studs top and bottom, zero deck. know all about working out for comp ratio etc, just thought before I go hacking into these heads I would ask, the chi heads are for something else.




What's the Lobe separation on that cam? 108,110,112???

#16 xyturboute

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Posted 20 July 2014 - 12:11 PM

it is 110, still can not paste pics,  gutted.



#17 jeffb5.8

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Posted 20 July 2014 - 08:43 PM

When u paste it, it will not look like a pic, it will be 2 paragraphs of text until u hit post, then the pic magically appears.



#18 xyturboute

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Posted 20 July 2014 - 09:35 PM

I am doing it right, am copying it right, just wont paste anything at all, googled what is happening and is a common problem, could even be this forum?? is a real shame as I took some xa porn pics today for you guys. 



#19 Gassed250

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Posted 27 March 2016 - 09:44 AM

302cc heads on a stock 351 gives around 10.6:1 compression



#20 FORD_MAN

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Posted 27 March 2016 - 11:21 PM

depends on the heads & the deck height of the pistons

my brothers 302C rod 351 Clevo is 12:1 without decking and random 302c heads


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