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| Mac Winter 76XB351GS |
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Gday,
My cousin is in the slow process of building a 351c. To get his XY on back on the road while hes getting his 351 together we've organised a 302 on the cheap. Just want to know if we can run the 351 heads that have been P&P, valve seats, roller rockers, ss valves, blah, blah...on the 302 until we get everything together. The 302 is a complete motor so its no big deal if its not possible. Thanks.
_________________ 76XBGS, 383c, custom crow cam, 4V p&p heads, Isky SS Valve+springs, extractors, 2.5"twins, MSD Ignition, Edelbrock intake, Forged bottom end, Barry Grant 750DP, thermo, discs, toploader, Holley fuel pump, SUPERCHARGED! |
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| toddy |
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by putting 351 heads on a 302 you will be lowering your compresion
and losing power
_________________ Turbo....bigger, badder......more....more........more |
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| Mac Winter 76XB351GS |
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And thats not what we want. Cheers
_________________ 76XBGS, 383c, custom crow cam, 4V p&p heads, Isky SS Valve+springs, extractors, 2.5"twins, MSD Ignition, Edelbrock intake, Forged bottom end, Barry Grant 750DP, thermo, discs, toploader, Holley fuel pump, SUPERCHARGED! |
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| aaron_hogan |
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I'm sorry but the previous statement was far too broad to base any decision on.
For starters you need to identify what heads you are talking about when you say "351 heads". I have opened a number of 351's to find closed chamber heads (colloquially known as 302 heads). 302's come with closed chamber heads. 351's come with open chamber heads (*in most cases). Running open chamber heads on a 302 will drop compression *slightly* yes, however its not a huge difference and can be compensated for by setting up your ignition with slightly more advance. If anything you need to have a look at the fuel type he will run in the engine. I'm finding that a stock 302 with closed chamber heads will ping slightly on ULP but not on PULP. Running an open chamber combo could be a fix for that if you are being tight and always running ULP to save a few cents on fill up. If the engine is just to get him moving for a while bugger doing any work to it like swapping heads. Just service and tune the thing and you will probably have a much more driveable car than something with mis-matched components. /my 2c
_________________ EA SVO Fairmont Ghia - Recaros, Bilsteins, Sunroof, SVO rims and body kit, Genie headers, DBA rotors. T5 steeda triax short shifter. 3.27 lsd. (EL 4.0 ported/polished, rebuilt and balanced, Dev5 cam. J3 chipped EL ecu, AU injectors). |
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| Walker |
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Personally i think it will drop too much and will go like a 990,000 km taxi lol.
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| aaron_hogan |
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Well i'm far too lazy to actually do the maths and provide a CR but it will be in the ballpark of 8.5:1 which really isn't all that bad.
If you've missed my point i'm suggesting NOT to do it but that is ultimately up to the owner. FWIW i just started driving a stock but freshly re-conditioned 302 black motor in an XD on petrol with carter thermoquad and electronic ignition. Goes quite well. Was a bit lazy on the ignition side of things and had a slight hesitation from stand-still when i got it. I brought up the timing to where it should be and its going really really well. Will smoke the tires easily. Too many people write off a 302 as being small despite it being ~5 litres, set up properly there is no reason that they can't be made to go as well as anything else of the same capacity and they will certainly respond to many if not all of the same mods as one would do to a 351. From factory there is only about 9kw difference in output between them as quoted in the ford literature...and possibly somewhere in the owners manual i found in the glove-box. Its always best to make sure that everything you already have is working 100% before you start modifying things.
_________________ EA SVO Fairmont Ghia - Recaros, Bilsteins, Sunroof, SVO rims and body kit, Genie headers, DBA rotors. T5 steeda triax short shifter. 3.27 lsd. (EL 4.0 ported/polished, rebuilt and balanced, Dev5 cam. J3 chipped EL ecu, AU injectors). |
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| balizticbobo |
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351 has much more potential. Not to mention the fact that the 302 weighs the same as a 351. I've got a mate that had 351 open chamber heads on his 302. Still seemed to light the treads... 302s need all the compression they can get to increase low down torque with those big heads...
_________________ 13.28@103.73mph |
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| xf_man |
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Age: 46 Posts: 624 Joined: 21st Mar 2005 Ride: Triton ute BA Futura Location: Woori Yallock |
Just drop the 302 in as is - get the 351 happening
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| The Dog |
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{USERNAME} wrote: I'm sorry but the previous statement was far too broad to base any decision on.
For starters you need to identify what heads you are talking about when you say "351 heads". I have opened a number of 351's to find closed chamber heads (colloquially known as 302 heads). 302's come with closed chamber heads. 351's come with open chamber heads (*in most cases). Running open chamber heads on a 302 will drop compression *slightly* yes, however its not a huge difference and can be compensated for by setting up your ignition with slightly more advance. If anything you need to have a look at the fuel type he will run in the engine. I'm finding that a stock 302 with closed chamber heads will ping slightly on ULP but not on PULP. Running an open chamber combo could be a fix for that if you are being tight and always running ULP to save a few cents on fill up. If the engine is just to get him moving for a while bugger doing any work to it like swapping heads. Just service and tune the thing and you will probably have a much more driveable car than something with mis-matched components. /my 2c U didn't need to write an essay mate  It will drop the compression and go like a piece of s**t. The only time I have ever seen the closed chamber (302) heads on a 351 is whne other people have put them there, not the factory! 
_________________ You'll ride a black tornado across the western sky
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| Walker |
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Perfect for a blower application LOL.
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| CRUSHU |
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{USERNAME} wrote: {USERNAME} wrote: I'm sorry but the previous statement was far too broad to base any decision on. For starters you need to identify what heads you are talking about when you say "351 heads". I have opened a number of 351's to find closed chamber heads (colloquially known as 302 heads). 302's come with closed chamber heads. 351's come with open chamber heads (*in most cases). Running open chamber heads on a 302 will drop compression *slightly* yes, however its not a huge difference and can be compensated for by setting up your ignition with slightly more advance. If anything you need to have a look at the fuel type he will run in the engine. I'm finding that a stock 302 with closed chamber heads will ping slightly on ULP but not on PULP. Running an open chamber combo could be a fix for that if you are being tight and always running ULP to save a few cents on fill up. If the engine is just to get him moving for a while bugger doing any work to it like swapping heads. Just service and tune the thing and you will probably have a much more driveable car than something with mis-matched components. /my 2c U didn't need to write an essay mate It will drop the compression and go like a piece of s**t. The only time I have ever seen the closed chamber (302) heads on a 351 is whne other people have put them there, not the factory! Right, Only 4V closed chamber heads were ever put on a 351 from the factory, and they are still bigger chambers than the "Aussie" closed chamber heads. |
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| Walker |
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I used to know all of the CC's of chambers off the top of my head, all forgotten now.
Now my memory has gone, but a stock 351 head was about 76 cc, stock 302 was around 62 cc and 4V Closed chamber was around 68 cc. Anyone can correct this, it's s**t i forgot 15 years ago... But it's a close rough guess lol. |
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| aaron_hogan |
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{USERNAME} wrote: U didn't need to write an essay mate
It will drop the compression and go like a piece of s**t. The only time I have ever seen the closed chamber (302) heads on a 351 is whne other people have put them there, not the factory! 
Closed chamber on a 351 is not in dispute here, nor did i anywhere in the above post claim that they were factory fitted, in fact i even specified *in most cases as i knew someone would jump in and suggest that 4v's came in Closed versions...but its hardly relevant for the purpose and context of the original question. I have had that many clevelands over the years that i can barely be bothered discussing them anymore, firstly because everyone knows everything there ever was and is to know about them, secondly clearly everyone knows that a 302c is a small piece of s**t and NOTHING you do to it can make it go any good at all whatsoever and anything you try to do will be a big step backward, a waste of money and is better anchor than it is a motor. (/end sarcastic rant without punctuation) Compression ratios are not the "be all and end all" that you make them out to be when there are so many other variables to take into account when setting it up. Now go back and read what i said about not bothering to play with it and just giving it a service. Have a nice day and thank you for assisting me to get my post count up +1. Aaron
_________________ EA SVO Fairmont Ghia - Recaros, Bilsteins, Sunroof, SVO rims and body kit, Genie headers, DBA rotors. T5 steeda triax short shifter. 3.27 lsd. (EL 4.0 ported/polished, rebuilt and balanced, Dev5 cam. J3 chipped EL ecu, AU injectors). |
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