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I have read where others have used the less expensive 1.94 and 1.60 chevy valves in their 351Ws. I have a set on Comp roller tip rockers that instruct me not to use the shorter tipped valves. Are my only options to buy new 351 valves or change the rockers??? If I use the chevy valves do I also have to buy chevy retainers and keepers??? Does the 1.94/1.60 combo make that much difference in HP that a person would modify newly rebuilt heads (stock valves) that are complete and ready to mount??? Does the fact that the heads are aggressively ported have any bearing on the valve size I should use? I do not want to spend several hundreds of $$ for a valve job, new valves or rockers etc. on perfectly good heads if I am only going to gain a few extra HP. Thanks for any help.
 

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Chevy valves are .100 longer then Ford valves. To keep rocker arm geometry correct, you'll need .100 longer pushrods too.

I've also read that generally the biggest intake valve you should use on early Ford heads are 1.90" . Any more, the valve starts to interfear with the sparkplug and flame front propagation.
 

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I had the same valves in my 289 and the shop had unshrouded the intake valve for me.
 

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As long as the Ford valves are available, I'd recommend using them, even if they are a bit more expensive (in the scheme of things, not much)...
I only ran Chevy valves in my early engines because Ford valves in those sizes were not available back then.

If the heads are ready to go with 1.84 and 1.54 valves, I'd just use them....only reason I'd go to the bigger valve was if the heads were modified with those in mind (IOW, the bowls were enlarged) and the valves were to be purchased.

The efficiency of the porting work, camshaft, intake and exhaust system choices will make much more difference than a small increase if valve size.....since you mentioned "stock" valves, my only concern, if this is a performance app with high rpms/spring pressures in its future, that the stock materials might not be up to the task...
Perhaps sharing some more about the combination and use might help educate us...
 
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