with the 58cc heads do they use the stock pushrod length? i know the x303 heads are suppose to use stock pushrods , just wondering if these did. is 178cc runner volume too much for a 302?
I have the Y303 heads and the stock pushrods work. But, I do have some rocker noise coming from the valvetrain now. From idle to about 1800rpm it clatters/ticks and is only noticable by me when I am sitting next to a car or wall in traffic. Too loose? I think I could go up to a 6.300" pushrod. Stock pushrod length is 6.272".
Being that the stock E7TEs' are a 58cc chamber like the X305 heads I think you will probably be okay. Unless you have a Cobra with cast iron GT40 heads with a 65cc chamber. Cobra engines, I believe, use the same 6.272" pushrods. If anything they will be slightly too long in which you could get the FRPP shim kit for $10 from SummitRacing to raise the rocker arm pedestal. That is the cheaper way to adjust the bolt-down rocker arms. If they are too short the shims will not help. The other alternative is to buy roller rockers with adjustable pushrod cups. The way I am looking at it though is the price for new pushrods ($90 from SummitRacing) + the price of 1.7:1 roller rockers is about the same as the Steeda shaft mounted rockers with adjustable pushrod cups.
I do know that the instructions for my Y303s included the X303 and X305 heads as well. They don't mention a need to get different pushrods or rocker arms.
A lot of people here were saying that the Y303s aren't worth it because they don't flow like the TFS TWs or AFR165s. I like them and the price was right. I gained .4 sec at the 1/4mile which is on par with the 10 horsepower per .1sec rule. The Y303 heads are supposed to be a bolt on 40 horsepower. That said the X305s are not going to be too much head for a stock 302 engine.
I have the Ford techincal sevice CD from 93-94 and it states that the 5.0 HO E7TE head combustion chambers are from 60.6cc-63.6cc each (the GT heads were not as meticulously manufactured as the Cobra GT40 heads so CC volume is not exact from cylinder to cylinder and varies some) while the Cobra GT40 heads have 62.5 cc combustion chambers all around according to the Ford Techincal Service CD.
Tim