LT1 heads...differences between years/casting #s?
LT1 heads...differences between years/casting #s? If this question has been asked, which I would imagine it has at some point but can't seem to locate in the search because everything BUT heads threads come up, I apologize. Anyway, my question is simple. Are there any differences in the LT1 heads between years ('93-'97)? Basically, did any come with different size valves, different flow characteristics, different/better or worse chamber designs, etc?
yep I know all the 97 LT1's had the 561 heads and assume the 96 LT1's are the same as well. in stock form they are all the same as far as performance but the 561's are lighter but you would want the 643's or 374's for porting capabilities.
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they can be ported just not as much as others. most people with 97's that are going to do ALOT of porting get the 643's or 374's off of other LT1's. im not an expert though so I would call lloyd elliot and ask him about the porting capabilities of the different cores.
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I personally have my stock 561's done by Lloyd Elliott. He said they may be 5-8hp down but doubt thats at all noticible. I believe he ran 561's on his own personal 383 LT1.
i thought the 561's flowed a little more in stock form but just dind't have the "meat" the others do to be ported? also not arguing, just thinking out loud more less, haha
Well, at the end of the day, the heads I will be porting/polishing/whatever, are going to be run on a daily driven mild car. I would like as much flow as possible for later potential possibly, but it probably doesn't matter on a daily driver car as I'm not looking for max power. I would like max potential out of a fast daily car basically. I also would have two sets of heads...the ones I bought for basically experimentation and the ones that are already on my stock '93 T/A. So either way I would have at least one set of the "beefy" heads as the '93 more than likely has the thicker ones. At some point I will be throwing a mild low-mid range cam and 1.6rr's, springs, etc. and I might just do it all to the heads I bought and throw it all on an assembled unit when I do finally do the job down the road and save some time there. Sort of thinking out loud here as well.
I had read the same, so I fixed a set for my race car only to have it slow down! That's how I ended up testing all of the aluminum LT1 castings. And yes, I tested several of each. I run unported heads, so this is important to me.
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