Who can i send my T4 heads to, Len does not want to rebuild anymore |
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Who can i send my T4 heads to, Len does not want to rebuild anymore |
jsayre914 |
Jan 25 2010, 10:57 AM
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#1
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Speed Up !!! Group: Members Posts: 3,188 Joined: 10-February 08 From: Timonium MD 21093 Member No.: 8,696 Region Association: MidAtlantic Region |
I just got a email from Len Hoffman today. He is focused on producing new Heads, not rebuilding used ones anymore (IMG:style_emoticons/default/sad.gif)
Every time i do a search, it always leads to LEN. Who can I send my 2.0 heads to now?? I need to get on this 2056 build. any other recomendations??? (IMG:style_emoticons/default/confused24.gif) |
HAM Inc |
Jan 26 2010, 10:50 AM
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#2
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Senior Member Group: Members Posts: 846 Joined: 24-July 06 From: Watkinsville,GA Member No.: 6,499 Region Association: None |
Now for a brief introduction to the AMC castings. They are FAAARRR superior to older castings as they have not been heat cycled a gozillion times over the past 35+ years. And that's not the end of the advantages. The AMC castings are stronger with more material in the ex port area.
Now for a not so brief intro into some of the quirks of the T4 head design. All T4 heads are weakest in the ex port area. If you can put your hands on a T4 head look into the ex port from the outlet side. Notice that it cuts directly beneath the combustion chamber. Also make note of how ~ 1/3 of the seat is supported by about 1/4" of aluminum and hangs out over the port itself. This is the hottest area of the head as well as the skimpiest area of the head with regard to material. Under heat and pressure the casting droops down into the port. You can't see it, but when you re-cut the valve seats it is obvious. It is a well established fact that the AMC heads hold a valve job better than the old O.E. castings. Between heat cycle fatique and less material the older heads just don't withstand the rigors of even mild performance engines with any degree of consistency. Some hold up well and were obviously lower milage cores, while others turn to putty pretty damn quickly. All T4 heads, it doesn't matter if it's a new AMC or older O.E. will develop some leakdown past the valves over time. The hotter they run the sooner it will happen. Gotta love the aircooled engines! The difference is that the AMC heads hold the valve job longer and when they do start to see leakage it is not of a degree that is consequential, unless the heads are over heated. Remember, aluminum melts at around 1450*'s and it gets extremely soft at 1200*, which is the ball park of the optimum full throttle EGT for power. Run you EGT's up and you will develop ex valve leakage. [/i]Fortunately the leakage doesn't hurt power or reliability;proved that on the dyno and track. Our House prepped 1.8 race heads based on O.E. castings /SCCA rules start out with 0 leak down around the valves and end up with 30% around the ex valves! We live with it because it doesn't hurt power and there just isn't a damn thing we can do about it. Please understand that I sympathize with owners who want to build an engine on a budget and aren't looking for anything more than stock performance. I know it's tough to swallow the cost of a new pair of heads. But there is a harsh reality to be dealt with; on average the cores that I have been seeing for the past year or so have ranged in quality from junk to marginal, with occasional cherries. I just can't run my business with an inconsistent core supply, hence the move. |
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