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Long story short, I've had enough grief from the worn-out heads I inherited when I bought my  my Speedster. I'm going to replace them with new. I'm happy with the performance of my 1776, when it's running, so I want to purchase a similar setup. I need to know how valves are measured to determine which heads are installed. Is the diameter determined by reading the ID of the seat, the OD of the valve, or something else?  

57 CMC widebody, 1776, Dell 40s, IRS, 4 wheel discs, 18" Boyds, 225/35/18

Last edited by Eric (McGruff)
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Panchitos would be good, or at least a pair of 044s......  Either would be great but realize that if you’re going to larger valves to match the flow of those Dell 40s going in to the heads, then you should also be looking at the diameter of the exhaust tubes and match those to the flow coming out of the heads, too.  You may find that what you currently have for an exhaust system is fine, or you may want to increase the exhaust tube size, too.  It’s all supposed to match to handle the flow properly. 

Depending on the cam and rpm range you're looking to make power at, the Panchitos could be too big. A small engine such a 1776 would be a little 'soggy' down low and unless you're looking to make power in the 6500-7,000 rpm range a set of properly ported stock valve (35x32mm) heads would be a better choice for all around drivability.

By my recollection, the Panchitos are made for small displacement engines—that's why they're named that. Downs claims he has flow numbers in the ported 044 range but intake velocity figures that are much better. That makes the heads "snappy" on milder, smaller builds. Low and mid torque, no soggy bottom AND very good top end power.

Again, according to Pat and Pat's dynos.

If he's right (and I have no cause to doubt him) then Panchitos are the best bet for anyone building a street engine from 1776 to 2332. 

A guy making a stocker or very mild "high miler" build could probably do better with smaller heads, yeah.

And of course race guys may want more port volume to make power at higher rpm.

But for us—guys driving engines that peak between say 5500 and 6500: Panchitos.

Last edited by edsnova

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