quote:What is Rousch recommended refresh/rebuild interval on the engine? I bet in NASCAR they tear them down after every weekend!
A lower rev limit would be wise to get longevity, but where is the cam happy for vintage racing?
If I drop my race engine shifts by 1000 rpm to 9500 I get maybe another 250 miles between rebuilds....
Yes, Roush takes them apart every race and freshen them up - typically 400-500 miles. The files for this motor shows very detailed monitoring of each component with miles and last replacement. It's not clear how many miles they put on all parts, but some are replaced every race.
With the kind of racing I intend to do, I would expect a much longer service life. I may restrict it to 7500-8000 rpm, so it will not run anywhere near it's potential.
That was my initial thought about purchasing this engine, an engine with high quality parts that I can run below it's full potential with good durability. The 351C is just more fragile, and I'll only consider that if I wan't to run the FIA sanctioned races.
Regarding the cam, I ordered a cam degree kit, to help determine duration and lift. The files show a 325C cam (duration maybe), with lift around .825 in/ex.
I am considering increasing head gasket thickness (Cometic gaskets come in many thickness and are reusable), and reducing lift/duration by changing rockers arms. This engine run a 2.1:1 rocker arm ratio, and by changing that to maybe 1.9:1, lift is reduced by around 10% and duration profile is lowered too (by how much I'm not sure). Rocker arms are available used/new from Yates, at reasonable prices.
I cannot lower rpm too much as the D3 heads are ported for high rpm, - they flow around 420 cfm on the intakes.
There's an interesting article about them at D3 heads
/Kristian