1964 429 cad for round track racing???

[Cadillac Jim]

Dished pistons are a way of providing a modified hemispherical combustion chamber with the aluminum pistion covering more of the area and taking more of the heat through the oil. This can provide an opportunity for better valve geometry and port angles. The disadvantage is that you get a very high compression ratio if you go to flat pistions, and dished aftermarket pistions are hard to get. With methhanol, this isn't an issue. Thys may be one of the reasons that the 429 wasn't picked up for racing more during the 1970's, when high octane gasoline was hard to get.

Your setup sounds bulletproof to me. Do you have the time and resources to try the engine for an hour or two, then do a teardown to identify any problems before you race?

[sawman48]

(Dished pistons are a way of providing a modified hemispherical combustion chamber with the aluminum pistion covering more of the area and taking more of the heat through the oil.) lets talk more about this (modified hemispherical combustion chamber )what do you think it will do to this engine, if i go with flat top pistons???since these pistons have a deep narrow dish that i have not seen on any engine but the 429 472 500 cadillac. just how much do you think this engine needs this dish for proper flow,combustion??any one no what degree these heads ?18-23-?? degree

[sawman48]

[Cadillac Jim]

Lots of engines use dished pistons. It's a common technique to provide high performance in a mass-produced car or truck while running regular gas. Sometimes it's a way of providing a regular gas version of a high-compression engine, and was common in the 1970's and 1980's. Examples that I can think of are the 400 cid Chevy small-block and some Ford and Chrysler larger engines. In the case of the Caddy 429, it probably also contributed to allowing valve and port angles for higher performance, as I said.

The most extreme example was the 1917-1932 Chevrolet four-cylinder, designed by Louis Chevrolet. This engine had perfectly flat pushrod OHV heads with excellent port angles, and deeply dished pistions with hemispherical combustion chambers. This engine was a staple of racing worldwide as long as they were available.

[sawman48]

thanks jim

[Cadillac Jim]

Sawman-48, I didn't address your questio about combustion flow. I would have to see the heads, as I don't have experience in building big block Caddys. The first thing to watch for is a total lack of squish area in the head, which I doubt that you will see. The second thing is the port angle; if it is nearly straight into the top of the piston for intake, or the path at TDC between intake and exhaust is blocked with flat pistons, the cam profile and exhaust headers must be designed for this flow characteristic.

The biggest thing to watch out for is valve clearance, particularly with high-lift aftermarket cams. With high duration racing cams and oversize valves, the pistons may need to be notched to clear the valves at TDC exhaust. This is very common even in factory high performance engines. But, I'm sure you alaready are looking at that.

[sawman48]

what do you think of hard blocking a round track engine????never seen it done

[Cadillac Jim]

What is "hard blocking?"

[sawman48]

HARD BLOK WATER JACKET FILLER is a specially formulated, cement-based product with refined, size-graded iron particles combined at an optimum ratio to provide maximum strength, vibration dampening, and heat dissipation required in high performance race engines. Its coefficient of thermal expansion is identical to cast iron engine blocks.