Stock Heater Boxes

[AirCooledCurtis]

Face it, not all of us live in California , and some of us drive our cars all year round.  So here is the question, up to what point can stock heater boxes be used without noticeable restriction on power?  I plan to build a 1641 with 041 39 x 32 heads, mildly ported, some 36 drla's, and an engle 110.  With the heater boxes, a 1 3/8 header would be small (I think), so do they make 1 1/2 non-merged headers anymore? What are my options guys ?

[deano]

Face it, not all of us live in California , and some of us drive our cars all year round.  So here is the question, up to what point can stock heater boxes be used without noticeable restriction on power?  I plan to build a 1641 with 041 39 x 32 heads, mildly ported, some 36 drla's, and an engle 110.  With the heater boxes, a 1 3/8 header would be small (I think), so do they make 1 1/2 non-merged headers anymore? What are my options guys ?

With stock exhaust valves, Engle 110 and your carbs, the larger exhaust would not make that much difference in power. Stick with 1-3/8 and stock heater boxes.

[Zach Gomulka]

Definitely a standard 1 3/8" header. You don't want 2&4 to be breathing better than 1&3. I'd use stock intake valves as well.

If you really want to pump some heat out, use a 356/912 top pulley.

[AirCooledCurtis]

You don't want 2&4 to be breathing better than 1&3. I'd use stock intake valves as well.

That is exactly what I was thinking.  but stock intakes? I already have the 041s, and what would be the consequence?  should I use a cam with a milder intake than exhaust?

[Zach Gomulka]

In my opinion, the intake to exhaust flow ratio will be off. The intake will be more efficient, causing an exhaust flow restriction and hotter cylinder head temps. This is why 041 heads commonly cracked and got a bad rap. I have no experience with split duration cams, but I suppose that is a possible solution.