# My Head's CFM



## PontiacJim (Dec 29, 2012)

One of the new young guys at work has a dad who owns/operates a machine shop that builds everything from street engines to Nascar engines. The owner used to work for one of the Nascar teams and was their head porter. So his shop has all the good modern tools and equipment, to include a flow bench. My heads, along with the rest of my engine has been sitting in pieces for over 3 years. 

I went and did my own head porting work on my 7K3 heads for my 455/469CI build. With the assortment of formula's on the Wallace website that can be used to determine compression, head flow, HP, 1/4 mile times, etc., I have always been curious as to what my work accomplished in creating more CFM's. The stock Pontiac iron heads seem to flow about 205 CFM's. So that was my base line to see what I got out of my work. I used the info from Jim Hand's book and opened up the bowl area, tapered the valve guides in the bowls, machine shop did a 3-angle valve job (Ferrea RA IV valves), I gasket matched the intake openings to RA IV size blending the port in about 1/2" or so, and did a little widening on the pushrod walls to equalize all the ports. Cleaned the ports up by smoothing them out. Did a little gasket matching on the exhaust ports, cleaned up some casting bumps, and smoothed things up - not any big modifications here.

These are the results @ 28Hg

INTAKE------------------EXHAUST
Lift----------CFM---------CFM
.100--------94.5----------48 
.200--------157-----------107
.300--------201-----------142
.400--------214-----------167
.450--------224-----------173
.500--------230-----------178
.550--------234-----------178
.600--------237

Overall, the CFM numbers are pretty good and can support my goal of near 450HP, but more importantly, with the solid flat tappet cam I have, I should be near 525 on the TQ number. My cam lift on the intake will be .483" with 1.52 rockers or .525" with 1.65 rockers, and .507" on the exhaust with 1.52 rockers or .551" with 1.65 rockers






















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## Old Man Taylor (May 9, 2011)

Nice work.


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## pontrc (Mar 18, 2020)

The 7K3 heads is what I have on my 400,Great work on them Jim. Notice they must be around 1972 exhaust ports with 4 bolts. And thanks for that posting that adapter to add the outer 2 studs👍


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## 1968gto421 (Mar 28, 2014)

As OMT said, nice work.


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