My Tunnel Port Heads Build

[1967 XR7 GT]

Hi
It has 5 angle seat, so I doubt it can be changed. I, think the valve size & port combo may have something to do with the lower lift flow. The other TP flow numbers were with the smaller int, so they had better numbers.

The 2.3" valve didn't do to bad, I am actually happy with it. Some Cubic Inches will probably help.

[1967 XR7 GT]

The gaskets I ordered showed.

The initial sample I received, I didn't like the material: NV-565, I didn't like it's feel, it was a crappy lower grade material, I ended up going with a higher grade material, CMP-4000, which should allow re-use several times easily.

NV-565:


The Upgraded CMP-4000:



 

[1967 XR7 GT]

Tunnel Port Chamber

2.300" INT
1.675" EXH

[1967 XR7 GT]

I, got my heads back after reworking the exh. Originally I went with th SE exh port on the Tunnel Ports with the 1.675" valve, same as the FE Power Cylinder heads with the SE exh port with te 1.675" valve which were flowing around 260 cfm @ .800" lift with no porting.

The problem, the SE exh ports with the 1.675" valve on the TP heads didn't flow the same numbers as the FE Power Cylinder Heads with the SE exh port and the 1.675" valve. The chambers on the TP heads were stock, and so were not designed like the FE Power Cylinder Heads, which had modified chamber locations, relocated valve locations with shorter & longer port lengths.

I, was concerned with the exh, so I had them ported, so the SE port with the 1.675" valve and ported,  didn't flow worth a crap.
I, had shrouding issues, I wanted a 4.250" bore chamber hence the shrouding issue. Ended up opening the Chamber to a 4.300" Bore to help relieve the shrouding issue a little.

Next, it was recommended to increase valve size to 1.750", to open the throat of the valve seat for better flow. It was also recommended to run a Tulip valve instead of the nail head design I was using. I believe the Tulip was a 25 degree angle, and the weight  from the 1.675" valve to the 1.735" Tulip went from 106g to 118g. As you can see the 1.750" valve is now 1.735" and that was due to flow testing, which determined that the Valve Margins need to be increased to help flow, I measured the magin and it's at about .090", I don't know what it was before the valve was cut down from 1.750" to 1.735".

Flow 1 is with the port work and  the 1.750" valves installed.
Flow 2  is with the valve margin increse 4.300" chamber bore
and chamber work around the exh valve, which picked up
mid range


TP Exh Flow Numbers
Lift.......Flow1.....Flow2
0.100......55..........58
0.200....107........119
0.300....157........181
0.400....189........208
0.500....210........229
0.600....230........240
0.700....242........244
0.800....247........247
                                               
The chamber bore increase to 4.300" may have help to relieve
the Int shrouding slightly and help with flow
   
My TP Heads Int Flow Numbers
.400     258.16 
.500     308.48     
.600     356.53   
.700     390.40
.800     411.79
.900     425.16
     

[1967 XR7 GT]

I, have been collecting the parts needed to complete my TP Heads. I went with Manley 10 deg Titanium Retaines, 10 deg Titanium Locs, Spring Locators and .015" shims. I, went with PSI Nascar Cup Springs. They were out of stock when I called, I had to wait 6 weeks for the next run, which just showed last week. I chose to go with the ML (Max Lfe) treatment, A proprietary, multi-step surface enhancement process that has been proven to increase spring endurance.

The heads are being built to meet the requirements of a billet core solid flat tappet cam I picked up, spec's are 265/278 @ .050", 108 LSA, with a .715" gross lif. The PSI springs will be set up with around a 1.935" installed height with about 224 pds closed and an open pressure of  around 534 pds at about 1.240" .090" Distance to Coil Bind, with a .695" valve lift after lash.