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7m5 Heads

  
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7m5 Heads

 
Pontiacman469 Pontiacman469
New User | Posts: 15 | Joined: 07/08
Posted: 07/15/08
02:11 PM

I have a set of 7m5 heads from a 72 455,i wondering if they would work with my .060 over 455 with trws,and a cam specs:244/252 with .548/.563 with my 1.65 rockers,i also have a ported 71 ho intake,and a holley 800 dbl.pmpr,any ideas on what kind power this will make?thanks for any help.  

Pontiacman8 Pontiacman8
Moderator | Posts: 5778 | Joined: 02/08
Posted: 07/15/08
02:36 PM

Yes they will work. Do you have flat top, dishtop, or dome pistons.Also do you know the part number for the cam. are the heads ported do they have a 3,5,or 7 angle valvejob.  
Engine builder,self taught auto body guy.
Horsepower sells engines and torque wins races

Pontiacman8
Pontiacman8
Pontiacman8

Pontiacman469 Pontiacman469
New User | Posts: 15 | Joined: 07/08
Posted: 07/15/08
03:40 PM

Standard run off the mill trw 2359,as the cam,the specs are ballpark,its a ho racing,hc-03a i bought in the 90s,i called ken and he said he made so many different specs of that cam he didnt know i had that info ona desktop dyno,so im guessing thats it.3 angle valvejob,comp 995s,just wondering if thats enough head/compression for that cam combo,like to have 450+hp,but dont know  

Pontiacman8 Pontiacman8
Moderator | Posts: 5778 | Joined: 02/08
Posted: 07/16/08
06:01 AM

I would recomend a compression ratio of 9-9.5:1 for your combo with the 114cc heads you have now you only have 8:1cr  
Engine builder,self taught auto body guy.
Horsepower sells engines and torque wins races

Pontiacman8
Pontiacman8
Pontiacman8

Pontiacman469 Pontiacman469
New User | Posts: 15 | Joined: 07/08
Posted: 07/16/08
03:27 PM

Another question on the same subject,i was researching last night and read that harland sharp 1.65 are really 1.71 when measured correctly,is there any truth,should i sell them and go back to 1.52s,hate to have the piston eat a valve,also would the lift decrease help with the compression delema?? Confused  

65pmdgto1 65pmdgto1
Enthusiast | Posts: 510 | Joined: 12/07
Posted: 07/16/08
08:46 PM

Your compression is to low to be effective to get you the HP you mention. Also sounds like a lot of lift for that short of a duration???
The only true way to measure the valve to piston clearance to bolt on a head, get a pair of solid lifters, put some clay in the valve reliefs and turn it over by hand one complete cycle. Remove the head and measure the clay. You can also measure the true ratio of the rockers. Measure the base circle of cam lobes and the high point subtract and you have the true lift number. Now that you know that number put an indicator on the tip of the rocker arm while you cycle it and record that reading. Some more simple math and you have the true ratio. You might also contact HS and ask them the true ratio.