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Larger exhaust valves?

I have a set of Ford GT 40x heads with 1.54" exhaust valves and want to install a set of 1.60's. Do I need to have the seats machined or can I just lap them in? My buddy says I can just lap them in but I don't know, I'm no machinsts.

5 Answers

  • 1 decade ago
    Favorite Answer

    A bigger valve with a smaller seat is still going to flow what the seat will let by. The seat needs to be replaced to a bigger size and the bowl needs to be hogged out.

    You really need to port the exhaust on SBF heads. Even if its a crude job it will help the flow a lot. The intakes are OK , its the exhausts that is the weak link . If it costs you $100 to get them ported it would be worth it.

  • 4 years ago

    all the different solutions are incorrect, and that i'm no longer loopy. The intake valve is often bigger. the only exception to this rule is a 5-valve engine (3 intake, 2 exhaust) the place all the valves are the comparable length; in spite of the indisputable fact that, those engines are few and lots between. The exhaust does not would desire to be as enormous with the aid of fact the intake with the aid of fact after the flexibility stroke, all the exhaust gas is warm and needs to boost previous the quantity of the combustion chamber at backside lifeless center. The smaller exhaust valve forces the exhaust to leave the chamber quicker than a huge it is easy to. This brings us to overlap, the place the intake valve and exhaust valve are open on the comparable time between the exhaust and intake stroke. the fee of the exhaust leaving the cylinder creates a vacuum which pulls a miles better mass of air/gas in the process the intake. As information that i'm wonderful and all people else is incorrect, i'm going to apply the information superhighway website of a cylinder head builder (subsequently, Edelbrock) and additionally you will see that the intake valve is mostly a miles better than the exhaust valve.

  • 1 decade ago

    You need to take them to a machine shop and have the heads machined and set up with the proper seats for those valves

  • 1 decade ago

    take them to a machine shop thier pros those head are expencive and you dont want to mess them up. But once there in happy wheelies.

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  • 1 decade ago

    i own a repair shop,and it will have to be done at a repair shop,they,ll have to re-do them so the bigger valves can be used ,,its not to expensive of a job though to have done,,good luck ,,merry x-mas.

    Source(s): been a certified mechanic for 36 yrs.
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