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Thread: pinto cheap airflow

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    pinto cheap airflow

    i had a call from someone building a sensible fast road pinto, not a big buck build only stuff thats really worth while, following stuff on the forum he had a skimmed injection head multi angle seats with the inlets cut to suit 1.8 valves, ex valves were std size but rimflow design.

    my only job was to blend the seats into the unported head, but a quick look and feel of the inlets with a finger and i thought it might actually flow quite well even though no porting work had been done, first stage was dig out and flow test an un molested injection head, then the modified one, then a bit of blending














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    Re: pinto cheap airflow





    i cant remember flow testing a std head carb ones are supposed to peak at about 85cfm @10 inch this one came in at nearly 90 so that sounded about right. whats clear is that with no porting the inlets gained a big chunk of flow, with a bit of grinding to take the big steps out and taking a bit out the corners of the short turn we had another worthwhile flow gain for very little work.

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    Re: pinto cheap airflow

    Those std. ports are shocking for poor casting / core placement - I'd guess ANY work would improve them!

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    Re: pinto cheap airflow









    ex was a different story, the seat cutting alone improved low lift flow, and lost some at higher to come back at really high lift , on a mild cam i think it would be better, but flow wise compaired to the inlets the exhausts were in real trouble, so i got a bit more drastic with i knocked the edges of the guide boss back without actually removing any of the guide length, radius ed the short turn and knocked the port dogleg back, that showed real improvements.

    conclusions, inlet wise as ive often said pintos like big inlet valves, just recutting the inlets with multi angles to suit saw a big flow gain.

    exhaust wise, id have to say the valve and seats are not the restriction.

    bang for buck this head ended up having some real improvements in flow for very little expense, what you see in the pics is how it ended up, not a trace of polish anywhere, but i think it could of been better, who ever did the seat work cut quite deep so i think with a lighter touch it could of shown more flow and more valve lift as the cam fitting wasn't generating its full lift.

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    Re: pinto cheap airflow

    Quote Originally Posted by katana View Post
    Those std. ports are shocking for poor casting / core placement - I'd guess ANY work would improve them!
    no thats someone being heavy handed cutting seats, even so inlet flow was well up on standard

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    Re: pinto cheap airflow

    Still, you can see how difficult it is to make real power out of a Pinto head. Nice improvement but far from high CFM numbers.

    I was expecting more improvement. Still it is worth doing because it does not take ages. Something you should always do for any serious rebuild.

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    Re: pinto cheap airflow

    Good work again.
    Can you explain the advantages of a rimflow valve over standard, please? Can never learn enough from these build threads, thank you.

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    Re: pinto cheap airflow

    the theory is the rimflows are shaped so they stop the inlet charge flowing back out the inlet valve again, on teh exhaust side im not so sure, unless the idea of them is to stop fresh charge being sucked out the exhaust

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    Re: pinto cheap airflow

    Quote Originally Posted by onyd View Post
    Still, you can see how difficult it is to make real power out of a Pinto head. Nice improvement but far from high CFM numbers.

    I was expecting more improvement. Still it is worth doing because it does not take ages. Something you should always do for any serious rebuild.
    the thing is the improvement i got was big given the very short time it took to get it, and i think it could of been better still, but i dont think who ever cut the seats did it with any real (if any ) knowledge of what a pinto head wants.

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    Re: pinto cheap airflow

    I would recommend to do this short time improvement any time a head get rebuild. Any cheap improvement is a winner. I see people spending on parts that never make a real difference but what can be done cheap, get ignored.

    But as we both can see, and to let people know who think they got a power Pinto head, it takes a lot of work to make a real high power head. It's not just a matter of grinding out metal.

    From time to time we have to lift a cylinder head on the dyno because we can't stop the engine from spitting back in the carbs or making funny noises in the exhaust. I do understand what you mean by cutting seats with no knowledge.

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    Re: pinto cheap airflow

    Quote Originally Posted by Graham View Post
    the theory is the rimflows are shaped so they stop the inlet charge flowing back out the inlet valve again, on teh exhaust side im not so sure, unless the idea of them is to stop fresh charge being sucked out the exhaust
    Thank you. Something learned again.

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    Re: pinto cheap airflow

    i remember when rimflows first appeared my mate commenting, thats fine until they are all carboned up! they wont work then!

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