Roller motor from P&P

Discussion in 'Parts Interchange' started by stumanchu, Dec 28, 2019.

  1. bmcdaniel

    bmcdaniel Senile Member

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    Custom cams are great for giving you exactly what you want/need for your particular engine, trans, gear combination. But, change your combination by too much and you just lost the advantage of a custom. Most cams for port or direct injection EFI have timing events geared towards flowing just air, they don't need to consider providing a good signal to a carb or handling a wet fuel charge.
     
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  2. Krazy Comet

    Krazy Comet Tom

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    A cam for stock speed densety computer system will idle around 18" of vac, maybe more. Gives great throttle response with a carb. With low vac, the carb power valve tends to be open a excessive amount of time, allowing a over rich fuel condition.

    Without converter and gear mentioned, I'd consider the TFS 1 to be a bit much for a carbed automatic. In my F-inj Bird only idled around 11" vac. Of course it's Mass Air so unlike speed densety, vacuum was unimportant. Worked out great as car also has electronic ABS that has no vacuum booster.
     
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  3. bmcdaniel

    bmcdaniel Senile Member

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    There is such a thing as too much vacuum, too. Intake vacuum is a function of how much restriction in the intake tract (valves included), how hard the piston is pulling on the intake charge. Too high vacuum = pumping losses in the engine. The XE cam in my signature provides 16" of vacuum at idle with 2.02" intake valves
    What year is your T-Bird? I had a '93, loved that car. Drove it until it fell apart...
     
  4. Krazy Comet

    Krazy Comet Tom

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    It's a ex-pressurized, half motor(Turbo Coupe) 1988, last year of Fox Birds. I used a parts '87 5.0 for the small & not so small pieces. Probably had more fun in the front seat of this car than any other. I had a '95 Sport with 4.6.. Somehow we never bonded(frankly compared to the '88, was a dog), sold it less than a year later.

    tc50snip.JPG
     
  5. stumanchu

    stumanchu Stuart

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    lol....pressurized 1/2 motor....That was a nice car Tom. The turbo-coupe body is a looker.
     
  6. stumanchu

    stumanchu Stuart

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    Blocking the exhaust crossover would give a little extra detonation resistance besides a more dense charge, but leaving it unblocked would insure uniform mixture? Or is the game to get the carb set up near perfect and block the crossover? Seems like unblocking it, or putting in the blocks with a 1/2" hole through them, might keep the cylinders from getting the oil washed off? Does anyone get concerned over it?
     
  7. Krazy Comet

    Krazy Comet Tom

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    A cold street engine can be a real ass with heat riser blocked.

    The heads on Comet have no heat riser, at freezing temps has taken as much as eight to ten miles to warm up enough that it doesn't buck, surge, hesitate etc. Mostly below 50*, I don't even try to drive it.
     
  8. stumanchu

    stumanchu Stuart

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    This poor motor never got to swim in a hot tank, and it had rust in a muddy layer down in the bottom of the water jackets. I filled it up with about a quart of vinegar on each side and let it sit for two days. I rolled it outside today and hosed it out with a pressure nozzle....that was one big batch of rust juice pouring out of that thing. Gave it a lot of rinse. Some parts on their way from Summit. Still gotta pull the trigger on a cam, and leaning toward custom. I think my junk will get the best harmonization with that route, and I doubt I will ever make any major changes.
     
  9. bmcdaniel

    bmcdaniel Senile Member

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    Where are you considering going for your custom cam?
     
  10. Krazy Comet

    Krazy Comet Tom

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    I'll take flack on this but in my opinion for a street engine with mostly stockish parts, a custom cam is a waste of money. In a competition engine where every ½HP is a plus, a different story.
     
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  11. RMiller

    RMiller My name is Rick Supporting Member

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    My thoughts exactly.
     
  12. bmcdaniel

    bmcdaniel Senile Member

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    All depends on how far off base the person picking the off-the-shelf cam is. If the person is relatively well informed they can probably get pretty close to what a custom will provide. If they're way off with their choice a custom cam added later will seem like a miracle.
    (Of course I'm not gonna discuss the 17 year old kid that put a full race circle track cam in his Maverick with a 289, 3-speed trans, and 3.08 rear gears. LOL)
     
  13. stumanchu

    stumanchu Stuart

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    I was thinking of using Buddy Rawls.

    I would say you are both probably right, and while I have done a ton of research, I am still a cam choice dullard. I think I might get a more responsive cam from a custom because the overlap will be tuned to a carburetor? lol....I am probably splitting hairs on the wrong half of my scalp. The other piece to this is the extra cost plus shipping is only about 50-60 bucks. If I can count on it being right, and not needing to be advanced or retarded, I can recoup some by not needing an adjustable timing setup. So, from a cost standpoint, I can consider it a mild consultant fee.

    From my understanding of it, they take all your info to determine optimum valve opening and closing events. Maybe un-important? I cant figure it out when I compare a 264 cam and a 266 and the description varies from seemingly very minor differences......so I just might farm it out. Of course, if a used XE258HR pops up for 150 bucks, my mind might suddenly get made up.
     
  14. bmcdaniel

    bmcdaniel Senile Member

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    You can't go wrong with a cam from Buddy. And yes, he'll want to know every detail about your car.
     
  15. jasonwthompson

    jasonwthompson Member

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    I agree as well. The stock 5.0 H.O. roller cam is not bad with just some bolt-ons like intake and headers, possibly 1.7 ratio rockers. However a stroked 347 with aluminum heads and large valves is something different. I have had both mild and somewhat wild. The mild is great for everyday driving with still enough oomph to be fun. The wild was fun when your foot was in it but not very enjoyable to putt around town in. IMHO, when you have around 1 hp per 10 pounds of vehicle weight, that's when the fun starts.
     

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