76volareman
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Last edited:
speedmaster(procomp) heads
- Thread starter 76volareman
- Start date
kkritsilas
Well-Known Member
5.05" valves? Do they even fit?
Kostas
Kostas
76volareman
Well-Known Member
2.02 1.60. Head dia. ~5.05" was length. .100" over typical chevy. 4.9xx length.
76volareman
Well-Known Member
looks like .100 over is too long. going to get a std chevy length. 4.9xx" set.. if i drop the valve .100" the rocker wipes nice. also with my titanium retainers i have over 2" of spring height. i need ~1.7 to 1.8. so .100 shorter valves plus some .070" under keepers and i should be good. also the seats in the heads look at be over .350" deep pressed into the head so thats good.
76volareman
Well-Known Member
valves and 1.81" installed heigth springs worked well.
76volareman
Well-Known Member
76volareman
Well-Known Member
76volareman
Well-Known Member
got engine and 518 in car and working. that weiand 180 intake was horrible. poor fuel distribution and fouling issues. put an xcelerator on it and was much better.
MiradaMegacab
Well-Known Member
:icon_thumright: Very nice! How do you like the 518?
76volareman
Well-Known Member
518 is great! gotta finish mounting it properly but with a 50psi n2o switch on the gov. line and a 6in. hg.
vac. switch on the carb nippple OD works well. amazing what a good intake and dbbl. pumper will do too. way better idle and sound than the old weiand dual plane.
vac. switch on the carb nippple OD works well. amazing what a good intake and dbbl. pumper will do too. way better idle and sound than the old weiand dual plane.
76volareman
Well-Known Member
i bought the heads bare cnc'd. chevy valves and ford FE performance springs were the key to getting the valve geo. correct. engine comes alive at 3500rpm. not that great under that.
MiradaMegacab
Well-Known Member
I had a 518 in a Mirada, low end performance was non existent.
There's a lot of parasitic drag with the 518.
There's a lot of parasitic drag with the 518.
A518 = A727 + an overdrive, nothing more. Not only is there more parasitic drag than the A9xx transmission series, but they don't have the low first gear of the A99x used in most of the M/J-body cars so they could get away with such pathetically-high gear ratios and still be livable. The A998/999 has a low ratio of 2.74, whereas all A904/727 transmissions have a low of only 2.45. So, if you replace an A999 with an A727 and have 2.26:1 rear end, it's like you just put 1.99:1 axle gears in the car as far as first gear is concerned. It'll be the same performance in 2nd as always, but it'll take longer to get there while the engine tries to climb over that ratio. On the flip side of this, if you replace an A904/A727 with the lower-gearset A99x, you suddenly just picked up a bunch of first gear acceleration. In a car that has 2.94 axle gears it's like installing 3.30:1 axle gears--but again the difference is only in first; your second- and third-gear acceleration would not change. To keep the gearing advantage, you have to stick with the A500, which is unfortunate because as far as I know, it's only available as a lockup transmission and Chrysler lockup converters are, well, not particularly reliable with any kind of power.
I'm sure you guys both realize all this, but I'm posting it as general information so that folks unfamiliar with this arrangement (or the importance of gearing overall) might learn something. It never ceases to amaze me how guys will drop in a $4,000 crate motor and complain that the car suddenly isn't running 12s, only to be told they never touched the rear axle gears. Fuel economy is a beautiful thing, but I think a lot of board members would be shocked at how quickly their car would accelerate with nothing more than a swap to even a mild ratio like a 3.23 or 3.55 out back, especially if they've got the low-first transmission.
I'm sure you guys both realize all this, but I'm posting it as general information so that folks unfamiliar with this arrangement (or the importance of gearing overall) might learn something. It never ceases to amaze me how guys will drop in a $4,000 crate motor and complain that the car suddenly isn't running 12s, only to be told they never touched the rear axle gears. Fuel economy is a beautiful thing, but I think a lot of board members would be shocked at how quickly their car would accelerate with nothing more than a swap to even a mild ratio like a 3.23 or 3.55 out back, especially if they've got the low-first transmission.
And to add the A500 was available with a non lockup converter, it has the 2 pin connector not a 3 pin. Same goes for the A518. They were the early units and very hard to find. You can also change out the front pump and output shaft on either transmissions to convert the lockup to non lockup and run any 904/727 performance converter you want.
All A500s were lockup from Day One. The early ones are hydraulic lockup, which is the same as the lockup A904. Neither requires an electrical input to operate. So, just like the A904 and A727 lockup converters, they are quite failure-prone with any kind of power. A OE non-lockup converter cannot be used on them, as the spline count is different between lockup and non-lockup converters. I do believe that some companies offer non-locking converters with the lockup spline, though.
Yes you are right, about the lock up on the a500, got it mixed up with the a518. The early 1991 and older non-lockup A-518s will have two pins towards the back of the main case just ahead of the rear oil line port. The input shaft will be splined all the way to the end.
