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  #16 (permalink)  
Old 12-16-2013, 10:37 AM
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Originally Posted by Daedalus View Post
time for an update,

so I tore down the motor and it turns out whoever built this had put in an isky "mile-a-mor cam" I couldnt find grind info but I believe is close to an RV cam?.... and although the cam was in very good condition, showing no signs of wear, the motor was only managing about 12.5mpg.

the condition supports my theory of the motor being recently built, but I was a bit worried, thinking it should have been performing better for the sum of the parts...

I also found some more builder mistakes, spring shims upside down, an exhaust rotator on an intake valve, which due to the higher spring pocket caused bad geometry and a rocker arm was actually hitting the rotator, different sized intake and exhaust springs, even tho the heads have deeper pockets on the exhaust side... no idea whats going on there, I thought they either had one or the other?
and a few other small things that just make you think,,, "wtf were they doing?!".
good news is the heads have screw in studs, and viton stem seals.

anyways I have installed and run in a howards 112571-12 as recommended by BigEd36 & JeffB, comp 981 springs, and also the weiand speed warrior dual plane manifold to replace the single plane team G....

Ive run it in, swapped springs and heat cycled and then taken it for a test drive...

the first thing I noticed was when running in the cam during first start up, the intake manifold was dripping with condensation, due to the amount of air it was pulling, never noticed this before so this was a good sign.

so I took it for a test drive, at low rpm <2000 it is somewhat similar, it might have a little bit more torque, but its not real noticeable, I think due to my 2.73 highway gears.
but from 2000 rpm upwards its like a different car, it has a very noticeable power increase, its more responsive and has more pull, and sounds a lot more like it should.
it has caught me out a few times "giving it a bit" in first gear from the lights and breaks traction, whereas before it was difficult to do so.
and stepping on it from cruising rpm makes a big difference too, it pulls harder and gets into the power a lot quicker.

also goes up hills a lot better. and it has a nicer engine note...

Im having a few teething issues, it only seems to want to idle with about 18-20deg btdc initial timing, but its not noticeably detonating on cheap fuel and temperature is stable at 195defF, so I need to get a piston tdc stop and check if my balancer outer ring has slipped, but it makes me wonder if I could have possibly installed the cam gear out a tooth?, even tho it seems to run well and I'm sure I took time to make sure it was correct.

the wideband is showing its a little rich on idle, so I need to fine tune that as well..

but all in all i'm very happy with it, considering the setup I have and how little ive spent on it, and when I do get around to changing to better rear end ratio and an overdrive transmission, im confident I will get significantly more improvement.

Sounds like you did a good job with this. The timing effect could be off a tooth but consider that a low compression engine will want more ignition timing to run its best. But yes check out true TDC.

The best way to get good mileage and good acceleration is to put more investment into the transmission and rear gearing. The 3 speed with a 2.73 simply is an inadaquate solution. The high ratio rear really demands a lower first gear which is not present in the TH350 or 400. A better solution is a bit of a compromise on axle ratio say a 3.08 or 3.23 behind the 700R4, 4 speed auto. This has a low almost a full ratio lower than the TH350, an overdrive 4th of about .8 and a lock up converter. The swap of the 700R4 is almost a simple bolt in, some trimming and wiring usually needs to be done, but nothing extensive nor difficult.

A 350, even a pretty high performance 350, doesn't need a 12 inch rear especially behind a street automatic as the torque values that can be generated with such a combination just can't shock load the rear axle enough to warrant a 12 bolt.


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Old 12-17-2013, 07:29 AM
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thanks Bogie, yeah im keeping my eye out for a 4L60. they came out in a local built car here in Australia during the late 80s / early 90s so one should pop up cheap soon enough.
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