Posted by Keith in Washington [172.71.142.68] on Saturday, March 02, 2024 at 15:33:26 :
Vaughn, a word of warning. Many Chey 327 engines have a press on front balancer. That can be a problem. They can fly off as they can work their way loose. I read stories where they come off at high RPM they will come up through the hood or bounce around and make a real mess.
My Carryall has a 327 with the press on balancer. I did come loose. Lucky for me I was idling down the street at 25 MPH. Mine slid forward on the crankshaft snout until the key was out of the way and the balancer was no longer spinning with the crank. Put it on the trailer and had to leave Hot August nights.
The solution for me actually was straight forward. I called a couple machine shops and they said the engine would have to be taken totally apart to drill the crank snout to accept a bolt. I took the front off the truck and looked at what I had. My crank snout had an untapped predrilled hole that was smaller and not quite deep enough for the Chevy bolt (it was about 3/4' deep). With the engine still in the truck I deepened the hole at the same diameter then enlarged it in a couple steps to the correct diameter for the required tap. It was actually quite easy to drill and I was well braced and the existing hole guided me. I then ran a tap to thread the hole, then followed with a bottom tap to get the threads as close to the base of the hole as I could. I then bolted on the balancer with the correct Chevy bolt kit using a little blue Loctite. It has work great for years.
The 327 is a good engine for the PW. First the fit is great. Second the engine loves RPMs which is ideal for this conversion due to gearing. You will be turning 3,000 RPM at 60 MPH. That is assuming no overdrive, 4.89 differentials and 36" tires which is how mine is set up. I had my 327 balanced and the head guy in the shop said I could turn 5,000 RMP all day and not worry about it. It has plenty of power and will do freeway speeds without any problems. I put it on a dyno at 5000 feet of elevation (Reno) and I had 200 hp at the rear wheels, which is not bad with the original worn distributor and the original small Carter 4 bbl carb that needed help. It now has a MSD distributor and ignition system along with a much better 4bbl carb. The dyne shop here says it should be well over 200 hp at sea level with the improvements.
The SM420 transmission is a very good one. You will never really use 1 st gear street driving which makes it a 3 speed transmission. With the gearing you will find that you will go through 2nd and 3rd gears pretty quickly unless you take the RPMs up. 3rd gear is a great gear when you push the RPMs and a fantastic hill climbing gear. It really sounds great in 3rd and you can feel the power that it has when you push it. It just wants to go. You really shouldn't push the RPMs in 4th gear as you will be north of 80MPH real quick at 4000+ rpm, I know I have been there. Just make sure you have front disk brakes, at a minimum, as you will need them. I switched to a hydroboost system for the brakes as vacuum boost was not strong enough as I needed a 7" diameter vacuum booster to fit under the hood. It was a trick to get the power steering pump installed, for the brakes, due to interference with the radiator shroud.
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