For those of you who have completely rebuilt a 216 to run better and perhaps yield more power what did you modify/add? My car is original and I am restoring it original but will go through the motor/tranny to make it a strong driver. I am guessing not much you can do but having built motors in the past I am thinking a few things possibly. These are questions as much as comments:
1) Oversized pistons seem to be available. 2) Reground cam 3) A Pertronix pointless ignition and coil. They can be nicely hidden to look like stock. 4) Different carb jets....from who, size? Current carb is all rebuilt as original. 5) Different plug than the AC's? Better wires conductivity than stock. 6) Anything different for the fuel pump? 7) All new cam, main and rod bearings to keep things real smooth.
With how low a HP engine this is, small things can make a difference.
I re-built my 52 216 to completely stock. Stock spark plugs (AC45) and stock wires. Stock distributor and it runs fine. Lots of power. I can take off in second gear and it climbs hills fine in high gear.
You can install "different" camshafts but they will only move the torque to different engine speeds. The 1940 216 has a "mild" cam grind for best power in the low to medium speed ranges (10 to 60 MPH in high gear). These are the safest higher gear speeds for a 216 with a 4.11 axle ratio. These are unfussy engines and little things you mentioned make little or no difference. I personally would install a good grade of lighter aluminum pistons, any over bore will add a very little HP and do everything recommedned by the shop manual in 1940. For better high speed driving the 3.73 axle ratio will allow you to crusie at 65 MPH, add one or two miles per gallon and reduce high gear acceleration slightly under 40 MPH and reduce steep hill climbing in high gear....a cam won;t help here. I have the above combination in my '39 and makes for a good overall driving car of that age.
Thank for all of that...pistons, rear end ratio. So you are says even though aluminum's will lighten the load and give "easier" rpm's doesn't matter much if they are 20 30 or 40 thousandths over? Of course if I can find them stock I don't need the block redone.
The aluminum pistons must be fit as per the makers specifications and is better that they have a perfect bore where as the cast iron pistons are more forgiving. Remember all 1937-1940 pistons are slightly domed so do not use the flat top 1941 and up pistons or you will end up with a very low compression ratio.
I though I had posted a reply to this question but it must be lost in cyberspace or whatever. Any way my 1938 216 underwent a complete rebuild in 1951, bore to .040 over size, replaced cast iron pistons with aluminum (purchased at Sears Roebuck for 27 bucks) heavy flywheel weight reduction something along the line of 18 pounds and added dual intake and split manifold. The car was a Ford eater at the stop lights. Did the same thing with my 51, but due to the shifting it was not so good as a street racer. I am not promoting street racing but in 1951 where I lived it was a way of life.
Thanks guys and yes you did post it and I read it. I included the same post in this section as well for additional inputs. And yes, plan to have it rebored. I just wonder how much difference it will make in power/compression if (for reasons of cost and labor) to mill the head instead of drop in new pistons. May end up doing both. Looks like a pretty good aluminum piston supplier in Vintage Auto Parts (vapinc.com).
Milling the head and raising the compression Will increase the power and fuel milage. To make it worth while .125" would need to be milled off. That would raise the C.R. from 6.25 to about 7.25. When this is done the intake valves must be recessed into the head by that amount, spacers used under the valve spring for that amount. Spacers must be used under the rocker arm stands and the side cover bolt holes for the head elongated. I think I remembed everything. Would add 5 or 10 H.P. at all speed ranges.
Interesting facts and figures. That's an average 15% gain in CR and about a 9% (?) gain in HP. Wow. Sounds like you have done this. So did you have to increase octane? The head mods coupled with Pertronix Dist and coil may be easier route than the pistons.
I didn't but a friend did years ago on a 1949. The C.R. is still low enough for todays 87 octane regular. I wouldn't suggest any performance improvements with out making sure the bottom end is perfect. Other things he did. Lighten flywheel, dual exhaust and carbs., high lift rocker arms (intakes), bore out to the limit, aluminum pistons, installed a 3.73 rear end. Would run up to 100 MPH on the speedometer and at least keep up with an Olds 88 which was one of the fastest cars in the early '50's.
Several of us have rebuilt 216 engines in the last few years. I would do an Advanced Search of the index of our past chat posts for comments and advice. Do a search using the Keyword "Rebuild," fill in the Display Name as "Mike Buller." The Date Range should be Newer Than "3 years," and Older Than "6 months." This will highlight my rebuild process.
Good Luck, Mike
P.S. Larry, if you are into Hot Rodding your 216 you may want to check out Freezerburn's postings on H.A.M.B.http://www.jalopyjournal.com/forum/threads/feezerburns-build-log.916808/ He does an excellant job of documenting his build process from the day he purchased his car to where he is now. His engine rebuild isn't completed so time will tell how successful he will be.
thanks much Mike- I will do some more advanced searching on the topic. NO, I am not doing hot-rodding. As I mentioned, with cars like this I keep them original (as this one is) but with tweeks that are not apparent but felt...like specifically engine performance. Larry
Hey Gene. Thanks again. A little more detail on this head mod please in this regard: If you are a) milling it and then b) recessing the valves by the same amount and then c) raising the rocker assembly then aren't you effectively increasing that quench area that you set out to reduce (for more compression) in the first place? I understand you need to do "c" if you do "b". And obviously you potentially need to recess the valves in case they are going to create collision with the pistons. I get all that. I would think: 1) Mill the head. OK..if it is an 1/8" then alright. 2) Install the head with gasket and clay the top of the pistons so you see the valve clearance. 3) Recess valves according to what you find out in "2", or maybe they do not need to be at all. I don't know enough about what the stock clearances are to start with. 4) Depending on what you do in "3", then you raise rocker assembly the same.
Or.....as I implicated in "3" above, you decide how much you can mill the head and that is all you do because your clearance from open valve to piston top is OK.
I was following this thread to see what info I could pick up. I had rebuilt several engines but never a full rebuild on a six. I am confused on something, I don't understand how adding a shim to the spring will change the travel of the valve. The lash has to be removed from the push rod, so as I understand it the travel will be the same from push rod contact point on the rocker to valve contact of the rocker, correct? Even if the push rod assembly is "raised" the lash adjustment will compensate for that and the travel of the rocker would be the same. Unless I am missing something here. Even if the shim is placed under the spring, it has to travel the distance or something would brake. The spring keeper is still going to be in the same location from the deck of the head, all you are going to do is create more tension on the spring, correct? The only ways I know of are : Different ratio rocker arm, or use of a different piston. If I am missing something I would love to learn. The valve geometry is relative to the angles of the rocker arms. I know on fixed valve engines like the Buick Nail head the valve height it critical because there is no valve adjustment. Even if the valve stem is shortend the valve still has to travel that distance it is pushed which is determined by the rocker arm ratio. I don't want to pirate the thread, but I know I am not the only one who has this question.
John
1954 Belair Sport Coupe 1960 2 door Impala Hardtop 348/340HP 4spd 1962 2 door Impala Hardtop 409/409 4spd 1962 2 Door Biscayne Sedan 327/250 Auto 1977 Monza Mirage 305 4 Speed 1988 Celebrity Wagon 2018 GMC Sierra 2500 HD Diesel
The shim(s) are placed under the spring because the valve seat is ground deper into the head. This increases the distance between the area that the top and bottom of the spring ocupy. Actually any time the valves are ground and this demension increases it must be measured and valve spring shims added to compensate for the change. This is seldom done but very important to get a long life out of the valve job. Weak valve springs (which this will equal) causes the valve to not close tightly had higher RPM's and not closing properly will cause and exhaust valve to burn. Will also cause "valve float" at a lower than "correct" engine speed.
Spacers (washers) must be placed under the rocker arm stands because the head will be sitting 1/8" lower - the alternative would be to used shorter push rods but push rods do not come in "shorter" lengths. The difference is more than the adjusting screw can compensate for.
I hope I explained this OK - would be easier to put it into words through talking.
After checking my hot rodding book the 1937-1940 head with combustion chambers designed for the domed pistons of those years, are not recommended for milling the head....Years ago they made pistons with a kind of a knob on top to increase the C.R.. The alturnative mentioned if filling the combustion chamber.
With all the valuable inputs and choices coupled with some local folks here in So Cal that know the 216 fairly well for years I have decided to do 2 things for efficiency and performance. 1) Change out the rear end to the 3.55 2) Fenton Headers and better system down the exhaust "chain". So, gears and "exhaling". Wish there was some good stuff you could do to the W-1 to make "inhaling" better. I have a couple of them to experiment with, so if anyone has any proven ideas. I guess I heard you can swap it out for a Rochester which I will search on this forum.
I do have an extra head 216 stock that I might put hardened seats into for the unleaded issue but that is not a priority at this point.
I am not sure if this is an improvement or not, but the 216 in my 51 has a 235 manifold and carb. set up and a 235 distributor. The car was previously owned by an "old time" chevy mechanic. It ran strong and I had no problems other than when I went to do a tune-up and changed the rotor not knowing the dist. had been changed.
