Good morning all. This is a word of warning. On the right are a pair of 110 heads I received as a core. These were rebuilt 3500 miles ago. I decided to use them on my 65 Vert as an initial dyno test so can have a baseline HP of a stock 110 engine. But... upon inspection I noticed something not right. Look at the machining on the fins. This cut is to provide clearance to the cylinders when the heads have been flycut on the headgasket surface. The cut on the fins is not parallel to the headgasket surface. But it is parallel to the valve cover gasket surface. Problem is the valve cover gasket surface has a 2 degree call meaning this surface is angled downward 2 deg relative to the headgasket surface. The rebuilder did not know this and supported the heads on the valve cover surface and proceeded to cut the headgasket surface and cut the fins for clearance. This angled cut requires nearly an eighth of an inch cut at the spark plug hole in order to get a flat surface all around the headgasket area. This also makes the quench angled with the greatest thickness opposite the spark plug. During operation this area becomes a pocket of mixture that is not turbulent, harder to ignite due to the distance from the plug and becomes a source of detonation.
I disassembled the heads to check them thoroughly and found the new bronze exhaust guides at maximum wear. The exhaust seats are very wide and look beat up. And on number 1 exhaust spring no spring shim was used. The damper had started cutting into the spring seat.
I decided to use these heads anyway so I welded the quench and flycut back to the headgasket surface. Upon flycutting I noticed the surfaces were all high at the 4 o'clock position. So a headgasket failure was eminent. I had to follow the mis-cut the previous rebuilder made but for a baseline test these will now work. After the first dyno pull I'll pull these heads and install the bigger valves. Then on to a second dyno pull. I'd like to know for sure how much power the bigger valves are worth. I will need to properly rebuild them after the dyno pulls.
So my warning is this: make sure you know who is rebuilding your Corvair components and that they know the details necessary to do the job correctly.
The 3rd picture is of the valves I removed from the butched 110 heads. Notice the excessive carbon on the intakes. I think the gas quality has changed quite a bit in recent years. I recommend using BG brand 44K or Seafoam fuel system cleaner in the gas tank at least every 6 months. Z Max might work too but I have not used this product. Yet. This engine ran the Ted Brown EFI system. Also notice the excessive carbon buildup on #5 cylinder. Not sure what caused this.
10.13.2012
Here is the latest update on these butched heads.
New guides are in and reamed. Repaired 2 spark plug holes on #'s 2 & 6 cylinders. Cut the seats with the Neway cutters. All the intakes cleaned up easily and with a minimal of material removal. The exhausts on one head were all high near the quench. Mostly due to me not getting the head shimmed exactly right when I reamed the guide bores. Nothing to index on in a quick way. The exhaust seats on the other head cleaned up really well. And this head was shimmed the same as the first. Go figure.
Now here is the interesting thing. The excessive carbon in #5 chamber. I had not planned to even start to look for the cause of this carbon. But I did find the cause. I assembled both heads yesterday. All was going well until I got to installing the exhaust valves on the second head. One of the valves did not fully seat. I tried a different valve and it seated just fine. Tried the suspect valve in a different guide and still it would not seat. Any guesses guys? The valve problem is a case of being improperly machined. The "tulip" area at the stem is taller than the other exhaust valves. This is hitting the guide before the valve face hits the seat. All the guides are installed to the same depth. This is the only valve with this problem so I am pretty sure it was installed in #5 cylinder. My fix was to use a countersink bit in my drill and add a chamfer to the end on the guide. The valve seats just fine now.
10.24.2012
Poorly rebuilt 110 heads
Welding ald flycut finished, need to clean up quench edge.
Valves from above heads. Excessive carbon already. See text.
Horse Power and the N/A Engine
I wanted to talk about horse power and what needs to be modified on a Corvair engine to get more.
First I want to discuss the Corvair engine basics. Starting from the core. The crank. Needs to accept the pressure from the pistons and connecting rods that was generated when the fuel/air mixture was ignited. The rods. As above and are used to connect the pistons to the crank. Pistons. They seal against the cylinders via the rings, transfer the combustion pressure to the rods and on to the crank. Running a bigger bore for more displacement will help a bit but will not double the output. None of these items can be modified to raise the engine's hp much over stock. How about the camshaft? This little guy will change the output somewhat and raise or lower the power band but not give the engine a huge boost in power without other mods. Ok, compression. Just raising the compression will require a few changes to use properly. Like camshaft, fuel grade, fuel/air ratio. But again, raising the CR will not give the engine a worthwhile hp increase.
Carbs? Too much carburetion will load up the engine unless many other mods are done first. EFI? This will give a lot of drivability and good mileage if use on a stock of slightly modified engine. But not a big hp boost. Headers now? We're skirting around the real problem here and still need to look elsewhere.
Heads? Here we go. I keep seeing how much power current race engines have been making in the last 10 years up til today. Such as the V8 Supercars. In the 650 range. Not bad for a 5.0L V8. The Nascar Cup cars at approx 950 hp. Damn that's a lot. The 3.8L Porsche water cooled engine... over 400 hp. And there are many others but listing some of them is useless. The real step in right direction is in the use of the flow bench. 30+ years of use have taught us a lot.
What's wrong with our Corvairs? We can install a pair of 3bbl Webers and still not be close to the current power to displacement ratios of a modern race engine. What's wrong here? I've known this for quite a while. The power is in the cylinder head. But where? Well, its in the ability of the engine to breath. After all, the engine is just a glorified air pump. The real problem with the Corvair head is 2 fold. First is the port runner itself. This little guy is appallingly poor quality. Designed in the 50's for an economy car targeted at the VW Bug. And never changed on production cars for the life of the Corvair. Then there is the "manifold" A small rectangular tube connecting 3 port runners on a head with a small hole for a carb to breathe into. This design has 2 90 degree turns - great for power. I don't think so. First 90 degree is where the mixture leaves the carb and enters the "manifold". The second 90 degree turn is the manifold to port runner. Nice design for a lawn mower but a car? Certainly not for any real hp generation.
Ok, so you say the 140 heads corrected the wimpy small valve heads but did they? Really? I don't think so. The Chevy engineers only enlarged the manifold and runners but left them just as poorly designed as on the small valve heads. Including the exhaust. What is really needed for big power increases is to open and straighten the intake runners in order to increase the ability of the port to flow higher volumes of air and fuel. And... maintain good velocity in the port at each step of any modification. Just hogging open a port and expecting it to work is just asking for trouble. Without testing each change on a flow bench is the wrong approach.
Our Corvairs are port limited. In both hp and ultimately maximum rpm. A planned approach with head mods will get us near the current power to displacement levels enjoyed by people racing other makes and models. All it takes is time and money. Like the old racers' saying; "Speed costs, how fast do you want to go?".
So there you go. My opinion. I hope someone reads this. Any comments?
Tom...
05.22.2013
Helpful Info
I have a new SS float unit in my fuel tank on my 64. But the gauge reads empty. I drained out the gas, pulled the unit and found the brass float cracked in several places. I emptied it and soldered up the cracks. Didn't add very much solder or weight. The gauge still reads empty. A friend from Houston, Mike Tidwell, told me he uses a Ford float. Here is the Ford PN: COAZ-9202-B. This looks exactly like the replacement float available from Corvair parts vendors. But this feels like a thicker walled material. I have yet to drain the tank and replace mine but the time is coming soon.
09.17.2013
Stuff I Like
I need an area to post various data besides other interesting things.
How about some flow data to start...
Stock 140 intake and exhaust flow numbers:
Intake-
18.0 53.5 53.1 0s < MARK 0.10
11.5 94.1 93.4 0s < MARK 0.20
8.96 119.9 119.1 1s < MARK 0.30
7.51 138.0 137.0 2s < MARK 0.40
6.78 148.8 147.7 0s < MARK 0.50
6.50 152.9 151.8 0s < MARK 0.60
;Edit
bone stock 140 intake;
Exhaust -
12.9 32.2 32.0 0s < MARK 0.10
10.0 59.3 58.9 0s < MARK 0.20
8.39 80.2 79.7 4s < MARK 0.30
7.66 90.3 89.6 6s < MARK 0.40
7.27 95.6 94.9 6s < MARK 0.50
7.11 98.0 97.3 7s < MARK 0.60
;Edit
bone stock 140 exh.;
The 3rd column is the CFM. The MARK number is the valve lift the data is measured at.
If you have flow data on your heads but don't know how they stack up to stock, here you go.
11.14.2010
And here is the flow data for a stock 110 head... intake only at this time.
z 28.4 40.9 40.6 < MARK 0.10 21.3 71.3 70.8 < MARK 0.20 18.7 83.4 82.8 < MARK 0.30 17.4 90.1 89.4 < MARK 0.40 16.9 93.4 92.7 < MARK 0.50
Once I fire up the flow bench I'll test the exhaust on a 110 head.
02.07.2011
Here is the flow test but on a 95hp head exhaust port in totally stock form:
.007 .004 0.0 .006s z 13.7 20.8 20.7 0s < MARK 0.10 11.2 44.5 44.2 0s < MARK 0.20 9.95 55.4 55.0 0s < MARK 0.30 9.48 60.0 59.6 0s < MARK 0.40 9.35 61.8 61.3 0s < MARK 0.50 .001 .006 0.0 .000s
Doesn't flow really well. And is noisy during the test which indicates turbulence. I think the 110 head would be quite close to these data.
10.24.2011
While working on the 65 140 Corsa heads on the EFI engine I decided to check these heads with a racing intake valve I like to use on the race heads I build. These valves are stainless, have a 5/16" stem, tulip shaped and are stock at 1.72". I didn't change anything on the head, just added blue tape to the stem to take up the clearance to the guide. This shows a nice increase in the CFM over a stock intake.
02.27.2015
Totally stock valve, no backcut angle
CFM Valve lift in inches 39.4 33.0 32.7 0s < MARK 0.05 32.3 63.1 62.6 0s < MARK 0.10 25.2 95.2 94.5 0s < MARK 0.15 20.2 124.6 123.7 0s < MARK 0.20 16.6 152.1 151.0 0s < MARK 0.25 14.1 174.6 173.3 1s < MARK 0.30 12.5 193.3 191.8 3s < MARK 0.35 11.3 207.8 206.3 2s < MARK 0.40 10.9 212.7 211.2 0s < MARK 0.45 10.4 220.5 218.9 2s < MARK 0.50 9.87 228.4 226.8 3s < MARK 0.55 9.51 234.1 232.4 2s < MARK 0.60 9.36 236.6 234.9 5s < MARK 0.65 .004 .004 0.0 .002s
CFM is 3rd column, starts with 32.7. Valve lift starts at .050"
Racing intake valve
CFM Lift in inches 37.8 34.7 34.4 2s < MARK 0.05 30.5 66.4 65.9 2s < MARK 0.10 24.3 97.5 96.8 2s < MARK 0.15 19.0 129.5 128.6 4s < MARK 0.20 15.4 157.1 156.0 4s < MARK 0.25 13.1 180.2 178.9 4s < MARK 0.30 11.6 197.0 195.5 4s < MARK 0.35 11.0 205.0 203.5 3s < MARK 0.40 10.3 214.8 213.2 3s < MARK 0.45 9.61 225.6 224.0 4s < MARK 0.50 9.06 234.3 232.6 4s < MARK 0.55 8.70 240.5 238.7 2s < MARK 0.60 8.50 244.8 243.0 3s < MARK 0.65
.003 .004 0.0 .001s
This is a video of a very good friend of mine named Steven Earle. He races Ferrari's in Europe. On this video he is explaining the best way around the Mugello track in Italy. So, if you have a chance to race on this track you might want to watch this...
Once on the Kessel Racing TV site, click on the C.I. GT MUGELLO link then on the bottom center link "La Pista". Turn up the volume.
At right are some currect pictures of Steve Earle's latest ride. He won the Championship last year in a F430 Ferrari and this year he will drive the 458 Italia. These are of the Italia taken in Europe. I need to find out what track they were racing on.
02.04.2012
Good front view, mean looking car
I like this...
Here are a couple of videos I took while at the PW6 in Indy this spring. This is Michael LeVeque's Stinger clone. This is a really nice car with great HP and an awesome sound. Check these out. They will take a bit to download but is worth it.
The first vid is of the second pull and as the RPM's rose the engine started to miss - lost a plug wire I heard.
The second vid is a fine pull... all the way to the top. Really nice.
03.15.2010
Here is a link to a video of a Renault championship hill climb car running in Romania. This car is set-up with a SDS EFI, the same system I will run on my 2 Vairs. And my Subaru powered 1985 Vanagon.
