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I don't think i've posted this before on here but for anyone interested semir and i bought a set of scales last year and we can now do corner balancing along with alignments.
Over the past month or so, I continued to grind away at de-rusting and degreasing the Peter Coen MGA 1600 engine. I suppose about 70% of the engine is salvageable. The engine block, connecting rods, crankshaft, front and rear plates, block oil fittings, oil pan, distributor drive and oil pump drive spindles are reuseable with some machine shop work. The valves need some parts but the head appears usable. Otherwise, a mix of miscellaneous 5 main bearing MGB engine parts were included that I won't be able to use. What I haven't tossed, I've boxed up for storage.
On January 2nd, the machine shop called with news that the combustion chamber revisions for the head for the Allen Johnson engine (MGA 1622) had been completed, so I went to picked up that project. The engine has domed pistons, thus requiring the combustion chamber modifications. I was wondering if I had made a mistake and should have just installed flat top pistons. But the damage is done, the head is in the basement while the engine remains in the car awaiting removal.
The Allen Johnson engine should be low hanging fruit. As near as I can discern, it appears that Allen Johnson rebuilt the engine for the 2012 race season (1958 Devin MGA) with CVAR in Texas. He sold the car in 2013 into Massachusetts and it was used thereafter as a street car until 2017 or 2018, when the engine was pulled. I bought the short block in June 2018 and it has been sitting in my basement ever since. The head and roller rocker were swapped to the Devin's new engine.
I suppose that I have to dig into the engine to see what really is there. Here's what I think I know so far based on engine paperwork - all good: base engine is a MGA 1622 with mechanical tachometer. Bore - 3.041"; Venolia pistons with .120" dome, internally milled; Teflon wrist pin buttons; pistons @ 342.4 grams, pins @ 71.88 grams; NPT oil gallery plugs; valve reliefs in block; new cam bearings in 2012; crankshaft +.010 rods, +.010 mains, balanced 2012; Pauter connecting rods (wrist pins may be offset by 0.170") (will require a discussion on the motorsports thread); camshaft may be a Kent Camshaft KC254@106*, but maybe an APT VP-18 - lobe - centerline 108*, lift - intake .3355", exhaust .3361". The engine has the 18V lifters, but pushrods must be replaced. Also, an aluminum rear plate and a Fidanza flywheel.
In other news, I removed the brake and clutch pedals from the MGA's pedal box in anticipation of welding on a pedal stop, thereby addressing my clutch overthrow problem. But a lot of surface rust due to brake fluid, both on the pedal box top surface and in the driver's side footwell. I cleaned most of that up and painted the affected areas - but due to cold temperatures, I expect that I must wait a week or so before touching.
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And in still other news, now that a "track car" has been loaned to me, I've been thinking about how I can cure my sluggish reaction time to unexpected oversteer! When the rear end kicks out unexpectedly - I feel like it's happening in slow motion and takes me a second or so to react. And then, I invariably overcorrect and end up fishtailing the car several times before giving up and putting both feet in, hoping to land in a safe place. I can saw the wheel intuitively like a champ through an understeer, but find it impossible to correct the unexpected oversteer.
Part of my assessment involved making excuses for my spin of the S2000 into the tire wall at Lime Rock in 2021. From time to time, I've felt a surface "deviation" coming out of the Downhill (about halfway through track out and mid track), where the car is "thrown" or "lurched" towards the outside, but without a discernable loss of grip. I always thought this to occur when I crossed over the pavement seam in the middle of the track. Well, I found a Lime Rock track description by Tom O'Gorman. He describes an area coming off the Downhill as "the float", where there is indeed a loss of camber and, therefore, traction. But I still need to react more quickly and apparently in a different manner. In any event, I found this video which I think will be helpful in my quest for better control. A different perspective is offered for correcting the unexpected oversteer.
Jeff - Lime Rock has several corners where Oversteer can surprise you. The riskiest one in my book is the Uphill. Like you, I have also crashed at the Downhill and have also had a very scary moment at the Uphill. And then there are those who've fought the car when it had two wheels off past Turn 2 only to make contact with the Inside wall. Also had a moment at the left-hander. So suffice it to say, each corner at Lime Rock probably has its own section of fans (those wary of the corner) among the driving public.
And as for Oversteer, everyone falls victim to it, even F1 and IndyCar drivers. So don't overthink it. You have saved the car and yourself more times than you have lost it.
Coming to the S2000. It has the CR shocks and the Karcepts Front Sway Bar. The tires are Fallen Azenis RT 615K+. These tires are not super grippy like the Super 200s but fall lower on the grip and lap time scale alongside the Hankook Ventus RS-4. They will deliver consistent lap times for longer. I haven't driven these on the track like I have the Hankooks, but I expect they will hold up to extended lapping sessions well and without wearing out. Do keep in mind that as they age, they could get slower but will still be consistent.
My plan with the S2000 was to eventually do something like an STR build but use it for the track. The STR prepped S2000s, at least the good ones handle like a dream. I drove one that was built well and it felt very similar in handling to the Skip Barber MX5s with the Penske shocks - it was a dream in slow corners but also handled the medium to high speed corners well. Mike (NoDelta) with the changes to his car, should have one that handles like that. Your (my) S2000 will not. Because it was only partially prepped, it will do great in medium to high speed corner and will still understeer in low speed corners (think Turn 3 at Thompson Speedway).
Lets talk about Thompson Speedway - Turn 3. This is a second gear corner in my S2000. In Third gear it takes a while to get into its power band as you exit the corner. But getting into second also means you will need to upshift mid-exit. One way around that is to have a car that can roll through there with greater speed or better yet a car with a tune on it like the Civic where I can leave it in third and still make up ground. The point I am trying to make here is you have to drive the car you have.
So lets get back to Lime Rock. The Skip Barber MX5 was set up so well that at Turn 3, all it needed was a tap of the brakes to get it rotated. In comparison both the S2000 and the Civic need more brake there to get the car rotated. Likewise at the downhill - the MX5 just needed a lift on the downhill and then back on the gas and it felt very secure doing that. The S2000 and even the Civic and the BRZ always felt more comfortable with a tap on the brakes. It was really up to me and how I felt about how much risk I could take at that corner on a given lap. Was the 10th I would gain there worth the lap time? In some cases it was. Like the time I was doing my first TT with the BRZ at Lime Rock with EMRA. The guy that was the Stock Class champion was braking at the downhill and I was following him for a few laps. On one lap, I mentally made a note to just go through with a lift and pulled it off. That gave me the lap record for the Stock Class at Lime Rock.
This last year, at the Mohud-CART Time Trial at Palmer, Mike and I were comparing data traces. I was faster than him going through the Turns 1 through 4 section and yet he was clawing back the advantage on the tighter sections of the track. He was driving his car to the way it was set up just as I was. The Civic being FWD will understeer at some corners where the S2000 gets through a lot more comfortably.
You could always get more practice on the skid pad and practice car control. That will make you better, but there is no guarantee that it will 100% protect you from Oversteer. Therefore my recommendation is to maximize the corners that you are comfortable with and perhaps try not to risk it all on the one corner you are never 100% comfortable with. The assurance that the Skip Barber MX5 provided as well as a well set up STR S2000 can is something I have never had in my cars. The Civic is probably the best among the lot currently, but there are still moments where fear is present. So rather than push it on the Downhill every lap, I will try to roll more speed and maintain it going through Turns 1 and 2 and see if I can get West Bend right.
All of this is to say that you should give yourself more credit than you normally do. You are a good driver in my book.
Oh boy, that’s a bummer after all that machining. What options do you have at this point? Could some kind of spacer be added to make sure the pistons clear? Is that even a viable solution?
I'm going to have to grind back the four combustion chambers in the head where I feel the interference.
I ordered up some "Prussian Blue Paste" from Goodson Tool as well as a few aluminum oxide grinding stones ("mounted points") - and a few other goodies that I can someday use. I have a couple sets of the carbide cutters from Eastwood, but I don't want to go overboard. In the meanwhile, I'll try to clean up the pistons and prepare a couple of sacrificial valves to drop into the head to protect the valve seats while I'm grinding back the offending interferences.
I've never used the blue paste before, but my understanding is that you spread it on one surface and it marks the opposite surface where there is an interference. I'll try putting it on the pistons (one at a time) and spinning the engine. The paste should transfer to the head where it makes contact.
12-20-2023, 09:57 AM
