Throttle got stuck! - 8000 RPM for 10-15 seconds - Did I hurt my engine?

butzi73 · 06-21-2007, 09:14 AM

I have a 73' RS clone with a 2.7. I just got it 2 weeks ago and am really excited to finally have a great classic. The car is amazing. This is my first older car, so it's something of a new world to me, but I feel privileged to finally be a part of it.

Yesterday while I was really enjoying my car on a quite country road I floored it in 2nd. The petal stuck to the floor! The engine was screaming and sounded really strained. I have an Electromotive Direct Ignition System which has a rev limiter on it. The limiter was working because the engine was revving up, then cutting, then up, then cutting, etc. - real fast - and the tach was bouncing off the 8000rpm max. I would have hoped the rev limiter would have stopped the engine at a lower RPM (It is set to 6500).

It was a bit overwhelming and (unfortunately) my first instinct was to try to get the petal unstuck with my foot. That didn't work. My passenger reached down and pulled the petal but it just separated from the linkage, which was still shoved all the way in. Finally, after maybe 10-15 seconds of chaos, I came to my senses and turned the key off. I wish I had done that sooner!

After about another 10 seconds of sitting there (engine off) a good amount of smoke started coming off of the engine. Yes, I have a fire extinguisher and it was in hand as we waited by the engine. The smoke was primarily coming out of the fan area. I assume it was burning oil, but I'd like your opinion on that.

Eventually the smoke died down. We dug into the petal area and found that the linkage joint behind the petal got jammed behind the edge of the floorboard hole that it goes through. I'll be able to fix that by repositioning the linkage or even opening up that whole a bit more. No big deal.

I drove away and the car ran fine. I drove it again to work this morning and the car drove and sounded fine. Of course I didn't floor it!

My question to you guys is do you think I hurt my engine? Can this engine handle that kind of pounding? It seems to run fine, but did I take a chunk of life off it?

It has 40mm PMO carbs and JE Pistons and only has about 1000 miles on a rebuild. I am due for a valve adjustment which I was planning on doing next week.

Cheers,

David · David's Garage

A leakdown would help tell if any valves were bent. A valve adjustment might help finding any valve problems. The other issue would be if the rod bolts stretched and loosened. If they're ARP, they can probably handle 8000 rpm so it shouldn't be a problem. If they're stock bolts you may have a problem. Other than tearing the engine down, you could listen closely for any knocking indicating a spun rod bearing.

On the plus side, if there are any cracks in any engine parts, they've been overloaded so you get a retardation effect which slows further crack propagation.

joetiii · joetiii's Garage

The Electromotive system has a soft limit and hard limit. Soft retards ignition and hard limit cuts it out I believe. If your system is in fact set at 6500, and your tach was bouncing off 8 grand, I'd be inclined to think that the tach is off quite a bit. 8 grand should do some damage to the valvetrain but that seems ok, correct. Rod bolts are the next weak link as 125 shifter has already said. Do the valve adjustment and keep an ear out for unusual noises.

Tyson Schmidt · 06-21-2007, 10:32 AM

Probably fine. The tach needle was likely swinging past the actual RPM.

Long Nose · 06-21-2007, 10:42 AM

Another thing to watch is the oil pressure, as that can give you an indication. Spun rod bearing might result in low oil pressure.

Watch for oil leaks, indicating pulled or broken studs, this will also be evident during the valve adjustment.

Sweet ride BTW

vntgspd · 06-21-2007, 10:47 AM

I think Tyson hit the nail on the head (of course!). These old tachs have a lot of needle movement/bouncing so when the engine was bouncing off the 6500 rpm limit, the needle was bouncing too.

BTW, if you have a RS-spec 2.7, you will want to raise that limit once the engine is broken in. You are missing a lot of fun between 6500 and 7000+ rpm!

Deschodt · 06-21-2007, 11:12 AM

Regardless of engine situation, may I say your car is gorgeous, nicest RS clone I've seen in a long time. Great color combo !!!

Paul Ferradas · 06-21-2007, 11:14 AM

This reminds me that I need to fix my pedal also. I installed a after market racing style pedal and it binds with something when I floor it HARD. Ive only done this with the engine off but i would hate for this to happen to me like it did to you.

butzi73 · 06-21-2007, 12:32 PM

Thanks for all the great feedback, and so fast. Wow, this group is great! I'm so glad to have such a great resource for my new car.

I will check out all of the items mentioned here, and the upcoming valve adjustment will be the time to investigate.

The tach needle does jump around a lot so I was kind of hoping what Tyson and Long Nose was a possibility.

Thanks for the great compliments Long Nose and Deschodt. I will post more photos again sometime.

And, Paul, I'm glad to provide the reminder. I have to say having your throttle stick wide open is the quickest way to go from super happy to supper bummed (besides a crash).

I think the smoke must have been from the fact that I was stopped and there was no cooling, and the oil just overheated. The fan needs to be going and the oil pumping to cool it, right? Hopefully no damage done there.

I love this car! It's so fun! What an amazing and totally engrossing driving experience.

Cheers,
~Cary

dd74 · 06-21-2007, 01:24 PM

butzi73 - I wouldn't worry. I have nearly the same engine as you, and have miss-shifted into second when wanting fourth on the track. Unless your engine is smoking a whole lot or making knocking sounds, it's probably fine.

Nice car, btw. Who makes your door mirrors?

butzi73 · 06-21-2007, 01:45 PM

Thanks dd74. Your words of reassurance are nice to hear. I hope you are right.

I was told the mirrors were "turbo" mirrors. Maybe someone here can identify them a bit better than that. I personally don't care for them too much and plan on putting on the more original chrome rectangular mirrors. The old mirror holes are no longer there, or they are sealed over anyway. I will have to find them and redrill (yikes).

I also want to replace the black door handles with chrome door handles. I just think that would look better, more classy with the silver body. I have to say I love the older style chrome horn grills and blinker trim, but I guess I'll leave that black to stay RS correct.

Yes, I'm going to take it to the track as well. I can't wait for that.

Here are some more photos ---

Tyson Schmidt · 06-21-2007, 01:55 PM

Nice car!

One suggestion. Get the car aligned. Looks like you have positive camber in back. There's way too much tire sticking out of the fender on top for an 8" rim. You'll want the negative camber for handling and tire life at the track.

If you want to keep it as mostly a street car, then I'd recommend -1.25 front and -1.75 rear, with stock toe settings in back, and zero in front.

Oh, and a good corner balance.

dd74 · 06-21-2007, 02:03 PM

Butzi - listen closely to that Schmidt guy who keeps posting here. He set up my car two years ago - and it still never fails to amaze me. Too bad he moved up north.

BTW: I'll take those door mirrors off your hands if you're thinking of selling. I want to try out a new mirror style.

butzi73 · 06-21-2007, 02:10 PM

Thanks! You're right about the camber Tyson. I have an alignment appointment set up already (with Eric Leman - Pacific Power Motorsports in Concord - He seems pretty knowledgable.) My tires have rubbed a few times already.

I really appreicate your advice. Maybe I can come meet you R-Gruppe guys sometime. I'm in the Pleasant Hill/Walnut Creek area.

~Cary

Tyson Schmidt · 02:48 PM

Sure, anytime. I work here in San Carlos.

BTW, what are your intentions for use with that car? I can offer more pointed advice if I'm better informed. That is, if you want any.

David · David's Garage

That is a gorgeous car!!! Welcome aboard. You can answer almost any question with a search here. Too bad we don't have a "best thread forum" with maybe the top 100 threads

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GrantG · GrantG's Garage

Quote:

Originally posted by vntgspd BTW, if you have a RS-spec 2.7, you will want to raise that limit once the engine is broken in. You are missing a lot of fun between 6500 and 7000+ rpm!

[/B]

Absolutely! I have a 7700rpm cutoff. If your motor is built to race specs, you'll be fine having hit 8k for a little while...

Moses · 06-21-2007, 07:06 PM

Engine is toast. Car is ugly beyond description. I live 5 miles away from you. You can hide that car in my garage if you want to save yourself further embarassment.

Lukesportsman · 06-21-2007, 07:14 PM

Not that Tyson needs confirmation, but that tach is sloppy. That or my 2.7MFI is one killer lightened engine because it's tach responds faster than my race car. It is great to impress the novice, but if you blip the throttle whatch how the needle lags the rpm and probably exceeds the max rpm reached. Inertia seems to influence these too much.

Welcome, and beautiful RS Clone. Nice choice! You could do far worse than to listen to Tyson.

joetiii · joetiii's Garage

Has anybody thought about the what caused the smoking engine condition after Butzi was banging the limiter. I'm curious why smoke would be coming from inside the fan area?