Boosting the rpm's on a "Town Cruiser"

[Geistfahrar]

Getting ahead of myself a bit, since I haven't got my '69 2000 back on the road yet, after about 4 years in mothballs, but I am looking for sage advice from the folks that spend a lot time re-conditioning their engines, and/or are familiar with the effects of driving the roadster over a wide range of conditions.

In the summer of 1974, I took the guy up to the yellow ( about 105 mph ) between Las Vegas and Mesquite NV, but usually kept it below 4500 rpm on trips up US-395, between Ridgecrest & Bishop CA. After the re-build in '83, the roadster ceased to be a daily-driver, and was mainly a "town cruiser" and a Ski-tripper, on the US-395 route just noted. When it is put back in operation, it will probably be just a town cruiser. My guess is that about 12k miles of the 25,574 rolled up since the re-build were between 4,000 & 4,500 rpm, so I am wondering how big a ridge I have acquired at to top of my cylinders. Since I now have to rely upon other folks to do all the heavy stuff, I am afraid that if I leave the roadster in the hands of some unknown lot-jockey, he will try and "take it up to the line", with the rings then hitting the ridges.

Is there any safe way, over the course of 4-5K miles, of "easing the top rpm's up 6,500 rpm", without damaging the rings?

[bobd]

The rings will not go any higher up in the cylinder when the rpm increases. There wouldn't be enough wear in 25,000 miles to wear a ridge in the cylinder anyway. There will be some carbon build up, if it is excessive, it could cause detonation. You can always look in the spark plug hole to see what the top of the piston looks like.

Here's what I would do:
Squirt some Marvel Mystery oil in the cylinders and let it sit a few days.
Spin the engine with the starter, plugs out.
Fresh gas with some Sea Foam, drive it around town, see how it sounds and feels.
If all is good, take it up on the interstate and blow it out.

This is my opinion and you will no doubt get plenty of advice.

[Geistfahrar]

Thanks for the advice. I was assuming there would be some increase in rod-length between 3500 & 6500 rpm (guess I was wrong). I was just guessing about how much of a ring would be formed in 25K miles, since I never checked the ridge 107K miles before the re-bore. I have no experience with Sea Foam, but used Marvel Mystery Oil decades ago, when I manned the fleet truck lube ^ tire racks at the uptown San Diego Chevvy dealership ( 1950 - 1952 ). Back then we added the MMO to all the fleet trucks, because all were pre-war, with more than 200K miles on them. I agree, that before taking the roadster back on the road after4 years sitting with old oil in the cylinders, a shot of MMO is advisable. BTW, what octane booster do you use to get your gas up to the recommended 95? I don't know what the max is in Florida, but here in CA, it is 91. When the roadster was last operational, I added NOS ( MMT ) octane booster to the gas, at the rate of 0.75 oz. per gallon. Years ago, when the lead was 1st removed from the local gas, I used a lead substitute additive, but my mechanic said it wasn't necessary. Any opinions on gas additives?

[Gregs672000]

You're worrying about nothing my friend. What's far more important for the life of the engine is making sure timing is good, valves are properly adjusted, good oil, and providing enough quality fuel with a high enough octane to prevent knock or ping (91 or 92). I'm able to run a hipo engine with 11.7 to 1 compression on 92 pump gas here in Western Washington, granted with a lot more control over my ignition timing than a distributor and points. One mod I would highly recommend is the electronic ignition distributor or the 123 programable distributor option if you're running into ping or (worse) knocking issues. Review 311s.org for threads on these distributors. You also might benefit from adding or doing some tuning with a wideband Air/fuel meter on a dyno (or on the street with one installed, I have one mounted) to make sure it's fueling properly at the rpms you're at. Don't want to go lean at 6000rpms.

There are a number of things that need to be working right on the U20 to get the best out of it. Start with a good tune up, good plug wires, adjusted valves, good oil (I like Valvoline VR1 10/30) and go from there. Let us know how she does!

[FergO2k]

+1 on what Greg recounted.
I take my U-20 out and regularly flog her in order to "clean out the carbon build-up". (now there's rationalization!)
While I regularly drive around town at 3k- 4k rpm, on the backroads drives/rallies I have been going on, I have a self-imposed red-line of 5k, which often gets exceeded to 5.5k. Other than a little weeping of coolant at the elbow (I am obviously spinning the water pump up and making some pressure) she loves it and runs better afterward. Fresh oil, topped up coolant and a sharp eye on the temp gauge, always. I also err on the side of letting it warm up for a good while before spirited driving. (set idle at decent revs while I check all the tire pressures, I have one rim with a slow leak at the bead)
Good luck and happy roadstering.

[Geistfahrar]

Thanks for the updates. I guess I have been worrying too much. Like Greg said, getting the guy into a good tuneup will probably solve the pinging on 91 octane, I had heard about the 123 dizzy before, but hadn't researched it. After reading several posts on this forum on the pros/cons of the 123, I believe that it is over-the-top too flexible a device for a casual driver like myself. I had already downloaded the installation instructions for the GB dizzy sold by East Coast Roadsters, so I think I will continue in that direction. My original dizzy, with 130,699 miles on it, is undoubtedly too sloppy to achieve a good tune. The advance is still set at the original zero-degrees TDC, and I will re-set it to 16d when I drop in the new dizzy. All smog parts except the pump have been removed & the head ports plugged with Dean's injector replacements. Penetrating oil has failed to loosen the fittings on the intake manifold, so I think I will take the "cowardly" approach to crimp, bend & solder them shut. I am undecided about leaving a gutted pump in place to "fool the inspectors", or leave it off. I need to remove it from the engine, in either case, to easily remove my busted water pump, & put in the new one. I agree that a good "flogging" at 5K rpm would be a good thing, but I no longer have the free time to take it up to the high desert for a long run-up. My best bet is a 4-mile stretch of freeway ( route to Daughter's, abode ) where Min-speed to avoid being rear-ended is 80 MPH.
Fergus mentioning "keeping an eye on the temperature gauge" to avoid problems, reminded me to search the forum on another topic -- Best replacement for the long-gone original temp-compensated fan coupler.

Thanks for the advice Garry S.