Re: Fresh 350 in a 74 Chevelle

by bracketchev1221 Tue Apr 18, 2017 4:03 pm

I would try to shift at 5000.

by bigredlaguna Tue Apr 18, 2017 4:29 pm

I am considering modifying the governor to accomplish that. Right now it has the stock governor that makes it shift at 4-4200 rpm.

by bracketchev1221 Tue Apr 18, 2017 4:46 pm

I wouldn't expect that cam to make power much past 4600, but you want to shift it past the peak power and let it run back and forth over the HP peak. So if you shift it at 5000 and it drops to 4, it will run back and forth over the peak for a better average power.

by bigredlaguna Tue Apr 18, 2017 6:21 pm

I'll relay that strategy to my daughter this weekend. Right now I just want it to do better than it did last fall. I do believe I have accomplished that.

I just adjusted the pump linkage to the innermost hole, and now the bog is gone. Just have to adjust the vacuum modulator on the transmission because part throttle shifts are too early. I think I got this running as good as it can without a dyno tune.

by fasrnur Tue Apr 18, 2017 7:16 pm

I modified the governor on my last TH-350 and it made a difference when I let it shift itself.

by bigredlaguna Fri Apr 21, 2017 11:19 am

Well the drag event this weekend is postponed due to rain today. It's several miles of dirt road to get to that old airstrip.

by bigredlaguna Sat May 20, 2017 4:28 pm

I did a little bit of tuning on the carburetor today. Put in some primary rods that would richen the air fuel ratio and now it just flies. I'm sure some dyno time will get better results, but it is definitely close now. Power through 5k. The drag event is re-scheduled for 6-22, can't wait to see how it does compared to the previous time.

by Roadcaptain S3 Sun May 21, 2017 5:38 am

Me neither. Smile

Keep us posted

by bigredlaguna Mon May 22, 2017 8:02 pm

Well, I just took my daughter out to practice manually shifting the column shifter. Did several practices at low speed-low throttle so she could get the feel for it. So when I thought she had it down good enough for a full throttle run, this happens---

The engine still runs fine, no knocks, no fluids draining, but we did lose the alternator belt and a few bits of the shroud.

by bracketchev1221 Tue May 23, 2017 3:24 am

And so is the is the reason for many swaps to a floor ratchet shifter. Shes not the first one to mis-shift a column shifter. Possibly have her push forward as she goes into drive, if I remember there is a detent that moves the handle forward.

by bigredlaguna Tue May 23, 2017 6:16 am

I'll see if it does that, otherwise she will just keep it in D and I will modify the governor to raise the shift point.

by bigredlaguna Tue May 23, 2017 6:21 am

What does backfiring in the mufflers sound like? What are the possible causes? I have my suspicions, but would like to confirm them or look for a reason I haven't thought of.

by clanceman427 Tue May 23, 2017 6:29 am

It does sound good! Well, what ignition is on it? if you have an electronic ignition or plan to upgrade, the embedded adjustable rev limiter will protect it.

by clanceman427 Tue May 23, 2017 6:34 am

Looks to me it got to 7000rpm for an instant, not all that bad. I also didn't hear it breaking up at that rpm, if I heard it breaking up I'd be concerned about valve float and valves too close to pistons, but I think you're OK except of course for the fan shroud.

by 73ss Tue May 23, 2017 2:15 pm

clanceman427 wrote:Looks to me it got to 7000rpm for an instant, not all that bad. I also didn't hear it breaking up at that rpm, if I heard it breaking up I'd be concerned about valve float and valves too close to pistons, but I think you're OK except of course for the fan shroud.

X2 Cool vid. Something to show the grandkids someday. Car looks like its pulling hard.

by bigredlaguna Tue May 23, 2017 3:50 pm

It has a regular HEI for the ignition. Previous pulls had made some noise under the rear seat area that didn't happen in the video.

by bigredlaguna Thu Jun 22, 2017 11:21 pm

A couple of weeks ago, I looked at the spark plugs and found some issues that prompted me to tune the carb and adjust the timing. The #8 wire was just barely on its plug (as in not snapped on), so I'm pretty sure this was what was causing the weird noise I heard in the mufflers. I also got a 4" deep groove pulley for the alternator to reduce the chance of tossing another belt. Along with that I had to use some washers to space the alternator back to correct a pulley misalignment (due to an Autozone water pump that has the bosses too far forward- so if you get a parts store pump, compare the bracket bosses to your original)

Just now I got a spare governor from my trans builder and ground down the weights to raise the shift point. Let me just say that I believe I have a bracket racer now. First try ever for me on modifying the governor and I got it to shift at 57-5800 on the 1-2 shift and 5200 for 2-3. Perfect!

The fun drags at the Ingalls airstrip is on for this weekend and the forecast is for a high of 75 or so. Even more perfect!

by bracketchev1221 Sat Jun 24, 2017 12:17 pm

So did it run?

by bigredlaguna Sat Jun 24, 2017 7:23 pm

I'm calling this day a success. Went there (20-30 minute drive @ 3k-3.2k rpm), made at least 20 runs, and drove back. Nothing broken and made some new friends. The only negative parts are the sunburn on my forehead, and as the day went on, it became more grudge racing. I made more solo passes than anyone else I think because the car was too quick for the slower ones, and too slow for the faster ones. And my wife didn't get to race because her asthma kicked up too bad for her to stay there.

I timed it with my phones stopwatch as close as I could, and consistently got 9.5-9.6 second E.T.'s. (1/8 mile) The last run I got the radar reading from the sheriff and it was going 75 mph.

I'll get a video or 2 of it running after I sort through what we got.

by bigredlaguna Mon Jun 26, 2017 8:46 pm

Ok, here are a few videos I got of her, and perhaps some she got of me. There are videos of other stuff there if you care to see those. The fourth video has the same car we raced last fall, the Chevelle did much better against it this time. We raced a few times and both won depending on if the Laguna had an issue or not.

by Limey SE Mon Jun 26, 2017 9:03 pm

Very Cool Sir Good to see it out

by bracketchev1221 Tue Jun 27, 2017 2:49 am

Based on your estimated numbers you look like you have a high 14 second car, low 90's in mph.

by bigredlaguna Tue Jun 27, 2017 5:37 pm

Unless I put an overdrive trans in it (very likely), I am now just in maintenance mode for this car. Time to get busy on the Laguna, and do everything I just did on this car again.

My daughter does like to drag race, but we still have the 77 Skylark that would be a better vehicle for that purpose.

by bigredlaguna Thu May 17, 2018 9:00 pm

Well, so much for just maintaining this thing. My daughter wants to make this car quicker. I talked to my engine builder today about getting a bit more horsepower out of this engine, and he recommended getting a better torque converter before doing anything to the engine.

I am in agreement with this course of action. I also want to go with a little bigger cam, and my builder recommended staying at about 225* duration @ .050 with these heads.

She has already bought a set of drag radials that are a bit shorter than the 295's on the rear now. They are 275/50-15 Nitto 555's. We tried them out last night, and the car definitely felt quicker and powered through first gear better than it did with the street tires. The engine has enough power to do a burnout on the 295's, but the Nitto's won't budge. On either set of tires, you can tell it needs a little more stall because after releasing the brakes, the car goes then a little later you feel the power come on.

So I would appreciate any suggestions or experiences about torque converters that would be suitable for the current engine setup and with a cam in the 225-230 range.

by bracketchev1221 Fri May 18, 2018 3:56 am

I'm assuming its a stock converter in the car now? If you plan on going 225-230, I don't think you need much more than a 24-2600 converter, especially if you are going to drive on the highway.

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