Technical 340 in a 1937 Dodge truck

I finally got a day to play with my truck, and here is what I did. I started at the timing, and checked tdc with a stop and that was right on. Next I went to timing while running. That is still at 12 and 35 all in at 2100. Idle is at 750 rpm. I went to the plugs, and they were looking pretty white, like on the lean side. On to the carb, first thing I noticed was I believe that I had the accelerator pumps set to tight. I changed jets from 71 to a 72 on the primary, and it was 78 to a 79 on the secondary. Im sure people will say I should have went up 2 sizes, but I didn't so there. If it needs more I will go up more. I believe I adjust the idle screws on each corner to get a little more, but it seems good now.

While sitting still it now hits the rev limiter. I have only driven it once today and it did hit the rev limiter in first gear. When I shut it off it has shut off so far, so I believe I am getting closer. if not raining next Wednesday I will take it to the race track and see how it goes.

Thanks for all the input.

Tony

 

I went to the Out of site drags, and was hopeful for a 11 sec run, well that didnt happen. I kept getting slower and slower no matter what i did. I believe it is the fuel pump, and i will be swapping that out today, and will try to run on Wednesday at Rockfalls. I did have alot of good people giving me ideas, and trying to help, and I thank them.

Tony

 

Detonation or spark knock can result from ignition timing problems. Too much advance, too much timing under heavy engine load, sticking mechanical and/or vacuum advance mechanisms, etc. Lower grade fuels and high engine temperatures will also magnify the problem.

Dieseling or engine run-on is usually caused by other, less controllable, sources of ignition. High cylinder temps or carbon hot-spots in the combustion chamber can get hot enough to ignite the air/fuel mixture at the wrong time, with no ignition spark present. But there still needs to be a combustible air/fuel mix getting into the cylinders for this to occur.

This is why it's critical that the throttle plates are not open too far at idle. Many carbs use a idle stop solenoid to allow the throttle to close more completely when the ignition is shut off. It's also helpful if you can adjust the idle without so much throttle opening that the engine begins pulling fuel thru the main nozzles. On a modified engine with a radical cam it's not unusual to look down the carb at idle and see fuel dripping out of the main nozzles onto the throttle plates. This gives the engine an unwanted air/fuel mix even after the ignition is shut off. With enough heat in the combustion chamber it will try to keep running, at least for a short period of time. Ideally, when you shut off the ignition you want no fuel and little to no air to enter the combustion chamber. The engine can't diesel without them.

 

I'm sure you'll get it figured sooner then later. Oddly enough , shortly after talking with you in the staging lanes, Paul Zielsdorf told me he is having the same problem with his impalla. He was sure it was ignition related, and changed the whole system. It helped, nutrient cuts the problem.

 

What kind of fuel pressure are you making? Will it make keep making fuel pressure on the big end in top gear? This is where a fuel pressure gauge is very handy. But, a big but, NHRA will not allow a mechanical fuel pressure gauge in the car without an isolator. When I was bracket racing, I had mine installed on the cowl.


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I am not sure of pressure on top end but at idle it is at 7 to 8 psi. I can rev to 6800 and do a burn out to 6800, but when under load is where the problem is. I come out of the hole good until i shift then it bogs down and builds but not to 6800, maybe 6000. I had a edelbrock high flow pump on it but now i have a stock one. I have a pressure gauge but cant see it when running. I will be modifying it so i can see it on the big end.

Tony

 

500 lift cam in a small block with big duration, and you expect vacuum? Be lucky anything close to 10 in your combo. Ditch the power brakes for sure, go manual brakes and problems solved. SHould be a hell of a runner.

 

I got a chance to try it out, and still the same thing i lose power when i shift and cant get it back up in rpm range. Fuel pump was not the problem. I have to do some more looking, hope i find the problem soon this is getting old.

Tony

 

Pump may not be the problem, but volume could be. Is the fuel line big enough? Any tight corners? Is the pick-up tube in the right place? Is the fuel system vented properly?
Above all else, what is the fuel pressure doing through the whole rpm range?

 

I have 3/8 line all the way with no tight bends. This is the same setup that i was able to pull 6500 rpms last year. I now have a fuel pressure gauge so i can see it. I will try to make a few pulls today.

Tony

 

Just marking to watch discussion. Thanks everyone.

 

Just took it out to stretch its wheels, and found that i have 3 1/2 psi of fuel at 5800, couldnt get past that. I then took the gas cap off just to check for venting, and no change. I know i should have more fuel pressure, but this is with a stock pump, and i do have a high flow. Running out of things to check, but that means im getting closer.

Tony

 

It has been found, i mean the rpm's i couldnt find. I took off my valve covers, because of some noise i was hearing, and i found a loose rocker, adjusted it, and it got loose again. I pulled intake, and there was 2 bad lifters and a bad cam. Then i had to stop to go to work for a couple of weeks. While working i ordered a new cam lifters and springs. I was also not happy with the brakes, so i got rid of the booster at the same time.

I did get it back together, after total disassembly, and cleaning, just in time for Wednesday night drags. The cool part of racing on the 19th, is that it was the same day that i first raced my truck in 2017 at the HAMB drags on my birthday. In 2017 it ran 15.5 at 90 mph, now it just ran 11.7 at 116 mph, and there is still more in it. I will be racing it at the Fallout, and hopefully be faster.

Tony

 

...ouch....

Good to hear of your 'progress' in finding the gremlins.

.

 

I went to the Rockfalls Fallout #5, and it was a blast, there was alot of good racing on Friday, but not much on Saturday. I had my best run on saturday morning, i went 11.56 @ 117 mph, with a 1.62 60 foot time. I had alot of people asking what was done to make it run like that, and all i can say is a screaming little small block. With a few little changes I believe I can get it to low 11's. Just in case ya want to know my set up, it is a 1969 340, trickflow heads mild cam, a 5spd and 4:11 posi. There is nothing special here, just a good setup.

I am looking for a video or pics of the race on friday where i raced my buddies maroon falcon and his hood blew off. If anyone has one please pm me. My goal is to play with it this winter and bring it out faster without adding anything to the motor.

Tony

 

Its that time of year again to get the truck out, after a few changes. I didnt like the gears in it so I went from 4:11 to a 4:30 gear. The breaks were a little soft so getting a new master cylinder. It has been running good, but I think it could be better. I put a AFR gauge in and it says i need to tune it as it runs at 10.80 afr, so time to lean it out a little. Sent out the gauges to get redone and those should be back in shortly. On the up side I still drive it while working on it.

Tony

 

I ran a W2 roller motor for years decades ago , I found one of the best improvements I made was installing a crank trigger system. From Chrysler back then and used a MSD 7AL gold box. You had a off/on switch and a start/run switch. You could set the start timing at say 12 degrees , start the motor and switch to the run position and then you have your full timing of whatever you have it set at. Nothing in the dist. except the rotor and a hole drilled in the cap to index the rotor with a timing light to the number one post. And you have rock steady timing that won't be bouncing all around .

 

Took the truck to Rockfalls Raceway, and it ran like a banshee again. I love to tell people to be careful of this screaming little small block, some listen and some don't. To date, I beat a, 1963 falcon with a 520 cubic inch 429, and beat him 4 out of 5 times. I also beat a Durango with a 900 hp hellcat motor 2 out of 3 times. Sometimes it is the driver, and not the car. I am pretty sure that I have the set up right, and with some fine tuning I think I can get into the 10's. I will be at the Out of site drags, stop by and bs with me if ya see me.

Tony

 

You can run the 6AL with a points distributor, I use a Mallory dual point with one set of points removed per the MSD instructions.

 

1) go to max 35-36 at 3.000 rpm. dont care for initial timing at idle.
2) if you have hard times adjusting the idle (no or little reaction when you adjust idle screws), your problems are likely relate to your carb setup as radical cam and pretuned carbs dont match (yet) and idle circuit is surpassed.
3) if carb reacts sensitive on idle check mechanical advance curve.

just my opinion: your carb is a little too big. i love the 750dp, but velocity is low on a 340 with this high carb cfm.

got souped up HP 440 and that runs on stock jetting with 750

 

Did you make your own headers

 

Yep I built a step set of stainless set. They go from 1.75 to 1.875. Not sure if they helped but I would think so.

 

My luck with this truck has finally run out. For the past month i have been fighting one thing after another. It started on break in. Mud wasp built a nest in 3 oiling holes then it seized up in 20 minutes.

 

20 minutes after that i ran my 9 month old puppy over and broke his leg in 2 places.

 

Got everything fixed 10 days later and i take it for a drive, all goes well until i get in my drive way. The rear frost plug popped out. When i measured itit was .005 smaller than the one i put in.

 

I get the plug fixed after pulling trans and i drive in on Saturday with wife. Put 15 miles on and all is good. Then sunday it goes really bad. The valve keeper comes out of #5 and it stops running again. This time its 2 pistons and rods, a couple of valves and a head, and a new rocker. I have around 3 weeks to get all back together and make it to dragweek. My fingers are crossed.

 

Ugh, is it SBC crate time yet? .
Damn.

 

My truck would run away from home if said I was putting a sbc in there.

 

Just messing with ya