several issues 78 dually

[gafiredog]

Hello all, I have this 78 dually I have been working on little at a time. when I bought it the po had rebuilt the engine 350 cu in. 4 bl. rebuilt the trans. turbo 400, rebuilt rearend dana 70, rebuilt frontend, bushings, etc. I have several problems I'm stumped about. the truck had set up for about 18 mo,- to 2 years. I put a rebuilt 600 holley on it, and it fired right up when I bought it. It sat and ran 15-20 min. I shut it off. went to restart it and it acted like a batt. had run down, barely turned over. I let it sit several hours, fired right up. got warm, cut it off, same thing happened, acted like a bad batt.( replaced batt. several times) thought bad coil? put in a new dist. with a new coil. did same thing. thinking bad starter? 2nd issue, brakes needed going through since sitting up. brakes locked up. bled them, pushed pedal, locked up again, everytime this happened, put on new rebuilt calipers, new wheel cylinders in rear. when done, brakes great. let it sit for about a month . today I went to work on it, front right caliper locking up again. dont have a clue to prob. master cylinder was replaced by po. could this be prob.? 3rd issue. from time I bought it, it has a high pitch vibration. in park, and driving. po said he put wrong flywheel on when rebuilding, ( a 400) thats the prob. there, said just replace flywheel with a early one and that will fix that. also backfires through carb. now. changed to a 600 edlebrock, still backfire, no power at all. any ideas??? I'm stumped. thanks, Art

[Eyegore]

On my sons Dodge dually the front brakes kept up locking also. Change rotor, calipers, brake lines, pads everything. Finally the mechanic found out it was missing the gasket between the firewall and brake booster.

For the other issues I would check to see if its grounding out, sounds like a short somewhere after it warms up.

[gafiredog]

thanks, what, where would a short be after! it warms up??? when it comes to wiring on a scale of 1-10, I m about a -4. where should I look?

[Eyegore]

From the alternator to the battery, battery cables, wiring @ firewall, look anything frayed or wrapped with tape, all connections see if their corroded.

[gafiredog]

thanks, will do.

[marvgarr68]

For the brake lock up you need to check the proportioning valve. It probably is jamming up. It is under the front of the truck attached to the front cross member. The hot start is timing or is running too hot, gauge could have wrong sender as the later trucks are different. I had an engine do this gauge said temp was good found it to be running around 230. It would start like the battery is real dead. Timing is probably to early. Who knows could have wrong balancer and timing tab causing the timing to be off when set right. Third you need to get that 400 flywheel off before you pound out the mains and might break the crank. Just get a flex plate for a 350 they're like 40 bucks at the parts house.

I would pull #1 spark plug and put a small wire down it to find TDC and check the balancer and timing tab reference.

[gafiredog]

thanks for the info. will check it all out tomorrow.

[shippman]

You may want to check the brake hoses on those front brakes. When they get old they tend to collapse and not let the fluid return to the master cylinder and hold pressure in the calipers. Cheap fix if that's the problem.

[f.monroe]

Hard start issue when warm can be timing too far advanced. Retard the timing a little and try it again.

For the vibration I would start by taking the belts off all of the accessories on front of the engine. Everything . start it and see if the vibration is still there just don't run it over a minute or so. If still there disconnect the torque converter and try again. If it's still there you have an engine vibration. Check for counter weights on the flexplate or an externally balanced harmonic balancer . 350 should not have externally balanced flexplate or harmonic balancer.

Brakes are probably internally collapsed rubber lines. When it locks up open the bleeder screw on the caliper. If it unlocks I would start with the rubber line.

Frank

[gafiredog]

Thanks, I will check, I did replace the drivers side hose when I put the calipers on due to it leaking, it has no problem.

[D13]

Carb backfire is valves or timing, it soulnds like your timing is early. Once that is fixed, if it still is not wanting to crank at full speed when restarting hot, bad starter, improperly shimmed starter, or bad battery cable. Cables can look good and be bad inside. Particularly suspect with headers or exhaust routed close t ocable or starter.
If you have an externally balanaced 40 0flywheel on a 350 it's not gonna be happy, need to fix that ASAP and see if it cures your vibration.
i would be concerned with someone who 'rebuilds' an engine and uses the wrong flexplate. I'm guessing it was a 400 engine and he put in a 350 and didn know enough to swap the flexplate.

[gafiredog]

I agree D13 with the rebuild. I looked up the vin. said it came with a 454. would the 454 flywheel cause the vibration? also, it has no power now. won't get out of its own way. tried several different carbs. to see if it made a difference. not really. any ideas on this??? thanks Art

[cheepin]

Yes 454 is externally balanced. 350 internally.

[gafiredog]

thanks for the help, plan on checking it all today.