fixing truck, few questions

[hcaz095]

1972 c10 lwb highlander...350 with th400.

Just got all the HEI on, new plugs, wires, and skip white distributor, along with new batt cables, altenator, voltage regulator, and battery...plus a few new wires here and there... If anyone wants all the orig parts to rebuild them, let me know (PM).... everything on this truck appears to be completely original...delco remy alt and regulator etc, orig points distributor etc.



Now Im onto the fun stuff... my temp gage isnt working, and I really want that one fixed.... it has never moved from the 0 point... where do I start?

My fuel gage is also not working, which isnt a big deal as I write down my fill-ups and keep track of miles. I wonder how much of an improvement I'll see in mileage after replacing all the ignition and loosing my camper top (6 in taller than cab, must have weighed 300lbs)...

Also, I get a backfire when trying to accelerate hard sometimes, like im giving it gas too fast... it will go but I have to roll on the throttle a bit... any thoughts? My exhaust is still stock (single tube 2.5"?) and is now blown apart a bit from when my points arc'd... might new exhaust clear up the backfiring issue?


thanks,


~Zach

[68gmsee]

First and very important (if you haven't done it) is to go to the auto parts store and pick up several ground straps (I used 4 on mine).

Clean the surface real good and install them here:

1. Battery to radiator support.
2. Engine to the cab. (Should have had one on the back of the engine to the cab orginally)
3. Engine to the frame. I used a battery cable.
4. Bed to the frame. (I placed one under the bed in the rear. Had to drill a hole for a self threading screw.

The reason for all of this is that these trucks have been sitting for a long time and all of the metal to metal bolts have dirt, grime and corrosion that prevents a good ground.

The backfiring could be a timing issue. I'd try advancing it more and see what it does.

[hcaz095]

I was thinking about advancing the timing, as stock I believe is at 4 deg advance with the automatic, which seems quite small... with the HEI, 8.5mm hp wires, and plugs gapped at .045, what would be the next step in timing? 8-10 deg? or do it by 2 deg increments?

My idle also seems ridiculously low...(seat of the pants like 450-550rpm...aka barely running, and will eventually idle out if sitting uphill for 25 seconds). without a tach how can I check what im idling at? is has the quadrajet 4 bbl orig carb... how much would I want to turn up the idle screw? 1/4 turn? full turn?

I like to take things one step at a time though... which should I do first?

Also, my truck, being a Ca truck in '72 had a belt driven airpump to supply air to the exhaust manifold as an afterburn... I'm definately thinking about taking this off as It is very much in the way... what size bungs are the holes in the manifold? where would i get them? people at this small town Napa/ auto value have no idea what I'm talking about as they have to use books instead of computers most of the time...

Thanks in advance for everyone's help..

~Zach

[mclairmo]

I would set timing at 10 degrees and see if that helps. A good digital mulitmeter has a tach function and the instructions will tell you how to hook it up. It's a very useful tool and a must, IMO. It will also have volts for testing the battery and ohms for testing various other electrical components/sensors, like your temp/fuel gauge and senders. I have my idle set at about 1,000 rpms but I'm not using the choke either. You can also just raise the idle until it is smooth and sounds good, you don't have to use a tach. You can buy exhaust manifold plugs from Rick's First Generation Camaro (see the gold plugs in the pic, part no. RC-615 $10.99) or use regular stainless pipe plugs (the silver ones in the pic). If the idle is not stable and smooth, you may want to rebuild the carb yourself, it's easy to do. Just buy a rebuild manual and a 1 gallon can of Berryman carb cleaner and go at it. The small orifices in the carbs often get gummed up and clogged up causing all sorts of driveability and idle issues.

[mr48chev]

The plugs aren't a pipe plug but a flair nut plug. They should be available at that same NAPA store in the brass fitting catalog.

Consider yourself very lucky if you can go to a parts house that the guys pull out the books instead of looking on the computer there are many many others on here that wish they had that problem to deal with at the parts house they frequent.

[piecesparts]

You get a backfire when you accelerate hard......check your carburetor and see who made it Is it a Q-jet made by Rochester or Carter? The Carter bodies had a problem with the secondary needle orifices erroding away, since they were cast into the carb's body and not brass rings pressed into the body like the Rochester bodies. When you accelerate, there is too much gas initialized into the secondaries and the result is a bog/backfire and then acceleration. I have seen it in several carb bodies of this manufacturer's listing. Find a Q-jet body made by rochester and the brass inserts are in it and use your parts on the new carb body.

[mclairmo]

Originally Posted by mr48chev

The plugs aren't a pipe plug but a flair nut plug. They should be available at that same NAPA store in the brass fitting catalog.

Consider yourself very lucky if you can go to a parts house that the guys pull out the books instead of looking on the computer there are many many others on here that wish they had that problem to deal with at the parts house they frequent.

Are you sure he needs a "flair nut plug"? I thought he wanted to remove the tubes and plug the holes in the manifolds? Everyone I know and everything I read calls the silver plugs I showed as "pipe plugs". Maybe the gold ones I showed are "flair nut plugs"? Also, I think the spelling is "flare."

[kwmech]

The holes in the exhaust manifold are not tapered, they are straight. You need a 5/16'' tubing plug.

[mclairmo]

I have "pipe plugs" in mine and they work great and look better since they are flush.

[68gmsee]

Originally Posted by hcaz095

...............My idle also seems ridiculously low...(seat of the pants like 450-550rpm...aka barely running, and will eventually idle out if sitting uphill for 25 seconds). without a tach how can I check what im idling at? is has the quadrajet 4 bbl orig carb... how much would I want to turn up the idle screw? 1/4 turn? full turn?........Also, my truck, being a Ca truck in '72 had a belt driven airpump to supply air to the exhaust manifold as an afterburn... I'm definately thinking about taking this off as It is very much in the way......~Zach

I know this may sound dumb but don't confuse the idle screw with the idle air adjusting screws. I had a buddy trying to adjust the idle with the two idle air screws. He didn't know there was a separate screw for the idle only.

I'd get rid of the airpump if you can do it without messing up anything else.

[BCOWANWHEELS]

Sounds like accelerator pump isnt doing a good job in the carb for backfire under full throttle