Hello - relatively new to the forums for posting, but love reading and learning what you guys know. I have a 71 350 4sp. It was a barn find about 3 years ago. Been tinkering on it ever since; when I first got it the fuel tank was shot, so I dropped a new one in, ran new lines, popped on a new fuel pump and it fired up. Turned it off and got to work tearing it down and building it back up. Clearly, I either did something wrong as I'm posting this message, but recently, I've gotten it to a point where I thought I could start it. Prior to that I tore the carb down and rebuilt it after reading Lars documentation; cleaned up the frame and grounds and ran new 2g wire from the battery to the starter; new battery, new starter, new alternator, new plugs. Also followed Lars documentation on the 71 points system/timing and I'm fairly confident I have it on spec (fantastic document if you've never read it) - so thanks Lars.

With that said, I attached a video, when i turn the key the starter engages, but it just seems to be struggling to turn over. I have 12 v at the battery, 12 at the starter, 12 at the alternator and I have fuel squirting into the carb. I'm not 100% sure where to go, I don't want to keep just 'trying' to start it because i don't want to damage anything. I was wondering anyone had some thoughts about where/what I could try. Appreciate any input. Thanks - Aaron

 

Hello Welcome. There are a few things that come to mind. 1st would be the quality of the starter. I recently purchased a new starter, installed it and it didn’t work right. I did that 3 times in 1 day before I finally got one that worked correctly. 2nd would be that if you have had the distributor out it is possible that you could have gotten it 180 degrees off when putting it back in. You can check this by making sure that #1 cylinder is at TDC on the compression stroke and then take the distributor cap off and verify that the rotor is pointing towards the #1 spark plug wire on the cap. #3. A battery can show 12V but will not have the cold cranking amps to turn the engine over as fast as it needs to.
I don’t know how much time was between the time that you replaced the fuel system and got back around to starting the engine again but if the battery sat in the car for a couple of years it could be bad. Might be worth taking to your local auto parts store and have it checked. I hope you get it figured out. Keep us posted. 👍

 

Hi! Thanks for the reply. I picked up the starter from Autozone it was the ACDelco Gold it, fit in nicely as expected. I did bench test it before I put it in so I know that it engages, but I have no way to tell if it's really 'working' correctly. I feel good about the distributor as I followed Lars documentation and i 'walked' every tooth around clockwise to find proper location. The battery had been sitting on a trickle charge for that amount of time. When I went to get the starter I had them test the battery and they said it tested 'good' 92% health. Could that battery still be bad with low amps?

 

Try unhooking power to the coil. Thus no spark. How does the engine spin. Thus eliminating possible issues with ign. timing. If it's still struggling to turn.
Hydraulically locked engine? Remove all plugs. Spin engine.
Bad starter? Yes it happens.
Battery load tested good? Should be good but you could try a battery out of another car just for testing.

 

Yes, that so-called 92% battery could be weaker than it may seem.
The Best way to test is go to an area/local auto electric shop where they do routinely rebuild alternators, generators & starters on-site. That shop will likely have a "Carbon-Pile" type battery load test rig. It's entirely electrical; Not electronic. And, by far, most reliable method to assess true capacity of battery.

I did not see where you also replaced the shorter Negative Ground cable from Battery to Frame; that cable typically fails (hidden cancer corrosion beneath insulation) before the long positive cable fails.

 

Cranking doesn't seem to be cycling smoothly through the strokes. Even with a carb not adjusted well, with squirts of fuel down the intake, it should fire up to some degree. I think it's a timing issue...

Do you have spark at a couple different plugs?

What are the details of tearing down and building back up? Did you put in a new timing chain?

 

Aaron,
This is a definite concern until you get a better handle on the problem. If the carb is supplying fuel, continued cranking can cause something called "fuel wash" where the cylinders are stripped of their protective oil coating and fuel ends up in the oil system. Not good for cylinder wall wear or bearing protection.

 

You either have no spark or no fuel.
What have you done to determine you have both?
You mention Lars papers but give no specifics as to what you did to ignition or carburetor.
Did you set dwell to 30 degrees?
What is your initial timing?
Does the choke fully close?
Did you pump the gas pedal more than once prior to starting?
If you open the throttle by hand do you see gas squirt on the primary side of the carb?

 

Wow - thanks for all this information guys; I appreciate it very much. I think i addressed all the questions above/below.

A few notes:

1) Yes, I replaced the negative ground strap from the frame to the engine block. I agree, it was corroded and gross, so I put a new one on.
2) I just removed the + lead to the coil and tried to start it, and it sounded very similar, I couldn't tell a difference with it unhooked.
3) I reconnected the coil, pulled plug 3 - had spark, put it back, pulled plug 5 - had spark.
4) Pulled the dipstick and oil looked clean; no watery looking mixture in it.
5) Radiator has 50/50 mix of coolant; it sat in my heated garage over winter so I don't think it would have had the opportunity to freeze. With that said, doesn't mean there wasn't an issue before I had filled it with fluid, i suppose.
6) regarding the tear down, that was misleading; i didn't really tear the engine down, i changed all fluids and i really tore down the interior and built that back up.

Stopped there - I'm leaving today for STL for work so won't be able to touch it for about a week; will give me some good time to think about it.

When I get home i'll pull all the plugs and try to turn it over. Is that test ran manually or do i crank it over at the ignition - Should it turn relatively freely using the crankshaft bolt if manual turn? do i need to loosen the belts or anything else to test this?

seriously, you guys rock; thanks for all the ideas. i love it.

 

Since you have spark and fuel, it's got to be a timing issue. When you get home, remove all the plugs as you planned -- how do they look? Are they wet with fuel? You can then turn the engine over by hand using the bolt in the front of the crankshaft - no need to remove belts if you can reach the bolt and have enough room to wrench it over.

I'd be checking the distributor rotor position - crank the engine until the #1 cylinder builds pressure in the spark plug hole. Alternatively, you can remove the driver's side valve cover and watch the two forward-most valves. When they both are fully up (push rods fully down) you should be at the ignition stroke for #1. Now look at the harmonic balancer — the timing mark should be at about the 0° mark on the timing tab. At this point, turn your attention to the distributor cap.

Make a mark or place a piece of tape indicating where the #1 spark plug wire is on the distributor body or something nearby - try to be pretty accurate. Remove the cap and see where the rotor's tip is aimed - it should be pointing at your mark or tape. If it's 180° in the opposite direction, you'll have to "restab" the whole thing as it's set to fire #6 rather than #1. If it's pointing to #1, then I'd try something called "static timing" to get the timing darned close to firing easily.

To static time, move the engine's timing mark to ~8° BTDC/Advanced. (You can rotate it backwards, but go well past the 8° mark and then bring it forward to 8° to remove any slop in the timing chain.) Then rotate the distributor housing until the points just open and snug it down. (It's been a while since I've done this - if you do a forum search the full procedure is described.) Put all the plugs back in and give it a crank for about 10 seconds. If the engine doesn't have any firing activity, squirt a couple teaspoons of fuel down the carb and try again.

 

If you have slow internet response and hit reply too many times

 

Comment deleted

 

👍 Thanks 🙏

 

Check your points to make sure you have them gapped properly and that they are actually opening and closing as they should.
You wouldn’t be the first to not have tightened the lock down screw enough and the points aren’t opening and closing as they should.
Also check to make sure you are getting the correct voltage to the coil “during cranking”.
If you don’t have the coil/distributor wired correctly, the voltage may not be correct and you could be getting spark at the plugs but it could be a weak spark, also common.
You responded to Rebelyell and stated you replaced the engine to chassis ground strap.
But I believe he was referring to the actual battery ground to chassis cable.
Its very common for the battery to chassis ground cable to be corroded under the insulation, which will create the exact condition you are experiencing.
You may also have a bad coil, even if it’s new it may not be putting out the correct voltage and you could be getting a weak spark.
You said you had it running before you did work.
Double check your work and that you have the correct cap, rotor, points, condenser, coil and any other parts you installed.
Check your plug wire routing, you could be off by one post (also common) on the cap.
Let us know what you find.
Its probably something simple.

 

You might double check and just make sure that you have the spark plug wires in the correct location slash firing order. IE 18436572
I know you have probably done this but it’s an easy mistake to make. Even guys that have done their entire life occasionally get a couple of wires switched around by mistake.

 

May make no difference but on my hot rod projects I always run the battery ground cable directly from the battery to the engine block and then engine block back to the frame.
If you want double check to see if the balancer has slipped on the dampener using a piston stop on #1 rotate the engine slowly by hand in one direction until the piston is stopped by the piston stop. Mark the the dampener and the timing tab. Rotate the engine the opposite direction until the piston hits the piston stop. Mark the dampener. TDC should be right between those two marks.
I think I got this right but others should chime in if I didn't since it's decades since I've done the above.

 

Yes, but again, did you replace the Heavy, Round, Insulated Cable that serves as Sole conductor from Battery - Neg Post TO Chassis ?

 

I did replace this as well, Neg Battery in compartment through hole, attached to chassis with wire brushed frame; clean contact.

With that said, I just got home from traveling for work I will read through all these and run a few more tests and come back with results.

THANK YOU all for the suggestions. I really appreciate your input. Looking forward to circling back!

 

Hey, It’s been four hours!
Whats taking you so long?

 

It's cranking very slowly, & to me sounds uneven...as others have said, verify 12V AT THE STARTER WHEN CRANKING, that will immediately tell you if starter is getting BAT voltage. You'll still see batt V at the starter even if the cable or terminals are corroded or a poor connection when not cranking, have to test it under load. Do that before going through the other stuff. Just put a test light or DVM on the starter batt terminal & ground it to the frame or block, have a helper crank it & see what the voltage drops to... My money's on the battery or a bad starter... it's rampant how many bad "new" or reman parts are out of the box.