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Old 01-30-2017, 11:28 PM   #1
dave`12
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Hard start question

Put a v8 and summit headers in the truck.

Good battery (12.6 off and 13.8 running volts). New remanufactured starter with new solenoid.

Starts instantly when cool. When hot, very hard to turn over. Once it turns over, it starts quickly.

I got a heat shield wrap around the starter and the solenoid. I've tried to route the cables as far from heat as I can. The small ones going the the solenoid are also wrapped with heat reflecting wrap.

What should be my next step?

I have cheap autozone battery cables, they don't say the gauge, but I'm gonna guess 4 gauge. And the + is quite long.

Do you think going to 1 or 2 gauge should be next? Also considering header wrap, but I'ver heard bad things about that stuff.

Last edited by dave`12; 01-30-2017 at 11:35 PM.
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Old 01-31-2017, 12:39 AM   #2
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Re: Hard start question

I think you nailed it when you said cheap battery cables, yes change them out. 2ndly, what starter do you have? Stock, mini high torque? Lastly, how's the timing set? Is it to advanced possibly?? These are the areas I'd check, good luck.
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Old 01-31-2017, 01:10 AM   #3
El Dorado Jim
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Re: Hard start question

Quote:
Originally Posted by dave`12 View Post
Put a v8 and summit headers in the truck.

Good battery (12.6 off and 13.8 running volts). New remanufactured starter with new solenoid.

Starts instantly when cool. When hot, very hard to turn over. Once it turns over, it starts quickly.

I got a heat shield wrap around the starter and the solenoid. I've tried to route the cables as far from heat as I can. The small ones going the the solenoid are also wrapped with heat reflecting wrap.

What should be my next step?

I have cheap autozone battery cables, they don't say the gauge, but I'm gonna guess 4 gauge. And the + is quite long.

Do you think going to 1 or 2 gauge should be next? Also considering header wrap, but I'ver heard bad things about that stuff.
running headers is most likely the problem,I had the same problem...the starter gets too hot and wont spin, I installed a Ford solenoid on my inner fender that puts a full 12 volts to the starter, the way the gm starters work is you dont have a full 12 volts and when the starter is hot isn"t enough voltage to spin it.....you have to find the small wire that activates your starter, splice onto it so it will reach the new solenoid you mount on the inner fender,then run a 10 gauge wire from + side of your battery to the solenoid, then run a 10 gauge wire from the solenoid to your starter......maybe some others will chime in here and explain it better, Vette Vet?
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Old 01-31-2017, 04:17 AM   #4
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Re: Hard start question

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Originally Posted by El Dorado Jim View Post
running headers is most likely the problem,I had the same problem...the starter gets too hot and wont spin, I installed a Ford solenoid on my inner fender that puts a full 12 volts to the starter, the way the gm starters work is you dont have a full 12 volts and when the starter is hot isn"t enough voltage to spin it.....you have to find the small wire that activates your starter, splice onto it so it will reach the new solenoid you mount on the inner fender,then run a 10 gauge wire from + side of your battery to the solenoid, then run a 10 gauge wire from the solenoid to your starter......maybe some others will chime in here and explain it better, Vette Vet?
There's been enough info and debate on this subject to fill a small book.
The primary cause of heat soak failure is the high resistance created in the
solenoid windings or the starter windings caused by the excess heat of the exhaust, especially headers. This creates a need for more voltage from the battery circuit to overcome this increased resistance.

Any weak batteries, old cables, poor connections or bad wiring, must be corrected before any fix can be made. These things can cause problems on their own, but they may not be bad enough to cause starter failure until the heat soak factor enters the picture.

I find that the easiest way to diagnose heat soak or any other starter problem is to isolate the starter from the rest of the starter control system. I.E. small wiring, ignition switch, neutral start switch, firewall connection block and the purple wire to the solenoid.

Let's assume that we have a fully charged battery and both cables are good and cleaned connections on the terminals and the negative ground and the connection on the starter is clean and tight.

The next step is to jump from the large cable on the solenoid to the small S terminal on the solenoid. Before doing that it is important to use safety precautions. Truck out of gear or in park. Ignition switch off or coil wire removed. and wheels blocked. Remember, if the engine spins and these are not done, the truck may move and cause harm or damage.

If the starter is heat soaked this method will provide the most voltage and current you can get at the starter, and if it is ever going to work, it will then.
If this test causes the starter to spin the engine over and it otherwise won't until it cools the we can assume that heat soak is the problem. If it still doesn't spin then nothing but a new starter is going to cure the problem.

Using a jumper battery or a starting charger should also work if available, the
main thing is to provide enough voltage to overcome the heat soak.These methods don't eliminate the starter control circuit, but if the starter works under cold conditions then they should be OK.

Most heat soak problems involve the solenoid and the resistance in it's windings may not allow it to engage the starter windings or throw the starter gear into the flywheel gear. It may only click weakly or not at all. A new solenoid or a relay such as mentioned by El Dorado Jim may fix the problem for a while. The best fix is to remove the heat source with a heat shield or heat wrap. Others may argue that the best fix is a heavy duty starter, larger cables or a bigger battery. Some suggest the Mini-starter is the only way to go.

If the starter spins the engine in my test then we can consider the options i mentioned. But first we have to test the purple solenoid wire to be sure we are getting a full 12 volts to the S terminal at the solenoid. If not the all that may be needed is to correct that problem to cure the heat soak issue.
Just measure the purple wire at the solenoid with the wire off and test between the wire and a good ground, while some one turns the key to start.

If we get the solid 12 volts then we can consider using a Ford solenoid or a large relay to overcome the voltage drop on the purple wire. Here is why it works with the Ford solenoid.

The Ford solenoid does not need as much voltage to close as the GM solenoid since it does not actuate the large bendix gear that the GM solenoid must in order to spin the flywheel. Keep in mind that we do not replace the GM solenoid with the Ford, we're just using the Ford solenoid to get more voltage to the GM solenoid's S terminal.

Here are a few diagrams.

This is the original circuit for the starter.

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This is one way to use the Ford solenoid to send a full 12 volts to the GM S terminal.

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Another way.

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I like this one the best. You need two short positive cables but no Purple wire to the GM solenoid. There is not power to the starter until the key switch powers the FORD solenoid and then the S terminal is jumped with a full 12 volts right at the starter.

Name:  starter_solenoid.gif
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Old 01-31-2017, 05:02 PM   #5
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Re: Hard start question

Vette Vet, you are the electrical wizard!
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Old 02-02-2017, 05:22 PM   #6
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Re: Hard start question

Thanx so much you guys. Would have responded earlier, but had to go out of town.

I remember thinking, I wish the solenoid was on the fender like my old Jeeps. Gonna try the jump tomorrow.

It's a new remanufactured starter. I wanted to get a better one, but this was the only one that summit had because mine has a different nose cone that bolts to the bell housing not the engine.

everything, cables starter, etc. all new. Look like good connections.

I do know that I'm getting 12v to the starter from the btty cable.

So I will try this tomorrow. Does the engine need to be hot? I already have one burn on my thumb from the last time I was down there. Man, those headers are close.

I like that last one. If it cranks good when I jump the posts, can I just order this solenoid? It's what my old Jeep used. Also, I have one wire to the S post on my selenoid, but I have another to the other post (not the big btty one). What should I do with that wire?

http://shop.advanceautoparts.com/p/o...FQkHaQod1sgH2A

What gauge btty cable should I use. I have 4g now. Or what would you recommend?

Thanx again for all the awesome help!
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Old 02-02-2017, 08:25 PM   #7
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Re: Hard start question

I decided to go back and read your posts from the top and I'm not sure if it's heat soak that's your problem or too small battery cables, or even too much advance in the timing.

If the starter turns over it indicates that the solenoid is not heat soaked or it probably wouldn't even click.If you are getting a slow roll all the time when the engine is warm then the Ford solenoid is most likely not going to help.

As mentioned above any engine with too much timing advance or high compression is going to turn harder when warm.

Heat will build resistance in the starter windings and cause it to turn slower so a larger battery cable would have less voltage drop and provide more amps to turn the starter. I think most guys would agree that a 2.0 gauge would be enough to get the job done.

Quote:
So I will try this tomorrow. Does the engine need to be hot? I already have one burn on my thumb from the last time I was down there. Man, those headers are close.

I like that last one. If it cranks good when I jump the posts, can I just order this solenoid? It's what my old Jeep used. Also, I have one wire to the S post on my selenoid, but I have another to the other post (not the big btty one). What should I do with that wire?
Your engine would have to be in the situation that it is when you have the problem. Like I said, if the solenoid is engaging, then jumping the starter won't help. Do you know how to do a voltage drop on the battery to starter cable?

the two small posts on your starter solenoid are for the purple S terminal from the key and the other one is a 12 volt jumper wire to the factory external ignition coil to send it a full 12 volts during start. This give a hotter spark for easier starting when the engine is cold. If you have an HEI ignition system then you won't need this wire and you can tape it off or eliminate it.
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Old 02-03-2017, 01:48 AM   #8
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Re: Hard start question

Thank you vette.

The starter does turn, but slow when hot. So following you, it's not the solenoid.

I put in an HEI, so do I need to eliminate that wire, or is it doing nothing and ok there?

I think I have a 4 gauge cable. the + is quite long, 4-5 feet if I recall. The - much shorter, 2-3 feet.

my btty is pretty new 575 cold cranking amps.

I will do the test tomorrow, just saw a u tube video on how. Not sure the permissible drop on + and -, video was for a late model car.

Too bad, this issue is the last thing keeping me from enjoying the truck!

p.s. I tried to set the timing best I could, but I don't know what cam is in the engine, or if it was degreed. But it cranks beautifully (and starts immediately) when cold..

Last edited by dave`12; 02-03-2017 at 02:05 AM.
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Old 02-03-2017, 10:47 AM   #9
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Re: Hard start question

Ok, I did a series of tests:
all cranks are for 5 seconds.
unhooked power to HEI

beginning btty volts 12.67
btty post to post cranking drops about 1 volt

leads of multimeter: + btty to starter main line 000
" " cranking .25 (so 1/4 volt loss?)

leads btty - to starter case .2 loss
" " cranking .25 loss

I also checked "s" terminal:
+ btty to "s" terminal
12.47 volts (my btty is draining from tests, I think)
+ btty to "s" terminal cranking .96 (so I'm losing a volt?).

btty voltage after tests is 12.4

btty cranking now is around 10.7

hooked up power to HEI so it would start:

started immediately, but volts went down to 10.6

I really don't know if these numbers are ok. I'm thinking the btty is not staying as strong as it should during the tests?
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Old 02-03-2017, 12:57 PM   #10
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Re: Hard start question

Your tests look pretty good until the 2 volt drop on the battery. 575 CCA is borderline low IMO. I would go with a minimum of 600 and 800 will most likely solve your problem. Just for insurance I'd replace the 4,0 cable with a 2.0. The ground cable is fine at 4.0., if you're going to the engine block first.

Do a timing check with the vacuum line off the distributor and plugged. if you're at 12 degrees BTDC, back off to 10 and if at 10 try 8. You want to run as much advance as you can without detonation and loss of performance.
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Old 02-03-2017, 02:58 PM   #11
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Re: Hard start question

Thanx Vette. I backed off the timing some 4 degrees and it seems to be doing much better.

I really don't know how to set the timing. The engine was purchased off craigslist. The guy told me that he bought it from a friend. Sounds a little like it has a performance cam, but he and I have no idea what cam and whether or not it is degreed. So, without taking it apart, I really don't know what numbers I should shoot for. My idle vacuum is low (around 12-14), hoping that's the cam. But that's off the subject. At any rate, it seems to run ok and start much better now.

thanx
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Old 02-11-2017, 08:22 PM   #12
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Re: Hard start question

Truck ran better before I backed off on the timing.

Do you think an optima 800cca battery will be significantly better than my generic (but new) 750cca?
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Old 02-11-2017, 08:39 PM   #13
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Re: Hard start question

Using different size cables makes no sense since exactly the same current flows out of, and into the battery. You can use jumper cables to add capacity to the existing cables to see if it helps.
Using another solenoid is a bandaid rather than solving the actual problem.
Look for hot spots in the cables and connectors that show resistive spots. Make sure the - cable is connected directly to the block.
Saying the timing was changed but not saying what it was or what it is now doesn't provide much info. Did it crank better when hot w/ the distributor disconnected?
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Old 02-11-2017, 09:07 PM   #14
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Re: Hard start question

thank you franken, to answer your questions:

Starts perfect when cold. When hot, turns over very slow (sometimes start, sometimes it won't turn fast enough). A jump will make it start fine when hot. I tested the cables. Although they are not that big, I did not see a large voltage drop. The numbers are above. New starter with a heat wrap.

One thing, the ground is going to my alternator bracket that bolts to the engine (see pic). I'm getting good voltage there, you think I should move it? You can see where I have it grounded. The cables are routed about a well as possible, but I guess I could heat wrap them.

Anyway, I backed off on the initial timing and it now starts fine when hot, but I noticed a power loss.

Was thinking perhaps the optima 800 might allow me to get the timing back up.

I'm tempted to buy some Ramhorns, I'm sure it's the headers.
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Old 02-11-2017, 10:08 PM   #15
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Re: Hard start question

You might try measuring voltage to the block, starter body, and battery - terminal while cranking.
Still wondering what the initial timing is and was at. Maybe I missed it. Initial advance set to not factory settings will cause slow crank because the cylinders are firing too soon.
I have 2 350s w/ headers that start w/ dodgy wiring and no problems. It may be of interest that both use truck bellhousings (3 horizontal bolts) and truck starters. There are actually different motors. If you look at the solenoid to starter + connection, some have a spacer and the starter body is shorter. The spacer is just a small tube.
Moving the ground from the alt bracket of your setup isn't likely to make a difference since it looks recently worked on.

Edit: I may be wrong. I just looked at a couple starters off a 350 and on a 454. Both are the 2 bolt style. The starter bodies were the same length and the solenoids were different lengths. I didn't crawl under the Camaro or pickup that have the other style starters and measure them. The steel motor body was about 5 and 11/16" including the end cap.

Maybe its been mentioned but you should have correct starter bolts and the starter to block bracket.

Last edited by franken; 02-11-2017 at 10:32 PM.
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Old 02-12-2017, 08:19 AM   #16
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Re: Hard start question

I have the old style starter, 3 bolts to the bellhousing. There is no spacer. It's all new and clean down there. The starter with solenoid is the only one that summit had that fit my mounting style. No brackets.

I did check while cranking, the numbers were pretty good, they are above. Note the engine was cold. The headers are too close to the starter/solenoid to make checking while hot a desirable exercise, but I guess I could do it.

I'm not sure the initial timing. It has an unknown cam and it's probably, but not for sure degreed. I've just been timing it by ear and feel.

The battery is new, but only 575 cca. That's why I'm considering the optima with 800.
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Old 02-12-2017, 11:42 PM   #17
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Re: Hard start question

seems like you need a better battery, if you say you jump it and then it starts up just fine...
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Old 02-13-2017, 09:43 AM   #18
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Re: Hard start question

Put an optima red top in it yesterday. After driving 1/2 hour, was reluctant to start (but did). I'm going to get better cables. Also, my electric fans are on while cranking, going to change that. Thanx for all the advice. Hopefully this will solve it, if not I'm going to be selling some new headers
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Old 02-17-2017, 01:40 PM   #19
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Re: Hard start question

Any update on this?
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Old 02-17-2017, 03:11 PM   #20
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Re: Hard start question

This morning, I moved the cooling fans and the fuel pump to switches so that I can shut them off while cranking. I also installed 2 gauge battery cables.

I have some other stuff apart right now, so I could not test the truck today. As soon as I get it back together, I will test and report back.

If this does not fix the problem, the headers are coming off. I hope I don't have to go there.
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Old 02-17-2017, 04:41 PM   #21
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Re: Hard start question

Quote:
Originally Posted by dave`12 View Post
This morning, I moved the cooling fans and the fuel pump to switches so that I can shut them off while cranking. I also installed 2 gauge battery cables.

I have some other stuff apart right now, so I could not test the truck today. As soon as I get it back together, I will test and report back.

If this does not fix the problem, the headers are coming off. I hope I don't have to go there.
shouldn't have to remove the headers, lots of us are running them
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Old 02-17-2017, 05:33 PM   #22
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Re: Hard start question

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Originally Posted by El Dorado Jim View Post
shouldn't have to remove the headers, lots of us are running them
I don't have enough space between my starter and headers to slide my finger between them. That has to be the problem.

Perhaps I just have the wrong headers?
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Old 02-17-2017, 10:16 PM   #23
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Re: Hard start question

You can make or buy clip leads which are wires with alligator clips on each end. I like to have a couple long ones like 6-8 feet so I can measure voltage for example while not under the vehicle.

Until you know the voltage at the starter to ground (starter body), you have no idea why you have slow cranking. Battery voltage when cranking would also be of interest.
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Old 02-18-2017, 02:30 PM   #24
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Re: Hard start question

Thanx franken for your advice.

I did all the voltage tests, cranking and off. The numbers were all good.
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Old 02-18-2017, 09:40 PM   #25
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Re: Hard start question

Can you post the numbers? Good isn't always as good as one might think. Its only 2 values.
12.6 is good. Not 12.6 could be not good. Chances are you aren't seeing 12.6 because that's in a perfect world.
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