IH 674 NO FIRE

langdangnebraska · Nov 29, 2021

Hello everyone, I've been working with this old 674 for over a year now. I bought it locked up, got it unlocked and running and then found out it had a cracked head. I pulled a good head and valve train off another C200 and got everything put together. When I'd try to start it, it acted like it wasn't getting any fuel to the cylinders. I've had the carb apart so many times I just decided to buy a new one (Zenith 14997). It STILL isn't acting like it's getting fuel to the cylinders. It has plenty of fuel going to it, plenty of vacuum, and I've adjusted the rockers a few times, plenty of spark. I broke down and gave it a small shot of either and all it did was pop, not try to fire, but I'm not giving it any more of that stuff, I don't feel like buying another head. Is there something I'm missing here? This should not be that complicated. Any info would be greatly appreciated! Happy Holidays!

Ozlander · Nov 29, 2021

(quoted from post at 12:46:50 11/29/21) Hello everyone, I've been working with this old 674 for over a year

Have you got spark at TDC on the compression stroke?

rustred · Nov 29, 2021

when u want to know if its a fuel problem remove the plugs and squirt some gas in each cyl. then it will fire up for a few seconds. BUT DO THE COMPRESSION CHECK FIRST , you need to know what your dealing with. do you know how to adjust rockers? cause you say you did it a few times. once correctly is all it takes. its not complicated.

rustred · Nov 29, 2021

Steve@Advance · Nov 29, 2021

If you hold your hand over the carb inlet and crank, do you get strong vacuum AND your hand wet with gas?

If so, double check the ignition timing and plug wire order, check the spark quality at the plug end of each wire.

Seen this before, so do be insulted, but are you sure it has gas in the tank, not diesel or ???

langdangnebraska · Nov 29, 2021

Not so wet with gas, definitely plenty of vacuum.

langdangnebraska · Nov 29, 2021

i honestly just took the same rockers that were adjusted off the head i used. I turned it over a few times to make sure that they were all somewhat tight. i will try going off of that diagram later today if i can get to it. thatnks you for the help

langdangnebraska · Nov 29, 2021

I will be doing a TDC compression stroke later. From my understanding, according to the picture, when its at TDC the rockers labeled 1 should have compressed springs?

langdangnebraska · Nov 29, 2021

I will check that this afternoon.

rustred · Nov 29, 2021

well u just posted your problem !they have to be set. the valves are not sitting the same in each cyl. not yet another head. plus if you would have checked compression that will also tell the story. do you have the valve gap setting for that engine??? i dont know if its .017 as the early ih tractors use. as i asked do you know how to set valves using a feeler guage ?

rustred · Nov 29, 2021

at TDC compression DEFINITLY NOT! that is where u set the gap at the factory spec.

rustred · Nov 29, 2021

even just the torqueing and retorqueing of the head changes the valve clearance, seat and valve face wear changes the clearance by decreasing it. valve and rocker wear and push rod wear increases the clearance. when you do a major tune up that includes the valve lash setting.

Steve@Advance · Nov 29, 2021

Sounds like clogged main jet.

If it's an adjustable main, is the tip of the adjustment screw broken off in the jet?

You did verify fuel in the bowl?

caterpillar guy · Nov 30, 2021

Start with the simple stuff. Do you have a good blue spark, with the plug out of the carb does it fill a pint jar quickly not in a few minutes but in seconds, Are the plug wires on in the correct rotation,is there fuel in the tank more than an inch deep. Like 3-4 inches,is the voltage up in the battery? Low voltage/charge will allow the spark to be weak/non existent for starting. Are the points gaped right? Is it in time? Lots of stuff to check. Are you sucking air at gasket joints?

showcrop · Nov 30, 2021

Elaborate on "plenty of fuel getting to it" and "it acts like it is not getting gas to the cylinders". Describing what you observe as opposed to just what something is "acting like" can get your message across a lot better. If it is cranking but not firing your spark plugs should be getting wet if it really is getting gas into the cylinders.

langdangnebraska · Nov 30, 2021

It's got clean gas going up to the carb. Brand new jet. I'm leaning towards a timing issue.

langdangnebraska · Nov 30, 2021

All of that stuff looked good to me. I'll be able to look into it more this afternoon.

langdangnebraska · Nov 30, 2021

Got it, I was alittle mixed up. Thanks for the help!

rustred · Dec 1, 2021

well i will ask again ... when do u plan on setting the valves???

rustred · Dec 1, 2021

no its not complicated, but you are making it that way. lots of things suggested here. but u GAVE YOUR SELF AWAY when u said u just swapped rockers without adjusting the valves. so un till the valves get set there is no sense posting and asking more questions. things get done in order on an engine like getting dressed in the morning. setting valves is after the head torque. some of us here have lots of experience and have a mechanic's ticket also to help the back yard guys if there willing to listen.

showcrop · Dec 2, 2021

(quoted from post at 10:01:27 11/30/21) It's got clean gas going up to the carb. Brand new jet. I'm leaning towards a timing issue.

Stay away from timing until you have addressed the basic things. follow the suggestions that you have already been given, and don't insist on looking for more complicated problems.

IH 674 NO FIRE

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