Did you change anything else other than the head change?
Head swap help needed
- Thread starter brianproctorla
- Start date
brianproctorla
Well-known member
The compression was a pretty consistent 90 lbs with plugs pulled and throttle wide open.
I swapped the head, carb and intake.
I swapped the head, carb and intake.
Sounds like either the valve train is consistently mis-adjusted/held open or, more likely, your short block needs a little tlc. At least it's consistent. That's a good sign, it wore evenly. What was the original problem after the swap, could you not get it to fire up? Then checked the compression? Did you compare those pedestals? You shouldn't be at the end of the adjustment on your rockers.
brianproctorla
Well-known member
Might have found the issue. The 250-2v rockers have a nut that is screwed in on top of the rocker that limits travel. This is not present on my 250.
I bet if I remove this the adjuster won't bottom out on the nut.
I bet if I remove this the adjuster won't bottom out on the nut.
Do you have a picture? Some of the rockers used a jamb nut to lock the adjuster from moving if that's what you have you first need to back that nut off some (loosen it) before you can adjust the valves. After it's set you then re lock the jamb nut. Good luck 
brianproctorla
Well-known member
Definitely a jamb nut. I removed it and tried to set the lash again.
With the plugs out and the lash set, shouldn't I get a mist to spray out of the spark plug holes when cranking? I don't think it is pulling in fuel even when I spray starter fluid .
It seems a little better now, but I can't get sustained detonation.
With the plugs out and the lash set, shouldn't I get a mist to spray out of the spark plug holes when cranking? I don't think it is pulling in fuel even when I spray starter fluid .
It seems a little better now, but I can't get sustained detonation.
brianproctorla
Well-known member
Is 90 pounds of compression enough to get the engine to start?
Yes at 90 PSI it should run.
brianproctorla
Well-known member
Man, I just can't seem to figure the one out.
Shouldn't i see some puffs of vapor coming out of the piston holes when cranked?
Is there any way to test if fuel is being pulled into the cylinder?
I was thinking that perhaps the head bolts bottomed out and kept the head gasket from sealing.
Shouldn't i see some puffs of vapor coming out of the piston holes when cranked?
Is there any way to test if fuel is being pulled into the cylinder?
I was thinking that perhaps the head bolts bottomed out and kept the head gasket from sealing.
brianproctorla":baqa55yj said:
With the plugs out its not going to pull any fuel into the cylinder, there is no vacuum to pull the fuel in with it open. Some checks you can do with the air cleaner off look down the carb throat to see if you have an accelerator pump shot, you could place your had over the carb if it's a 1V to see if it pulls fuel this acts like a choke.
On the head bolts if you think they bottomed out you could get some head bolt washers and put them under one head bolt at a time so as to not disturb the head gasket. Good luck
brianproctorla
Well-known member
I've got a Holley 350 on it, and I can see a shot of gas going in from the fuel pump.
Ok you should be good to try and start it put the plugs in and give it a go.
brianproctorla
Well-known member
I tried it. It seems a bit closer to starting, but really has no sustained detonation . I can't even get a few seconds of run time off of a blast of starter fluid.
Should I do a wet compression test?
An intake leak would be able to pull in some vapor correct?
Should I do a wet compression test?
An intake leak would be able to pull in some vapor correct?
A vacuum leak will draw in extra air leaning the fuel mixture, check over the complete intake manifold for missing plugs or fittings. Since I am not able to see your combo of parts and how it's all assembled here are some more things to check. Pull the carb off the intake and check that the gasket is sealing completely around all the openings on both top and bottom. If there is a insulator spacer plate between the carb and manifold do you have the correct gasket under it and is it sealing? Does the carb have a choke and is it set up correctly? Since you have a Holley did you check that the wet fuel level is set correctly? Do you have a PCV valve and is it hooked up correctly? Ok let's also go over some of the other basics, are the plugs gapped to .034 - .035? Have you checked the timing lead 10 - 12 BTDC should be close to start? Do you have a good hot spark, "Nice bright blue and jumps 3/8 to 1/2 inch with a snap"? Have you checked that the crankshaft dampers timing mark is actually at TDC when the number 1 piston is at TDC? If you loosened, turned, or pulled the distributor out then Are the plug wires in the correct firing order? Is the number 1 cylinder on the compression stroke when the number 1 spark plug wire is firing? Good luck
brianproctorla
Well-known member
I will start checking the spark first. When I put an inline spark tester on it, I get an orange spark.
I am going to charge up the battery and test again both with an inline tester and with holding the lead against a ground.
You might be right about carb gaskets. This requires an adapter and I had to create a gasket for both the adapter and the intake.
Given the many gaskets, could I pull the carb and put a shot of starter fluid into the intake, cover the opening and get a few seconds of run time? I would like to isolate the carb if I can verify that the spark is correct.
Before the head swap, I had changed the points and checked gap and dwell. The engine ran pretty well
I am going to charge up the battery and test again both with an inline tester and with holding the lead against a ground.
You might be right about carb gaskets. This requires an adapter and I had to create a gasket for both the adapter and the intake.
Given the many gaskets, could I pull the carb and put a shot of starter fluid into the intake, cover the opening and get a few seconds of run time? I would like to isolate the carb if I can verify that the spark is correct.
Before the head swap, I had changed the points and checked gap and dwell. The engine ran pretty well
brianproctorla":1lbuab8q said:
Excellent making sure the battery is fully charged is very important! If after the battery is fully charged you don't get a good Blue Spark then the Coil needs to be replaced!It's important in trouble shooting not to change to many things at once so you can tell if your making any progress, so first thing I would focus on getting the ignition system in top shape and it sounds like you might be close. On the starter fluid it should not be needed if everything is right, over use of it can cause damage to an engine. I would not spray it into an open intake (without the carb on). If the carbs accelerator pump is squirting fuel down the carb that should be enough to get it to run. A better alternative if it's very cold were you are if it's at all possible to get your car inside of a shop or garage and use a heater to warm up the surrounding area, air, and the engine it will really help. Good luck
brianproctorla
Well-known member
I have power to cool and when I hook up a test light between negative coil and ground, it flashes on cranking. I am getting a weak spark at the high voltage lead. Thinking it could be coil.
Yes from your previous description I would say the coil is weak and should be replaced. brianproctorla
Well-known member
I reset the points, checked the dwell, went to check the timing and she started up.
I am not out of the woods, but she ran for about 10 seconds!!!
I am not out of the woods, but she ran for about 10 seconds!!!
