Hgpilot

Hi, I'm a new member to this forum. I have an XY Ute with an XF 4.1 carby engine in it. It's been sitting in the shed for about 10 years so I have decided to do something with it. It would hardly run at all with constant misfires and backfires about 2 weeks ago. I since found the distributor just floating around with locking screw undone. Set timing to 6 deg btdc and replaced leads and plugs. It runs alot better now and actually idles. The problem though is that it makes an awful POP sound every 3 seconds or so and the engine shakes and will even stop if in gear. I suspected maybe blow past one of the exhaust valves but I checked compression and all cylinders are between 120 and 150 psi. Also the POP can't be heard in the exhaust, only in the engine, I think from the carb. The popping gets less severe as the engine heats up and stops completely when revs are high. It does pop every time the throttle is suddenly opened. Any help would be appreciated. Thanks!

Interesting. I might try some diesel oil for a bit before the next change. Then some HPR 30 looks like the go.

Ok fair enough. I will give this oil a bit of a run through and flush it again and put some heavier weight stuff in.

Just some 10w-30 Castrol stuff I think it was. Not sure, the old oil did the same though.

Yeah ok I will look into that. Dad is the one who told me to rip the head off and replace all the lifters. I might ask him again and see if he has ever pulled one out without taking the head off. He said he could tell me every thing about a holden 253 but he only ever had to fix 1 falcon in his short time as a mechanic because they never break.

Ok, I'm curious now on how you get the lifters out without taking the head off. Because it really is only one lifter tapping. The rest are all pumped up nicely. But like you said it might come good. In fact, I started yesterday and the oil pressure came straight up too 40+psi (much better than the 20 or less it did have) and there was basically no taping. But, when it heats up a bit, the oil pressure comes back down and starts tick fording again.

Yeah not sure I can be bothered now. You would have to take the head off I'm assuming? I might still do it yet but would probably just get a whole set of lifters. Yeah the oil has been in there at least 15 years and only ever ran cold basically. Not to mention the thermost housing and water pump were rusted out.

Haha Tick Ford, that's good. Unfortunately this Tick Ford doesn't have any more power. Yeah he reckons it's the all gunked up. The oil that was in it was horrible sludge. We ran eninge flush and new oil hoping to free the lifter. My oil pressure is much better now (I have a gauge) so who knows, it may come good.

Yeah my Ute is running really well now apart from the clacking. The transmission is still doing some funny things though. I might need to start another topic lol.

Haha true

That's a good point. Not sure how the intake rod didn't fall out. Still might!

Alright, update! Dad came over and we pulled the 2 lifters and rods out. Both rods were straight so we put them back in and fired it up. It runs! No pop! Revs up and idles no problem!. The exhaust lifter is working like a new one. The intake lifter on cyl 4 on the other hand is still a bit loose and tapy. Dad thought that with an engine flush and some new oil the rod might pump back up. Put new oil in and had engine flush along with some liquimoli lifter juice stuff but still lifter taps. I think I should have just put a second hand lifter in like you said deankdx. Anyway thanks for your help guys! It's going pretty well now because of the advice I have got here. I will no doubt be back with more questions soon. Thanks!

I hope you guys are wrong. I have already thrown $250 in leads, plugs, thermostat housing, water pump, and starter motor. I'm holding onto hope because I found the rod out of the lifter completely just floating around. I should know by tomorrow. Thanks!

Yeah that's what I thought, but no they are all touching. Some are just pushing the spring down more than others. Yeah dad is a Bush mechanic alright, he will probably look for a straight enough stick to put in there!

Yeah no others have any play at all. The exhaust rod was disconnected at the top. I pulled the whole rod out and it looked straight. The intake rod I think may be off at the bottom. My father is coming over tomorrow and he used to be a mechanic so I'm going to get him to check it out. I am happy with temporary fixes as this is only a temporary engine in this car until I can afford a 351! (So probably in there forever)

Thanks, I pulled the rocker cover off (didn't unclip the throttle cable though :/) and sure enough I have a loose intake push rod and the exhaust rod is not even connected! Check this out! (ignore my noisy kids)

Ok, So, you guys must be right. Pulled all leads off one at a time and sure enough... stops popping when cylinder 4 lead is off. In fact, it runs smooth as with cylinder 4 unplugged. I can't touch the exhaust on all cylinders except 4 I can grab hold of. I have never worked on a push rod engine before, and I am no mechanic but I will see what I can do. Any suggestions on what I do from here? Thanks!

If the exhaust valve isn't opening you will still pass a compression test, it's even possible that cylinder will measure higher than the others, a closed exhaust valve Will causing popping out the carb on every second time that cylinder fires as the fuel is getting to the cylinder and being ignited but then it has to escape out the carb instead of the intake and then the cycle repeats Ah I see. This is why I'm here! You guys know your stuff!

That's a good idea. I will try that. I am thinking you guys are onto something because(I probably should have mentioned this) it used to run really rough but I never noticed a pop. The fisrt time I head the popping was after I pulled all my old plugs out, gave them a clean, and put them back in. Perhaps I had that cylinder not firing at all until I cleaned the plug. Thanks!

Was it popping from your carby like mine? I have wondered about the dizzy cap as there is some corrosion on it.

Yeah maybe. I hope not though! I originally thought it was exhaust valve but I have good compression on all cylinders. The pop doesn't come through the exhaust at all, only the carb. But If your right, I might look at a new engine. Thanks!

Yeah new plugs and new leads Bear

Here is a video of it running when cold https://youtu.be/qquUU1uhZEU And when its warm https://youtu.be/S0t5a5eNbfE Let me know if links dont work. Thanks!

Ok, no worries. I will try and get a vid for you guys. Thanks!

Interesting . It does get.much better as the car warms up. I had it not popping at all when warm today but soon as I put the engine under some load in gear and take it for a spin, it starts popping again. And still pops when cold. I have looked up a few vacuum diagrams but they are all different to mine in one way or another. Thanks for info!