Bend pushrod on #4 intake

[wrenchnride247]

Zeroaxe, If you get mill set P/N GB 700B the cutter head comes with the 3/4 shank (for 3/4 mill collet) that threads into the 7/8 9 threaded hole in cutter. They do this so the cutter fits their drill press version also. The drill press version would be the easier one to set-up and use. The mill version can be a PITA if you've never used a mill before.

The pictures do show major head leaks, having poorly machined heads will do that.

Moog, thanks for posting. I'm glad someone else is wanting to help too.

[zeroaxe]

wrenchnride247,

I am now officialy confused, lol. Are you saying that there is an optional shank that needs to be bought for a drill press?(I meant to say earlier it is for a drill press I would like). I tried searching for a pic of the fly cutter assembled with the shank but came up empty handed...

[wrenchnride247]

The drill press version comes with a base that bolts to your head stud holes, and the shank and stop collar (so you get the hole depth the same, and centered on all cylinders every time ) this cost about $275 US in a 2000 copy of Berg price list I have, maybe higher now though. It includes everything need, but drill press.

[zeroaxe]

Well, here is a quick update...

Today I spend a lot of time modding my engine stand, adding a third 'arm'. I dont feel cofortable with a whole engine hanging only from the two arms. I have seen those mounting plates bend too much for my liking.(plus, the bottom stud that it would normally bolt onto has pulled it's thread again. I fixed it once already! should I try and get hold of helicoil inserts, or does it not really matter *that* much on a motor that is supported at the back with an engine bar(like a Vanagon/Transporter)?

Anyway, using this tool:

I found the following deck height readings with a vernier caliper.

#1 = 1.26mm/0.049"
#2 = 1.5mm/0.059
#3 = 1.26mm/0.049"
#4 = 1.22mm/0.048"

What do you guys make of this? Is this considered 'in spec'?

Tomorrow I hope to get the readings off the valves and check for coil/valve spring bind.

Thanks for your input!

[Moog]

I would say those readings are OK as far as making sure the pistons are not going to tap the heads while revving, BUT...

Variation from piston 1 to 2 is quite a bit - why is this? Is it piston variation, or are the cylinders sitting at different heights. Both cylinders on each side must be perfectly matched in order that the head sits square - if not then it sits askew and you blow out of one side of each chamber - as at least one of the heads seems to be blowing on one side of each cylinder only, maybe this is part of the problem?

With these deck height readings what does the compression ratio work out at - have you cc'd the combustion chambers to work it out?

Of course, there is still the possible issue of coil bind, and at least one valve tapping a piston - put some thin layer of plasticene / blu-tack on each piston crown, do a dry build, turn the engine over by hand, then take it apart to see the marks the valves leave in it - slice it carefully and you can measure how close the valve is getting to the piston crown.

Hope this helps...

Moog

[wrenchnride247]

moog "hit the nail on the head" as we say across the pond.

If your case was just opened up for larger p/c's then its could be the piston tops are a little thicker on top than one another(quite common), but if the case was "bored and decked" then one of the decks could have been machined a little too much .

P.S. you have a e-mail w/autocad program

[zeroaxe]

Originally Posted by Moog

I would say those readings are OK as far as making sure the pistons are not going to tap the heads while revving, BUT...

Variation from piston 1 to 2 is quite a bit - why is this? Is it piston variation, or are the cylinders sitting at different heights. Both cylinders on each side must be perfectly matched in order that the head sits square - if not then it sits askew and you blow out of one side of each chamber - as at least one of the heads seems to be blowing on one side of each cylinder only, maybe this is part of the problem?

Moog, I get what you are saying. I am going to torque down the cylinders and re-measure, at least once to see if I get the same reading/s. I suspect that the head is not sitting straight. There is too much evidence to ignore the facts.

Originally Posted by Moog

With these deck height readings what does the compression ratio work out at - have you cc'd the combustion chambers to work it out?

Ok, so I just CC'ed the heads today. And what a surprise. I must eat *some* of my words. This guy actually had a good eye for machining those heads. Here are the readings:

48,48,48,49cc !! The 49cc reading is on the head where the valve hit the piston(#3). But this doesnt make sense to me. If it was machined 49cc, that means he took 'too little' off. And the piston doesnt come up that high compared to #4. So I dont get that, that should be the problem. Or am I missing something obvious?

According to this site's calculator I calculated the compression ratios per cylinder as follows:
#1 - 1.26mmDH 48cc = 8.9CR
#2 - 1.5mmDH 48cc = 8.69CR
#3 - 1.26mmDH 49cc = 8.76CR
#4 - 1.22mmDH 48cc = 8.93CR
They are all over the place!

Originally Posted by Moog

Of course, there is still the possible issue of coil bind, and at least one valve tapping a piston - put some thin layer of plasticene / blu-tack on each piston crown, do a dry build, turn the engine over by hand, then take it apart to see the marks the valves leave in it - slice it carefully and you can measure how close the valve is getting to the piston crown.

Hope this helps...

Moog

After rechecking deck height, I am going to clean the piston crowns and do the blu-tack thing. following that with the coil bind check.

I also want to ask... Under the rocker shaft, do I need some kind of washer/spacer? I have been told just to assemble it with the little rubber ring/washer underneath to prefer an oil leak

[zeroaxe]

Ok, so I mocked up the #3&4 side with blu-tack and torqued the head properly. I put in the cam lifters with the pushrods and turned the motor a few times to see if the lift-n-fall smoothly on their own steam. #3 exhaust side lifted but didnt go down on it's own steam(with the weight of only the pushrod), so added some oil and 'aided' down a few times turning the engine. After that it would lift-n-fall fine. Next, put the rocker arm on, back the adjusters out all the way and bolt it down securely. Again I turned the motor a few times, and then commenced with valve adjustments. Turned the engine a few times and there were no obvious 'counter force'. No resistance at all.

Disassembled everything(while saying to the wife:"Stay here. Before you leave I want to show you something") and went ahead making a fool out of myself in front of her(oh, the humiliation. There goes the ego! ). No marks on the blu-tack at all!? Huh!? What the heck? The blu-tack was about 3mm thick on the piston head!? At first I thought that I didnt place it well on the piston, BUT, where the intake valve hit the #4 piston the blu-tack was on the mark!?

Now I am at a loss. the only thing I can think of now is that I had a coil bind on that valve, causing the bend PR(but saying that, I should've felt it turning the motor over by hand). Or, it slipped out of the rocker's cup and on the way out the edge of the cup caught it and added +/-5mm of lift, pushing the valve too far? I understand it like this: The valve got hit when the piston came up for the compression stroke? How else can an intake valve be hit? Valve float? It should never be open when the piston is on it's way to TDC, no?

I will do this same excersize AGAIN tomorrow, just to make sure I wasnt a moron. I will (hopefully have time to) do the rocker geometry measurements, if they check out, then I dont know what the reason would be for 2 bend pushrods? It cant be badly adjusted valves, because by nature(when it comes to these kind of things) I am paranoid and re-check measurements 3 or 4 times!

More later.