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0-360 pushrod length question

lostpilot28

lostpilot28

Well Known Member
I'm building an ECI engine kit and I've come across one problem...when installing the rocker arms into the heads, the manual says to check the gap between the rocker arm and the valve stem. The clearance should be between .028 and .080.

My exhaust valve clearance is fine, but the intake clearance is about .092. The kit was shipped with the shortest pushrods (p/n 73434). Is it common to have to swap out pushrods like this? What if only one or two cylinders needed the different length pushrod? That's not the case with my kit, but is having varying lengths of pushrods normal?

Thanks!
 
Not sure about the engine kits. I would think they would know the right ones to send. However, at overhaul, it is very common to have to swap out pushrod lengths.
I'm sure that ECI will swap with you.
Different lengths on different cylinders is not uncommon.
When I rebuilt my engine with aftermarket roller rockers and a reground cam, I spent some time at the lathe making pushrods.
 
Thanks Mel. I would think that by using all new parts, ECI would be able to figure out the right length to send. But, with that said, I can see that a few thousandths of an inch would be tough to nail if you didn't pre-assemble the kit.

I'll give A.E.R.O. a call on Monday to see if they will swap them or if I need to call ECI directly.

On a side note, I have to commend A.E.R.O. for their outstanding customer service. They have bent over backwards for me, and have even sent me a few small parts free of charge. I would highly recommend them to anyone looking for parts.
 
lostpilot28 said:
I'm building an ECI engine kit and I've come across one problem...when installing the rocker arms into the heads, the manual says to check the gap between the rocker arm and the valve stem. The clearance should be between .028 and .080.

My exhaust valve clearance is fine, but the intake clearance is about .092. The kit was shipped with the shortest pushrods (p/n 73434). Is it common to have to swap out pushrods like this? What if only one or two cylinders needed the different length pushrod? That's not the case with my kit, but is having varying lengths of pushrods normal?

Thanks!
Click to expand...

What you are checking is call the Dry Tappet Clearance Test. Make sure that your tappets are dry and bottoming out. Then do the clearance test. There are different length pushrods to adjust for this clearance.

JF
 
I just got home from a workshop at Mattituck. One of their guys who assembled the engine , an ECI kit, had to replace 2 of the pushrods with the next longer one, he called it a 35 as opposed to a 34 ( I assume it was the last 2 digits of the P/N) which was what the kit was supplied with. It helps to work there, as he had a ready supply of new pushrods from which to choose.

BTW, the workshop was awsome! Treated like royalty. It was a lot of traveling, but well worth it.
 
Had same problem

I finished the rebuild of my O-320 a few weeks ago and used all new ECI Titan cylinders. I was only able to use two out of eight original pushrods. Fortionatly I had a friend that had a large box of pushrods that I could sort through. At the end of the day I still had to turn a long one down to get the right clearance. A local mechanic who rebuilds engines frequently told me that this is common with the ECI cylinders.
 
Thanks guys...very helpful info. Dave, it sounds like the -34 & -35 is the pushrod part number. The 73434 is the shortest one, so going to a -35 should fix my gap-problem.
 
The push rods are made in .030" increments. I've built two ECI engines and both have required one push rod be the next size up. It just absolutly baffles me that it has to be done this way. When I ordered my first engine from AERO Jesse told me that this could be a possible problem. ECI will make an exchange for you.
 
Hi Rivethead...I just went out and did the "dry" check on all of the rocker arms and 2 of the intake valves (1 and 3) were at .080". On the other side of the case, cylinders 2 & 4 were just under that at around .075".

Do you think these 4 pushrods should be exchanged? Jesse's been a great help and I'm sure he'll take care of it...I just want to know if I need the next-longer length rods.

Just an FYI - the exhaust pushrods were all in the .065 range. That's on the upper end of the .028 - .080 range, but within tolerance. I don't plan on swapping them out, unless someone has a different recommendation.

Thanks!
 
If anything, you want to err toward the upper end of the range. As the new valves "seat in", the gap will tighten up slightly.
 
Hi Mel, I thought that with wear on the rest of the parts (valve stems, both ends of the rocker arm, pushrods, tapets and cam) that the clearance would widen up. Is my thinking off on this?

I figured that with any wear, the 2 rockers that are at .080" would be out of tolerance...Unless the intake valve seats make up for the rest of the wear and then some. I guess I'm just worrying that I have 2 rockers that are litterally at the upper limit, and 2 more that are really close. Should I stop worrying about it?
 
I agree with Mel on this. Pretty much, in the case of valve pushrods only the one's that are over or under tolerance need be replaced. When the engine is running the tappets fill with oil and all clearance goes away, as you probably already know, and the valve system becomes tight. You shouldn't hear tapping rocker arms. Also the geometry of the system is such that adding .030" to the system is not an .030" change in the gap, I believe you will find the change is larger in sum (smaller gap). When you get your longer push rod you may want to check that out for yourself on one of your other valves (be careful not to pull the piston assembly out of the tappet). At that point you would know if you really want to change anything else.
 
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lostpilot28 said:
Hi Rivethead...I just went out and did the "dry" check on all of the rocker arms and 2 of the intake valves (1 and 3) were at .080". On the other side of the case, cylinders 2 & 4 were just under that at around .075".

Do you think these 4 pushrods should be exchanged? Jesse's been a great help and I'm sure he'll take care of it...I just want to know if I need the next-longer length rods.

Just an FYI - the exhaust pushrods were all in the .065 range. That's on the upper end of the .028 - .080 range, but within tolerance. I don't plan on swapping them out, unless someone has a different recommendation.

Thanks!
Click to expand...

You are not going to have much wear. If you do, you will have other problems. I overhauled a TSIO 520 at 1560 hours, 160 over TBO and I had to replace 2 pushrods that exceeded the upper limit. For a better comfort level you might consider changing out 1 and 3.

JF
 
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