Alright guys, getting ready to pick up my head studs and valve springs in the next couple of days, Comp 910 as the title says. Been searching to try and find the procedure for changing the springs without pulling the heads, seems I saw somewhere once that you could bring the piston for a given cylinder to TDC and the valve would stay mostly up. What is the crank/balancer mark position for each cylinder? Also I've seen that these are supposed to be shimmed, I didnt order shims so would I gain anything by putting them in without shims?
Searched but cant find my answer, Comp 910s
- Thread starter Hyde
- Start date
icanfixall
Official GMM hand model
I'm not the most help for this but I know when number one cylinder is at tdc so is number 4 cylinder. Both of those cylinders time our idi the same. I sometimes use the number 4 because I can't get a good read off number one cylinder. All van idi engines are timed off number 4 cylinder because its eaier to reach in a van. The next cylinder in the fireing order at tdc is number 2 but I'm not sure what companion cylinder is also up. I do know the crank needs to be turned only a quater turn to get number 2 at tdc. The fireing order is an odd one too. Its 1,2,7,3,4,5,6,8. This type of fireing order is why our engines start and stop on one of three places on the crank. Thats also why we wear out the starter ring gear in those three places. I know someone has the cylinders that match up so hang around for some answers. You are going to need the special spring removel tool too. If your interested in renting it from me because I have one please pm me and we can discuss it. Maybe someone on this forum will do it for you or offer the tool for free. It can't hurt to ask.
come on gary. companion cyls. if one is companion with four, then it is 2 and 5, 7 and 6, and 3 and 8
jlwoods99
Registered User
My uncle once told me about taking a spark plug and knocking the ceramic off drill it and weld on a air fitting for compressor. He'd pressurize the cylinder with both valves shut and he could do work on the valve springs. Don't know if you could do it with a old injector.
jim
jim
The only mark on the damper is for #1 and #4 @tdc. Mark on damper aligned with 0 mark on plate. You will have to divide the circumference of the damper into four equal parts to make the other marks. The other cylinders come up as the damper is rotated 1/4 turn. At tdc the valve can't drop far. Are you studding without removing heads? Engine in truck? I have heard it can be done.
Thanks for the info guys, I have an overhead spring compressor and can borrow the "pliers" type. What special one is required?
Tahoe: Yes I'm studding without lifting the heads, one at a time. I know most on here don't like the method but that's the way its getting done. Id not like to start another debate on it.
Anyone know about running without shims?
Tahoe: Yes I'm studding without lifting the heads, one at a time. I know most on here don't like the method but that's the way its getting done. Id not like to start another debate on it.
Anyone know about running without shims?
Thanks Leeland, just read a very extensive thread on powerstrokearmy, unfortunately I don't have shims or a spring mic. You will gain seat pressure by putting them in without shims but not nearly as much or necessarily even. Still gotta be better than old stock springs. Now I just have to decide if I want to half ass it or buy tools haha
sle2115
NRA LIFE MEMBER
Yep, as was said, you have to set the compressed valve closed height of the spring, shims will be how you would accomplish this. How much difference it makes? Well, it can make quite a bit. Not sure of the 910's rates and such, so I can't say for sure.
There is also an air adapter that you can use in the glow plug hole. Looks like a compression tester, but you hook a hose on it, I'm sure you can make one.
Also, not to start the debate, but are you sure you can get all the studs in with the heads in place? Is the engine in the truck? Does it have ac? Been a while, but I know many use rubber bands to hold the studs in the head while setting the head back on the engine as there isn't enough room for the stud to clear the evaporator box and go into the appropriate hole in the head. Just and FYI...there was a couple write-ups about which ones were problematic.
There is also an air adapter that you can use in the glow plug hole. Looks like a compression tester, but you hook a hose on it, I'm sure you can make one.
Also, not to start the debate, but are you sure you can get all the studs in with the heads in place? Is the engine in the truck? Does it have ac? Been a while, but I know many use rubber bands to hold the studs in the head while setting the head back on the engine as there isn't enough room for the stud to clear the evaporator box and go into the appropriate hole in the head. Just and FYI...there was a couple write-ups about which ones were problematic.
sle2115
NRA LIFE MEMBER
You mean the evaporator? On the firewall correct? Then it sounds like you know the fix for that issue.
sle2115
NRA LIFE MEMBER
I think it's the box around it that gets in the way, which you have to have as air cycles through it to the inside of the truck. By the way, not to be an ass, but the condenser is what is in front of the radiator. Anyway, sounds like you know what to do.
icanfixall
Official GMM hand model
What tools are you thinking you need to buy.. Just a little tip on doing this job. Providing the pistons are at tdc when the keeper are removed the valve will drop about 60 thousands till it hits the piston crown. An easy way to remove the two piece valve keepers I like a magnet and a small screwdriver. I really can't offer information about shimming the springs with the heads on the engine. Under the valve spring is an item called a valve rotater. That must be reinstalled the same way it comes out if you remove them for any reason. What they are designed to do is rotate the valve a tiny amount each time the rocker opens the valve. This valve rotation keeps the seats and valves from pitting and ruining the seal. The rotation cleans any material that sometimes get caught between the valve and the seat.
A .030 shim under each spring is a good idea for a starting point since the heads are not coming off to do it, it gets difficult to do on the engine without extensive tooling.
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