Actually I have 3 questions,

1. How do I measure the deck on my block? I need to measure this before the machine shop will shave my 74cc heads.

2. How do I measure for the pushrods? I have hydraulic rollers. I have an adjustable length pushrod checker I got from summit when I ordered the bolts and gaskets for the head swap.

3. When I get everything setup, I need to check at least 1 cylinder with clay for any clearance issues, how do I do this also?

Basically I am going to be swapping out my 113 heads for a set of AFR 195's. Any tips, pointers, general suggestions for a first timer very welcome.



Thanks,
Doug

 

1. The deck height clearance is a measurement of how far below the deck surface of the block the piston is at TDC. Finding exact TDC requires a dial indicator and a degree wheel. Set the dial indicator up with the plunger on one of the pistons and rotate the crank to bring the piston up until the indicator stops moving one direction and starts going back the other. Go back and forth to get a "close" TDC. Then position a pointer on the degree wheel at zero. Then rotate the crank backwards until the piston is .050" down and note the reading on the degree wheel (~12 degrees before zero). Then rotate back up and past TDC until the piston is .050" down again and note the reading on the degree wheel. Let's say it's 14 degrees after zero this time. That means your "zero" is off 1 degree. Adjust the pointer and check again until your find the middle, and then with the pointer at zero your on TDC. Then you can measure the deck height with a depth gauge or a straight edge and some feeler gauges.

2. That's a tough one. The best bet there is to get a geometry checker like Moroso makes (or at least used to), which is a little device that slips over the stud and rests on the valve tip and push rod end. A clearance or gap on either indicates the pushrod needs to be longer or shorter. You want to check this with the lifter on the base of the lobe )i.e. valve closed). The tool should come with instructions.

3. They say a picture is worth a thousand words, so let's try this:

Put clay on the piston, put the head on with a gasket (just a couple head bolts), a couple lifters, pushrods and rockers, adjusted, and rotate two full revolutions, then remove. One thing you have to be careful with on hydraulic lifters is that the spring pressure can push the plunger down in the lifter during this operation and then the valve won't open all the way and you won't get a good reading. There are light weight "checker" springs available for this situation. Be sure to degree the cam first, because changing the cam timing can change the clearance (the valves are opening at different time in relation to the position of the piston). You can also do this without a head gasket, and if you have good clearance then, you'll certainly be fine with a gasket on there.

Dan

 

Thanks Dan!

I already have an adjustable pusshrod, and the local engine builder will let me borrow a solid roller lifter, does the tool you tallking about go on in place of the rocker arm? Anyone able to give me a better idea of what it is?



Thanks,
Doug

 

At summitracing.com check out PRO-66789 or MAN-42137. The tool fits over the rocker stud in place of the rocker arm. When checking the pushrod length use your hydraulic lifter in case the length of the lifter is different.

Dan

 

Awesome! Thanks for the help! So I can check pushrod length with my hydraulic lifters installed? I thought there was an issue with no oil pressure. And to check if I understand the use of the tool, I put it on in plcae of my rocker arm and check to make sure there is no gap on either end. Do I do this static, or should I run through a complete cycle?

Thanks,



Doug

 

Here's a tip if you don't have "check springs" or don't want to buy them or wait on them. Have you ever seen those little yellow flags on a piece of wire for marking off building or yard projects? They can be bought in quantity for a few bucks and I had some left from a project. The wire on them is stiff and when I needed to check piston to valve clearance for my new heads, oversized valves, etc. last year, I wound a couple of these into some nice little springs for the purpose. They retained their shape and tension fine and readings were consistent. I still have them and will need them again soon for a new piston and stroke set-up.

 

You have a adjustable pushrods, now you need the checking springs. Once you get the springs you adjust the pushrod so the rocker tip starts on one side of the valve tip and goes an equal distance to the other side when rotating the motor once. Then you measure the pushrod and get the pushrods that come closest to you measurement since they are usually sold in 0.050" increments.

To check your piston to valve clearance you use the same checking springs and put a dial indicator on top of the valve without the rocker arm in place. Turn the motor over and keep pushing down on the valve until it hits the piston. Keep turing untill you find the shortest point, shoot for .100" clearance, a little less is acceptable on a sub 6000RPM motor

 

Okay, I bite....what is a check spring? I am guessing a spring I would use to make the rod length/clearance measurements?

Thanks for all the great info guys!

 

Those are simply light weight springs that are just strong enough to hold the retainer and locks in place, and hold the valve against the seat or rocker tip, while you "check" things like valve to piston clearance and pushrod lengths, etc. They are light enough that you can easily compress them by hand, and will not force the plunger down in a hydraulic lifter. Go to summitracing.com and type in "check spring" for a search.

Dan