Piston and Valve Interference?

[nastyf150]

I am putting my head and block together finally. Robert at the machine shop told me I needed to do a mock-up because 1) I have longer valves stems on the che**y valves 2) more lift (.485 in and .515ex) 3) The 360 flat top pistons were about .100 more compression height than the 300 stock 4) the deck was milled .010 and 5) the head was milled .020.

I put some playdough in #1, put the rockers on, put the push rods in. Rolled it over and could see through the spark plug hole that the valve did not even come close to the top of the pistons. I put cam lube on top of the playdough to keep it from sticking to the valve, and that was not even touch.

The question is--I didn't have my lifters "pump-ed" up, will that make more than .100 difference? If so, should I be good to run it? The pistons have valve reliefs. Looks to me like they don't come .500 from the piston, at least?

First Time Sixer, (boy am I provin' it)
Jeff

 

[addo]

The lifters are unlikely to pump up more than about 120 thou. That said, you should remove the lifters and relube the rubbed off areas on them and the cam. It's generally not advised to turn a motor over until startup. Rest it at #1 TDC firing.

Cheers, Adam.

 

[rbohm]

8) valve to piston clearance checking must be done with a solid lifter. a hydraulic lifter will pump up more than .100" and could cause problems. you also need to turn the crank through 2 full revolutions when checking v/p clearance, remember that the cam turns one time for every two the crank turns.

 

[nastyf150]

How bout I try putting a washer in the hyd. lifter that will allow the ball of the rod to sink in to the hole part of the washer (i.e. 5/16 rod with a 5/16 washer) and then turn it over.

Let me ask this since you mentioned the crank and cam rotations:
Am I correct in saying that TDC is between the comp. stroke and the power stroke? Consequently, The exhaust valve is the first valve to open on #1 cyl after TDC and has the highest lift (.515). IIRC, the ignition timing is BTDC Can I put my playdough down in that valve relief and get my measurement or do I need to do intake and exh. alike?

The intake lift is only .485 and I have stock adjustables for a 240ci so the ratio is still 1.61 to 1. Therefore, the real v/p clearance is for the exhaust valve.

Let's say there is less than .100 clearance btwn the v and p, what then? I am over budget now as it is (had to sell my Volvo to keep the funding coming, and could have built 3-350s :x on what it has cost me to get just this far-it seems to have a permanent home on the engine stand)!!! .

I NEED to get this thing put together and running in my new daily driver!

Jeff

 

[simon]

I NEED to get this thing put together and running in my new daily driver!

Jeff

rushing things is a surefire way to skimp and ruin your otherwise good work.

take your time, 'cause if its not enough time the first time, it'll be plenty o' time the next time.

 

[nastyf150]

Ah, Bro. Simon,

Thanks for those words of wisdom and edification! Fear of loss is a path to the dark side.

The fruit of the Spirit is love, peace, patience, kindness, goodness, and SELF-CONTROL, faithfulness, and gentleness; against such there is no law (emphasis mine).

Now that the metaphysical problem has been addressed, what about the washer suggestion--

How bout I try putting a washer in the hyd. lifter that will allow the ball of the rod to sink in to the hole part of the washer (i.e. 5/16 rod with a 5/16 washer) and then turn it over.

 

[rbohm]

8) either valve can interefer with the piston if clearances are too tight. the exhaust valve tends to more because it chases the piston down the bore, whereas the piston chases the intake valve up the bore.

as far as putting a 5/16" washer in the lifter, no. you need a solid lifter. if the washer should slip, you would get a false reading.

 

[nastyf150]

Okay, I tried to buy two solid lifters from Crane and they said that the mock-up had to be done with the lifters that are designed for the cam (hyd. ones instead of solids). He said to pump them up and then to the clearance check.

Jeff

 

[nastyf150]

What is degreeing the cam? Can anyone shed some light on that? Since I am being patient, do I need to get a degree kit and degree the cam or will it do fine without that? I have built engines in the past and have seen the degree wheels and stuff, but have never even attempted to degree a cam.

Jeff

 

[rbohm]

8) degreeing a cam is where you verify the timing events that are listed on the timing card you got with your cam. you need to find exact top dead center on the compression storke, and there is a way to do that. then you you use a dial indicator to follow the lifter, and check the events as you turn the crank.

as far as v/p clearance needing to be done with the type lifter that goes on the cam, hogwash. if hte cam is a roller cam then you need a roller lifter. a flat tappet cam needs a flat tappet lifter. you can use a solid lifter to check v/p clearance and to degree the cam. in fact it is recomended. if the guy at comp cams would not sell you a couple of solid lifters, try comp cams or lunati.

 

[nastyf150]

In between r and r of a/c compressor and drier and fixin flats, I got the bottom buttoned up on my 303ci. I don't think degreeing my cam is necessary in this street application.

I am going to pump up my lifters by using my drill motor and an hex head I welded to a rod, then check my clearance. I am going to but .250 of clay above my piston top to see if i can even get a mark.

I am eating supper right now and am going back to the shop to finish the mock up.

Jeff

 

[Stubby]

Okay, I tried to buy two solid lifters from Crane and they said that the mock-up had to be done with the lifters that are designed for the cam (hyd. ones instead of solids). He said to pump them up and then to the clearance

Just go down to the parts store and buy one mechanical lifter.
Set the lash to .000 and check them one at a time.
This should be fine for your application.
Don't be shocked if they have to order one.

 

[80broncoman]

When they say use the lifter designed for the cam, they mean roller lifter on roller cam and solid or hyd for non-roller. This is because mixing can cause the profile to change.

Also helpfull is to use "checking valesprings" as these will usally not compress the lifter at all.

 

[nastyf150]

Thanks guys,

It is all over now!! I decided to do my best to pump up the lifters with a rig I made and do the check. I put .300 clay above the piston top. It did not even come close! The only mark on my clay was were the combustion chamber ended and the head surface began. I looked through the spark plug hole and they[valves] had plenty of room.

I pulled the head, took out the clay, replaced the head, and attempted to put the rocker arms close to where they are 'sposed to be. All that v/p clearance stuff I consider resolved.

Now I am looking at more things than one when I get into starting the motor up--1) I need to brake in my cam for 20 minutes 2) adjust my valves if they are noisy and 3)watch the gauges. Not to mention I have a new carb that will need some attention immediately. Any suggestions?

Jeff

 

[MustangSix]

One other thing you could do is to buy two solid lifters to do the mockup. The cost of those is low and they work fine to check clearances even with a hydro cam.

 

[Twinscrew]

I dissassemble one lifter and pack it full of news paper wads. I use a fairly lightweight spring at the valve. Play-dough on the piston with grease on the valves. Works like a charm. Don't let young kids see you putting Play-dough inside the motor. They will think that Play-dough belongs in the motor and may want to help you by putting some in there while you aren't watching. Don't ask me how I know that.