Help me tear down and inspect my 440..
- Thread starter Canadian1968
- Start date
Canadian1968
Well-Known Member
I checked one of the combustion chambers tonight.
A 1/8 piece of clear acrylic plastic with a hole drilled in it. Used some Vaseline smeared around the bore . Pressed the clear piece over top and started adding ISO with some green food coloring . I simply used a 10ml syringe and started counting.
It is a bit of a tedious process , you have to be patient putting in the fluid, and when u get close to full need to get that air bubble below the hole to fill .
I had some spillage on filling and ended with 91cc . I know that was to high and a result of my sloppiness! With the chamber completely filled I didn't reverse and measured as I took it out. I got 85.5cc , allowing for the smallest amount left in the chamber and a bit residual on the plastic, I will call it 86cc.
To the best of my knowledge the heads have been cleaned up twice. Given a 88-89cc oem head I feel the 86 to be in the ball park?
A 1/8 piece of clear acrylic plastic with a hole drilled in it. Used some Vaseline smeared around the bore . Pressed the clear piece over top and started adding ISO with some green food coloring . I simply used a 10ml syringe and started counting.
It is a bit of a tedious process , you have to be patient putting in the fluid, and when u get close to full need to get that air bubble below the hole to fill .
I had some spillage on filling and ended with 91cc . I know that was to high and a result of my sloppiness! With the chamber completely filled I didn't reverse and measured as I took it out. I got 85.5cc , allowing for the smallest amount left in the chamber and a bit residual on the plastic, I will call it 86cc.
To the best of my knowledge the heads have been cleaned up twice. Given a 88-89cc oem head I feel the 86 to be in the ball park?
Canadian1968
Well-Known Member
Well I checked the piston to deck height tonight. I zeroed the dial on the deck then moved over top of the piston. Gauge reads .009 will call it .010 down.
Given
4.35 bore x 3.75 stroke
5.6 cc dish piston
86 cc chamber
.01 deck
.039 compressed head gasket
= 9.8 : 1
I could go with a steel head gasket of .020 that would put me at 10.2 compression. Wonder if it's worth it ?
Also have a picture of the other head and what to me looks where I had 2 small exhaust leaks
Given
4.35 bore x 3.75 stroke
5.6 cc dish piston
86 cc chamber
.01 deck
.039 compressed head gasket
= 9.8 : 1
I could go with a steel head gasket of .020 that would put me at 10.2 compression. Wonder if it's worth it ?
Also have a picture of the other head and what to me looks where I had 2 small exhaust leaks
Canadian1968
Well-Known Member
Looking for some help with my engine clearances. If I'm thinking of running a .020 headgasket , my main concern would be my valve to piston clearance correct ?
How do I check this, I'm sure there is more than one way? Do I need to bolt everything together and physically check with some putty on top of the piston ? Or what's the best way to go about this?
How do I check this, I'm sure there is more than one way? Do I need to bolt everything together and physically check with some putty on top of the piston ? Or what's the best way to go about this?
BSB67
Well-Known Member
No. I wouldn’t be worried about P/V. But I’d still measure it.
Your piston to head, at about 0.030” is close. I think most would tell you “no”….too close. The safe general rule number is 0.040”. There are several variables and unlikely anyone will tell you with certainty if you’d be okay or not. I have only one experience - SBC at 0.028” left witness marks. That motor was pretty loose and reversed pretty high. And it ran really well.
Check P/V at 8, 10, 12 degrees BTDC and ATDC for exhaust and intake respectively. Use clay, or checking spring and dial indicator. Don’t need the gasket. Just account for its thickness in the math.
Last edited:
Bobzilla
Well-Known Member
I think you had it right before: piston to head should be checked and considered. The edges of the chamber may be exposed into a 4.35 bore. They did on mine with 4.375.Wait. Open chamber heads right? Disregard everything I said on piston to head.
gtxrt
Well-Known Member
why do you want to run a .020 steel head gasket ? 9.8 compression is plenty plus the leaks you could get with a steel shim head gasket.
Canadian1968
Well-Known Member
Entertaining the idea. The .020 gasket as mentioned before would get me around 10.2 CR .. not quite half a point. My guess is that gains from the compression increase are not worth the other troubles that come with it ? Plus I was also interested in what would need to be considered if I absolutely wanted to do it.
Basically trying to expand my knowledge of the fine details of engine building.
So little confused of the last few post. The piston to valve clearance is something to consider with the open chamber 906 ? Or not ?
^^^ this. I had a 60 over 383 with 906 heads and some pistons were definitely smacking the edge of the chamber. We fixed it up and raced it for a few years and the crank ended up falling out of it. May as well stay with the felpros, I'd go with a 1009
BSB67
Well-Known Member
The P/V is not a function of an open chamber or not. My statement comes from simply doing motors similar to yours. With those piston valve notches and your little cam, you could probably measure your P/V with a yard stick.
But still measure.
Canadian1968
Well-Known Member
What you guys are talking about is bore of the cylinder being slightly larger than that of combustion chamber ?
With .010 deck and then .039 headgasket does that not give me .049 between the piston and the head?
With .010 deck and then .039 headgasket does that not give me .049 between the piston and the head?
Canadian1968
Well-Known Member
I didn't think it would be very close especially with the valve notches in the pistons. But then again, this is uncharted territory for me !
So I would need to throw the head back on rocker shaft , and set of rockers and push rods . Do a few rotations to open both valves , then pull the heads and see what the putty looks like?
gtxrt
Well-Known Member
yes .049 unless you have a dome piston.
Yes.
Yes.
To check it, best case would be a solid lifter, with some way to adjust it to zero preload. With checking springs.
Canadian1968
Well-Known Member
What is the concern with the bore being slightly larger than the chamber ?
Then the piston is larger than the chamber...
The chamber is cast, not machined to perfectly clear a piston that travels far enough to collide .
Modeling clay is better than putty because putty has rebound and clay is basically deadset. You can set the head on the block without the gasket and do a rotation and then add the compressed gasket thickness to arrive at your p to v clearance. Remember the piston chases the valves so the closest tolerrance isn't at tdc.
The piston chases the exh valve. The intake valve chases the piston. That's why exh clearance is far more important.
Canadian1968
Well-Known Member
Ok perfect!
Im not going to worry about the thinner headgasket then.
Im not going to worry about the thinner headgasket then.
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