Deck height

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krazykuda said:
You may want to take both heads to your head guy, along with your cc data. Have him evaluate which one is best for you to use.

He may be able to clean up the first one with milling a bit off of the head to get it flat. This will just make the chambers slightly smaller, depending on how much he needs to take off to get it "true" again. The other head may need a slight clean up, but not as much.


He also may want to look at the condition of the valve guides to see which one is best to use.


If you are thinking of using a cam above .500" lift, then let your head guy know so he can make sure that there is enough travel in the valves to accomodate this and not get into coil bind/valve bottom out. Make sure that you have some "wiggle room", ie. if you are going to run .500" lift, make sure it has a minimum of .550" or .600" travel in the valves, depending on how much lift your cam will have.
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See above as to where I am at with the heads and give your opinion.

I am not going to use a cam that large.

At this point do we have enough info to say how much has to be removed from the head to get to the compression I am after?

What order am I too approach this.

My plan is

1- Have the head re-conditioned replacing any valve guides that need replacing and installing the over-sized valves.

2- porting the head to increase flow

3- shaving the appropriate amount from the head to get to a 9.1 9.5 to 1 compression ratio. Amount still un-known at this point. Dont know how to calculate that. Must be something more specific than 6 thou = 1 cc so figure 48 cc to get to 9.1 ......just off the top of my head

What would be next in other words?
 
1930 said:
See above as to where I am at with the heads and give your opinion.

I am not going to use a cam that large.

At this point do we have enough info to say how much has to be removed from the head to get to the compression I am after?

What order am I too approach this.

My plan is

1- Have the head re-conditioned replacing any valve guides that need replacing and installing the over-sized valves.

2- porting the head to increase flow

3- shaving the appropriate amount from the head to get to a 9.1 9.5 to 1 compression ratio. Amount still un-known at this point. Dont know how to calculate that. Must be something more specific than 6 thou = 1 cc so figure 48 cc to get to 9.1 ......just off the top of my head

What would be next in other words?
Click to expand...



Did you check your volume above the piston in the block with the cover plate that you used for the head?

Give me that number, the engine size you are working on (225?), and if it is overbored or std bore. I can calculate for you and walk you through the process.
 
1930 said:
I may be wrong when talking machine ( ing ) talk but these two heads are not far from each other...in other words prob. no great advantage to either of them as far as having any kind of gain to save a few bucks cause alot of material has already been removed and paying to have material removed is where I am nearing at this point.

I feel better about using this head I think cause I already paid X dollars to have the other one done and technically it is done ( maybe not done precisely ) and it will be a good spare.
Click to expand...

I didn't know that you had them machined flat already. I thought that they were used just taken off an engine and cleaned up (grease/carbon wise).


I would use the second one with the 60 cc chambers, as it was more consistent. The other one will still work on a daily driver, 1 cc won't make a noticeable difference.

I would do any porting first, just in case the seats may get accidentally knicked. It's best to do the porting before the valve job.

Then get the oversize valves installed.


Too bad you're not closer, I know a guy near Detroit that does good porting and valve jobs reasonably. (He gives good head - LOL!)...
 
1930 said:
See above as to where I am at with the heads and give your opinion.

I am not going to use a cam that large.

At this point do we have enough info to say how much has to be removed from the head to get to the compression I am after?

What order am I too approach this.

My plan is

1- Have the head re-conditioned replacing any valve guides that need replacing and installing the over-sized valves.

2- porting the head to increase flow

3- shaving the appropriate amount from the head to get to a 9.1 9.5 to 1 compression ratio. Amount still un-known at this point. Dont know how to calculate that. Must be something more specific than 6 thou = 1 cc so figure 48 cc to get to 9.1 ......just off the top of my head

What would be next in other words?
Click to expand...


We need to know where your pistons are. How far below the head deck is the top of the piston at TDC? Are they flat tops? Any eyebrows/valve reliefs?

Put the piston at TDC and measure the volume above the piston to the head deck with the cover plate as described in the compression check thread. With that info, we can start figuring out where you are and need to go and how to do it.

I would not recommend trying to mill the head and block to get compression. If you do too much milling, you may now have issues with push rod length. It may be better to see if there are any affordable pistons that will get you close, then do the milling.


I gotta go for a bit. The kid wants to do some work on the cars for a while. I will check back in when we take a break....
 
krazykuda said:
Did you check your volume above the piston in the block with the cover plate that you used for the head?

Give me that number, the engine size you are working on (225?), and if it is overbored or std bore. I can calculate for you and walk you through the process.
Click to expand...
No, I did however check it with the dial caliper ( came up with .155 below deck on truck #1 ) which I thought you had said would be acceptable. Since then I have a proper depth gauge and will take a possibly more precise measurement. I cannot take this measurement now however cause it is raining cats and dogs and my tools are in a detached workshop.

I will have this measurement with certainty some time this week after work or next weekend at the latest.

Yes truck #1 is a 225 and overbored 40 over.

Just to catch you up I have a 1986 W-100 that I have restored, original 225, 4 speed, 4 wheel drive.

I had the engine machined and re-built by a local shop. Truck has been together a few months now, never did run right, I still do not know the issue. I call this truck # 1.

Truck # 2 is also a 225, 1983 model, 2 wheel drive, I bought it just for my learning, a test bed, something that I could build and learn from and then once I have all parts dialed in how I want I will remove those bolt on parts ( dist/ignition system, head, Super six set-up ) and put them on my # 1 truck.

I do not have to worry about scratching the paint on the #2 truck.

I guess I am going to give you the deck height of the engine that I am building all of this for since that is where all these parts will eventually be going.

I am hoping that you can help me to understand how I can figure out these things for myself though cause I see future slant builds.

Unfortunately I did not make it far in school and never got past simple math.
 
krazykuda said:
I didn't know that you had them machined flat already. I thought that they were used just taken off an engine and cleaned up (grease/carbon wise).


I would use the second one with the 60 cc chambers, as it was more consistent. The other one will still work on a daily driver, 1 cc won't make a noticeable difference.

I would do any porting first, just in case the seats may get accidentally knicked. It's best to do the porting before the valve job.

Then get the oversize valves installed.


Too bad you're not closer, I know a guy near Detroit that does good porting and valve jobs reasonably. (He gives good head - LOL!)...
Click to expand...
Only the one head ( with the eratic CC measurements ) was re-built/machined, just a few months ago.

The second head that I have measured is from truck #2 that I purchased just as a test-mule. Nothing has been done to it as far as I know.


Quote: I would do any porting first, just in case the seats may get accidentally knicked. It's best to do the porting before the valve job. .............

I had asked if installation of these oversized valves was going to require new larger valve seats, I did not get a response so far, asked maybe a week ago on slant.org.

I am concerned with this because much of the porting is done in the area directly underneath the valve seat, if these oversized valves require new larger valve seats than any material I remove now will not be enough after they install new valve seats.

I will make a phone call to someone and try and verify that I can use my existing valve seats.

Quote: I know a guy near Detroit that does good porting and valve jobs reasonably............

I am looking forward to doing the work myself, I enjoy the opportunity to learn something new.
 
krazykuda said:
We need to know where your pistons are. How far below the head deck is the top of the piston at TDC? Are they flat tops? Any eyebrows/valve reliefs?

Put the piston at TDC and measure the volume above the piston to the head deck with the cover plate as described in the compression check thread. With that info, we can start figuring out where you are and need to go and how to do it.

I would not recommend trying to mill the head and block to get compression. If you do too much milling, you may now have issues with push rod length. It may be better to see if there are any affordable pistons that will get you close, then do the milling.


I gotta go for a bit. The kid wants to do some work on the cars for a while. I will check back in when we take a break....
Click to expand...
I will re-measure as noted above, they are flat tops, no nothing, just flat.

Quote: I would not recommend trying to mill the head and block to get compression. If you do too much milling, you may now have issues with push rod length. It may be better to see if there are any affordable pistons that will get you close, then do the milling. .............

My understanding is that there are very little ( custom possibly ) to no piston options avail. for the slant motor. Ask anyone and anyone will tell you that taking .100 off the head and more is how to get things done. That is how compression is gained on these engines. Just what everyone is doing to get the job done.

Evidently very few problems with push rod length and I am still not clear why there are any at this point, I am however going to double check all of these things myself.


I do not want to remove the engine from truck #1, all machining has been done, new pistons, bearings, rings, cam bearings ect has all been done. I do not want to get into any of that again and so milling the head is the option I have and will take. ( unless of course someone tells me I am way off and there are actually a ton of aftermarket parts to choose from )
 
I hope I am not confusing you, maybe I should stop referring to the two different trucks ( 1 and 2 ) and just give the numbers needed for the build I am working toward.
 
When you mill a total of .100 off the head and/or block, pushrod length can be an issue. It will need to be checked. With a stock to mild cam, the pushrods might be too long. With a high lift cam, they might be ok. If you are running a hydraulic cam, pushrod length is more critical, as there is no adjustment for the valve train.
 
Thanks Charlie, can you confirm that aftermarket higher compression pistons are not avail for the slant and that removing head/block material is really the only way to go unless of course I want to have custom stuff made up.

I do have hydraulic and I will be checking these things once I get figured out how to check.
 
In a 225 motor you can get the Wiesco pistons and K-1 or Molner connecting rod combo, as "off the shelf" parts. Not "cheap" by my standards, but still the best deal out there. There are some other mix/match combos that should work, but not the best course of action. My opinion, for what you are trying to do (mild street motor), just use a stock type piston, and mill the head and/or block to get the compression you want. My thinking 9-1 with a stock to mild cam, up to 10-1 with a moderate cam, with a big cam compression can be over 10-1. But with increased compression, you will need to adjust the timing curve.
 
Charrlie_S said:
In a 225 motor you can get the Wiesco pistons and K-1 or Molner connecting rod combo, as "off the shelf" parts. Not "cheap" by my standards, but still the best deal out there. There are some other mix/match combos that should work, but not the best course of action. My opinion, for what you are trying to do (mild street motor), just use a stock type piston, and mill the head and/or block to get the compression you want. My thinking 9-1 with a stock to mild cam, up to 10-1 with a moderate cam, with a big cam compression can be over 10-1. But with increased compression, you will need to adjust the timing curve.
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Thanks, that is what I had read as far as piston connecting rod combo. Over the top for what I am trying to do for sure.
 
I did get around to getting all my numbers together and are as follows.

Hoping Karl will check my work. Thanks
 
I found a discrepancy in the bore. IF it is stock bore of 3.400", then @ .040" over will be 3.440", not 3.435".

What is the actual measurement of the bore? You can use dial calipers or micrometers to measure and to get us in the ball park.

I will check the numbers later, but we have to get he bore figured out. I have to do a little running around and will check the numbers later tonight.
 
krazykuda said:
I found a discrepancy in the bore. IF it is stock bore of 3.400", then @ .040" over will be 3.440", not 3.435".

What is the actual measurement of the bore? You can use dial calipers or micrometers to measure and to get us in the ball park.

I will check the numbers later, but we have to get he bore figured out. I have to do a little running around and will check the numbers later tonight.
Click to expand...
Yes, I thought 3.440 but measuring twice I come up with 3.435. Maybe its user error but I do not see how at this point.

Measured again and there is a pretty heavy coat of grease at the top of the cylinders, I usually get 3.435 but sometimes see 3.437. Hard to get up there lean in also cause the truck sits kinda high.
 
krazykuda said:
I found a discrepancy in the bore. IF it is stock bore of 3.400", then @ .040" over will be 3.440", not 3.435".

What is the actual measurement of the bore? You can use dial calipers or micrometers to measure and to get us in the ball park.

I will check the numbers later, but we have to get he bore figured out. I have to do a little running around and will check the numbers later tonight.
Click to expand...
No problem, I patiently wait :)
 
The calculations seem correct, but I don't know what milling .084" off of the deck will do to pushrod/rocker arm geometry.

Or you could find pistons with .081" higher "dome" height and be the same compression.
 
krazykuda said:
The calculations seem correct, but I don't know what milling .084" off of the deck will do to pushrod/rocker arm geometry.

Or you could find pistons with .081" higher "dome" height and be the same compression.
Click to expand...
I guess I will have to find out about the rocker arm when I get to that point.

Thanks for all your help with this, a couple of months ago I did not even consider that I would be able to do all the stuff you have taught me in this thread.

I am in the process now of working out my degreeing the camshaft deal over here http://www.hotrodinlines.com/forum/ubbthreads.php?ubb=showflat&Number=5046&page=all

This guy like yourself has alot of patience and likes to see people interested in getting things right correct.

Is is very much appreciated!
 
1930 said:
Yes, I thought 3.440 but measuring twice I come up with 3.435. Maybe its user error but I do not see how at this point.

Measured again and there is a pretty heavy coat of grease at the top of the cylinders, I usually get 3.435 but sometimes see 3.437. Hard to get up there lean in also cause the truck sits kinda high.
Click to expand...

The 'crud' at the top of the cylinder can cause you not to get an accurate reading. I would use a 3" wire wheel on a drill to knock off any carbon ring/build up and then measure with clean metal.
 
krazykuda said:
The 'crud' at the top of the cylinder can cause you not to get an accurate reading. I would use a 3" wire wheel on a drill to knock off any carbon ring/build up and then measure with clean metal.
Click to expand...
Will do
 
krazykuda said:
The 'crud' at the top of the cylinder can cause you not to get an accurate reading. I would use a 3" wire wheel on a drill to knock off any carbon ring/build up and then measure with clean metal.
Click to expand...
Did this and re-measured, still came in at 3.435. Talked with machine shop tonight that is doing the head work. They said that is fine. Pistons are always smaller than the bore size to allow room for rings and expansion.

Depending on type/brand of piston used during re-build they would machine the bore to the tolerance of those particular pistons.

Too be .005 shy of an expected 3.440 is nothing too be concerned with evidently.
 
1930 said:
Did this and re-measured, still came in at 3.435. Talked with machine shop tonight that is doing the head work. They said that is fine. Pistons are always smaller than the bore size to allow room for rings and expansion.

Depending on type/brand of piston used during re-build they would machine the bore to the tolerance of those particular pistons.

Too be .005 shy of an expected 3.440 is nothing too be concerned with evidently.
Click to expand...

No concern. It doesn't vary the compression numbers much either. It's just nice to know where you're at....
 
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