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Discussion Starter #1 (Edited)
Engine Build Help - Need Cam Rec

1. Intended use - Daily Driver/Cruise In classic truck

2. Vehicle info - 1967 Ford F250 long bed with C6 trans and 4.11 rear Dana 60. 285 tires.

3. Fuel desired to use - Regular unleaded

4. Parts I already have:
466 bored short block with football rods and pistons are not as deep in the center as the stockers I have. Low mileage and previously run. Looks to be mid 70-80's. Straight up timing chainand all bearings look clean and no issues seen in cylinders or any play anywhere. New oil pump and windage tray. Possible 9:1 compression. Want to run cheaper gas and it likes to drink it.
Heads are decked D3VE stock compression heads that have been ported both sides, milled and set with studs and roller rockers, stock valves
Intake is Edelbrock Dual Plane Performer
Holley Carb 750cfm Vacuum Secondary single feed
Custom L&L 2.25 headers made for earlier trucks with 460
2.5 inch Exhaust with cross over and Mufflers
Ignition is Cardon dist with Pertronix I and coil recurved. 10 degree initial timing to 36 final.

Looking to see opinions of any decent cam that would work with this combo. I do have a new cam listed below but being told that it's to big for my combo. Any recommendation other than custom grind would be great.

Cam I have in the box is an Older NOS Laser Cam SS6153 specs (lift I-536 E-531, duration at 0050 I-220 E-225, FF 270/275-08H flat tappet)

Any input would be appreciated as this site has a ton of info and expertise.
 

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HI, just an FYI since you milled the heads you might need to mill the intake as well... When you mill the heads you move the ports down and closer too and making it a tighter fit for the intake.
 

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If you have the original 70's era dished pistons you need small chamber heads to get the compression ratio up for that cam.

D3's + bath tub pistons = no bueno in any type of performance build.
 

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Low static compression ratio
 

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Hi compression is power a low compression motor can be made to perform but NOT very well. your combo of heads and pistons make LOW compression.
 

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Is the builder piston dish .240" deep or .180" or .060" deep?
Deck height?
How much have your D3's been milled?

Establishing static c/r by way of piston dish, deck height and approximate chamber volume is going to be necessary in order to spec out a proper cam for your application.



Since the IE ratio on ford iron heads is about 60% whether ported or non ported the proper exhaust split is important when grinding a cam. OEM cam timing was 193 / 206 @ .050" ground on a 113 lsa and in at 110 ICL.

We add 12 to 16 degrees additional exhaust timing for best results.


More information is needed.


The cam you list is going to be lazy if static c/r is below 9 to 1.




SJ
used 2b RHP


:D
 

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Discussion Starter #9
Can’t say how much the heads have been decked as they were acquired with no info. I had to have them decked to square them up recently but can’t say how much was already gone and how much is left.

Pistons look like 15cc pistons. Can’t locate name or brand but they are 30 over and the dish is a lot shallower than the stock set I have.

How would I go and get these measured to confirm and determine what the CR would be? I am also not set on that cam as I was with the set up. Guy told me the cam was cut for the heads but not 100% sure on that.

Just looking to build a nice street able motor.
 

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Discussion Starter #10
Update: pistons measure at .060 dish depth and sit almost flush at the top of the block. Will measure and compare heads after i pull the old ones off.
 

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Update: pistons measure at .060 dish depth and sit almost flush at the top of the block. Will measure and compare heads after i pull the old ones off.
That is the 88 to 92 EFI piston. Approximately 6 cc dish volume.

There is a V cut out on the exhaust side of the deck of the cylinder head. The V is typically about .105" deep OEM. Carefully measure it for remaining depth. For every .0055" milled from the deck chamber volume will be reduced approximately 1 cc. 97 cc's is a typical oem chamber volume.

Deck height is an important part of static c/r calculation. Measure it.



SJ
used 2b RHP


:D
 

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Discussion Starter #12
Measured it and the V comes out to .089 depth using feeler gauges and a straight edge across the end.
 

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If I’m doing the math right (.089/.0055=16.18) would put me around 81cc chamber?

NO.

Starting at the typical .105" you now have ..089". .016" has been removed making the chamber about 3 cc's smaller. Figure 94 cc's.



SJ
used 2b RHP


:D
 

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So, then I would be running about 9:1 compression?
With the pistons at 0 deck.



Compression Ratio Calculator
ENTER YOUR DATA CALCULATED DATA
Cylinder Head Volume (cc)
94
Cylinder Head Vol (cubic in.) 5.734
Piston Head Volume (cc)
6
Piston Head Vol (cubic in.) 0.366
Gasket Thickness (in.)
.041
Swept Volume (cubic in.) 58.275
Gasket Bore (in.)
4.5
T.D.C. Volume (cubic in.) 6.752
Cylinder Bore Diameter (in.)
4.39
Gasket Volume (cubic in.) 0.652
Deck Clearance (in.)
Note: Neg. number above deck, Pos. number below deck
0
Deck Volume (cubic in.) 0.000
Stroke (in.)
3.85
STATIC COMPRESSION RATIO 9.631


In order to establish actual static c/r you need to check DECK HEIGHT

If the pistons are .020" in the hole the static would drop to 9.26 to 1



SJ
used 2b RHP



:D
 

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Discussion Starter #17
Looking tonight but suspecting the .020 below height. At the 9.26 ratio, what would be a good cam selection for this set up?
 
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