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Topic: Compression and Cleveland 4V Head ID
From: Celina, Tx, USA
Registered: Oct 2001
posted 12-03-2001 08:55 AM
I have a 351C with 4V heads on it. The person I bought the motor from said they installed 11.5/1 Pistons. I am finding that real hard to believe as a stock starter has no problems turning over the motor. Plus it is easier to rotate by hand than my 10.5/1 440 Mopar. I suspect the 11.5/1 pistons are for if you have closed chambered 4V heads. I may have the open chambered heads. I am thinking it is more like 9.5/1.
My questions are:
1. How can you check compression levels without tearing the motor apart and check the parts? What is the formula?
2. How do I ID if I have the closed quench chamber heads vs the Open chamber heads. Is there a part number or Identifyer on the heads that will tell me w/o pulling the head to check the chamber?
From: Saco, Maine MCA # 47773
Registered: May 99
posted 12-03-2001 07:37 PM
1. You can't. It's all a measurement of volumes. If you know the chamber CCs, and the dome volume of the piston you can guess pretty close.
2. By checking the casting numbers, located under the intake ports in the lifter valley area. Closed chamber heads are the D0AE-H,R or the Boss 351 head, D1ZE-B.
'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC
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