I received a free complete 302 motor but without the upper half of the intake. I am changing it over to a carbed setup for my 67 mustang. While takeing off the lower intake manifold I noticed it had a plate going to the rollers. long thin plate about a half of an inch and tabs going off to each lifter. I noticed in a catalogue that this was a retainer plate for a roller cam. Does this mean I have an h.o. motor, or a non h.o. motor with a roller cam or a non h.o. motor. The motor is stock from the factory and has not been opened besides me. The reason i am asking is because of the firing ordear i should use. The one time i ran it with a regular 15426378 firing ordear it sounded realy crapy. Also is there any other ways to tell if I have an h.o. motor. Any help would be great. Thanks
How do I tell if i have a 5.0 h.o. motor
- Thread starter mustangdude67
- Start date
Mr. Rustypwnz
Advanced Member
the h.o firing order is 137---48 cant remember the rest, but I might not be a h.o. i really dont think it would have even ran with a different firing order.
This doesn’t prove that the block is HO. Some trucks evidently use a HO firing order
with a low lift cam. However, it will definitely prove that a block can’t be HO because the firing order is wrong.
Remove the #1 & #3 spark plugs. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Slowly turn the engine until the TDC mark and the timing pointer line up. Mark TDC on the balancer with chalk or paint. Put your finger in #3 spark plug hole and crank the engine 90 degrees. You should feel pressure trying to blow past your finger. If you do not feel pressure, repeat the process again. If you feel pressure, it is a HO engine.
No pressure the second time, remove spark plug #5. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Put your finger in #5 spark plug hole and crank the engine 90 degrees. If you feel pressure now, the engine is not a HO model, no matter what it says on the engine.
Using a small carpenter or machinist square to mark the harmonic balancer off into 90 degree sections may be helpful here.
A 15/16 deep socket & breaker bar or ratchet may be used to turn the engine.
The HO firing order is 1-3-7-2-6-5-4-8.
Non HO firing order is 1-5-4-2-6-3-7-8
with a low lift cam. However, it will definitely prove that a block can’t be HO because the firing order is wrong.
Remove the #1 & #3 spark plugs. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Slowly turn the engine until the TDC mark and the timing pointer line up. Mark TDC on the balancer with chalk or paint. Put your finger in #3 spark plug hole and crank the engine 90 degrees. You should feel pressure trying to blow past your finger. If you do not feel pressure, repeat the process again. If you feel pressure, it is a HO engine.
No pressure the second time, remove spark plug #5. Put your finger in #1 spark plug hole. Crank the engine over until you feel compression on #1 cylinder. Put your finger in #5 spark plug hole and crank the engine 90 degrees. If you feel pressure now, the engine is not a HO model, no matter what it says on the engine.
Using a small carpenter or machinist square to mark the harmonic balancer off into 90 degree sections may be helpful here.
A 15/16 deep socket & breaker bar or ratchet may be used to turn the engine.
The HO firing order is 1-3-7-2-6-5-4-8.
Non HO firing order is 1-5-4-2-6-3-7-8
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