I have a 1985 bronco 5.8ho,the truck had an engine swap before I got it and it seems to lack power,how can I determine if it is an ho motor with ho heads???where will I find casting numbers on the head??What is the cam profile of a 5.8ho?? any help would be appreciated
thanks dr,larry brown

 

I would aso like to know how to identify an "HO"

 

the HO's don't have different heads....they run a 4 barrel (Holley I believe) instead of the 2 barrel on the sleeper 351. The HO has decent power (210HP 300lb/ft) which is comparable to the newer model EFI engines.

 

isn't a 351 HO a roller block?

 

Not in '85

 

What made the HO and HO was a bigger cam and a 4bbl Holley. Listen to one at idle you will hear is "lope".

 

a more aggressive non-roller type camshaft?

 

not sure on the roller, should have asked dad he's rebuilt a couple, he's at work now........

 

one engine reman company told me the HO had 9.3 to 1 compression as well?? anyone know the specs for an oe HO cam so I can check the lift and not waste my time pulling it out if I dont have too??? Thanks for all the help ,I really appreciate it
Dr Larry Brown

 

If the 1985 HO engine is like the 1986 HO engine, it has 8.8:1 compression and a Holley 4180 Carb. I measured the HO cam specs when I pulled the engine at 200K. The lifters had a fairly broad wear pattern, but the cam was still in good shape.

The intake lobe measured:
284deg duration at 0.004" tappet lift
206deg duration at 0.050" tappet lift
112deg duration at 0.200" tappet lift
0.283" max tappet lift
112deg ILCA defined at 0.050" tappet lift

The exhaust lobe measured:
290deg duration at 0.004" tappet lift
218deg duration at 0.050" tappet lift
110deg duration at 0.200" tappet lift
0.272" max tappet lift
120deg ELCA defined at 0.050" tappet lift

You can see that this is an emmisions performance cam with quite early exhaust valve opening time. The 206deg intake lobe at 112ILCA would have given some decent power if the stock exhaust system didn't kill it off.

The engine power, torque and throttle response of this basic engine can be drastically improved at all RPM with the following straightfoward changes that I made:

1. Pocket port the intake, full port the exhaust and remove the Thermactor injection boss

2. Modify Hedman headers to 1 1/2" by 42" primaries (38" if you are just interested in the uppper RPM), and 2 1/4" by 15" collector to the first area change at a crossover pipe or x-pipe, or y-pipe into a high-flow cat. 2 1/4" duals or 3" single with the cat. You can read more about this at my website.

3. RV type cam like a 205/210 with LSA of 110 and ILCA of 105.

4. The Edelbrock Performer 351W EGR manifold helped, too

This combo gives about 285HP at 4500. You will think you are in someone else's truck.

 

thank you very much this is the info ive been looking for /the cam profile I have chosen is very close to your recomendation and the manifold and headers as well are the exact ones I bought once again for the confirmation
Dr Larry Brown