I thought cams for a turbo build had different profile requirements
All Big Six Best 300 head for a turbo build.
- Thread starter BigRigTech
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BigRigTech
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I just picked up an 86 F250 2wd today, solid old truck with good bones for a rust belt rig. 300/C6. A good home for my turbo build but really I bought it with hopes my 13yr old boy will show some interest in working on it with me. He has high functioning autism so he's a little different than most kids his age, very mature beyond his years and smart. I told him if he got his hands dirty I would let him drive it when he gets his license in 3yrs. She's running and on the road but she's kinda rough to look at LOL. I'll likely pull the engine this winter, re-bearing it and re-gasket it to stop some leaks until the fresh turbo engine is ready. I can put the offy port-o-sonic intake and a 2bbl Holley on it to smarten it up a bit in the mean time.
It all depends on the exhaust system and rpm range. Just like all other component, it is about Application.
Log exhaust manifolds have no scavenging and high back pressure so the cam profile gets a short exhaust duration with a wide LSA typically 114 degrees.
As you move towards single primary pipes the exhaust duration can get closer to the intake duration and the LSA can tighten up a bit but still stay wider than the N/A version because street cams don't have a lot of overlap anyway. That why I recommended having the 140H cam ground on a 112 LSA.
For racing and applications where the primary exhaust pipes are long, the exhaust durations can exceed the intake duration by a bit but because of the larger lobe durations the LSA stays wide to decrease overlap to help spooling during launch. Some of our turbo racing cams were on a 116 LSA.
This is also engine specific as different cylinder heads have different requires for intake versus exhaust flow.
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"Blower cams" generally have a large split in durations with the exhaust side having a longer duration than intake. This gives better power in the higher rpms but gives up a slight bit in the low end.
But the so called 'blower cam' is not necessary for any forced induction, its just a different grind to get more power in the 3500+ rpm range. Engine masters just did a video on this.
Your 1986 carb head will have an open chamber and pedestal rockers that wouldn't need machining for larger studs or guide holes. It seems shimming for correct pattern is all that is needed with the longer valves and Scorpion roller rockers. Cam selection might need some reconsidering.
1985 and 1986 carburetor heads have pedestal mount rockers. If your head has studs along with slotted pushrod guide holes then it is an earlier head.
I converted my 1985 head to stud mount rockers.
Because the 1985 head does not have slotted pushrod guide holes I had to install pushrod guide plates under the screw in studs.
In order to keep this type of information accurate we created a reference section.
Here is the engine specific info:
catalog of conceptual build plans for the b.b.ford sticky
the momentum currently being experienced on this boad coupled with the, ahem, aged experience and ahem, wisdom of the ,ahem elders here, I thought a good idea might be to catalog the wide number of current or conceptual build plans to hold in perp. for example: "these part numbers with this...
fordsix.com
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We have run into unexplainable engine components before.
The head number should start with E5 if it is a 1986 truck head.
The next earlier head with rocker studs should start with D8
I have read of a case where a 1986 truck owner had an industrial 300 in the truck from the factory.
The the CSG649i industrial engine is not the same as the HD engines that where used the the F600.
It also doesn't use pedestal mount rockers.
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