All Out Log Head

[Anonymous]

I want to build a 170 with a 200 crank to run in HA/GR and must use the stock head. This is an all out race motor that will leave the line at 3000rpm and go through the lights at 7000rpm. I'll be running a 280 Duration 480 lift Cam with zero deck height pistons (they may even be above the deck a little) for a 11 to 1 compreson ratio(racing gas only). I had thought about running three 170 or 180cfm Holley 1 barrels on a home made tri power setup. But I was looking through the Holley book I have and the Model 2110 "Bug Spray" 2 barrel cought my eye. It is a 200cfm 2 barrel and has a mounting flange that with 3 would put a barrel over each runner on the Log intake. Has anyone ever run three of these carbs on a log intake before?
Please give me you feed back. again I must run Period looking carbs and can not run a Holley 4 or 2 barrel or side draft carbs. idea:

 

[lyonsy]

cam is a bit small id go a 300deg with 520 lift min your not worried abouyt anything under 3.
unsure on carby's but a 100 cfm for each cyl is a bit less then id want for that rpm 3 350 or pref 500 holleys id prefer..
have those pistons up are close as you dare.
can you run a 2v head or cut the log off.

 

[Anlushac11]

8)

Is there enough flow in a ported and polished log head to warrant a cam with more than .480" lift?

I thought flow started falling off rapidly over .450" lift and was pretty much done by .480" lift.

Here on Classic Inlines page showing airflow with a Oz 250-2v head there is only 1cfm additional flow at .500" lift and no change at .600" lift.

I could be wrong but it seems to me the only way to get more air in is to run longer duration but no need for higher lift since your not gaining any airflow.

 

[XFlow_Fairlane]

how stock does it have to be?

if you are cutting off a log you COULD remove the top of th eexports and "raise them up" to get more flow on that side it would require a custom manifold though. intake side would have to be some tube stubs welded on a stock runners (I would port while it was apart first)

and if you are talking a full out race motor then you would want to cut down the guides as much as you can also.

 

[XPC66]

8)

Is there enough flow in a ported and polished log head to warrant a cam with more than .480" lift?

I thought flow started falling off rapidly over .450" lift and was pretty much done by .480" lift.

Here on Classic Inlines page showing airflow with a Oz 250-2v head there is only 1cfm additional flow at .500" lift and no change at .600" lift.

I could be wrong but it seems to me the only way to get more air in is to run longer duration but no need for higher lift since your not gaining any airflow.

Something you have to consider when using higher lift cams, is that although the curtain area may equal the port area at some point in the lift, the flanks and ramps will be steeper and therefore the opening and closing gradients. Whether that's desirable in this instance is another matter.

 

[wsa111]

Remember if the intake or exhaust does not flow more past .480 lift if you have .480 the port sees this lift amount once, where if you have .515 lift the port sees the .480 lift twice, on opening & again on closing.

Makes sense. William