Thread: Low RPMs

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Hey Fellas,
have a 1968 galaxie , 390 , primarily stock right now.
It was originally a 2 barrel. I put an Edlebrock performer intake and a Holley 4160 on it. Only other additions are a pertronix module to replace points and an Advance curve kit.
Seems to run fine I'm just curious what my max RPMs should be like. At Wide Open throttle driving, it hits about 4K then drops down to about 3K then slowly comes up to about 3500. Does this seem right for maximum RPMs. If not, then what kinds of problems am I looking at? If this is normal then what types things can I do to get a higher RPM?
Thanks Much
- Mac

Check your exhaust system. Fords of that era often had double wall tubing, and the inner wall can collapse, restricting flow. Any cylinder head ever built will flow more than enough to rev up without acting like your engine does. I've seen cars act like that from mouse nests in the muffler, and from collapsed mufflers, too.
A buddy put a 425 Olds in a '65 Impala and used the single exhaust for the 283, just to get it on the road. It ran much like yours, but worse. Hold it to the floor and it would actually stall, then shoot flame out the carb as the pressure released.

So how is it possible that the casting number on the heads: C8AE-H is the same as the number for Mustang GT& Rachero GT heads? are heads designed specifically for 2 and 4 barrel applications? sorry about the ignorrance,but it's why I'm here.
Thanks

Laying down at 3,500-4,000 can be valve springs.

On the circle burner, we turn 6200 rpm with a Rochester 2G carb... Takes a combination of the right cam, heads, ignition, timing, advance, exhaust. With an old engine as others have mentioned the valve springs could be fatigued, exhaust restricted, advance mechanism(s) stuck, or probably a combination of all of the above..

Thanks very much to all.... Keep the suggestions pouring in .
- Does Anybody need any airbrush work ? That's my specialty !
- Mac

Originally Posted by artymac

So how is it possible that the casting number on the heads: C8AE-H is the same as the number for Mustang GT& Rachero GT heads? are heads designed specifically for 2 and 4 barrel applications? sorry about the ignorrance,but it's why I'm here.
Thanks

Same head. C8-H's had 8 , 14 and 16 bolt patterns on the exhaust side. It depends on the car they were being used in. Most of them have the extra bosses to drill and tap holes if your bolt pattern is not the same. There was no 2bbl vs 4bbl head application for the C8-H's.


G.

Originally Posted by FFR428

Same head. C8-H's had 8 , 14 and 16 bolt patterns on the exhaust side. It depends on the car they were being used in. Most of them have the extra bosses to drill and tap holes if your bolt pattern is not the same. There was no 2bbl vs 4bbl head application for the C8-H's.


G.

Do you think that these are quality heads ?

They are pretty good heads. Ford used them on lots of cars. They would be better with a little working over but fine as is for a stockish build.

G.

Thanks alot G!

Hey Denny,
Well most anything possible my friend. Where do ya want it? wanna drive to California? heh.