FLH cam , valve springs , compression , pistons
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Please do not start new topics here, but here: New Panhead and Flathead topics
Please do not start new topics here, but here: New Panhead and Flathead topics
FLH cam , valve springs , compression , pistons
I have a 63 FL i am assembling . The bike is going to be mostly original adding a S&S oil pump and 73 -up oil modification . I do have a stock rebuilt Linkert carb NOS pistons and rings and acccess to NOS FLH piston rings and also have a NOS "Victory " cam to put in. The question is :
I know i will have to put the FLH harder valve springs with the VICTORY cam correct?
The FLH motor has a compression ratio of 8.00 :1 which i know is greater than the FL motor compression. How is this accomplished int tne FLH ? Different pistons? different springs or both? What if i don t change the pistons and stay with my stock FL compression?
I ve read that the FLH is harder to start . Is it because of the higher compression (more effort to crank ) or because of cam timing and lift?
My heads also use stock exhaust valves but have been modified to later early shovel bigger intake valves.
Thanks
I know i will have to put the FLH harder valve springs with the VICTORY cam correct?
The FLH motor has a compression ratio of 8.00 :1 which i know is greater than the FL motor compression. How is this accomplished int tne FLH ? Different pistons? different springs or both? What if i don t change the pistons and stay with my stock FL compression?
I ve read that the FLH is harder to start . Is it because of the higher compression (more effort to crank ) or because of cam timing and lift?
My heads also use stock exhaust valves but have been modified to later early shovel bigger intake valves.
Thanks
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You can't go wrong with the Factory formula.
I lost count of the customers that I have made very happy by replacing their damaged andrews cam with a common "H", usually found still on their shelf in their garage.
Too many "performance" hop-ups add up to nothing more than bragging rights at the bar.
Alas, the original Sifton line is extinct, as they really made people happy!
....Cotten
I lost count of the customers that I have made very happy by replacing their damaged andrews cam with a common "H", usually found still on their shelf in their garage.
Too many "performance" hop-ups add up to nothing more than bragging rights at the bar.
Alas, the original Sifton line is extinct, as they really made people happy!
....Cotten
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pistons
Yes but your 94 EVO is not a panhead with Iron cylinders, a diffrent oil system and if all you want is good usable power and not bar bragging rights as Cotten has so stated then, as he said, "stick with the factory formula" put all FLH components in there unless you can locate a REAL Sifton cam. Your bigger valves are going to be usless if the engine isn't balanced as far as flow and cam profile, carburation and ignition. as many times as you hear it some people just build themselves right out of the ballpark. those big intakes are just going to kill your low end torque. depending of coarse on your cam selection and just how big they really are.
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cams
Cams (guest),
I miked the height and width of an original FL camshaft that has no markings on it indeed. All lobes are 0.240 inch taller than the base circle diameter. That brings 0.360 inch valve lift with the 1.50 panhead rocker ratio.
Another easily discernable pecularity is the difference in lobe profile between intake and exhaust. Look at lobes two and three (lobe one is closest to the gear). They point (approximately) in the same direction, but three (front intake) is somewhat wider than two (rear exhaust). In other words, there is more intake duration than exhaust duration. Quite an unusual feature, which has possibly to do with the long and winding intake tracts in our pans.
Not easily discernable is the timing diagram. I miked it, but I don’t know how to post pictures. It shows the long intake duration and the identical intake timing for front and rear cylinders. I never miked an FLH cam, but according to most aftermarket cam manufacturers lists, ‘stock’ cams (their words, they almost certainly refer to FLH cams) have different front and rear intake timings, allegedly to compensate for the unequal suction intervals between front and rear cylinder. I wonder why none of the other big twin ohv HD cams nor any aftermarket cams show this feature....
I miked the height and width of an original FL camshaft that has no markings on it indeed. All lobes are 0.240 inch taller than the base circle diameter. That brings 0.360 inch valve lift with the 1.50 panhead rocker ratio.
Another easily discernable pecularity is the difference in lobe profile between intake and exhaust. Look at lobes two and three (lobe one is closest to the gear). They point (approximately) in the same direction, but three (front intake) is somewhat wider than two (rear exhaust). In other words, there is more intake duration than exhaust duration. Quite an unusual feature, which has possibly to do with the long and winding intake tracts in our pans.
Not easily discernable is the timing diagram. I miked it, but I don’t know how to post pictures. It shows the long intake duration and the identical intake timing for front and rear cylinders. I never miked an FLH cam, but according to most aftermarket cam manufacturers lists, ‘stock’ cams (their words, they almost certainly refer to FLH cams) have different front and rear intake timings, allegedly to compensate for the unequal suction intervals between front and rear cylinder. I wonder why none of the other big twin ohv HD cams nor any aftermarket cams show this feature....
cams
the stock flh cam has a h on the back lobe and the valve lift and duration is different between front and rear for cooling as well as the reach and angle of the pushrods to the heads. I had previously installed a bh grind andrews and regreted it with a passion once i found a stock cam the bike came alive and ran better than it ever has. always started 3 kicks cold(2 priming with choke full on and ignition off) open the choke 1 notch from full and started first time every time.
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Re: cams
Hi. You are right about your cam. It is a stock FL cam. I recently looked at the difference of the two cams side by side. The FL cam has longer durations on their intakes as compared to the exhaust. The FLH is the opposite. Andrews offers an A grind & an AB grind. The AB has a longer duration exhaust for cooler running? There's the reason. Fl cam came out in 48. 8 years later...FLH. Must have been an improvement.52WLCnFL wrote:Cams (guest),
I miked the height and width of an original FL camshaft that has no markings on it indeed. All lobes are 0.240 inch taller than the base circle diameter. That brings 0.360 inch valve lift with the 1.50 panhead rocker ratio.
Another easily discernable pecularity is the difference in lobe profile between intake and exhaust. Look at lobes two and three (lobe one is closest to the gear). They point (approximately) in the same direction, but three (front intake) is somewhat wider than two (rear exhaust). In other words, there is more intake duration than exhaust duration. Quite an unusual feature, which has possibly to do with the long and winding intake tracts in our pans.
Not easily discernable is the timing diagram. I miked it, but I don’t know how to post pictures. It shows the long intake duration and the identical intake timing for front and rear cylinders. I never miked an FLH cam, but according to most aftermarket cam manufacturers lists, ‘stock’ cams (their words, they almost certainly refer to FLH cams) have different front and rear intake timings, allegedly to compensate for the unequal suction intervals between front and rear cylinder. I wonder why none of the other big twin ohv HD cams nor any aftermarket cams show this feature....
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Re: FLH cam , valve springs , compression , pistons
If your looking for a daily runner--You cant go wrong with this combo!--I put on a lot of miles yearly,& I use FLH cam--(they are marked with a H).CAST PISTONS-8.5 to-,comp. & Hastings Iron rings!.--Stay away from FORGED PISTONS & anything CHROME-MOLY!--(you wont be happy!)-The OEM heads are best left ALONE!--just a sanding mop to takecare of any casting nerds in the ports!.--DONT try to port them & play JERRY BRANCH!--It will run like crap!--If you can PUT your stock size valves back in!--UNLESS its oversized because of TO many valve jobs & sunken in to far!--Bigger valves in a pan DO NOT WORK!--YOU just burn more fuel & screw-up your TOURQUE!--Remember these are TOURQUE MOTORS!--If anything change the tranny sprocket to a 24 tooth.-It helps kepping the motor in the Tourque band at 60mph.---CHECKOUT the k-BASE real good!--(great info there!)---RESPECTFULY---RICHIE