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Discussion Starter #1
Was wondering how much ET would be gained going from a solid flat-tappet to solid roller with similar duration numbers.

Current cam is 247/255 to a 248/254 roller both on a 106 lobe seperation
 

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You need the "Complete" Duration Numbers not Just .050 to compair the profiles. FT and Mechanical Roller Profiles can be a whole lot different.

Also Lifts, Rocker Ratios and head Flow to see if it will make any gains.
 

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Discussion Starter #3
at .200 sft is 159/166 roller is 170/176
lift 560/576 614/621
same 1.6 rocker arms for both

heads are Stock Edelbrock RPM flow 250 @500
 

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Wnat motor? How Many Inches?

Your Roller Cam is not the Same at the FT, Its quite a bit Larger.
 

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I've seen 2 or 3 tenths on most applications, but i'm sure its not always true.
Way less friction....An all roller motor will rev twice as fast...
I'm a nobody but thats what i've seen....
 

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You should see again of about two tenths .You don't only gain on the lower friction but a roller is cut with a more agressive profile .This keep the valve at max lift longer filling the cylander better.This all depends on how fast your going now , the faster you go the harder it is to go fast.
 

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You may gain nothing, you may pick up a couple tenths. I know people on each end of the spectrum. You -should- pick up a little power, however don't expect it to be a different engine. A guy I know with a 351C installed a solid roller with apparantly the same specs as his solid, and ran exactly the same as he did before.

If it's a RACE car that sees limited street use, it might be worth it to step up to the roller. If it's a STREET car that sees a lot of miles, you'll probably be better off with a modern designed solid flat tappet... or a hydraulic roller if you don't rev it too high.

Engines that respond to solid rollers the best, are ones that need all the lift they can get. In other words, if the engine has fairly small heads for its displacement, it's going to need the valve lifted as far and quicky as possible, while keeping duration in check. A roller stands a much better chance of making a significant difference on this type of combo.

Your 393W with stock Edelbrock RPM heads would probably be a good candidate, as long as you don't mind keeping a CLOSE eye on the roller lifters, and it doesn't see TOO many street miles. Keep the idle speed up, and run a fairly tight valve lash to minimize pounding on the valvetrain.

Good Luck!
 

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I have make cam changes somewhat like that an got a 57 HP increase-- I dont think anyone would go to the trouble of changing to a roller cam and not getting a better grind when they do it. I cant ever imagin getting the same specs when you want to upgrade your combo.The higher you rev the engine, the more room you have for improved performance from a roller.

JOE SHERMAN RACING ENGINES
 

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You may gain nothing, you may pick up a couple tenths. I know people on each end of the spectrum. You -should- pick up a little power, however don't expect it to be a different engine. A guy I know with a 351C installed a solid roller with apparantly the same specs as his solid, and ran exactly the same as he did before.

If it's a RACE car that sees limited street use, it might be worth it to step up to the roller. If it's a STREET car that sees a lot of miles, you'll probably be better off with a modern designed solid flat tappet... or a hydraulic roller if you don't rev it too high.

Engines that respond to solid rollers the best, are ones that need all the lift they can get. In other words, if the engine has fairly small heads for its displacement, it's going to need the valve lifted as far and quicky as possible, while keeping duration in check. A roller stands a much better chance of making a significant difference on this type of combo.

Your 393W with stock Edelbrock RPM heads would probably be a good candidate, as long as you don't mind keeping a CLOSE eye on the roller lifters, and it doesn't see TOO many street miles. Keep the idle speed up, and run a fairly tight valve lash to minimize pounding on the valvetrain.

Good Luck!
I tend to agree but not with the last bit. I Haven't had anything to do with those particular heads but looking at their published flow data....they are virtually done at .500 lift... gain only 4cfm at .600 and flow drops at .700".
I would tend to think that because the heads are "done" early in the
piece flow wise, you are unlikely to gain much going to a roller.
In other words, if the current cam is meeting head (piston) demand , which is quite high with a 393, you will gain nothing by opening the valve sooner or giving it more lift as the heads flow "window" is already "full".
 

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I tend to agree but not with the last bit. I Haven't had anything to do with those particular heads but looking at their published flow data....they are virtually done at .500 lift... gain only 4cfm at .600 and flow drops at .700".
I would tend to think that because the heads are "done" early in the
piece flow wise, you are unlikely to gain much going to a roller.
In other words, if the current cam is meeting head (piston) demand , which is quite high with a 393, you will gain nothing by opening the valve sooner or giving it more lift as the heads flow "window" is already "full".
The smaller the head is for the combo, the more 'strangled' it is going to be. In this situation, it is very beneficial to get the valve open to where it needs to be as quickly as possible... then hold it there as long as possible before setting it down... all while staying within the required duration. A slow acting valvetrain on a small set of heads will give the engine 'asthma'. LOL

Nobody said a 0.800" roller was going to be installed in this 393W with RPM heads. A good roller with the proper lift would probably give this engine a nice little pick-me-up... especially if the solid cam that's in it now is on the slow side.

If the engine already had more cylinder head than it could really use, a roller probably wouldn't be worth that much over a good, modern solid flat tappet with the right specs.

Good Luck!
 

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Nobody said a 0.800" roller was going to be installed in this 393W with RPM heads. A good roller with the proper lift would probably give this engine a nice little pick-me-up... especially if the solid cam that's in it now is on the slow side.
Some of the answer is already there......

at .200 sft is 159/166 roller is 170/176
lift 560/576 614/621
same 1.6 rocker arms for both

heads are Stock Edelbrock RPM flow 250 @500
 

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Not to me.... some slight gain , yes .... but not enough to justify (roller) cam changing expense imo.
 

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Not to me.... some slight gain , yes .... but not enough to justify (roller) cam changing expense imo.
That argument can be made for -anybody- considering switching from a solid flat tappet to a solid roller.

With the big cubes and small heads, his is probably one of the better candidates for a solid roller... but is it worth the expense???? It just depends upon how bad he wants a little extra power. :)

Personally, I frequently street drive my car, so I enjoy the low maintanance of the solid flat tappet. I don't like worrying about solid roller lifters and broken valvetrain parts.... as the quick valvetrain motion and associated heavy springs put a lot of stress on things.
 

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That argument can be made for -anybody- considering switching from a solid flat tappet to a solid roller.
No, not really Mike. We have two major influencing factors here, large(ish) displacement and mediocre head flow. If cylinder demand exceeds head flow capacity gain's are small, you may get alittle better filling earlier in the intake stroke but during the "bulk" cylinder filling period (at max piston speed), the head is already at its capacity..... gains are small/none, in other words - the heads are the bottleneck. If the head has some additional (or untaped) capacity, gains will be much larger ofcourse.

It reminds me of a class racing scene we were involved in which is using smaller displacement engines and (equally) restrictive heads. They relaxed a rule regarding only FT cams being allowed....everybody thought - GREAT...had roller cams ground up in all sorts of configurations, expecting much better performance. It didn't happen. Some of the "clever" ones had small gains in lap times... and some had none.
Huhh???? Whats going on here? They didn't realise at the time that the heads were the limiting factor , not the cams. There are STILL guys running FT cams even now as there is very little in it.... and they generally win the reliability "race" hands down.
 

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With my 347/AFR185's/funnel web, I went from a trick flow stage 3 hydro roller cam to a comp cams 294s solid roller I went from a 12:80 to a 12:65 and I believe there is more left in it. The big gain I saw was being able to turn it to 7500 opposed to a valve floating 6500 on the hydro. The draw back to this is I'm running 4:88 's im my galaxie with 28" tall tires and I am still not going through the traps at an ideal rpm.I think if I drop to a 26" tire I would gain quite a bit more. But the 88's are already causing traction issues and It will only be worse with the 26" tall tires.
Now changing from a hydro roller to a solid roller cost well over $1200.00 in the end. Is it worth it ????????????? Who can say, but I can now say I got a 347 in a 4000lb galaxie that will go 12:60's and shifts at 7500. Hell yeah its worth it!!!!!!!
 

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Fair enough 347LX but keep in mind that your 185's flow a fair bit more than the RPM's.... and your 50 cubes less.
Nice numbers at that weight though....

Edit: I guess what I am trying to say here is that for the cost involved, you would get FAR more benefit from putting the dollars into some better heads , (even with the same cam) than your ever going to get from going to a roller.... and the cost to change is going to end up around the same or less by the time you sell the RPM's.
Its a bang for your buck thing.... the heads are the issue, they are just too "small" for the cubes.
 
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