1.72 RR on stock 5.0 ??

Katmandu · Jul 7, 2007

I need to replace the valve seals in my stock 5.0 soon. I'll be doing it with the engine still in the car.

I figure this would be a good oppurtunity to upgrade the RRs and Springs.

Q: Will 1.72RRs work ok on a stock 91 5.0 ?? If so, will I need to upgrade the springs as well ??

nitrous_bob · Jul 7, 2007

yes they will work, no you won't

it's good upgrade too

Katmandu · Jul 7, 2007

nitrous_bob said:
yes they will work, no you won't

it's good upgrade too

Isn't it worth about 15HP ??

BlownFiveLiter · Jul 7, 2007

Isn't 1.72 a typical SBC upgrade? I never saw them for a SBF, only 1.7's.

Foxfan88 · Jul 7, 2007

my FRPP rockers (made by crane) say 1.73 on them.

and i dont think its a 15 HP gain. it actually makes no real difference. might give you the placebo effect but as far and real power gains i dont see them doing it, i put 1.7s on my car when it was pretty much a stock motor and it didnt really do anything.

88mouse · Jul 7, 2007

I can tell a diff. with the 1.7's on my car they move the power up in the rpm range.

Katmandu · Jul 8, 2007

88mouse said:
I can tell a diff. with the 1.7's on my car they move the power up in the rpm range.

How much higher ??

bgjohnson · Jul 8, 2007

That's kinda impossible, considering if has nothing to do with changing cam events or duration. It might just supply more air because of the increased lift, but it can't change RPM peak performance.

Roland69 · Jul 8, 2007

will they still clear stock valve covers

Foxfan88 · Jul 8, 2007

depends on the brand

usually the common belief is that a higher ratio rocker arm needs more clearence.

the rocker arm ratio doesnt even really affect the clearence in a valve cover.

i had some 1.6 scorpions that i traded to my friend for his 1.7 FRPP rockers

the FRPP fit fine under stock valve covers. i removed the oil fill baffle because i didnt want to backtrack if they didnt fit but they fit perfect. i didnt have to grind on the covers at all.

but my friend, with the 1.6 scorpions i traded him. they hit the valve covers. just the beefiness of the rocker arm made it hit. he had to grind a bit to get them to fit.

as for ratios. picture a seesaw. now take the fulcrum ( the point balancing the seesaw.) now move the fulcrum over to one side. the other side now has the ability to move farther with the same amount of movement from the other side.

give you an idea how that works.

Katmandu · Jul 8, 2007

bgjohnson said:
That's kinda impossible, considering if has nothing to do with changing cam events or duration. It might just supply more air because of the increased lift, but it can't change RPM peak performance.

Actually it DOES change the cam events.

http://www.fordmuscle.com/archives/2001/10/rockerarms/

[FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1] Lift and Duration
We all know that stepping up to a cam with a little more lift and duration can yield a nice gain in performance.

[/SIZE][/FONT][FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1] Many people incorrectly assume that a change in rocker arm ratio has no effect on the duration the valves are open. In actuality there is some change to the duration at the valve depending on the lobe profile of the camshaft.

Comp Cams explains that by lifting the valve an additional 7-8%, but beginning and ending the lift at the same point, the opening and closing rates become steeper. This increases duration, measured at the valve at 0.050" lift, by 1-2 degrees. You can measure the actual duration change by using a degree wheel and dial indicator set on the valve retainer.

Coincidentally the principle of a steeper rate of opening and closing is what Comp Cams has engineered into their Extreme energy camshafts to enable more valve duration for a given lobe duration.[/SIZE][/FONT]

facemelter71 · Jul 9, 2007

I've changed Rockers on my 86.Your stock cam has .444 lift. At the valve. When you change them to 1.72 it changes VALVE LIFT by about .030.So your new valve lift with 1.72 rockers is .477.Thats at the valve.So your opening the intake and exhaust valves another.030 more then you would with stock rockers.And just for giggles,take your baffle out.You would see more of a gain with mass air car then you would with speed density.Although you will not notice a seat of the pants feel.Oh,and if you plan on getting a cam in the future just get 1.6 roller rockers.Itll save you frustration in the long run.

BK_CAULEY · Jul 9, 2007

you are not gonna gain any power. our cars induction systems dont flow well enough to warrant the use of a higher ratio rocker. and your stock springs dang sure wont handle them. you will have serious valve floating going on. (never mind just saw upgrading springs) but still you will not see or feel any difference. even on a dyno.

FordGuy88 · Jul 9, 2007

If you want more performance then put in a different cam. You want the cam to do the lift not the rockers. If you decide to do valve springs let me know I have 2 new sets that you can choose from Ill give them to you cheap. If your intrested PM me.

bgjohnson · Jul 10, 2007

Katmandu said:
Actually it DOES change the cam events.

http://www.fordmuscle.com/archives/2001/10/rockerarms/

Maybe it was misunderstood what i was trying to say. You can't change lobe separations, or valve overlap. Therefore, all your article is saying is, it increases VALVE LIFT at different rates or "steeper" rates in the set camshaft ramp rates. Like i said, just more lift, the valve's open and closed times are still exactly the same.

Foxfan88 · Jul 10, 2007

the valve wil open and close faster. due to the fact its having to open .030" farther in the same amount of duration

cenok is family · Jul 10, 2007

i had to take out the baffle to make my crane 1.7's fit under my stock valve covers.

BYRDPE · Jul 10, 2007

I will be installing the 1.7 rockers along with a B cam and I found a set of the Cobra valve covers to clear the rockers.
IMO...you don't want to removing the baffles with all the posts about oil in the intake.

cenok is family · Jul 10, 2007

BYRDPE said:
I will be installing the 1.7 rockers along with a B cam and I found a set of the Cobra valve covers to clear the rockers.
IMO...you don't want to removing the baffles with all the posts about oil in the intake.

true, but you can just remove the hose from the valve cover to the throttle body, cap off the throttle body and put a breather cap on the valve cover.

cenok is family · Jul 10, 2007

oops...double post. sorry.

1.72 RR on stock 5.0 ??

Katmandu

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1.72 RR on stock 5.0 ??

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