to 1.7 or not to 1.7

Cobra R...anger · 12-09-2001, 02:04 AM

if i have an 85 5.0 H.O with lightly ported E7TE's, an edelbrock performer intake, stock 600cfm carb, 1 1/2" long tube headers exhaust without cats would i notice much of a difference in performance and what kind of a difference by using 1.7 roller rockers over using the stock rockers. also will i then have to replace the springs and pushrods and will there still be enough valve to piston clearance using the stock 4 valve relief pistons. or should i spend my money elsewhere? thanks alot for your help

Cobra R...anger · 12-09-2001, 02:41 AM

also does this sound like a good combo?, would my money be better spent on an diferent carb, also i am not planning on running any emissions equiptment does anyone know what must be done for this?

Cobra R...anger · 12-09-2001, 07:32 PM

anyone?

84LX89GT · 12-10-2001, 03:28 AM

Getting the 1.7rr's over the stock 1.6 non rollers would probably give you approxamately 10 horsepower....that's what i've "heard" but i've never seen a dyno test or seen results. With your combo, those roller rockers would act like a slightly larger camshaft which in my OPINION would be a good match to your current combination.
Also, if you don't want to run emissions on your car, step up and buy a non-emissoins 600 cfm holley. The stock Holley-Motorcraft carburetor is jetted fairly lean (and you'll probably get pinging if you disable the EGR) and is tamper proof and is actually officially rated at 580cfm. I took all the emissions off of my '84 and put on a 600cfm non-emissions holley and it worked well without any jetting changes, although it probably would have bennefitted heavily from a dyno tuning session.
If you do decide to go with the 1.7 roller rockers, it's a GOOD idea to change out the valve springs and get hardened pushrods since you're in there anyways (i think you can use the stock length pushrods, but you should contact the manufacturer of the RR's) so that way you don't take any chances.
My '89 has 1.7:1 roller rockers and i'm pretty sure the previous owner didn't change valve springs or pushrods and i know he didn't baby the car and i've had NO problems with it so far (about 5,000, he drove about 30,000 with mods). So i would recommend it on my limited experience and from word of mouth it would probably be a worthwhile investment, since it broadens the power band to optimize your current combination and also reduces friction.
Good luck,

84LX89GT · 12-10-2001, 03:30 AM

I forgot to mention that you shouldn't have any interferance problems since you have the pistons with valve reliefs and not the flat-tops.

Cobra R...anger · 12-10-2001, 08:44 PM

Thank you very very much for the help
-Jason

12-09-2001, 02:04 AM	#1
Cobra R...anger Registered Member Join Date: Oct 2001 Location: Kincardine, Ontario, Canada Posts: 25	to 1.7 or not to 1.7 if i have an 85 5.0 H.O with lightly ported E7TE's, an edelbrock performer intake, stock 600cfm carb, 1 1/2" long tube headers exhaust without cats would i notice much of a difference in performance and what kind of a difference by using 1.7 roller rockers over using the stock rockers. also will i then have to replace the springs and pushrods and will there still be enough valve to piston clearance using the stock 4 valve relief pistons. or should i spend my money elsewhere? thanks alot for your help

12-10-2001, 03:28 AM	#4
84LX89GT Mustangs Join Date: Jul 2000 Posts: 1,938	Getting the 1.7rr's over the stock 1.6 non rollers would probably give you approxamately 10 horsepower....that's what i've "heard" but i've never seen a dyno test or seen results. With your combo, those roller rockers would act like a slightly larger camshaft which in my OPINION would be a good match to your current combination. Also, if you don't want to run emissions on your car, step up and buy a non-emissoins 600 cfm holley. The stock Holley-Motorcraft carburetor is jetted fairly lean (and you'll probably get pinging if you disable the EGR) and is tamper proof and is actually officially rated at 580cfm. I took all the emissions off of my '84 and put on a 600cfm non-emissions holley and it worked well without any jetting changes, although it probably would have bennefitted heavily from a dyno tuning session. If you do decide to go with the 1.7 roller rockers, it's a GOOD idea to change out the valve springs and get hardened pushrods since you're in there anyways (i think you can use the stock length pushrods, but you should contact the manufacturer of the RR's) so that way you don't take any chances. My '89 has 1.7:1 roller rockers and i'm pretty sure the previous owner didn't change valve springs or pushrods and i know he didn't baby the car and i've had NO problems with it so far (about 5,000, he drove about 30,000 with mods). So i would recommend it on my limited experience and from word of mouth it would probably be a worthwhile investment, since it broadens the power band to optimize your current combination and also reduces friction. Good luck, __________________ 2005 Suzuki Hayabusa GSX1300-R 1980 Ford Thunderbird - 255 V8 ported heads, 5.0L ported stock headers, O.R. H-pipe and Flowmaster 2-chambers, dual roller timing chain hi-po Mack Truck hood emblem 1985 Mustang GT 5.0L T5, F-303, GT40p, headers, off-road h, flowmasters, MSD stuff, etc. Sold 02/06/04 1989 Mustang GT ET: 13.304@102.29 mph (5-24-03) Sold - 1998 Mustang Cobra coupe, 1/4 mile - street tires: 13.843@103.41 (bone stock)

12-10-2001, 03:30 AM	#5
84LX89GT Mustangs Join Date: Jul 2000 Posts: 1,938	I forgot to mention that you shouldn't have any interferance problems since you have the pistons with valve reliefs and not the flat-tops. __________________ 2005 Suzuki Hayabusa GSX1300-R 1980 Ford Thunderbird - 255 V8 ported heads, 5.0L ported stock headers, O.R. H-pipe and Flowmaster 2-chambers, dual roller timing chain hi-po Mack Truck hood emblem 1985 Mustang GT 5.0L T5, F-303, GT40p, headers, off-road h, flowmasters, MSD stuff, etc. Sold 02/06/04 1989 Mustang GT ET: 13.304@102.29 mph (5-24-03) Sold - 1998 Mustang Cobra coupe, 1/4 mile - street tires: 13.843@103.41 (bone stock)

12-09-2001, 02:41 AM	#2
Cobra R...anger Registered Member Join Date: Oct 2001 Location: Kincardine, Ontario, Canada Posts: 25	also does this sound like a good combo?, would my money be better spent on an diferent carb, also i am not planning on running any emissions equiptment does anyone know what must be done for this?

12-09-2001, 07:32 PM	#3
Cobra R...anger Registered Member Join Date: Oct 2001 Location: Kincardine, Ontario, Canada Posts: 25	anyone?

12-10-2001, 08:44 PM	#6
Cobra R...anger Registered Member Join Date: Oct 2001 Location: Kincardine, Ontario, Canada Posts: 25	Thank you very very much for the help -Jason