I was thinking of doing some mild bolt ons. My engine has about 120,000 miles on it. I was thinking thumper heads, tmoss intake and 1.7 rockers. But not sure that my engine can handle all this and at what point do i need to recalibrate the maf and change out the fuel injection. Then back to my original question, what do 1.7 rockers do? what else do i need to change in order to run them? thanks in advance!
what does 1.7 rockers do?
- Thread starter old_blue
- Start date
-
Sponsors (?)
86bandit
Member
As long as the short block is in good shape you should have no troubles with a new top end. I went with Gt40 iron heads,Typhoon intake, 65mm TB and 75mm MAF personally on a 150K+ short block...no problems at all. You shouldn't have to recalibrate your MAF unless you change injector size. The 1.7 rockers should just bolt on (as long as you get pedestal mount ones) and all they will do is increase lift on the cam. I will get around to doing this same thing shortly myself.
bock
Founding Member
Michael Yount
Mustang Master
The first place to start is to run a cranking compression and or leak down compression test on your engine. That will tell you if the cylinders are sealing a way that they can safely accomodate some performance additions. Does the car smoke blue or burn significant oil between changes? If so, modifying it for more power will probably only exacerbate those problems. However, there are many 5.0's out there with more original miles than yours and much more significant mods that are working just fine. So if the engine's been reasonably cared for, you shouldn't have any problems. Email tmoss and/or Thumper about the changes you're considering - they have good information about what you can expect in terms of performance, and what the impact of using the stock throttle body and maf will be. You shouldn't have to make any fuel injection changes to accomodate the pieces you're thinking about, although as suggested above, the larger throttle body and maf changes may help out a bit. Ask tmoss - he'll know.
The stock rocker arm is a lever. When the pushrod pushes up on one end, the other end of the rocker pushes down opening the valve. It's not an equal length lever - it's offset; it is 1.6 times longer from the fulcrum to the valve than it is from the fulcrum to the pushrod. So, if the cam lobe is .300" tall, when you push the rocker up .300", it pushes the valve down 1.6X.300" = .480". When you substitute 1.7 rockers, they have more leverage than the 1.6's. Using the same example, if the cam lobe pushes the rocker up .300", then the 1.7 rocker pushes down on the valve 1.7X.300" = .510". So, with the higher ratio rocker you get more peak lift at the valve, and the valves are open to higher levels a bit quicker than they would be with 1.6 ratio rockers. It has the effect of putting in a camshaft with a just a bit more lift than whatever you have in the engine. Because of that, it stresses the valve spring a bit more. But, if you're going with Thumper heads - just tell him you're gonna run the stock cam and 1.7's and he'll pick valve springs that will deal with that just fine. Oh (edit) - I wouldn't expect significant gains from the rocker change. Your big hits will be the heads and lower intake - so if there's one of the three that you decide you can't do - it's definitely the rockers.
The stock rocker arm is a lever. When the pushrod pushes up on one end, the other end of the rocker pushes down opening the valve. It's not an equal length lever - it's offset; it is 1.6 times longer from the fulcrum to the valve than it is from the fulcrum to the pushrod. So, if the cam lobe is .300" tall, when you push the rocker up .300", it pushes the valve down 1.6X.300" = .480". When you substitute 1.7 rockers, they have more leverage than the 1.6's. Using the same example, if the cam lobe pushes the rocker up .300", then the 1.7 rocker pushes down on the valve 1.7X.300" = .510". So, with the higher ratio rocker you get more peak lift at the valve, and the valves are open to higher levels a bit quicker than they would be with 1.6 ratio rockers. It has the effect of putting in a camshaft with a just a bit more lift than whatever you have in the engine. Because of that, it stresses the valve spring a bit more. But, if you're going with Thumper heads - just tell him you're gonna run the stock cam and 1.7's and he'll pick valve springs that will deal with that just fine. Oh (edit) - I wouldn't expect significant gains from the rocker change. Your big hits will be the heads and lower intake - so if there's one of the three that you decide you can't do - it's definitely the rockers.
88stangmangt
Active Member
I just finished taking off the .050" duration from my stock 88 cam and found it had 219° duration on the intake and 212.5° on the exhaust. I decided to keep that cam rather than switch and I'll probably run 1.7 rockers on it.
93 teal terror
Founding Member
Tom , just wondering but is your 88 a late year production model or early? Ive read that the 87s and halfway through the 88 have a more agressive cam and yours looks like it does
My car was built in 2/88 and all the dated stuff on the engine is dated in 87, so I have a 87 cam.
Michael Yount
Mustang Master
Tom is that the same cam you tested before? Wasn't the 'advertised' duration the other way around - exhaust biased - that was the 'surprise' wasn't it? How could it be longer on exhaust duration at .004", and longer on intake duration at .050"? Are you scratching your head and wondering about that cam? I've never seen (based on posts) a stocker exceed 210 at .050". Something seems amiss....
Michael Yount
Mustang Master
93Teal - The cam change occurred for the 89 model year. 85-88's had the 266/266 cam; 89-95's had the 276/266 cam. Ford claims they softened up the ramp intake ramp rates on the 89-95's to quiet valve train noise. The result, even though the later cam has more intake duration, is that the earlier cam made 3 more HP.
93 teal terror
Founding Member
cool, I knew i read somewhere that ford changed the cam early on but wasnt sure of exact years. I wonder if it also had something to do with the switch from SD to MA. Anyone know if the 88 cali cars had the 266 or the 276 cam?Michael Yount said:
Michael Yount
Mustang Master
I believe all 88's including CA cars had the same 88 cam; the switch to mass air in 88 for the CA cars was to deal with the then more stringent CA regs.
Michael Yount said:
Mike, if you are still subscribed to that thread you should have seen my last post about problems I had with the method I used on the lifter - breaking it down and flipping the plunger over - didn't get consistant repeatable results and found the inverted plunger was not seated sqaure and the round tip of my Starret dial micrometer was using the round tip of the bottom of the top plunger section. So, I redid the results using the flat lip on the lifter body and got good repetable results. This time I took measurements at .0005" rather than .005" (dial is in .001" increments so I can see .0005") just for s*its to get total cam measurements and then took off the .050" lift numbers - the ones that really count anyway. Checked them 3 times and they came up the same every time - .050" duration of 219 intake, 212.5 exhaust with 113 ICL and 112.5 ECL with 112.5 LSA. Lift was .448" intake and .437" exhaust for the #1 cynlinder. I might be 1° off in any direction. I have one of EDC's old posts that indicate he does find them over 210..............
-"The factory cams range from about 204-212 duration @ .05” and 0.437-0.450 lift and 112-119 LSA because of poor quality control". Ed Curtis
Remenber that this is an 87 cam - one of the early aggressive ramp rate cams as my car is a 2/88 car and all the date data on the car engine has 87 markings.
After finding the true cam timing out, I recalled another thing EDC said which makes me happy with this stock cam...........
-"When I sent out some cam profiles with more duration on the intake than the exhaust, some uneducated posts said it was all wrong. Of course when these customers picked up power, these same people fell off the planet! But hell, what do I know about making strong combinations?" Ed Curtis
I'm gonna try it out on the new GT40P heads and Explorer intake and see what I get.
Michael Yount
Mustang Master
Thanks Tom - I didn't follow the whole saga. I guess spotty quality comes out to be a real blessing in disguise sometimes!! How are you gonna install it timing-wise?
Michael Yount
Mustang Master
Did you check actual timing of the intake valve opening at .050"? Given how far off the cam specs are from what Ford's data indicates, I'd be real curious what the actual valve event timing is/was.
Yep, those numbers were taken off actual valve events, .0005" and .050".
I took the first valve movement of .0005" and then took the next reading by advancing the dial mic to .050" of lift for intake and exhaust opening "events" and then on the closing events took the lobes down to no movement, backed up to .0005" lift to mark closing event and backed up to .050" lift for the "closing" event. I have the events at home and I'm doing this from work.
I took the first valve movement of .0005" and then took the next reading by advancing the dial mic to .050" of lift for intake and exhaust opening "events" and then on the closing events took the lobes down to no movement, backed up to .0005" lift to mark closing event and backed up to .050" lift for the "closing" event. I have the events at home and I'm doing this from work.
Similar threads
