mark kibort

IT runs!!!!! started out a little shakey, but the noise i thought that could have been a big issue, turned out to go away when the oil was hot. stickey lifter . now it sounds very tight. a lot less noisy in the engine area too. anyway, took it out for a spin and it feels kind of flat. did my highway run with the stop watch, and its kind of slow there too. 60-80 a few times and times were a little weak in the 3.0 second range. (normal is 2.8 for the S4 with 320rear wheel hp) finally got enough guts to run it up to redline. 60-100 a paltry 6.3 seconds (normal is 5.9 or so) did another and another, and still even cheating slightly, 6.2. whats up??? flappy seems to be working too.

Hmmmm. So im thinking when i attached the rotor, the cam pulleys were advanced in the same way on the holbert car and the timing turned out to be good, but i couldnt attach the rotor, as one hole was not in the window exactly. so, i loosened the nut on the cam pulley and rotated the crank so i could get the rotor bolt in and threaded. bet it was 3-4 degrees of crank position. anyway i wonder if one cylinderbank retarded 4 degrees could hurt performance that much. thinking about pulling the cam covers and re-measureing what i have done, or just going to the dyno , or both!

anyway, the good news its running!! the bad news, it may be down on power , a little.

It sure was an easy job with the information you guys provided (and that handy website info)

however, it was all perfect until eveything was buttoned up except rotors and caps and found i couldnt screw the rotor in right on one hole. could that make that much of a difference? I marked the pulleys before i disassembled and its still pretty close to the marks now.

Mk

mark kibort

Now its bugging me. I may have to pull the driver side cover and check. by the way, just glancing over the manual, and it talks about torque of the bearing caps and front bridge. M6 7.5ft-Lbs and M8 used on later 87s to be torqued at 15ftlbs. where are M8 bolts, or are all of the 87 bearing cap bolts M8??? while im in there, i may tighting things up a bit! the allen is 6mm, but i dont recognize the size. can you just measure the diameter of the bolt with threads, or do you need to measure it some other way. anyone know? Im thinking they are M8 cause they look a lot like Scots bolts used to hold the cam towers to the heads. (15ft-lbs)

Mk

SharkSkin

Measure the shank of the bolt -- if it doesn't have one, measure the threads and round up to the nearest mm.

mark kibort

did it last night, after finding out scots cam tower bolts were M8 and then pulled one of the visible bearing bridge bolts and it was the same 7.7mm or so. so, pulled the cover and torqued everything on the driver side, to 14ftlbs!

then, checked timing again, and readjusted the timing to 2.0mm. (it was kind off off due to my seemingly little movement to make the rotor screw on, and it turned out to be a lot of movment. close to 4 crank degrees. ended up making the timing in the 1.5mm range. Now, its 1mm at 10degrees and 2mm at spec , 20degrees. put it all back together and it should be better. Now , wondering if i should go in there and torque the other side down. they are all at 7 to 10ftlbs . (used the 85 spec by accident based on, i think, the 85's use of M6 bearing cap bolts)

comments??

thanks guys,

Mk

PS, by the way, this all took about 2 hours exactly. (10:30pm to 12:30am) to pull the cover, tighten bolts and measure, check and adjust timing and put it all back together again. (the wife didnt even know i was working on it in the garage!)

mark kibort

Went in in 30 min and pulled the passenger side cover and tightened all the cap bolts to the 14ft-lbs. they are all M8s! so, its all buttoned up, verified the timing while i was in there to be 1.7mm exactly. (spec for S4 is 1.8mm and 85 is 1.6mm so i split the diff)

any guesses on HP now that the cams are timed correctly? (and the 5 degree error on the driver side is now re-adjusted to spec, 2mm)

dyno appointment at mustang ranch at 12pm thursday! feeliing like 20hp missing on the last 60-100mph run. we will see!! (maybe less now that the timing has been corrected)

Mk

Mongo

Mark are you running the stock timing still on the car or an advancement? If the car was either too advanced or retarded for the cams you are running now, there will be some HP issues if thats what you are worried about.

Setting the timing right on should give you the results you expect: power gain and/or restored horsepower.

mark kibort

i timed it correctly, then changed the driver side to allow for the fit of the rotor. didnt realize how much i moved it until i pulled the covers off and checked it to be around 4-5 degrees. Now its back to stock,and was able to get the rotor to screw in too! (but its maxed out on the window of the pulley, but timing is right at stock spec, or 2mm at 20degrees ATDC #6 passenger side)

anyway, my question is if one cam is retarded by 5 degrees could that kill 10-20hp??

thanks,

MK

ps i know that L.Ott tested a range of timing and got 20hp diff for a retard vs advance cam setting, but that was both cams. mine is only one. heck, maybe thats worse!!

SharkSkin

Not trying to be a PITA here Mark, but an M8 bolt has 8mm diameter threads! Usually M6 has a 10mm hex and an M5 has an 8mm hex. 14 ft-lbs sounds OK, so there should be no harm done. But if you managed to confuse yourself and torqued those bolts to the M8 spec, I think you would be sorry...

mark kibort

Are you sure.. the manual says M6 to 7ftlbs and the M8 (later than '85 ) to 14.5ftlbs. Now, i went to the manual and found bolts i knew where they came from and had in my hand. cam tower to head bolts on an 83. they are M8 and spec is 14ftlbs. AND it takes a 6mm allen. (as does the cam bearing caps i have with the same size diameter shank bolts of 7.8mm or so)

M5 are the little bolts that hold the rotor to the pulleys and a bolt version was a 10mm hex or maybe even 8mm. (used those to hold the pulley in place when adjusting the timing and the 17mm bolt is loosened off the cam.

correct me if im off base above!

thanks for the reply, cant be too careful!

MK

SharkSkin

My mistake -- I thought you were talking about the three bolts on the cam sprocket -- nevermind!

mark kibort

dyno run scheduled for 12 noon Thrusday at Mustang ranch. Hoping for at least my normal 320rwhp. I did fix the cam timing of the driver side to 2mm at 20degrees ATDC and verified the passenger side at 1.7mm. Now, we are going to see how these cams stack up to the Holbert cams and GT cams!
I just hope it all stays together!!!

MK

mark kibort

WELL, good news and bad news. good news its running fairly strong, and survived another day of 60-100mph runs and a dyno session. thought i was down 15hp due to the 60-100mph times of 6.3-5,and i was right. Bad news, its down 15hp to a total of 308hp at the rears. flappy wasnt working so i took a needle nose vise grip and locked on and kept it open manually. gave about 50ftlbs of torque from 3700 to 5000and then it was a little stronger at the top.
Interestingly, actual numbers (*308 was SAE) were 312, vs my last dyno run a couple of months ago of 322 actual and 321 SAE.

Now, im confused again. maybe its the cams, maybe its something else. cams are 85s set at near stock timing at 2mm . however, a GT cam is set at around 3mm on the intake lifter at 20degrees ATDC. wonder if that could be it. why are the GT and GTS cams set at near 3mm vs the S4, and 85's that are set at near 2mm???? however the holbert cams were set at 2mm for both sides. puzzling. lift is the same with the 85 vs the holbert cam.

any ideas??? maybe i just have to get the holbert cams fixed by the gear fixing guys recommended by Webcams and the 944 guys.

????


MK
Ill post the dyno runs soon

mark kibort

Here are the dyno runs.

The first graph is the flappy being held vs the flappy not working. here you can see the effect of the flappy used over the entire range, vs not working.

The second dyno graph run is the flappy being held open over the entire run with the '85 cams vs the Holbert cams with flappy not working (notice the first hump is not there with the flappy held, but a HUGE increase in torque in the midrange to 5krpm, and then who knows if it helps or hurts to redline.



The interesting thing here is the shape of the curves are pretty close, even with the new cams. looks like ive lost hp in the max hp range as well as max torque range. pretty uniformly. the dyno operator said that the Air fuel meter was not working properly, so the ratios are real lean, but supposed to be not a true reading. (sure seems like that could be the problem though.)

I changed the fuel filter and will maybe kick up the fuel pressure a half turn just in case.

flappy had a cold solder joint on the dianostic cut i made when fixing it the first time. now its working!

let me know if you guys think i should try advancing the timing at least on the passenger side, as the holbert cams were timed at 2mm both sides. plus the cams had more advanced intake lobs anyway. maybe i should use the GT spec of advance and see what it does? has anyone tried this?

MK

PorKen

Easier?


clic pic for thread

(Tool in use)

928SS

I'm no expert, but I suspect AF could easily be the culprit - a glance at louie's pages show gains of 15rwhp from a mixture tweak, and I gained 40rwhp just going from .75lambda to .85lambda... if you are lean, I'd expect the same kind of power drops on the other side of optimal too...