Sunday Drags

Discussion in 'Drag Racing' started by mcknight77, Apr 17, 2016.

  1. mcknight77

    mcknight77 Member

    Joined:
    Dec 4, 2004
    Messages:
    325
    Likes Received:
    13
    Trophy Points:
    77
    Location:
    Boise, ID
    Vehicle:
    74 Mav drag car, 1970 Maverick, 1971 Bronco, 66 Nova, 67 Ranchero
    I talked to a local guy who is a nationally recognized head porter this morning and he asked about spring pressure and clearance before coil bind. He said he's done hundreds of these heads for 5.0 Fords and that I don't have enough spring pressure (150seat/350 open) and recommended a .045 shim addition. I will do that tomorrow. He also said with a laugh to throw the hydraulic roller away and go to a solid flat tappet cam.

    I also managed to capture the first run on Saturday on my GoPro. If I can figure out how to get it on here I'll post it.
     
  2. groberts101

    groberts101 Member Supporting Member

    Joined:
    Apr 22, 2007
    Messages:
    3,708
    Likes Received:
    365
    Trophy Points:
    197
    Garage:
    1
    Location:
    Minneapolis, MN
    Vehicle:
    1971 Comet GT
    only 350 open seems a bit low'ish but then again I'm just another nationally un-rocognized head porter. LOL Apologies up front.. blanket statements like those usually bring out my inner smart-ass. :yup:

    Flat tappet?.. an even bigger LOL there. Wait!?.. what year is it? :D Pretty easy to suggest things that increase long term durability/risk factors when it's not your motor and advice comes with no expressed or written warranty. Keep your salt bucket handy. Also consider that warmed over cam lobe's lift curve blows away many older school full race style mechanical cams and things are not like they used to be when it comes to comparing hydro rollers. Not only that.. but is he actually implying all SBF AFR headed motors only spinning to 6,000 rpm need much higher spring pressures to keep from spitting through the carb and pissing power out the exhaust? Hmmmm.. me thinks real hard about that one. And a simple .045" shim fixes that? :scratchchin:

    Can't say I know the head porter guy but I'm certainly old enough to have learned that before assuming credibility in one aspect of engine development equals proficiency in all others?.. I'd be looking at many other AFR headed combo's(351W's included) to see what springs people are using in relationship to rpm and valvetrain weights. 351's taller/heavier valvetrain packages can rev to high heaven all over town and back with those spring pressures. Not saying more spring pressure shouldn't be considered here.. 1.7 rocvker ratio means greater lift/seat velocity which taxes a spring quicker.. only that you generally want just slightly more than is actually required to get the job done to further reduce wear and parasitic power losses. Cheaper springs need slightly greater pressures due to new spec's "going away" sooner.

    What specific brand/spring number? If 1.4x" dual I might have full set of Ti retainers you could use to free up rev's if this is in fact the case. Seems doubtful when you consider the motor was rpm'ing better end of last year and didn't suddenly go all to hell like it appears to be doing now. Even more doubtful when you consider the actual valvetrain weights involved here. Yes roller lifters are obviously heavier than flat tappets but the pushrods are also shorter and the valves are shorter/lighter to help offset it. Plus the valve side of the rocker is well known to be 10 times more important than the lifter side of the equation.. mainly due to the smaller and slower un-multiplied lobe movement on that side of the equation. Like comparing rotating to reciprocating weight when it comes to bob-weight crash diets.. one is far more important than the other.

    Hope I'm wrong and stiffer racing springs clean up the engines rev range. Doesn't hardly seem likely though since I've run this exact same cam lobe with a 1.7 ratio on heavier valves. Beehives need less pressure and resist surge much better but 7,400 rpm from 130/380'ish seat/open pressure spring is damned good considering the SBC has heav'ish valvetrain weights overall. 11/32" valves and 1.4x" cookie cutter dual springs(maybe 140/360) where matched to the XE282 retro-cam when I bought the truck(s10 Blazer), heads and tri-y exhaust were too small to go much past about 6,200 rpm before the power fell over a cliff but it didn't miss a beat even past 6,500. Comp cams link bar lifters are a fair bit heavier than your oem pieces too. Also had a 1.8 rocker on similar build but even more aggressive lobe(TK or TX lobe can't remember right now). 165/405 seat open went past 8,000 rpm(was far over the cliff but never broke up at all) with 8mm LS 100 gram 2.02" valve. Heavier thick walled 7.450" long pushrods and link style lifters too.

    Seems prudent to troubleshoot the tune first.. then buy more parts if need be. Anywho.. wish you the best of luck on sorting it out. :cheers2:
     
  3. mcknight77

    mcknight77 Member

    Joined:
    Dec 4, 2004
    Messages:
    325
    Likes Received:
    13
    Trophy Points:
    77
    Location:
    Boise, ID
    Vehicle:
    74 Mav drag car, 1970 Maverick, 1971 Bronco, 66 Nova, 67 Ranchero
    Greg, as always thanks for your insight. You crack me up sometimes. :D

    Adding shims will be a very cheap (free) solution if it helps. I really don't need but a couple of hundred rpm to get me through the lights. The springs in it are 1.290 double Pac springs. Don't know the part number.They are installed at 1.85" and open at 1.280 and coil bind at 1.160.

    Here's his business: https://www.kingcylinderheads.com/ He's actually living here locally and ports heads out of his shop here. Well respected by everyone I've talked to. https://www.facebook.com/profile.ph...=pb&hc_location=friends_tab&pnref=friends.all

    I will also check the ignition and fuel systems.

    :tiphat:
     
  4. tbirdz12

    tbirdz12 Member

    Joined:
    Jun 3, 2006
    Messages:
    232
    Likes Received:
    42
    Trophy Points:
    62
    Garage:
    1
    Location:
    Scottsdale, Az
    Vehicle:
    69.5 Mav
    FYI, consider this, I have a matched setup for ya. I have a killer solid Roller setup (Cam, Solid Lifters, AFR Solid roller springs) just taking up space in my garage. Made 391 RWHP at 7000 rpm in my 331. $300 plus shipping and its yours. Only about 1500 miles.
     
  5. groberts101

    groberts101 Member Supporting Member

    Joined:
    Apr 22, 2007
    Messages:
    3,708
    Likes Received:
    365
    Trophy Points:
    197
    Garage:
    1
    Location:
    Minneapolis, MN
    Vehicle:
    1971 Comet GT
    I do get the optimism for quick and easy fixes once the season has started but reality has beaten most of that optimism out by now. On the other hand, I'm here to attest to the fact that even a blind squirrel finds a nut every once in a while.

    I seem to vaguely recall that vid of tbirdz old 331 combo. Nasty fast cam for a bare bones 12 second bracket car though. Better include the t-shirt with it too.. "Got throttlestops?".... :biglaugh:

    Jim.. run.. I smell salesman. :dizzy: PM me if you're interested in spending less money on a barely used set of polished Manley Nextek 221436 dual springs and matching tool steel retainers. Guaranteed to be as new and right at factory spec's. Came out of a N/A "future turbo" longblock that unseated/blew the rings out before insanity(my pet name for my wife) finally tossed in the towel for that project. Well under max lift pressures with the stock Vortec cam and around 5,000 metro miles in about 9 months time. Similar 1.29" size but far superior and much longer lasting spring to those PAC's you have in there right now.

    http://www.manleyperformance.com/niche/chevy/chevy_ls_valvetrain.shtml

    That brings up another good question. Maybe call PAC and speak with them about these suspected valvetrain issues? I believe you may be surprised at the rpm levels various other parts combos are achieving with similar spring rates/pressures.
     
  6. groberts101

    groberts101 Member Supporting Member

    Joined:
    Apr 22, 2007
    Messages:
    3,708
    Likes Received:
    365
    Trophy Points:
    197
    Garage:
    1
    Location:
    Minneapolis, MN
    Vehicle:
    1971 Comet GT
    How goes the limited rpm battle, Jim?
     
  7. mcknight77

    mcknight77 Member

    Joined:
    Dec 4, 2004
    Messages:
    325
    Likes Received:
    13
    Trophy Points:
    77
    Location:
    Boise, ID
    Vehicle:
    74 Mav drag car, 1970 Maverick, 1971 Bronco, 66 Nova, 67 Ranchero
    Well, I spent Wednesday and Thursday putting a .045 shim under each valve spring. Hard work for an old fat man leaning over the fender. Thursday evening I ran it up in first gear by the shop and it did not valve float until 6500, so I may be gaining on it. My arithmetic calculations said I need 6250 to get through the lights. Since it floated at 6200 last time I didn't make it through. Maybe I will be able to now. I run it again tomorrow. Cross your fingers for me.

    I had about .080 clearance in the springs before coil bind at max lift after the shim. Can't be sure there wasn't some lifter bleed off going on. My calculations based on my spec sheet on the engine said I should end up with about .045 left before coil bind.

    A conversation with one of the guys I race with last night generated another question. I have about 55 lbs of oil pressure at idle hot. At rpm I have over 80. He said he thinks my pressure relief spring in my oil pump may not be working. He also said that if I had too much oil pressure it might be pumping up the lifters at rpm. I usually don't look at the oil pressure gauge during a run, but I will tomorrow. One more thing for the to-do list: add fuel pressure and oil pressure gauges on the cowl so I can see them.
     
  8. groberts101

    groberts101 Member Supporting Member

    Joined:
    Apr 22, 2007
    Messages:
    3,708
    Likes Received:
    365
    Trophy Points:
    197
    Garage:
    1
    Location:
    Minneapolis, MN
    Vehicle:
    1971 Comet GT
    Fingers and toes crossed. Not sure what your bearing clearances were set at on this shortblock.. but dropping down 1 notch for oil weight should reduce pressure about 5-8 psi. Those lifters should handle that pressure just fine, I've had upwards of 100 psi race pumps on them, but many guys drop oil weight/viscosity to diagnose and help reel in lifter metering issues. Just a thought, good luck with it this weekend.

    PS. If you think you truly have near .045" actual coil bind clearance?.. be VERY careful about running the motor too far into valve control issues. 100-200 rpm buffer before all hell breaks loose would be prudent to avoid a broken spring. Not trying to stress you out because I too have run down to about .030" clearance, just pointing out that you need to add some buffer in there with the rev limiter. Maybe set it to 6,400 and see how far past the limiter it actually runs.
     
  9. mcknight77

    mcknight77 Member

    Joined:
    Dec 4, 2004
    Messages:
    325
    Likes Received:
    13
    Trophy Points:
    77
    Location:
    Boise, ID
    Vehicle:
    74 Mav drag car, 1970 Maverick, 1971 Bronco, 66 Nova, 67 Ranchero
    Well, I broke it. #2 intake lost the keeper. I haven't taken the head off yet, but valve is stuck so I assume it is bent. So. on Monday I'll pull that head and get it fixed. It will also let me check spring pressure and coil bind without the lifter influencing it. And, hopefully the piston is OK. Might take both heads off and check both of them.

    It did run an 11.94/110 coasting the last 100 ft. But valve float was the same at 6200.
     
  10. groberts101

    groberts101 Member Supporting Member

    Joined:
    Apr 22, 2007
    Messages:
    3,708
    Likes Received:
    365
    Trophy Points:
    197
    Garage:
    1
    Location:
    Minneapolis, MN
    Vehicle:
    1971 Comet GT
    dammit.. well, at least the valve is still in the head which means your shortblock dodged a major bullet. Check everything out, guides included, and trash the springs.. or maybe even dump the rest on ebay.

    Let me know about those Manley polished dual LS springs mentioned earlier and I will give you a killer deal to your doorstep. They will support .660" lift @ 1.810 installed and the retainers are probably lighter than the stuff AFR bundles into their heads. Might have some Ti retainers that fit them too but would have to dig and measure/compare steps. Might even have a few other sets that would work for you too(test all my stuff and never keep/reuse moderate mileage or highly stressed full race parts).. but they will be bigger 1.4x" OD and probably far too much pressure for this little medium cammed motor.

    https://www.summitracing.com/parts/man-221436-16

    Glad is wasn't much more serious to cause driving over the pan. :eek:
     
    rotorr22 likes this.
  11. mcknight77

    mcknight77 Member

    Joined:
    Dec 4, 2004
    Messages:
    325
    Likes Received:
    13
    Trophy Points:
    77
    Location:
    Boise, ID
    Vehicle:
    74 Mav drag car, 1970 Maverick, 1971 Bronco, 66 Nova, 67 Ranchero
    Greg, I'm talking to tbirdz12 about his solid roller setup. Pretty sure I am going to trash the hydraulic roller setup if I have any money left after I fix the head.

    The springs I have on the AFRs is 1.55 in diameter.

    Can I run solid roller lifters and springs on my hydraulic roller cam?
     
  12. groberts101

    groberts101 Member Supporting Member

    Joined:
    Apr 22, 2007
    Messages:
    3,708
    Likes Received:
    365
    Trophy Points:
    197
    Garage:
    1
    Location:
    Minneapolis, MN
    Vehicle:
    1971 Comet GT
    Yes you can. And not to take away from his ongoing deal or anything.. but IMO you would be better off with this cam vs the larger one he has in such a small motor like this. Of course you may already know this which is probably why you even asked.

    What are the spring spec's on his setup?
     
  13. mcknight77

    mcknight77 Member

    Joined:
    Dec 4, 2004
    Messages:
    325
    Likes Received:
    13
    Trophy Points:
    77
    Location:
    Boise, ID
    Vehicle:
    74 Mav drag car, 1970 Maverick, 1971 Bronco, 66 Nova, 67 Ranchero
    I don't know what the spring specs are, but I think he bought them as a kit with the cam and lifters.

    And, yes my thought was to run my cam with his lifters and springs until I built a 347 and then switch to the bigger cam.
     
  14. mcknight77

    mcknight77 Member

    Joined:
    Dec 4, 2004
    Messages:
    325
    Likes Received:
    13
    Trophy Points:
    77
    Location:
    Boise, ID
    Vehicle:
    74 Mav drag car, 1970 Maverick, 1971 Bronco, 66 Nova, 67 Ranchero
    He said they were the AFR springs 220# seat pressure 1.55 diameter.
     
  15. groberts101

    groberts101 Member Supporting Member

    Joined:
    Apr 22, 2007
    Messages:
    3,708
    Likes Received:
    365
    Trophy Points:
    197
    Garage:
    1
    Location:
    Minneapolis, MN
    Vehicle:
    1971 Comet GT
    That's far too much spring for this particular cam. TBH, I'm not even sure that cam cores hardness level/heat treat will handle those open pressures for very long either.
     

Share This Page