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performance cam regrinding

Discussion in 'Technical Q&A' started by snj5, Dec 6, 2003.

  1. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Russ Turner
    Hello from snowy DC!

    Have visited this subject of cam re-profiling in the old board, but am now moving to actually do it. Both WebCam and Dema Elgin seem quite good at this and know what they are talking about, but was curious what experience if any folks have had with the hard welding cam reprofiling.

    I have the stock Kjet cams in now, and want to take more advantage of the Webers. Judging from 348 and 355 cam profiles, will probably keep my current exhaust duration and run the intake up to 255 - 260. Both WebCam and Elgin say anything more on a 4v is too much for the street. Shooting for a reliable 95 hp/liter (or better) from a qv 3.2.

    Any advice welcome.
    best to all
    Russ
     
  2. Dave

    Dave F1 Rookie

    Apr 15, 2001
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    Hi Russ,
    Doing the re-grind to your current cams is the most economical way to do it.
    You might also find a set of used cams for a good price to grind,
    that way you still have the stock units if you ever wanted to go back.
    Norwoods also has billet cam blanks for that engine,
    but they are much more expensive to complete than doing a temper, weld, regrind, harden, to your current cams.
    I have been following the progress on your car, and dig what you have done...
    At some point I will go through my 308 engine, but will be moving from 40 dcnf carbs to either 42 or 44.
    I will have to wait till I flow the heads to see.
    The only two requirements I have for my motor when I do the rebuild besides making as much power as possible are....
    #1. It Must still use carbs.
    #2. It Must run on pump gas.
     
  3. pma1010

    pma1010 F1 Rookie
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    Russ
    Sorry, don't have any input on this. Dema will and he'll also remember my 2v cams. Keep us posted.

    I also don't want to hi-jeck the thread, but, Dave, I too have thought about 44 DCNFs on my P6'd 308. I am not convinced it is a sensible upgrade. Le Mans 308s ran 40s. Only peripherally relevant, but a data point, Guy Croft did a comparison of 40s and 45s on a 2 cam Fiat engine. IIRC, the engine made less torque and less power across the entire rev range with the 45s...
     
  4. billb

    billb Formula Junior
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    Jun 4, 2001
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    I had Web Cams reprofile some spare cams to specs I'd sent them. The results were exactly as requested.
     
  5. Matt Morgan, "Kermit"

    Matt Morgan, "Kermit" Formula Junior

    Nov 12, 2003
    405
    Ferndale, WA
    Russ,
    I would recommend Web Cams without a doubt, based on personal experience. I particularly like the ramp profiles that they use, in that they are more like the old "cheater" cams, opening the valve faster at low lifts, thus encourageing flow.
    You may want to back down on the duration #'s if you want to be happy with the Bosch system. Too much overlap, or too late of intake valve closure will cause reversion, which will wreck havoc with fuel mixture, due to pressure pulses fooling the K-Jetronic into thinking the real flow is different than it actually is.
    HTH
    Kermit
     
  6. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Kermit
    Thanks for the words on Webcam!
    Not as worried about the Bosch FI reversion pulsing, as it has been replaced with 40DCNFs.
    best
    Russ
     
  7. mk e

    mk e F1 World Champ

    Oct 31, 2003
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    Cam technology has changed quite a bit in the last few years and I'm not sure if web has kept up. Computer designed ramps like Eglin uses let you open and close the valves faster without fear of bouncing on the seat or of the lobe. That lets you get more from less duration which makes a better street engine. I used Web about 6 years ago for a set of porsche cams. At that time, they were still doing all there cam grinding form hand made masters, not a bad thing, but it limits your options to the blanks they have, which were mild street performance or copies or ex-factory race grinds (i chose a race grind of couse). They were well made, but none of the choices were really exactly what I wanted. I spoke to Eglin about cams for the QV (before I decided to go with the supercharger instead) and was very happy with the answers I got. I think that if I ever decide to do something with my cams, Eglin is the way I'll go for what that is worth. I think Bret (the missing) bought his cams from Eglin, but I never heard how it worked out. Also remember that
    big cams+carbs=bad low end power
    although on a 4V engine I wouldn't expect it to be as big a problem since they like less duration than 2Vs alway.

    Good luck!
     
  8. pma1010

    pma1010 F1 Rookie
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    Dave
    I think the TWMs offer an interesting option for TB FI, and I did note the 44 DCNFs. I am not offering advice on this - I just don't know what the impact would be. Here's a scan from Guy Croft's book. The comparison is 48 TBs versus 45s. 48s had 42mm chokes, 45s had 40mm chokes. The results are staggering. Only way to tell on a 308 is to try them. But, as you know, it is a lot of work to set them up. Let us know if you try them.
     
  9. mk e

    mk e F1 World Champ

    Oct 31, 2003
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    There is something very very wrong with that graph...I seen a lot of dyno graphs, but I've never seen anything like that. I don't believe there is anyway increasing the TB size could cause that...I have no idea how they caused that, but there must be more to the story.
     
  10. pma1010

    pma1010 F1 Rookie
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    There is some clarifying material in the text (page 120) of the GC book. Basically Guy Croft built the motor c/w race cams ("3D" grind), valves (42.5/37mm), 10.2:1 pistons. Dyno'ed with the 48mm carbs. Torque curve shown. They couldn't understand it. Checked compression, checked cam timing etc. Finally figured it was low air velocity in the carbs. Pulled off the carbs, put on the 45s with the smaller venturis, dyno. Same motor, same day: "...results speak for themselves".

    I don't know if this is the 1800 or 1600 cc 4 FIAT/Lancia with 2, twin choke Webers, but, a 400 - 450 cc cylinder being fed with a 48mm carb/42mm choke "feels like" a lot when compared with a 36mm venturi within a 40 DCNF (my set up) filling a 375 cc cylinder 308. Perhaps someone out there can summarize the flow math and provide us with guidance.

    Russ, I apologise, I had not meant to hi-jack the thread.
    Philip
     
  11. Dave

    Dave F1 Rookie

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    Not to hi-jack the hi-jacking of the thread, but...
    It would be so awesome if we could all get together and brainstorm this type stuff over a few beers.
     
  12. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Phil
    I think this is very salient to the discussion - I always watch in amazement between you and Mark.

    I'm learning a lot.
     
  13. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    There is a book/cd combo at Barnes and Nobles called 'Desktop dynos' that runs all of the flow calculations when you put in the parameters. While I know it is not exact, I'm thinking about getting it to rough out the parameters.
    I think the qv will yield increase hp and torque across the band, but want to tweak the cam timing for a bit more torque in the 3-6K band.
    Will look at going to the 36mm venturis once the new cams are in, but may need to keep the 34s to keep the velocities high for streetability.
    Will keep the 244 exhaust duration and run the intake up to 255 - 260. Am still looking at overlaps and lobe centers. Any suggestions welcome.
     
  14. mk e

    mk e F1 World Champ

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    Russ,
    Normaly, long intake/short exhaust is a good turbo cam...making plans we don't know about????

    I think I would go to about 250-255 advertised, 210ish at .050" lift and put the lobes separation around 110-112 degrees to start with. That should shift your hp power up a little, to maybe 7200-7500. I think that's as far as I would go and still call it a daily driver. Are you running stock compresion? Any head work?...I should know, but I can't remeber. I think these cams will work best with around 10:1 CR, you'll probably be OK with stock head though now that the stock FI (also read flow restrictor)is gone.

    Phil,
    I was thinking TB not carb, my mistake. I guess if you put a carb on that is soooo big there is just no velocity, then there is just no way it can carburette. With injection, you can alway get the fuel right, so a way oversize TB just makes it hard to control RPM, but hp/torque don't change.
     
  15. pma1010

    pma1010 F1 Rookie
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    Russ
    Why not shoot Guy Croft an email (gcengines@aol.com). His site is www.guy-croft.com. I'd guess he can provide pretty good guidance from his experience tuning Fiat/Lancia's.

    Did Michelotto produce a 4v engine in the 308?

    Mark,
    FYI, I have a table of Ferrari engines produced from 1946 to 1974 from "Ferrari. The Man. The Machines" (excellent read btw). On the 1960, 6 cyl. 156 1.5L F2 car, Ferrari used 3 42 DCN carbs where each cylinder is only 246.1cc so bigger throttle bodies might be do-able on a 308 (365cc per pot). As I said in my earlier post, I don't have any feel, apart from believing that if Ferrari (or was it Garage Franchorchamps that ran the Le Mans 308 entry?) thought bigger carbs would provide more top end for the Mulsanne straight, he'd have done that on the 1974 Dino. In reality, they ran P6 cams with 40 DCNFs and 36mm chokes (same as I am running).

    Russ, also, weather permitting, I'd be tempted to try the 36mm venturis in your car if you are prepared to play around with the jetting. I should get the O2 kit this week and will get it installed on the car asap to provide some data on AF ratios. Also, weather permitting here in the Midwest.
     
  16. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Here we go. Have ordered the camshaft cores to be re-profiled, and although not as applicable to the 4v, am looking at an early 308 Euro 2v profile, which with a 4v head should be pretty yee-ha.

    Just to review the stock settings (intake has been matched and polished):
    3.2 liter 4 valve engine with stock 9.2 compression. intake - 16 btdc to 48 atdc (244)
    exhaust - 54 bbdc to 28 atdc (244)
    overlap 26 degrees.

    Would like to keep the stock lift for reliability and to keep stock springs. This will STILL be a trip and daily driver, so nothing too radical. Target is still 95+hp/liter. Exhaust is already opened up with a tubi and Stebro cat resonator.

    Here is the Ferrari Euro 308 2v profile:
    intake: 30btdc - 50 atdc (260)
    exhaust: 36bbdc - 28 atdc (244)
    overlap 58 degrees.

    I may be wrong, but I think I have one of very few, if not the ONLY carbureted Ferrari 4 valve engine in a street car, so no 4v camshafts to compare other than 348s and the like.(intake:247, exhaust: 243; overlap 24 degrees)

    Am waiting on a call from Webcam to discuss.

    As you have seen from the other post, will hopefully dyno the car tomorrow if the wx holds.

    any advice appreciated
    many thanks to all.
    Russ

    OBTW, for those of you new to my few ongoing upgrades from the old board:
    I've only uprated to 17" Speedline wheels, Michelin Pilots, mounted drilled brembo rotors, ss brake hoses, put on a tubi exhaust and replaced the cat with a Stebro resonator, switched the Kjet to 4 Webers, puting on an adjustable single distributor, having performance cams reground, and now am lowering the rear. Am I having fun or what?
     
  17. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    6,335
    F355 is 252 Intake and 256 exhaust with 32 degrees of overlap (16+16). (Intake might be as small as 248.)

    Back in my hot rodding days, we would run as much as 70 degrees of overlap (35/75 cams==3/4 race cam) on what we called a streetable car. This corresponds to 290 degrees of duration.

    The header needs to be sized to the cam-duration less cam-overlap, and the collector sized to the cam-overlap for best power and widest power band. So, you can't just throw a cam at an existing header, nor can you throw a header at an existing cam. They should be treated as a package.

    If you keep the cam-overlap as is, the exhaust residuals will be within the CATs design range. Highly recommended unless you are building a header to match the cam! As you increase duration, you loose low end to gain top end power. If you do increase overlap, bu sure to set the timing point for the 3rd exhaust pipe above the self resonance point of the header to avoid a nasty flat spot around 3000 RPMs.
     
  18. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Mitch -
    great , these are the things I am trying to learn.
    best
    rt
     
  19. pma1010

    pma1010 F1 Rookie
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    One thing Dema drummed into me. When referring to duration, lift and overlap, recognize how it is being measured -- with checking lash, operating lash, absolute etc -- it can all get a bit confusing.

    BTW, the P6 (2V) cams are about 95 degrees of overlap. And I am sorry, I don't recall if this is absolute, checking or operating lash!
     
  20. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Talked to Dema Elgin today.
    Plan is to keep the stock exhaust ( 244@20 ) and lengthen intake duration to about 255 - 260 @20 as optimal for the street.
    Will not alter overlap very much, but am open to suggestions.
     
  21. pma1010

    pma1010 F1 Rookie
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    Did Dema have a rec on lobe height and ramp profile?
    Philip
     
  22. Dale

    Dale F1 Veteran

    Oct 7, 2003
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  23. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Dale - quite a website!! Thanks.

    Philip
    Dema was not so much in a talkative mood. I'll be sending him all the specs and the 2 intake cores and we'll go from there. He said he thought he could re-grind for $600. Trutlands mailed the cam cores today.

    He did remark with a groan on how much work the P-6s were.

    May just do the cams and the new distributor (since it requires putting the drive in) at the same time.

    Check the 3.2 w/ carbs part 6 for the latest on carb jettings.

    best
    rt
     
  24. jjstecher

    jjstecher Formula Junior

    Jan 21, 2002
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    John Stecher
    Ok guys I have to revive this thread as I am looking to get a good new set of cams ground for the 348 to get myself both a little more top end and get the cam to be a nice balance between track and street.

    Looking at my calculations the 348 cam is really damn weak on the duration 248 intake / 244 exhuast. What do you think about going to a 260 duration intake and leaving the exhaust the same? Or should I move both out in duration? I dont want to screw to much with overlap as I have never had much luck building power with it on SB Chevy's and I cant see it applying here either. Estimates on hp from anyone with desktop dyno? My old CD wont install on Windows XP so I am screwed for the moment. :(

    I will be eternally grateful for any help :)
     

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