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jenks

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About jenks

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    Junior Member
  • Birthday 02/03/84

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    Fort McMurray, Alberta
  1. Disappointing L28 Dyno Results

    I don't see any threaded boss between #5 and 6. The cam towers are shimmed, so it appears that the combustion chamber volume was achieved through milling the head. Not sure on the details around how this played out with the valve train geometry, but the wipe pattern on the rocker arm pad and valve tip all seem to be ok. In other news, I decided to check the cylinder leak down last night as I there seemed to be a lot of blow by (decent amount of smoke and oil coming from the valve cover vent). Found that cylinder #3 was gurgling the rad pretty good. . I guess I'll be checking the items noted above after I get a new head gasket in there. This new engine is turning into a good learning experience if nothing else.
  2. Disappointing L28 Dyno Results

    I only had a few minutes in the garage today, but I did check the mains and air correctors and they are in fact both 160 and 160. Maybe because the engine is so anemic on the top end, the air correctors just don't have that much of an impact on the AFR. Just speculating here. I also popped off the valve cover and confirmed that the adjustable cam sprocket is still at the same setting that it was when it was assembled by the builder - supposed to be straight up. I know, I know - I will verify (not trust) that it was set up properly from the get go. Just didn't have time to get a degree wheel on it. I will chase down and verify the cam and ignition timing as you guys suggested. Jon, By all indications, the head is indeed a N47 and not the MN47. The build sheet has my combustion chambers at 37cc from the stock 44.6cc.
  3. Disappointing L28 Dyno Results

    Yep, you're reading the timing curve right. I was thinking the same thing you were, so I had asked them to run some 108 octane and put the timing curve back in that the car that it was delivered with (33° all in by 3000). That timing curve only made 149ft/lb. This is the only L-series I've seen that needs only 26° to make peak torque. Seems a bit odd... I'll double check the cam and make sure it's installed straight up as per the builders recommendation. I didn't actually check this before sending it off to the dyno as it was set by the builder. Maybe I shouldn't have assumed, but I'll check it. I'm with you guys on the 'not enough air' theory based on how the torque falls off a cliff at 5000. Having said that, I think the carbs should be good for a bit better than 156hp, but given my lack of experience with these engines, what I 'think' doesn't exactly carry a lot of weight. I'll go do some more searching and see how people have been doing with the N47 head as well. Thanks for your comments guys.
  4. Disappointing L28 Dyno Results

    Normally I would agree, but I think at the end of the day the AFR curve should trump whatever I think the jets should be. If they were in fact too small, wouldn't the curve be way too fat on the top end? I'll pop one out tomorrow and have a look. Maybe the tuner was mistaken on which ones ended up in there. So did you give up on the triples and go FI?
  5. Disappointing L28 Dyno Results

    I don't believe too much was done in the way of significant port work. More just cleaning it up and smoothing things out as opposed to a lot of material being removed. You're definitely not the first person that has mentioned that the carbs are too small, but I didn't think they choke things up that much. Seen a few guys with SUs making a decent amount more. I suspect the 40s would outflow the SU set up although I haven't actually seen the data to validate that assumption.
  6. Hey guys, I just got my car back from the dyno and I was a bit underwhelmed with the results - 156hp and 161ft/lb at the wheels (curves with AFR attached). The long block was assembled by a pretty reputable builder with the following specs: Bored out L28 to 2.95L F54 block with a N47 head 11.3:1 CR 290° cam with 0.490" lift Then I came along and messed something up with the following: MSA 6-1 header into 2.5" exhaust MSD 6AL-2 programmable ignition box triggered by a 280zx dizzy Cannon intake manifold Weber DCOE40s 36mm chokes 160 main 160 air correction F2 emulsion tube 3.5 A/V 55F9 idle The timing curve was initially dialed in by the tuner to eliminate knock with the 94 octane that I delivered the car with. The dizzy is locked out at 35°BTDC and the timing map they arrived at is attached. After the 1st round of results, I asked them to run some higher octane to get in all the timing that I thought was left on the table to control the knock. With 108 octane the car didn't pick up any power from advancing the curve that was developed with the 94. I found that a bit odd, but not sure how you argue with the data. The dyno was an eddy brake Land and Sea Dynomite axle hub set up. Let me know what your thought are on where I could look next, or if you think something is really bottlenecking the output. From all the searching I've done, it seems like all the hardware should support 200+whp, but we're not even close. Thanks! L28 dyno.pdf
  7. Building an L28 (NA)

    156 at the wheels. I don't want to hijack a thread here, so I'll be posting all the info and specs in the next few days to see what kind of feedback is out there.
  8. Building an L28 (NA)

    Following this with a lot of interest. I put in the STR stage III last year with DCOE40s, and finally got it on the dyno this year. Pretty disappointing results (pretty sure it's something I did and not the builder), so I'd like to see what another similar build will do!
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