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Dynamic compression ratio Q with new cam
https://www.slantsix.org/forum/viewtopic.php?t=62120
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Author:  wjajr [ Thu Mar 22, 2018 5:04 pm ]
Post subject:  Dynamic compression ratio Q with new cam

New cam showed up today!!!

225 ci 1968 block, 1977 peanut head no EGR

Dimensions:
Bore 3.430"
Stroke 4.125"
Rod length 6.698"
Head volume 39 to 40cc
Vel Pro Head gasket dia 3.525"
Head Gasket thickness .039"-0.041"
Piston down in hole .180"

New cam Oregon grind # 346
rocker ratio 1.5
Lobe separation 108*
Lobe center line Int= 1048 Exh=112*
Cam lobe lift I= .317" E=.319
Lash I=.012" E=.012"

Cam timing at .050" tappet rise:
Intake open=13 BTDC Close= 41 ABDC
Exhaust open=46 Close=2
15* overlap at 0.050"
Lift at valve intake= .476" Exhaust=.479"

Static compression ratio = 9.6


One calculator gave 8.7:1 dynamic ratio Elevation= 300'

Second calculator gave 8.2 Using 10:1 static dynamic =8.5

If my engine actually has static compression 9.6 and dynamic 8.16, from what I recall from other posts here, it should run on pump gas with no problem, is that right?

_________________
67' Dart GT Convertible; the old Chrysler Corp.

82' LeBaron Convertible; the new Chrysler Corp

07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Author:  sandy in BC [ Thu Mar 22, 2018 6:21 pm ]
Post subject:  Re: Dynamic compression ratio Q with new cam

You should be fine as long as your gears/convertor science is correct.

My Valaint with similar CR #s ran fine on 87...( 5 speed/ 3.55/ 24" tires)

Author:  DusterIdiot [ Thu Mar 22, 2018 7:33 pm ]
Post subject:  Re: Dynamic compression ratio Q with new cam

I ran it on my favorite DCR calculator... you are fine... it will be closer to 8 DCR... it should run on pump gas just fine (some recurve fine tuning will
allow it to run on 87 vs. 89).

Looking like a nice torque band from 2k-4500 rpm from 229 peaking at 241 ft/lbs at 4K, around 196-216 hp peak at 5000 rpm... will be very positive
at street rpm vs. a stocker with a super six and very kind rear gearing.

Author:  wjajr [ Fri Mar 23, 2018 10:50 am ]
Post subject:  Re: Dynamic compression ratio Q with new cam

3.55 rear gear, 2600rpm stall converter, 24.5" tires Runs 60 mph @ 3000 rpm.

Author:  sandy in BC [ Fri Mar 23, 2018 1:50 pm ]
Post subject:  Re: Dynamic compression ratio Q with new cam

Nice to see all those numbers lining up.

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