Need advice (free) for a street driven 351c with a c4, stock converter. I am considering a 204 intake duration, 214 exhaust duration hydraulic cam with .488" lift. 3.31 gears, car(1955 t-bird) weighs 2,900 #. Thanks
I used this in my 351M rebuild .... Idle is smooth ... tiny hint that there is something more .... https://www.summitracing.com/parts/cca-cl32-241-4/overview/make/ford
Good that it is 2V. I find the 4V ones too fussy for street use. What is the lobe separation angle (LSA) on the cam you posted?
Clevelands need more exhaust duration than intake The cam you listed is not a bad choice. I would try for a little more duration and a wider LDA. The "idle" sounds cool but you give up mileage with a pozer cam. As idle vacuum drops the idle circuit needs to get richer and the idle circuit stay in play to around 2000 rpm
Best to be conservative unless the CR is over 9.5:1 or so. If you go with a LSA of 112-110 it will have better street manners which is better with the automatic with a stock converter. The XE256 or XE262 are good choices. Look at the Lunati Voodoo cams, I'm running one in my SBC and am happy with it. https://www.lunatipower.com/voodoo-hydraulic-flat-tappet-cam-ford-351w-302-h-o-256-262.html
The 204/214 cam would be fine if you are happy with a stock converter and power from idle to 5500rpm. It may be better suited to a dual plane manifold like edelbrock performer RPM rather than your single plane but the 750 holley, headers and ignition are spot on. If possible use the small chamber quench heads and seek advice from cam manufacturer about how much compression your local fuel will allow, careful though... Take cam advice from the internet with a grain of salt. If a cam grind gives a certain result in a SBC the same grind will give a very different result in your 351c. Your engine has very good heads, the SBC not so much. Tune the Cleveland by selecting carb, intake and headers to let the cylinder heads breathe for HP and don't overcam or you risk losing low end torque. For better advice ask for a recommendation from Bullet Cams or check out www.351c.net for lots of Clevo information, I don't think anyone on there will be advising a Comp Cam.
I am running stock spec 70 SCJ cam in both 351C 2bbl/Edlebrock $bbl intake/600CFM/stock exhaust manifolds/2 1/4" system into turbo mufflers. The engine in my street rod gives 17 - 18 MPG, has just a hint of "thumping", gives good low end performance running with a FMX and 2.75 8". Jury is still out on the other engine that is in the Ranchero. The sound , idle, throttle response are almost exactly the same as the street rod. It is running on an AOD/3.56 9". No road trips yet to measure mileage.
With good flowing heads, the C doesn't need a lot of duration to fill the cylinder. They are also sensitive to valve overlap with a street exhaust system. More so with the 4 barrel heads than the 2. Unless you have a very free flowing exhaust, keep the duration reasonable and go with a wide LSA. The factory CJ hydraulic cam had a 117° LSA and the HO (Boss) mechanical had 116° LSA. Almost impossible to find in off-the-shelf aftermarket grinds, and even custom cam grinders are reluctant to go more than 114°. The wide LSA reduces the peak torque, but gives a wide, flat torque curve that makes the big heads less temperamental on the street.
I went to my shop this morning to try using full manifold vacuum instead of ported vacuum. I tried sevaral timimg settings, settling on 30* at idle with the full manifold vacuum. it idles very slow now(no tach yet), with a choppy lope and shakes the fenders. Just the idle I wanted!( I do not know the specs for this cam , i just measured the lobes with a mic to figure the lift before I installed it.) Very loud also, with stock T-Bird 1 3/4" tailpipes and straight through 12" mufflers. i'm spending money I don't have(credit card) now, so a new cam with less duration will have to wait. i do have another 351c short block I plan on building with the correct cam, heads, etc in the future. But I am happy as a hog in shit with this engine, so thanks for all the advice , Henry.
"most" cammy/snotty idling like a LOT of initial advance to get clean/crisp throttle response. But....don't over do the total advance. Light advance springs for a quick advance of 34-36* and no more. Good heads don't need a bunch of timing to make power but quick advance and a lot of initial advance could be what it needs. More initial advance normally increases the curb idle RPM....which in turn lets you close off more of the primary plate and keep it in the idle circuit. Idle speedjust high enough to allow engine to idle in gear and holding the brake. My SBF with Windsor jr. heads like 20* initial with about 16*mechanical timing for a total of 36*. All in by 2000RPM. One good thing about a snotty idling cam is NOT the poser sound so much but......it bleeds off some of the compression at lower RPM where lugging could lead to pinging. A big deal when running healthy CR and todays weak-kneed gas. Another reason why the cam guys recommend higher compression when running lopey cams. The "sound" is just a nice benefit it gives. Stock converter could hurt you when trying to idle-in-gear. 6sally6
The Jalopy Journal
