Cam...Could I do better?

[dwbiggs]

Current cam:
Hughes 3844 hydraulic 238/244 .536/.540 108 CL

Question: Could I do better with my combination with a solid or roller and have the same vacuum(11")/idle/drivability characteristics? Talked to a fella running a 461 ci Pontiac and he seems to think that I am holding combo back with cam. He suggested at least a solid in the 250 range duration.  He also suggeted a 112 CL for street.  Like to hear the input of the more knowlegable.

Combo in sig.

Dan

[MEK-Dangerfield]

Dan,

  That is a mild cam. What is the stall speed of your torque converter, and what rear gears do you have? I wouldn't worry too much about vacuum at idle, unless you have power brakes. My cam is in the 290 range, and I still pull 12" at idle. That is a little tooooo much for my mainly highway use, but it does have a nice lopey idle.

  Like I said, we don't know your converter specs or rear gears, or even how you drive your car, but given the compression ratio of your engine, your carb. could be a tad too small too.

  Mike

[matt63]

I'm surprised that you have that much vacuum with that cam based on my MP509 cam which had similar specs.  I would definitely talk to your cam supplier i.e. Hughes to get a recommendation.  They will want to know how much head work, if any, has be done as a bigger cam may not get you any more power and will decrease drivability.

[Chryco Psycho]

that actually is a decnt cam , 244* is approx 292 ad duration & should pull above 6400 easily , you have decent vacuum as well , with iron manifolds you would gain somewhat with a 112* CL but with headers that cam will work well , I have some other grinds that could get you into the 570-590 lift range with similar duration but depending what heads you are using & how much port work has been done I doubt the gain would be significant 

[dwbiggs]

Thaks guys...I am running a Turbo Action 10" tight converter and 3.55 gears.  The heads are out of the box Eddys.  And I do have power brakes.  I was just wondering if I could run a solid/solid roller that would yield more HP with the same or better idle characteristics.  I have no problem with the idle I have now and the car runs good...even with the 750 vacuum carb...but I'm just thinking if there is a better cam out there why not?  BTW, what does a roller setup cost and whats involved with install??


Dan

[matt63]

My hydraulic roller was $800 US for cam and lifters plus shorter pushrods and adjustable rockers.

[moper]

So it's already being driven then? Do you have any track times for it? That cam is what i'd classify as a medium size for a 3.75 stroke. You say it's 0 deck, what head gasket, and was the compression verified by measuring stuff? You can gain drivability by adding compression with any cam design. With modern heads, and good pistons, you can get up close to 11.25:1 and be safe from detonation with careful tuning. As to the swapping to roller...I wouldnt sepnd the money on a hydraulic roller. They are limited because of the nature of a hydraulic lifter, and the flat tappet performance cams are very similar to them, just a little smoother, and a little more power. But the power comes from lost friction, not really the cams making more..just not using as much. Solid rollers can be installed, but they are more money, and if it was done thru me you would have to bush the lifter bores. Typical costs are in the $1600 range when everything is said and done, and that's when the engine is being rebuilt. So to reftrofit, you'd have to pull it all apart. So add freshening costs to that (another $3-500). Typically, cams work like this. Hydraulics run quiet, need careful setup, and are maintenance free once put in. Solids need lash adjustments (roughly once a summer), require different pushrods and rockers, and again need careful setup, but make more street type power (torque and better idle for similar sized grinds) than the hydraulic. Rollers need the same 1-2times a summer lash adjustment, lifter bushings, pushrods, rockers, valve springs, oil pump drive, and the cam core and lifters are 3 times the cost of the flat tappet designs, but give the smoothness, idle quality, and both street and race type power (torque, idle quality for given size, and pull to high rpms very easily). If it were me, I'd upgrade to 11:1 static compression, and run a solid flat tappet cam if you are looking to improve. But, back to the first question...What does it run now? MHP in the 1/4 is the best wqay to see if it's doing what it should be now. Perhaps there are things to tweak. I'd think that engine in your car, with good tires, should be running at least high 11s, with mid 11s within reach. Thats about 490-510hp give or take. 

[dwbiggs]

Moper,

I am sure the CR id 10.5 with gasket...I told the machine shop that is what I wanted and they  new what gasket I was using.  I have not run it at a track yet but will be putting it on a chassis dyno pretty soon.  One place to tweak would be the carb, it is a Holley 750 80508 vacuum carb I ran on the car with the previous build.  It has stock jetting and I think I just put a lighter secondary spring in.  The car surprisingly runs well, no flat spots and is real responsive.  I haven't made any hard runs with it so I don't know if it will fall on its face at high rpms.  For my dyno runs I was thinking about a Proform main body or a larger 850 carb to try.  This car is 100% street and if going over to a solid would yield less than say 20HP I will stick with what I have...its just that people are telling me that solids will make such a big difference without harming streetibilty.

Dan

[Chryco Psycho]

I generally will use solid cams as a first choice Unless the customer doesn`t want to spend the $$ to buy rockers etc

[dwbiggs]

Chryco,

So you think I should be happy with what I have and shut up eh?  I guess with 3.55 gears I am pushing it with the cam I have.  Guess I do have some tuning opportunities with the carb when I get it on the dyno.  What kind of HP numbers should I expect on a chassis dyno so I know where I am when I see it? 

Dan

[Chryco Psycho]

as I said the cam is decent , there is always more but to switch to a solid cam & rockers & pushrods woulb in in the area of $1000 & you might gain 15-20 hp , I would get it on the dyno tune the carb , I usually get 15-25 hp just tweaking timing & carbs on the dyno

[moper]

as I said the cam is decent , there is always more but to switch to a solid cam & rockers & pushrods woulb in in the area of $1000 & you might gain 15-20 hp , I would get it on the dyno tune the carb , I usually get 15-25 hp just tweaking timing & carbs on the dyno

That was mt thinking too. See what you have, and how big a smile it gets from you. If it gets the numbers you intended, dont swap until you feel you need to. If it doesnt, find out why. Also keep in mind, chassis dynos are tools, adn the results vary by your driveline too. So if it lets you down (most times the numbers are lower than you thought) take it to the track and see what it weighs, and how fast it gets to in the measured 1/4. Then you know if it was just the dyno, or the engine. Tune for air and fuel, and to maximize power curves. Dont tune "for 420hp to the tires".