Slant Six Forum :: Cam hydraulic or mech.

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Cam hydraulic or mech. https://slantsix.org/forum/viewtopic.php?t=59067	Page 1 of 1

Author:	Mikedodge [ Thu Feb 04, 2016 6:17 am ]
Post subject:	Cam hydraulic or mech.
Just wondering about what stock cam is best use in a 225 I am puting together. I have a factory mech. Cam for 1974 and a hydraulic cam fo 1982. The engine will be going in my 1979 powerwagon 4 spd. Std. And 3.55 axle ratio. I don't pan on reving high I want best low rpm torque. Just seeing if any of you guys have tried the two cams before. Or have the specs on the two cams . I am assuming the hydraulic cam will be retarded timming for emission reasons. Thanks mike

Author:	DadTruck [ Thu Feb 04, 2016 9:38 am ]
Post subject:
the stock cam that was in my 83 D150 looked like this: IVO 6 BTDC IVC 42 ABDC EVO 36 BBDC EVC 12 ATDC 105 LSA Duration 228 I&E with the OE cam and a factory BBD, the stock 83 motor fell flat above 3500 RPM,, nor was there much torque at low RPM's. Not much on the bottom end and nothing on the top. That was with the Lean Burn dismantled and a electronic HEI ignition. since the cam is out,, for about 75.00 + shipping + lifters you may want to consider putting a re ground Oregon Cam profile on, if you want something that actually has some grunt. Hopefully you have milled the block or head and raised compression. The stock 83 was about a 7.4 compression, working with a basic stock motor,getting the compression up will give you the biggest bang for the buck. there are several good cam postings listed in the engine FAQ section. here is a posting from when I was working on the cam selection for the 83 D150. http://www.slantsix.org/forum/viewtopic ... light=1333

Author:	Joshie225 [ Thu Feb 04, 2016 9:46 am ]
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The '71-'80 mechanical cam is the best of the factory grinds. Even with the shorter lift and duration 1967 cam I achieved good performance increases through head work (bigger valves and porting), higher compression, and breathing improvements.

Author:	Reed [ Thu Feb 04, 2016 10:26 am ]
Post subject:
I agree 100% with the above posts. The best value for money when imrpoving the slant six is in the cylinder head. Improving compression and flow will reap the most gains. I say keep your stock cam for now and focus on improving the cylinder head.

Author:	SpaceFrank [ Thu Feb 04, 2016 11:10 am ]
Post subject:
I didn't read this site enough back when I was in high school and had my 225 rebuilt, so I wasted some money and had a hotter cam put in with no head work or deck milling. It didn't make a noticeable difference aside from giving the car a lumpy idle. I would agree with most of the "old timers" and say keep the stock mechanical cam you've got. If you haven't put the engine together yet, do all the measurements to figure out the motor's static compression ratio (SCR) as it sits. There are plenty of threads to search for on here explaining the process. Then if you want more grunt for very little added cost, have either the block or head milled to bump your SCR up. If you want to go even further, then you can get into bigger valves and porting.

Author:	Mikedodge [ Thu Feb 04, 2016 3:00 pm ]
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OK thanks I will definitely raise comp. Should I take .090 of head or is that the max I am using a 1982 head I will likely use the mech. Cam I have or maybe do are grind on the original 1967. Cam since I have new lifters and should I take some off deck of block too. I don't want to have to use premium fuel so 9.0 comp.should work. Fuel economy is main goal and reasonable power.

Author:	Reed [ Thu Feb 04, 2016 4:05 pm ]
Post subject:
You need to do the measurements and math to calculate what your dynamic compression ratio will be with the head, block, cam, pistons, and crank you are going to use. Then figure out how much needs to be milled of the head and/or block to decrease the combustion chamber size to attain 8:1 to 8.3:1 dynamic compression. Due to manufacturing tolerances and variations, there is no "take this much off the head/block to achieve this compression ratio" number. A reground cam woudl be fine. Look for info on the RV 15 cam grind.

Author:	Mikedodge [ Thu Feb 04, 2016 4:33 pm ]
Post subject:
OK thanks that rv 15 looks pretty good

Author:	Mikedodge [ Thu Feb 04, 2016 4:41 pm ]
Post subject:
Orfor heavy truck I may go with rv 10 unless that's basicly stock anyway

Author:	DadTruck [ Thu Feb 04, 2016 5:14 pm ]
Post subject:
as Reed stated, you need to do the measurements and calculations, to give you something to think about, for my 83 D150 stock cylinder head combustion chambers were 59 cc I had the head milled .041, that resulted in 53 cc chambers a common formula used on this forum is each .0068 of head face stock removal results in a one cc reduction in combustion chamber volume. that ratio changes as you get really deep into the head... , I also had a very light cleanup cut done on the block. final piston recession measured .162, using a Mahle head gasket with crush of .036 my calculated compression ratio is 8.5 when checking cranking compression, with the small duration cam / early closing intake valve, that I am running I get cranking pressures of 175 to 180, runs on regular gas and even with an aggressive curve in the distributor, no issues with pre-ignition.

Author:	Mikedodge [ Thu Feb 04, 2016 6:56 pm ]
Post subject:
OK thanks for the first nfo I.will be checking it all.soon a d figure out comp. What cam did you use with the early closing Intake and she. Does it close Thanks

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