Custom ground camshaft, low power

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sbh126

sbh126

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Okinawa, Japan
I've been told by multiple people that I have a poor choice in camshaft for my build. And according to the dyno I'm thinking they're right. Here's the specs I have;

Grind: HIFLOW1H
LOBE SEPERATION ANGLE : 108
OVERLAP : 80
INTAKE OPEN : 40
EXHAUST CLOSES : 40
INTAKE CLOSES : 76
EXHAUST OPENS : 76
RUNNING CLEARANCE : 0.00 HOT
VALVE LIFT (INT/EXH) : 0.472 / 0.472
DURATION (INT/EXH) : 296 / 296

CHECKING FIGURES AT .050 TAPPET RISE
OVERLAP : 12
INTAKE OPENS : 6
EXHAUST CLOSES : 6
INTAKE CLOSES : 42
EXHAUST OPENS : 42
DURATION INTAKE : 228
DURATION EXHAUST : 228
LOBE LIFT INTAKE : .315


This is in a 74 duster with a 440 (just rebuilt) and a 4 speed. 3.55 rear gear and 27" tires. I'm using stealth aluminum heads, a dual plane edelbrock rpm intake, a Holley 870, Schumacher headers with 1 5/8 primary and 3" exhuast.

I dont know a whole lot about what makes a good cam and I'm not entirely sure whats wrong with the cam I have. After looking at my cam numbers compared to several cams on summit it looks like the main difference is that I have low lift compared to similar cams. If this is the only issue couldn't I just use some 1.6 rockers to increase lift? According to my math 1.6 rockers would give me similar numbers to the mopar performance 509 cam. .504 lift, 108 lsa, and 296 duration instead of 292. Is there something I'm overlooking? I know this is somewhat a band aid for the real problem but I figure I'll be able to use the 1.6 rockers with a new cam down the road anyways. What do you guys think? Open to suggestions.

Right now I have stock worn out 1.5/1.4 rockers.
 
whats your compression? If your IVC or ABDC is 76 unless you have 11.8 compression you will not have have 8.5 DCR which will give you power and TQ, But you can have lower DCR. You just need to know what DCR you are right now meaning IVC ABDC, Compression CC of head
 
Can you list the rest of the engine specs? Who ground the cam? Was it degreed? What kind of power numbers are we talking about?
Larger duration vs actual lift is not a big deal, but other factors amy make any cam not work as intended. If the engine in a place where you can get some cylinder pressure readings? (is it in your car?)
 
Fst73_360 said:
whats your compression? If your IVC or ABDC is 76 unless you have 11.8 compression you will not have have 8.5 DCR which will give you power and TQ, But you can have lower DCR. You just need to know what DCR you are right now meaning IVC ABDC, Compression CC of head
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I was using a compression calculator and had all numbers except the exact piston deck clearance. I'm running stock forged 1970 crank, stock rods (resized), kb237 pistons. I know there is some variable in actual engine block deck height which can affect my piston to deck clearance but I should be close to 0 deck height with my pistons. I plan on getting an actual number next time I have the heads off. I was coming up with 10.35 or 10.65 to 1 depending on my unknown variable. When I plug this into a dynamic compression ratio calculator I come up with 7.39 or 7.60 to 1. Is 8.5 DCR the magic number I should shoot for? I'll check my actual cranking pressure today if I can get out to the garage.
 
moper said:
Can you list the rest of the engine specs? Who ground the cam? Was it degreed? What kind of power numbers are we talking about?
Larger duration vs actual lift is not a big deal, but other factors amy make any cam not work as intended. If the engine in a place where you can get some cylinder pressure readings? (is it in your car?)
Click to expand...

Engine is a 77 440 block bored .040 over. forged crank out of a 70 440 with journals turned down to clean up a spun bearing. kb237 flat top pistons with valve reliefs. What other specs do you need? I local machine shop (Edge bros) sent off to have it ground. Not sure who ground it though. I payed for it to be degreed when I had my long block assembled so It should have been done. I'm making 310 Hp at the wheels in my duster at 5500 rpm. (365ish at crank im guessing?) I'll have to look up the TQ numbers. Cant remember off the top of my head but I believe they were lower than HP. I can get pressure reading from 6 of the cylinders. #4 and #6 aren't worth the hassle. I can hardly put the spark plug boot on.
 
sbh126 said:
I was using a compression calculator and had all numbers except the exact piston deck clearance. I'm running stock forged 1970 crank, stock rods (resized), kb237 pistons. I know there is some variable in actual engine block deck height which can affect my piston to deck clearance but I should be close to 0 deck height with my pistons. I plan on getting an actual number next time I have the heads off. I was coming up with 10.35 or 10.65 to 1 depending on my unknown variable. When I plug this into a dynamic compression ratio calculator I come up with 7.39 or 7.60 to 1. Is 8.5 DCR the magic number I should shoot for? I'll check my actual cranking pressure today if I can get out to the garage.
Click to expand...

I'd also like to add that this is down at the coast. Low elevation. I plan on moving to Utah in about a year and will be at about 5000 feet. According to the calulator I'm using that'll drop me from 7.60 to 6.75. yikes.
 
What type carb?
What size carb?

You definitely should be making over 365 horse at the crank. That's small block horsepower. lol
 
agreed something doesnt sound right. your build sounds like an easy 500+ hp at the crank they say you lose 15-20% at the wheels but that should still be upper 300's and low 400's
 
72ScampTramp said:
agreed something doesnt sound right. your build sounds like an easy 500+ hp at the crank they say you lose 15-20% at the wheels but that should still be upper 300's and low 400's
Click to expand...

I'm glad to hear it. I've been thinking the same. You can imagine my dissapointment when I saw the dyno results. :banghead:
 
You really need those pressure numbers. What cam was reground to those specs? Does the paperwork with the engine actually show what the cam degreed to? You should have an assembly sheet with that info. If you're getting 300 to the tire, it's got problems. I would expect about 50hp more than that, on the low side.
 
Here's the compression results. I tested cylinders 1,2,3, and 8. all were within 2 -3 of 150psi. All were tested with 4 plugs installed in the engine and 4 out. I propped the throttle all the way open but saw no real difference between that and closed when it came to psi. I connected the battery to my trucks battery while it was running so I could get it to crank strong and hard for all cylinders.
While I was at it I used a leakdown tester just to check things out. All 4 cylinders were in the 40-50% range. I cranked the engine over until I could feel the cylinder on the compression stroke and checked it at about half way up the cylinder at 80psi. Did I do anything wrong? or are my rings shot? I couldn't really notice any air coming out the carb or exhaust but I did notice a slight amout coming from the dipstick tube. Same story for all cylinders. Of course this is a much smaller hole than the carb or exhaust so it would be easier to notice. How nmuch is a normal amount? I know there will be some leakage past the rings. I have chrome moly rings and the whole motor has maybe 1000 miles on it tops. Is it possible the rings haven't broke in all the way yet?

Also, my vacuum at 800 rpm is at 10", 1200 rpm is at 14". Isn't this alot of vacuum for a 108* LSA cam? I'm not to concerned with keeping my vacuum up because I dont have power brakes or anything that runs off vacuum. Minus the gauge I guess.
 
150 psi is low I like at least 180 which 8.5 DCR will usually get you... if YOUR DCR is 7.6 and the IVC is 10.6 your going to need 11.8 with that cam to get 8.5 unless you get a smaller cam like a XS282 S or something
 
moper said:
You really need those pressure numbers. What cam was reground to those specs? Does the paperwork with the engine actually show what the cam degreed to? You should have an assembly sheet with that info. If you're getting 300 to the tire, it's got problems. I would expect about 50hp more than that, on the low side.
Click to expand...

I dont think it was a reground cam. At least they didn't say anything about it being one. I never got any kind of assembly sheet. I've got a reciept for what I payed for and a sheet with the cam specs that I already posted on it. I really wish I would have done all the work myself.
 
sbh126 said:
Here's the compression results. I tested cylinders 1,2,3, and 8. all were within 2 -3 of 150psi. All were tested with 4 plugs installed in the engine and 4 out. I propped the throttle all the way open but saw no real difference between that and closed when it came to psi. I connected the battery to my trucks battery while it was running so I could get it to crank strong and hard for all cylinders.
While I was at it I used a leakdown tester just to check things out. All 4 cylinders were in the 40-50% range. I cranked the engine over until I could feel the cylinder on the compression stroke and checked it at about half way up the cylinder at 80psi. Did I do anything wrong? or are my rings shot? I couldn't really notice any air coming out the carb or exhaust but I did notice a slight amout coming from the dipstick tube. Same story for all cylinders. Of course this is a much smaller hole than the carb or exhaust so it would be easier to notice. How nmuch is a normal amount? I know there will be some leakage past the rings. I have chrome moly rings and the whole motor has maybe 1000 miles on it tops. Is it possible the rings haven't broke in all the way yet?

Also, my vacuum at 800 rpm is at 10", 1200 rpm is at 14". Isn't this alot of vacuum for a 108* LSA cam? I'm not to concerned with keeping my vacuum up because I dont have power brakes or anything that runs off vacuum. Minus the gauge I guess.
Click to expand...

the piston needs to be at TDC or a valve could be open... (probably not at half way though lol)
 
Fst73_360 said:
150 psi is low I like at least 180 which 8.5 DCR will usually get you... if YOUR DCR is 7.6 and the IVC is 10.6 your going to need 11.8 with that cam to get 8.5 unless you get a smaller cam like a XS282 S or something
Click to expand...

If I change my head gasket fro a .040 compressed thickness to a .020 it'd bump me from 10.65 to 11.2. Better but not all the way there yet.
 
I would wait and see what others say first. Might be safer to just change the cam. Check my past threads, I went through the same thing with too big of a cam killing Compression, I was able to sell it though.
 
Cam suggestions? I'd like to replace rockers as well. 1.5 or 1.6 will depend on the cam I guess. Besides the cam and rockers I'd like to keep everthing else as is. Unless there is something clearly wrong with my setup. My end goal is as much Hp/Tq as I can get. this is a street driven car but will see the track every few weeks. I dont need it to idle like my wifes jetta either. I'm fine with it being choppy as long as I'm making some decent power.
 
im not a big block guy but maybe XS282s for the BB? Should give you better TQ and power and raise that DCR to around 8.4-8.3 and run 91, but wait for others to chime in, they will be here soon.
 
That sounds like an old erson grind,low lift and mild ramps,similar to a comp 280 magnum but a bit smaller.What are the heads as far as performance?,how they are done is a major factor with regards to the cam.
 
I was kinda wanting to stick with a hydraulic flat tappet cam. whats the advantage of a solid cam over a hydraulic?
 
lead69 said:
That sounds like an old erson grind,low lift and mild ramps,similar to a comp 280 magnum but a bit smaller.What are the heads as far as performance?,how they are done is a major factor with regards to the cam.
Click to expand...

Here's some info on the heads I pulled from 440source.
Cylinder Head Technical Specs: ​
Intake Port Flow (at peak ~600 lift):290CFM @ 28" of waterIntake Port CC: 212CC*Intake Valve Head Size:2.14"
Exhaust Port Flow (at peak ~600 lift):220CFM @ 28" of waterExhaust Port CC: 72CC*Exhaust Valve Head Size: 1.81"
 
lead69 said:
That sounds like an old erson grind,low lift and mild ramps,similar to a comp 280 magnum but a bit smaller.What are the heads as far as performance?,how they are done is a major factor with regards to the cam.
Click to expand...

Winner... Old erson grind
 
sbh126 said:
I was kinda wanting to stick with a hydraulic flat tappet cam. whats the advantage of a solid cam over a hydraulic?
Click to expand...

Man, it's night and day! I will never run a hydraulic again! You should contact Clay Smith in SoCal. Give George your specs and he will get everything you can out of that build and you will only need a cam. No need to change your head gaskets. I can't say enough about how great these people are and they are one of the oldest speed shops on the planet.

http://www.claysmithcams.com/

714-522-3301
Clay Smith Cams
5870 Dale Street
Buena Park, CA 90621
 
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