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I hope.. I'm posting this in the right forum, Please move if I'm in the wrong place !
I need a Cam !!
I'm looking for a cam that ides like its stock, has some split duration with good lift numbers, and can take full advantage of all the parts listed below:
I really need someone that could help point me in the right direction, or can help me make a good solid cam chose for what i want to do.
This car will be a street/weekend driven, road racer, drag racing car that needs to keep good vacuum for brakes and cold A/C..Lol
I'm working with a full weight 1992, Z28, 5.7 Liter & 700R4 Automatic, and 3:23 gears rolling on stock 16 inch wheels, Plus: Subframe Connectors, a 4 point role cage. and 2 spot lights..
Here is a list of all the items on the car now, and the new items going on the car, as I know a lot of this will help someone guide me in the cam selection and choice.
1) Vehicle weight, about 3350 (Or So)
2) The 350 short block is stock.
3) A First Intake system, the lower intake has been "gasket ported to match the heads".
4) New 113 aluminum heads lightly ported, with 58cc and bigger valves: int. 2.00 flowing: 250 cfm @.500
exh. 1.56 flowing:190 cfm @.500
The New (Compression should be) around 10:1 or 10:5 with the new heads. (Subject to change if need be)
5) 700R4 tq. The converter is a just a little looser then stock,I believe it's called an S-10 converter maybe about 500 rpm looser.
4) Dyno Don's, 1 3/4 headers and y-pipe, no cats, true 3 inch exhaust, flowing threw a single 3 inch all the way to a walker Dyno Max muffler 3 inch in (2) outlets 2.5 inch
5) Injectors are at this time 22 lb. with an adjustable regulator & 155 pump (subject to change as needed)
6) 3:23 gears, really not wanting to go with anything stepper then 3:42
7) 16 wheels 245/50/16
(Cam 1 ) I like the spec on the stock Lt4 cam: with 1.6 rockers at: 203/210 .476/.479 lift 114.5 LSA
But, I know this cam is for a short runner intake, and I'm sure there are a lot better chose out their.
(Cam 2) Lingenfelter Roller cam L210025087 old part number 74216 with 1.6 rockers is: 213/219 .494/.504 112 LSA
But would the 112 LSA give the car a rough idle ?
I Really, Really.. appreciate any help or direction I can get on this !!
The black mustang make 1297.00 HP to the wheels !!
9 sec. ride with a full exhaust, you would walk right past this mustang in a parking lot while it was running and think nothing of it !!
So quite, ideals like a stocker and has cold A/C nice radio and no cage. It was a friends car but was sole a few years back..
What will your final compression be and how did you arrive at that number? Heads at 58cc, but what of the rest? Piston dish. Head gasket. Have you determined the piston below deck measurement or assuming it's a general factory .025" down (which tends to be more like ,030"+)?
I can't say I care for either of the two cams listed although both have used in various combinations with success. For one, with 10:1+, your cranking compression is going to go through the roof if you have a flat top piston. 10:1 works well with .050" numbers in the 220-225 range. And the lobe profiles are very dated and there are newer choices to go with.
But there's more to it than that obviously.
As for the 112 LSA, that should be easily tuned. Guys here can work with 110.
There a couple of members here on the board, (Orr89RocZ comes to mind) that have built and tuned similar packages. Maybe this post will flush them out.
No problem tuning 110 LSA at 54+ deg overlap. Do it all the time. But read below. Most over-cam an engine, and then wonder why it's sluggish in other than first gear under 2000 RPM. With your weight, Fast Intake and 3.23 gears, you'll want low end torque!. The Fast intake is going to fight against that. IMO, best to get something with an advertised RPM range that has the lowest low RPM and the highest upper RPM range. Regardless of LSA, anything over ~220 Deg duration at .050 will not be the best low torque option. Also, 22# injectors will be max duty cycle around 5000 RPM +/-. Cam accordingly, and be sure to always use the manufacturer's recommended valve springs. Floating valves are not fun.
HTH, Elky
Lobe Separation Angle
Lobe Separation Angle, or LSA, is the number of degrees that separate the peak lift points of the cam’s intake and exhaust lobes. LSA helps determine the cam’s behavior; you can take a given set of lift and duration figures, change the LSA, and get cams with vastly different characteristics. Generally, a cam with wider LSA (112-116 degrees) offers less overlap between intake and exhaust opening and closing events. That translates into a wider rpm range, better idle quality, and higher engine vacuum, but at the cost of less torque at low and midrange rpm. A cam with a narrow LSA (104-108 degrees) offers greater low and midrange torque production, but a narrower operating range, a choppy idle, and less engine vacuum.
For the street, you want a cam that offers a compromise–decent idle quality, respectable vacuum for operating power brakes and such, and good overall power production. Again, much depends on the overall engine combination and intended use, but as a general rule, cams with a 110-to 112- degree LSA offer good power and decent street manners.
A few questions to add with those already asked:
Is the DynoMax muffler their Super Turbo or Ultra Flo Welded? If it’s the Super Turbo, it’s going to hold you back. You’ll need to get one of their Ultra Flo (part # 17228 - $123) or one of the MagnaFlows (part # 12267 - $132) – both have a single 3” inlet and dual 2.5” outlets.
What are the valve spring specs on the heads? Coil bind height and open and closed/seat pressure? Need to know those before you can pick a cam – or are you willing to go with springs to match an aggressive lobe profile? You can get better performance and vacuum with one of the high rate of rise cams, but need good valve springs for them.
You say the converter is about 500 rpm over stock – have you driven it yet to know what the actual stall speed is? Is that 500 over the typical 1400 stall speed of the 700r4 or are you expecting more than 1900-2000rpm stall speed from it?
Are you willing to learn how to burn your own tune? It doesn’t cost much to get set up and it’ll be a lot better than having someone try and get the tune right remotely. If you’re willing to do it yourself, you can go a little bigger on the cam and make more power. If not, you’ll need to go with a moderate cam that can be tuned easier.
A couple general statements:
The FIRST is not like a typical GM style TPI – the long runner length will still limit the upper RPM capability (compared to a single plane), but the larger cross-sectional area and flow means that it will make peak torque a lot higher than a “typical” TPI. So, cam selection will be different than what you’ve typically seen for a “TPI”.
With your exhaust system (assuming one of the mufflers above) and your heads’ exhaust to intake flow-ratio (76%), along with the FIRST intake, you don’t really need a split duration cam. A single pattern cam would work best for you – adding exhaust duration will not add much if any power to your combination and will only drop your vacuum. Going with a single pattern over a split duration means you can run a tighter lobe spread than most and pull similar or better vacuum – this is a win-win as single pattern cams with tighter lobe spreads tend to make better low and midrange power, which will complement the FIRST intake.
If you want a proven combo, don't stop with the LT4 stock cam, step up to the HOT cam. It is not for a short runner intake. The short runner LT1/LT4 is an untunned intake (for the most part) that should flow well across the board as opposed to a TPI. Anyway, it would work well with the FIRST.
Wow, Thank you for all the feed back, my internet has been down, so im just getting a chance to read all this information, I will update you on some of the very good question ya'll have asked. After this Hurricane hits us her in Houston I will take the heads over to have them cc as well. Wish us well down here, I have lived here my hole life and these are either really bad..or nothing..Thanks again.
Shinny Z
My goal was a 9.8 - 10:5 compression
The pistons are stock, flat top style with valve reliefs
And yes the piston do seem to sit low in the block, so thanks for bring that to light, as you said maybe closer to .030 mark u spoke of how does one measure that?
I will have the new heads cc to be sure, of what they are.
The head gasket will be selected at some point based in part on the cc of the heads, the depth of the piston, I understand there is an ideal quench rate I'm looking also but as of this writing im in the dark on that one.
The cam's I selected, were more of a starting point to give the reader an idea of what type of cam/car I was looking for, I agree..there should be much better option out there, and I will keep looking.
Thanks for the great question, looks like I have some numbers to gather and report back on.
BadSS
I have the 3 inch in and (2) 2.5 out's
I will install what ever springs comes with the cam kit, I heard that was the best thing to do..
I have driven the car with the Tq. converter and it is 500-700 looser then a normal 700R4, It flashes at 1800-2100, This is a stock Tq. Converter they put in the S10 pick ups with the 4.3 and 700R4s.
I'm not sure i want to lean to tune, I know some guys do it great while other Fu.&(* Some stuff up..So I guess I will be looking for a good tuner.
This car put down 13.6 @ 99.5 mph, in pretty much stock form. Only mods being..The Tq.Converter, newer yellow ford 22 pd. inj. A fuel pressure reg. TB air foil, and maybe a smaller crank pulley.
and some K&N filters. With that said, I do like to pay close attention to the details, and you guys are a huge help !! Thanks you for your input
... idles like its stock, has some split duration with good lift numbers, and can take full advantage of all the parts listed below:
This car will be a street/weekend driven, road racer, drag racing car that needs to keep good vacuum for brakes and cold A/C..Lol
1) Vehicle weight, about 3350 (Or So)
2) The 350 short block is stock.
3) A First Intake system, the lower intake has been "gasket ported to match the heads".
4) New 113 aluminum heads lightly ported, with 58cc and bigger valves: int. 2.00 flowing: 250 cfm @.500
exh. 1.56 flowing:190 cfm @.500
The New (Compression should be) around 10:1 or 10:5 with the new heads. (Subject to change if need be)
5) 700R4 tq. The converter is a just a little looser then stock,I believe it's called an S-10 converter maybe about 500 rpm looser.
4) Dyno Don's, 1 3/4 headers and y-pipe, no cats, true 3 inch exhaust, flowing threw a single 3 inch all the way to a walker Dyno Max muffler 3 inch in (2) outlets 2.5 inch
5) Injectors are at this time 22 lb. with an adjustable regulator & 155 pump (subject to change as needed)
6) 3:23 gears, really not wanting to go with anything stepper then 3:42
7) 16 wheels 245/50/16
(Cam 1 ) I like the spec on the stock Lt4 cam: with 1.6 rockers at: 203/210 .476/.479 lift 114.5 LSA
But, I know this cam is for a short runner intake, and I'm sure there are a lot better chose out their.
(Cam 2) Lingenfelter Roller cam L210025087 old part number 74216 with 1.6 rockers is: 213/219 .494/.504 112 LSA
But would the 112 LSA give the car a rough idle ?
Originally Posted by Gen1
My goal was a 9.8 - 10:5 compression
The pistons are stock, flat top style with valve reliefs
And yes the piston do seem to sit low in the block, so thanks for bring that to light, as you said maybe closer to .030 mark u spoke of how does one measure that?
I will have the new heads cc to be sure, of what they are.
The head gasket will be selected at some point based in part on the cc of the heads, the depth of the piston, I understand there is an ideal quench rate I'm looking also but as of this writing im in the dark on that one.
The cam's I selected, were more of a starting point to give the reader an idea of what type of cam/car I was looking for, I agree..there should be much better option out there, and I will keep looking.
Thanks for the great question, looks like I have some numbers to gather and report back on.
Using a stock flat top piston shortblock for inputs along with an .026" head gasket and the 58 cc heads gets you about a 10.7:1 static compression ratio.
While plenty of SBC's have been built with that SCR, it takes some extended cam timing to make it work. That cam may not fit in with some of what you're building the car around. Either of the two cams listed will be too short and drive the compression pressure up to a point where it may unworkable.
A few assumptions in the absence of real measurements. The piston below deck at .025" is one. You can check that yourself and it's easy if you have a dial indicator and feeler gauges. Lay a straight edge across the cylinder with the piston parked at TDC. The thickest feeler gauge that fits between the straight edge and the piston top is your piston down the hole value. It's a little trickier without a dial indicator but with patience you could zero in on the number. Getting TDC just right is the hard part. The .026 gasket could be swapped for anything really but you mention quench and it has significance as best practices tend to achieve .040". The .026 gasket creates .050 so you're getting away for that already but at a possible 10.7:1, any tighter and your goals for the car are getting further away.
The short duration cams listed I think will drive up the dynamic compression excessively. Even a cam with 224@.050 on a 110 LSA is netting over 8.5:1 DCR. You may be able to get away with it with some good tuning and the aluminium heads extend the workable compression ratio a certain amount but the small 58cc chamber may make life difficult.
Should be fine with the lingenfelter cam. Its decent and i believe longer seat duration than most modern lobes so it wont have as much cyl pressure. Unless they changed lobe families.
90-91 vettes were 10.25:1 comp and ran fine on tiny stock cams. Alot of those guys ran cams like this or similar on stock heads or even stock shaved heads just fine. Just watch timing at peak torque!! It will want to be down several degrees vs peak hp rpm
Just watch timing at peak torque!! It will want to be down several degrees vs peak hp rpm
As I was saying.
Originally Posted by skinny z
You may be able to get away with it with some good tuning...
Now add another half point of compression and it becomes even more sensitive don't you think.
And there's the thing. Something I've learned along the way is the compression vs timing relationship. For the average street build (and I'm all average most of the time) the gains made with increased compression are all but wiped out with a castrated timing curve. Not only in power output (NA strictly here) but in efficiency. The best situation is high enough compression, even to the point of requiring premium fuel but still maintaining optimal timing. I went the other way (more than once) and it resulted in a difficult everyday engine. It ran strong but was always seemingly on the edge.
i wouldn't pull the trigger on any cam without a fully spec'd cam card anyway.
Tpi almost always needs a few degs out around peak trq vs peak hp regardless of compression. In fact most engines do. Peak hp may be 1-2 deg more for best power in some cases
BadSS
I have the 3 inch in and (2) 2.5 out's
I will install what ever springs comes with the cam kit, I heard that was the best thing to do..
I have driven the car with the Tq. converter and it is 500-700 looser then a normal 700R4, It flashes at 1800-2100, This is a stock Tq. Converter they put in the S10 pick ups with the 4.3 and 700R4s.
I'm not sure i want to lean to tune, I know some guys do it great while other Fu.&(* Some stuff up..So I guess I will be looking for a good tuner.
This car put down 13.6 @ 99.5 mph, in pretty much stock form. Only mods being..The Tq.Converter, newer yellow ford 22 pd. inj. A fuel pressure reg. TB air foil, and maybe a smaller crank pulley.
and some K&N filters. With that said, I do like to pay close attention to the details, and you guys are a huge help !! Thanks you for your input
Weird that the S10 converter is only flashing 2,100. It flashed about 2,100-2,200 rpm behind the 4.3 in my brothers S10 and about 2,700-2,800 behind the L31 Vortec 350 in my Express van and my brothers Suburban. The cammed L30 Vortec 305 in my Tahoe would flash one about 2,500.
Weird that the S10 converter is only flashing 2,100. It flashed about 2,100-2,200 rpm behind the 4.3 in my brothers S10 and about 2,700-2,800 behind the L31 Vortec 350 in my Express van and my brothers Suburban. The cammed L30 Vortec 305 in my Tahoe would flash one about 2,500.
Yeah, my S10 converter behind the L03 in my car flashes around 2300+ RPM.
Well to be honest, those were my best guess numbers, from a year ago..Plus, I have put a few of these S-10 converters in different vehicle and they all seem to be a little more or less a few hundred rpm's.
(Cam 1 ) I like the spec on the stock Lt4 cam: with 1.6 rockers at: 203/210 .476/.479 114.5 LSA
But, I know this cam is for a short runner intake, and I'm sure there are a lot better chose out their.
(Cam 2) Lingenfelter Roller cam L210025087 old part number 74216 with 1.6 rockers is: 213/219 .494/.504 112 LSA
But would the 112 LSA give the car a rough idle ?
I ran a 268/276 - 218/229 - 110 with similar lift in a flat-top 355, with heads flowing in the 240-245 range, and a FIRST. TH350, 3000 stall, with 3.23 gears. Ran 12.50s in high 80s temp (sea-level). Idled at 700 RPM with 18" vacuum (forget how much timing I added). Was a little hard to launch at the track with ET Streets but manageable with a little practice. I could take off fairly well with 245/45/17 street tires but could do a smoke show at will. It also would barely break spin/skate the tires dropping down into 2nd gear. Throttle response was excellent.
Don't do any porting to the FIRST other than a gasket match to the heads. The runners are smaller than the intake diameter inlet (1.75 vs 1.85), but leave the runners alone. Stock inside diameter is about perfect for a 355.
Your gearing within the 700r4 should make up a little for the difference in stall speed (compared to mine) and the tighter converter might actually work out better for the street. So, the 218/224-112 cam would be my choice out of those for sure. The FIRST can use a lot more cam than the typical TPI. I shifted 1st at 5800 and 2nd at 5600 - the car ran near identical times shifting at high as 6000 for both gears, so I just shifted it at the lower RPM. HTH
This car will be a street / weekend driven, road racer, drag racing car that needs to keep good vacuum for brakes and cold A/C..Lol.
Of all of these, which is most important? I think anyone here could spec a different cam for each scenario. Certainly one that's best for drag racing isn't going to the best weekend driven cruiser choice. And the "best all around cam" would be a compromise to all of them to some degree. Just asking because "intended purpose" seems to be the lynch pin of any cam request form. For example, when I approached Jones' Cams about my proposed 383 build, the spec I received was based on some specifics that I couldn't express through the online form. Once I had a chance to re-communicate my objectives for the car, the spec changed considerably.
There are some pretty smart folks here. This is something they may want to know too.
08-15-2020, 11:21 AM
