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What do you think will make them a little soft on the low end? The wide LSA?
Intake valve is going to close later resulting in a lower DCR vs the same cam with a narrower LSA. That's going to run smoother with a little taken from the bottom and a little added to the top.
If spinning it has to much tq if we in 3rd gear or not enough tire. I know I don't want a lot of tq with a daily and rain is part of a DD job ....
If a guy wants to keep it as is? Holley with the Davis traction control unit.
Ole question I had for self...so how could I control tq and not having a newer car with T/C and a tire smaller than 315's.
A little more rpm brings tq down also. Match the cam to the Induction knowing your vehicle and what's to be expected with all this tq and hp before hand and street usage
If spinning it has to much tq if we in 3rd gear or not enough tire. I know I don't want a lot of tq with a daily and rain is part of a DD job ....
If a guy wants to keep it as is? Holley with the Davis traction control unit.
Ole question I had for self...so how could I control tq and not having a newer car with T/C and a tire smaller than 315's.
A little more rpm brings tq down also. Match the cam to the Induction knowing your vehicle and what's to be expected with all this tq and hp before hand and street usage
It's like a riddle with you....dumb it down for the common folk....are you still high from last night? Explain the Davis deal please....grammar lol!
2 freaken second search from a 12yr Ole question I had 2 self...
Any answer pretty much Always has Been answered you just gotta want the answer or Know the Keywords used for Google search engine. Never Failed me ...Google search got me so close I designed my own cylinder head.
If spinning it has to much tq if we in 3rd gear or not enough tire. I know I don't want a lot of tq with a daily and rain is part of a DD job ....
If a guy wants to keep it as is? Holley with the Davis traction control unit.
Ole question I had for self...so how could I control tq and not having a newer car with T/C and a tire smaller than 315's.
A little more rpm brings tq down also. Match the cam to the Induction knowing your vehicle and what's to be expected with all this tq and hp before hand and street usage
Your overthinking this Andre. You control the torques with your right foot. Just don’t mat the gas if it’s wet out. Drive it like there’s an egg under the loud pedal. Easy peasy. Forget the Davis TC stuff. Leave that crap for the circle track guys that want to cheat.
Your overthinking this Andre. You control the torques with your right foot. Just don’t mat the gas if it’s wet out. Drive it like there’s an egg under the loud pedal. Easy peasy. Forget the Davis TC stuff. Leave that crap for the circle track guys that want to cheat.
it's great for Drag racing and controlling all that Boooost & Tq's.
Although it's not cheap it's a great way to integrate T/C into a older model vehicle..Driveshaft speed is how it's controlled with magnets like a crank trigger.
it's nice to have modern electronics in older cars...
adding ABS was a great read also...
Not something i would do on my budget...but once your no longer building and now driving it would be a good consideration as a add on and eliminating the factory ecu with the Holley ecu then adding on to with nice features like T/C.
Chevelle what got me was, I love hitting the T/C button on Dora the Explorer on a rainy day... Gas it to the floor (not literally but) no spinning out of control. Just drive, relax, and smoke that wacky green tobacco 🙃
Heavy foot can stay heavy.
I settled on a cam spec. Trying to get it on order today. This will use Comp's latest low shock lobe tech. Should be interesting! I got carried away as usual looking at much bigger cams, so I landed somewhere in between. It'll have the idle aggressiveness of the BTR stage 2 with 8* overlap, and I know I can smooth it out. I hate chop - it'll just be a pretty aggressive idle at ~900 rpm, but should run smooth.
I kept the specs where I can advance the cam 4 degrees if I intend to use the short runner intake. This will work great with the long runner intakes with a bit of bias toward top end power without getting too crazy on overlap. A ported MSD would really be the best choice, but they don't fit under-hood or at the firewall on my car. Maybe someday I'll make it work.
So I found a stock LS7 takeout for my car and put a deposit on it. At first I was just going to drop it in as-is, but I've been down this road before. My car isn't the best with traditional LS power delivery with smaller cams. Too much of a lump of low and mid-range torque, and not enough up top.
My deal I'm looking for something a little non-conventional. Would be open for input. I want to keep overlap minimal, ~5*+/- a couple degrees at .050" for minimal idle aggressiveness - looking for a smooth relatively stealthy idle (like sit next to CA police in traffic stealthy) around 900-950rpm, but tailor valve events for 4000-7500rpm operation. Engine is going in a 2800 pound, 6 speed, 3.90 gear mazda rx7 to enjoy on the street, and flog on track and in the canyons. Stock ls7 intake manifold for now w/ potential to change to holley sniper low pro or maybe an MSD in the future (both have hood/firewall clearance issues so it is not an immediate priority), 1 7/8" headers w/o cats, unrestricted intake tube, 10% UD pulley, RPS carbon clutch.
In internet speak, stage 1 overlap w/ stage 3 powerband is the goal. My priority is to shift the powerband up and carry torque at high rpm. I want usable traction and high rpm performance with a broad powerband to give it more of a sports car feel.
Valvetrain will be stock Ti intakes, stock exhaust valves, stock rockers, stock lifters, and unsure on valvesprings - still researching what works best with the ls7 installed height. The heads were gone through 10k miles ago. I prefer not to take the heads off.
I will be grinding Comp's new low shock hydraulic lobes.
This is what I've come up with so far. 234/247 118+3, .647/.650" lift w/ the 1.8 rockers.
What valvesprings do I need that aren't too expensive, work with stock lifters, and the taller ls7 installed height?
Would this also work with the short runner Holley Sniper low pro?
Oh NO!!!! Sorry, but I stopped reading at "CA Police!!" Best of luck to you with the smog Gestapo.......
I'm freaking stoked about this thing! It is in awesome shape. I wasn't planning on pulling the heads, but my old man convinced me when we saw it had ARP head bolts already. The heads were done by AHP 10k miles ago. The carbon will clean up when I run a couple tanks of e85 through it.
Since the heads are off I'm putting some Johnson 2116LSR lifters in I've had on the shelf since 2017. I also ordered some .040" thick gaskets, and the pistons were right at zero deck so quench will be nice and tight. With the stock heads that puts compression at 11.4:1.
I'm super tempted to put my ported LS7 heads off my other build on this thing, but I have the chambers cut down to 63cc. That would put compression at 12.3:1 and I run 91 octane with the option of flex fuel. The compression bump would be sick with e85, but I don't know if it is too much to reasonably use the car on straight 91 octane?
Using IVC at advertised duration it works out to a DCR of 8.55. Using IVC at .050" + 15* DCR is 9.7.
These low shock cam lobes have really long seat to seat duration numbers, but at .050 it is only a 234 intake lobe. At the seat it is 292* duration.
Great progress yesterday. Got everything thoroughly cleaned, carbon scraped, deck surfaces cleaned, heads assembled (my other set too), and the cam is in and degreed with the new wet sump oil pump. Also had to drill a 3/8 hole in the block for the dipstick.
Another nice surprise, it has Ferrea solid stainless exhaust valves already which is nice peace of mind. The guides checked out good as expected since they were just done 10k miles ago.
I had a set of new-ish and clean Ti intake valves so I swapped those in.
Pretty much ready to install the lifters, heads, measure for pushrods, oil pan, front cover and unless I'm forgetting something it'll be good to go! Gotta drag the FD up to my dad's to pull the engine and I have a few projects to tackle on the car as well.
Revised Deets:
LS7 SBE 427, 11.4:1
Comp low shock lobes 234/247, .665/.658" lift (1.82 ratio), 116+2
Stock ls7 heads w/ Ti intakes, Ferrea exhausts
4.150 .040" cometic gaskets
Johnson 2116SLR slow leakdown .093" travel
PAC 1207x .700" lift springs
TSP roller tip 1.82 rockers
Melling 10296 high volume/high pressure
Improved Racing Fbody pan trap door
Meziere EWP
ATI damper no underdrive
Tilton 246 twin disk organic clutch w/ sprung hub and strapped floaters
1 7/8" headers into dual 2.5" xpipe
I'm getting super close to having this thing on the road. Figured I could drop some updates in here since the engine is running now. It's been a huge pain in the *** - I've replaced everything in the EFI once over - new ECU, new harness, new cam and crank sensors. Lots of extremely frustrating problems, resolutions, more problems, and finally on the home stretch. I've been taking as many Fridays off from work as I can this year to try and get it back together. I also rebuilt the entire car, somewhat unplanned. The scope creep was unbelievable on this engine swap lol. Almost every part of the car I either tweaked or replaced.
I'm really falling in love with this engine. Most of the driving I've done has been for diagnosis and basic datalogs. I've been able to do some 2nd gear pulls to redline though and it has some *****. The tune is super soft too at 18-20 degrees timing on my baseline tune I built. I think there's a chance after I tune it this thing will be really pretty quick. It should take a lot more timing on 91, and I have flexfuel too.
After I thought I had fixed my cam/crank sensor problems - I learned it would lose RPM sync every single time at 6800 so I had to keep testing it, and finally got it fixed after just starting fresh with new everything. I took it out to 7600 rpm on the run after that and boy it sounds good and is pulling hard still. I hope for it to put up a respectable number, but I'm most excited that I can floor it in 2nd at 2000 rpm and it will stay stuck all the way through the midrange and keep hauling *** past 7000 rpm. I can't wait to see the shape of the power curve.
I have break-in miles to go still on the clutch, trans and the rear gears so I can't beat on it for real yet.
Congrats, that is a long time coming 👍Need to spin that thing like Jayyyyw after you get it sorted. Enjoy!
Thanks! Yea Jayyyy was like my canary in the coal mines 😂. I’ve got no problems with 7800-8000 if it’s useful to rev it that high. I am hoping to see peak power at 7100 and carry flat for a while. I’ve really wanted it to rev at least to 7500 - early signs promising. If I achieved that with this baby cam I’m going to be very happy.
Main motivator for this engine package is to give it a proper sports car powerband up top, and make it more tractable down low.
Last edited by spanks13; Nov 29, 2024 at 12:02 PM.
Thanks! Yea Jayyyy was like my canary in the coal mines 😂. I’ve got no problems with 7800-8000 if it’s useful to rev it that high. I am hoping to see peak power at 7100 and carry flat for a while. I’ve really wanted it to rev at least to 7500 - early signs promising. If I achieved that with this baby cam I’m going to be very happy.
Main motivator for this engine package is to give it a proper sports car powerband up top, and make it more tractable down low.
The build is still in the shakedown phases, but low hanging HP fruit I see is bigger exh for sure, optimize the intake piping, degree in the cam(as in play with the adv and see if it likes more), port the sheet metal intake too(I can port that for you in you need). Beyond that, maybe a cam change, but I would obviously play with what you got for a long time before that. Nice that you saw it through👍. I gotta get my junk back together soon and get my AMX project in gear.
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