Cam Suggestion - L28ET mild build w/MS

[Jersey]

Morning HybridZ'rs. Just received our (working on cousins '78 w/'83 turbo motor) Godzilla Megasquirt order and while doing some motor checks and cleaning up before starting the install, I noticed the compression on cylinder #4 was a little out of range compared to the others. It was at 150psi compared to 167-172 for the rest. Pulled the valve cover and noticed the #4 intake cam lobe is scored pretty bad and the rocker has a larger groove compared to all the rest. So... time for a new cam, rockers, pads, springs and possibly lifters. Haven't determined exactly what happened but it's been sitting for a while over the past few years with occasional starts so my best guess right now is/was an oiling issue. I really didn't want to modify anything else at the same time while installing the MS but now I've got no choice. I'll list the specs below of the current setup and of the MS specs I'll be installing. If anyone could recommend a cam/spring/rocker combo that would work well for what we have, that would be much appreciated. Not looking to go wild as it needs to be streetable but I do know from all I've read that the stock cam runs out of breath around 5500 and with the mods we've done on his car, a little more lift/duration should definitely help. Really appreciate the advice in advance.

 

Current setup:

1978 280Z

’83 L28ET Turbo motor/Stock ECU

F54 block, P90A Head (hydraulic lifters), N42 Intake ported to match P90A head

1-2mm (?) Metal head gasket (I'm thinking 1mm since compression #'s on the high end)

JE Forged Pistons

T3/T4, 50trim E wheel, .63 Stage III clipped

370cc Ford SVO Fuel Injectors

60mm 240sx Throttle Body

Walbro 255LPH Fuel Pump

SS 3/8” Fuel Supply Line

Custom Aluminum Fuel Rail

Modded stock Fuel Pressure Regulator

NPR Intercooler

MSD Blaster Ignition Coil

Manual Boost Controller

Greddy BOV

Custom DP w/3” Exhaust

Dual Electric Fans

(Yes, we've been rigging the setup with the stock ECU for far too long, why it was time to go MS!)

 

Installing from Godzilla:

MS2 v3.57 kit with a base tune from the specs we gave them above

Wideband O2

Retaining Single coil (for now)

Pallnet Fuel Rail

Bosch EV6 440cc Injectors
Aeromotive FPR

Electronic Boost Control

 

Think that's about everything. If any additional info is needed, please let me know.

 

Thanks - Jersey

[Brad-ManQ45]

You need another stock P90a cam or use timeserts to use a mechanical cam.  The best of those would be the "c" cam used in the 260's, but you might have problems w/ internal and external oiling.

[Jersey]

Thanks for the reply Brad. Are you saying it wouldn't be beneficial going with an aftermarket cam from like Isky or Schneider with this build?

[A to Z]

Stock early "A" cam, early cam towers and Yoes oil spray bar so you are on external cam oiling.  Have the head completely ported out.  Add boost. No reason not to have nice reliability and driveability for the 90% of the time you are driving around not spooled up.  Trust me....in time you are going to get tired of cruising in 2nd gear around town, to keep the turbo spooled.  I've been there.

 

Edited August 4 by A to Z
Jesus is the Living Son of God

[Jersey]

Thanks AZ. I think I'm leaning toward sending this P90A cam to Delta for a regrind for now.  Don't really want to do any head work at this time, that might be the winter project once we pull the motor to get body work done.

 

Anyone have a suggestion on what specs I should give for the regrind considering the mods I've posted above? Sorry, I'm real green when it comes to this as I've never done it before and I know a bunch on here have. Again, not looking to go crazy, mainly streetable with occasional blasts when needed

 

Jersey

[Brad-ManQ45]

If a lobe is bad you probably can't regrind the cam.

[Jersey]

Thanks. I spoke with Ken @ Delta earlier and I'll be sending him the P90A cam for a regrind and a slight mod (stage 1?).

[Brad-ManQ45]

You can probably get away with a bit more duration but not much more lift.  He will have to tell you what thickness of lash pads to use to make up for the smaller base circle.

[Jersey]

Yes, think he said something in the 260 range. I will definitely ask which pads he recommends once he's done with the grind, thanks Brad. I'm assuming something close would be the stock .160 pads, plus the amount of material removed from the base circle should put me in the ballpark? And then I'll need to check wipe patterns when installing to be sure. Great, now I need to learn how to check wipe patterns! LOL. See, told you I was green when it comes to cam selection and all that's involved. It's like a black art to get it all right!

 

Appreciate the time and info.

[Brad-ManQ45]

Actually a bit self serving on my part - I want to know if someone CAN Regrind a turbo P90a cam with a bit more duration and a bit higher lift that will work.  I'm only looking for peak power at 5800 rpm and max rpm ~6k.

[Jersey]

For some unforeseen issues, I may be switching gears on this once again and swapping over to mechanical lifters & time-serts in the P90A head. Question is, can I use the original Hydro cam that Delta just shaved down for me if i go this route or would i need to go with a solid cam/spray bar setup? I've read a few times now about the "clearance" or "opening" ramp being too aggressive on the hydro cams and will cause a noisy valvetrain and probable rocker/cam lobe damage if used with mechanical lifters.

 

True? Untrue? Over thinking?

 

Thanks.

[Brad-ManQ45]

You're probably gonna be better off with getting one of the Isky cams that have been documented on this site because of the hydraulic profile.

 

BTW - what are the specs on the regrind that Delta did and what lash pads did they say to use?

Edited August 29 by Brad-ManQ45

[Jersey]

Ken couldn't really suggest which pads would be right since the base circle was cut and I also had him resurface the rockers so, understandable. From the measurements I took if I were going to use the hydro lifters, it looks like I'd need something in the .190 range, and that's with guessing @ .020 preload on the lifters. Couldn't find the exact amount of preload that they should have but @ .170, the rockers were tight up against the cam. Time-serts, mechanical lifters and with springs are on their way. Ken said the grind was a "260" Stage 1, 212 @ .050 w/443 duration.

[Brad-ManQ45]

That would be .443 lift and 212° @ .050 lift, total duration of 260°...and whatever the radius of the base circle was reduced by is what you would add to the lash pads thickness.  That is the way Schneider derives their figure for their hydraulic grind that MSA now sells.

 

Did he keep the same opening rate/ramp angles as original?  If so it's probably too steep for non-hydraulic lifters. 

 

The amount of lift might be too much for hydraulic lifters.

 

If in fact he kept the same ramp angles as original then I'd say that cam is useless.

[Jersey]

Thanks Brad. Solid lifters, mousetraps and time-serts on their way. Figured the hydros were going to bite me sooner or later, might as well make the switch now. From my measurements, looks like he took just about .060 off the base. Hoping I wont need to go larger than .160 pads so I’m able to keep the stock retainers. He did say this grind would work with either the solids or hydros, but didn’t have the ramp angle spec. Might be time to get a dial indicator because now I’m curious and could pass this info along to others.

[Brad-ManQ45]

If it will work with solid lifters then it looks to be pretty close to the "C" cam and would work well...

 

Not so sure it would work with the hydro lifters - that lift figure is a big bump and not much more duration to tame it...

[Jersey]

We shall see. Thanks Brad.

[JMortensen]

Looks like I'm late to the party.

From Richard Holdener's videos I learned that any cam is a turbo cam. Since the stock Z cams are PUNY, I'd suggest you go with a healthy cam and get some benefit from it. I ran a .490/280 with SUs and Mikunis, that worked great and didn't lose low end power. I'd suggest something around there, and skip all this A and C cam stuff. ALL of the stock cams are way too small. Go bigger. Ditch stock springs and retainers, get lash pads and shorter stem seals. You won't be sorry.

Edited September 3 by JMortensen

[Jersey]

Thanks Jon. Nice to hear from a familiar member. Guess we'll see how this .443, 212° @ .050 w/260° of duration works out for now. This whole cam dilemma just became a bump in the road when I started the Megasquirt install. Received the solid lifters and time-serts today, hope to do the wipe patterns tonight to see which lash pads will be needed. Once I get this all sorted, back to figuring out how to tune this MS! Wish there wasn't so many variables but, is what it is. I do like your way of thinking though... Go big or go home!