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VN 5 litre camshaft upgrades

bjf66

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thinking of upgrading original Hydraulic camshaft
whats the largest flat tappet Hydraulic you can run without upsetting the ecu and having to play around with chips
or is advisable to jump straight to hydraulic roller
current compression 9.5/1, needs to be verified
car needs to be drivable it wont be track racing
 

harrop.senator

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None. The stock tune can be. Improved so much before adding a cam. If you're tight , just get a tuned memcal from ace performance. It'll run any cam he's confident of running with a mail order tune.

If he could do a mail order tune for a new lunati I'd be looking at a v262h
Part NoLT10810702
Supplier Part No10810702
DescriptionLunati 10810702 VOODOO HYD FLAT TAPPET CAM V262H SUITS HOLDEN V8 EFI
DetailsHydraulic (RPM range 1400-5800) Duration at .050¨ 219°/227° valve lift .515¨/.538¨ Suits engines with EFI cylinder heads only

Crane 284 if manual , 276 if auto.
Crow 4770 214/224 @ .050
 

gtrboyy

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You sure it's got 9.5:1?

I'd double check as looks stock in other thread although would open up options with higher compression & higher stall convertor.
 

bjf66

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not sure however spec of engine was 9.5. although i just pulled the pistons out to check bearing which are original with 7/8/1990 GM part # GMR770 bearings and bore look good
Pistons are GM #92080458
would like to get to flat tops and 9.5/1 if I can
the old ACL piston 9490H looks to be the go
if piston is flat top at 0 cc
deck height is 0.020"
then we are at:
with 0.043" gasket: 9.25:1
with 0.027" gasket: 9.50:1
if the bore mics out and just needs a glaze wasn't going to bore it, and look for some slugs to suit

Presently is the dished piston is 10cc then Im at 8.25:1 with 0.043" gasket...perhaps these 308/304" engines compression from factory may have been over rated or the compression calculation was done with leaving the gasket thickness out then your stating to get close to the numbers
 

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harrop.senator

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Yeah they never worked it out with the gasket and are renowned for being overrated on the comp. For stock stroke and not messing to much with geometry flat tops and love heart vt heads with .030 off is the ticket.

I've only worked out strokers with 304's it's always been flat tops of and .030 off the head to avoid manifold fitment issues. With banana manifolds always gone for cams that fall off at 5500 . It's lazy but it's tried and true and I've never ran in to piston to valve clearance issues and it's been a good amount of comp.
 

gtrboyy

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Rabbit hole territory!!!!

Yeah with stock pistons they fit so far down the bore 9.5 is unlikely when add headgasket thickness & volume of chamber.

Not worth shaving hell out of heads & getting manifold machined to suit etc after all that hassle could have just gone cheap scat or come crank to suit your vn rods & would have needed to buy pistons anyway.

With stroker crank higher cr pistons even if compression is low 9's won't matter will have way more torque from capacity increase then just add crane 284 & finish it off as stockish 355...or just it stock 304 without oil leaks.
 
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