I can get the ZZ3 cam cheap and i will be porting my stock heads too. Installing larger valves if possible.

I will be porting them myself as well.

1. How do I prepare the heads to handle high lift?

2. Would there be any valve to piston clearence problems?

Can anybody answer that?
Thanks.

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89Iroc, 305 TPI, WC T5, 3.08 Posi, Headers, Hooker Y-Pipe, 3 inch over the axle, Flowmaster 80, No Cat, Aluminium Driveshaft, Ported Plenum, Air Foil, K&N, All free mods,

 

with that much lift you must put in new springs, also some hardend pushrods wouldnt be a bad itea eather,

 

Daniel,

As Tempest indicated, you'll need to change springs. This means you will need to machine the spring seats for the necessarily larger diameter springs. This would also be a good time to cut the valve guides for Teflon valve seals. You should also elongate the push rod guide holes to provide clearance for the additional lift cam action, and remove the pressed rocker studs, tap the holes, adn install screwed studs. As long as the heads are in for machining, you might as well machine for guide plates. Even if you don't use them, the tops of the stud bosses will be trued and ready for spacers or plates.

You might also consider increasing the valve sizes slightly.

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Later,
Vader
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If you want to beat the World, it might reach up and pull you down...
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So 1.94's work good on these heads?

 

If you haven't done so already, check out the Standard Abrasives "Head Porting Do-It-Yourself Guide" at www.sa-motosports.com . They just happen to use a 305 head as an example.

Although they don't specifically address the intake valve (because they kept the stock 1.84"), they recommend at least 3/16" clearance between the valve and chamber wall when the valve is open ~3/8". With the extra .05" radius valve, that could also be a problem with shrouding the intake.

Remember any material you take out of the chamber increases the chamber size and reduces compression. But, the extra flow should more than make up for any loss of compression.

To install the larger intakes, have a shop tank the heads and rough-in the 1.94's. Do your port work, then take them back to the shop and have them finish the valve job.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4 (restalled TC). Ported World 305 heads, Crane PowerMax cam. ZZ4 intake, oil pump, pan & baffle. Accel HEI SuperCoil & module. Hooker 2055 headers, 3" Catco cat & 3" catback w/dual-opposite Flowmaster. 2.93 limited slip, Spohn SFCs. AMSOIL syn lubes bumper-to-bumper. Daily year-round driver. Best ET, speed TBD...
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