ZZ4 upgrades

[grumpyvette]

the old advice, about questionable parts, in any engine build-up would be
"if in doubt ,change it out!"
but Id sure visually check it out very carefully and swap it with the adjacent set of roller lifters to see, if the problem follows the lifters or the problem remains with the lifter bore location, if its the lifter bores, lifters or some other valve train component that's the problem, you need to correct it before proceeding in the build-up or it could cascade into something far more expensive later, if ignored.

I had a friend that chipped a lifter bore one time , forcing a busted lifter up out of a lifter bore, he failed to examine the damage carefully, he had in fact cracked the lifter gallery and ruined the block (I,m not saying that's probable in your case) but his lack of careful examination resulted in blowing the engine shortly after it was built costing him far more than just a replacement block, some welding metal stitching or re-sleeving a lifter bore ETC. which may have been the case if caught during the first assembly

http://www.sorenspecialties.com/cylinde ... epair.html

viewtopic.php?f=50&t=1926&p=5104&hilit=lifters+tube#p5104

http://www.hotrod.com/techarticles/buil ... index.html

 

[ZZ71s]

We finally got to start the modded zz4 I think I have a timing problem.
We turned it up to top dead center dropped the dist in and set it back where it always has been set the grease fitting right to the edge of the dist hold down bolt.
Then we put the timing light on it it says idleing at 22 and when you rev it it goes off the timing tape.
If I turn the dist counter clock wise the idle gets rough and if I turn it clock wise I get a rough idle and and a kind of rattle.
So what is the deal do I have a problem with the dist.

 

[grumpyvette]

read thru this thread and its sub links

viewtopic.php?f=70&t=875&p=7285&hilit=timing+tape#p7285

time ignition advance curve on the car at 3000rpm to show 34 degrees total advance on the timing tape and let the at idle timing fall where ever it lands as a starting point while your breaking in a new combo, you can make adjustments later but this will get you very close to correct without running the engine at low rpms while the cams lapping in.

 

[ZZ71s]

I am playing around with the idea of adding one of those small super chargers to my combo.
So do you think the zz4 powder metal rods will take i?
Will the lt4 hot cam work well with alsuper charger

 

[grumpyvette]

powdered metal connecting rods are not generally as strong as forged 4340 aftermarket rods, yes there can be exceptions , but your almost always going to want a quality 4340 aftermarket steel connecting rod design, with ARP bolts, over any factory production powdered metal connecting rod design.

Rods with cracked or "fracture-split" big ends are common on modern engines. The fracturing creates a unique interface that "locks" together only one way and does so very precisely. The more accurate interface ensures a uniform big end diameter and shape. yet this also means the rods can,t easily be re-sized or reused after extensive mileage, like you might do with a good forged steel connecting rod.

and hypereutectic pistons, and 10:1 compression,are not ideal in a supercharged engine, , its the fairly high compression ratio, tight ring gaps and pistons in the stock engine and the stock cam thats more likely to be a problem

you might want to read, or re-read, thru these links, and sub links

viewtopic.php?f=53&t=1168&p=11498&hilit=powdered#p11498

viewtopic.php?f=86&t=4685

viewtopic.php?f=86&t=3203


IM OFTEN ASKED WHY I DON,T REBUILD CHEVY CONNECTING RODS, WELL MAYBE A PICTURE WILL HELP,

a good set of SCAT FORGED 4340 forged connecting rods costs less than $400 and they are 150%-200% stronger than MOST OEM chevy SBC rods
it will cost you almost that much to replace the bolts with ARP wave lock bolts, balance and polish and resize stock rods and you have far weaker rods when your done