ZZ3 to ZZ383?

[Elm Zobens]

I have a 69' coupe with a ZZ3 small block (350 CI, 345 HP, 385 Torque) and would like to get some more bottom end torque. I've been toying with replacing the 350 crank with a 383 stroker crank and associated pistons. Since the ZZ3 only has about 4000 miles on it, I figure I won't need to do any major "rebuilding" and I can use the existing rods with the new crank.
Has anyone tried this before?
Any things to consider or look out for?
Do you think this is a worthwhile swap or is it too much work for the power difference I'd notice?
The ZZ3 has the aluminum 'D'port heads (not the fast burn Vortec style) with 58cc chambers and 1.90 Intake and 1.50 exhaust valves (or there abouts).
Any advice or war stories would be greatly appreciated!
Thanks-
Elm.

[GL Anderson]

Re: ZZ3 to ZZ383?

You will have to use the Chevrolet 3.80" stroke crank rather than the more common aftermarket 3.75" stroker cranks if you don't want to take the engine all the way down to have it bored .030 over. With the 58cc heads your compression will increase because of the larger displacement or not depending on your piston selection. If I remember right the ZZ3 crank uses the 1 piece rear main seal so you need to get the proper crank for that applicaton. As to how much power, well increasing displacement should net you some more torque, but it would be just a guess as to how much. There have been many magazine build ups of 350 vs 383 trying to use identical parts except for the increased displacement. Most show about 30-50 ftlbs of increased torque and 25-30 more hp. However, unless a very good engine builder like David Vizard does the work I would question if it really is an apples to apples comparison. I am sure those with more experience will chime in on this to help you make an informed decision. GL

[Mark #28455]

is it worth the trouble

If you're going through all the trouble of pulling the engine, complete disassembly and reassembly and re-using the stock heads, you have to ask is it all worth it? If your current engine has only 4000 miles and is in great shape with good compression in all cylinders, you could probably get a lot more bang for your buck by just adding nitrous or swapping just the heads and cam. If the engine needs to be torn down anyway, then you should consider swapping the heads as there are currently many more advanced heads on the market. Don't automatically pick the largest intake ports, but build for the greatest average torque through the RPM range you're really going to use.
Good luck,
Mark

[Elm Zobens]

Re: is it worth the trouble

Thank you all for your feeback-
I guess I really need to investigate what kind of power I can get out of the ZZ3 in it's current form before I invest in cranks and pistons. The problem I am having is in trying to find any information on the ZZ3 engine and what mods can be done. When I do a Google search on ZZ3, I get virtually nothing.

GM does list aluminum 'fast burn' vortec style heads for these motors at around $1200 a pair, but again, I don't know how much that will get me performance wise and I will also need to swap to a Vortec style intake which I don't know if it will create issues with my hood clearance etc. Once I swap heads and intake, I'm guessing that I'll need to swap cams and go to higher ratio rockers as well. I guess I am a little spooked at the $$$ signs with no real clue on what it'll buy me in the performance department.

Since I'm somewhat of and old fart/old school, nitrous is not an option for me- I would like to have a normally aspirated motor that is stong and all I need to put in it is gas and oil ;-)

Any suggestions on where I can get some ZZ3 hop-up info or some Gen II small block tips in general?
Thanks again!
Elm.

[Ted S.]

Re: is it worth the trouble

I have a ZZ3 also and from the research I've done it seems like a good path to go is to get the GM fast burn heads, the GM "hot cam" kit, new valve covers, and a new intake. The cost is around $2K. My understanding is that will get you really close to the ZZ430. There's a slight compression difference on the ZZ3 verses the ZZ4 and that's why it's really close verses the same as the ZZ430. The ZZ430 was 430 HP and 430 Ft. Lbs. verses the ZZ3 is 345 hp and 405 Ft. lbs (the torque is the ZZ4 spec, ZZ3 should be pretty close). If you go to the link below and put ZZ4 in the price and parts field you can look down through the ZZ4 packages they offer. This should give you some ideas on changes that can be made to the ZZ3. For example they have one version with AFR heads that is pumping out 464 hp and 440 ft. lbs.




Salee Chevrolet

[Elm Zobens]

Re: is it worth the trouble

Thank you for the tips!
I didn't realize that there was such a thing as a 'ZZ430'.
I looked up the info and it's quite impressive-
Basically (as Ted mentioned), it's a ZZ4 short block with the Fast Burn heads, hot cam and 1.6 rockers.
The ZZ3 is .2 lower on compression than the ZZ4 (9.8 vs 10.0), so I'm guessing that explains the different part numbers on the pistons between the two.
The ZZ3 is rated at 345/385 and the ZZ4 is rated at 355/405- I'm not sure why the ZZ4 has 20 more ft/lbs of torque than the ZZ3. I wouldn't think .2 CR would make that much diff since the heads and cam are otherwise identical.
Either way, the ZZ430 parts add a whopping 75HP and at least 25 ft/lbs of torque, so I should see around 420HP and 410 torque!
Not bad for a 350 small block!
Thanks again for the advice and I'll keep y'all posted on what I end up doing.
Elm.