ZZ4 with Victor jr. Heads - Hot Rod Forum : Hotrodders Bulletin Board
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Old 02-18-2005, 12:55 AM
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ZZ4 with Victor jr. Heads

I am very disappointed in the performance of an engine I just built.
I have a ZZ4 put in a comp cam roller, victor jr. heads, planned the heads to keep the 10 to 1 ratio, rev kit. it has accel fuel injection. The engine does not perform well.. its not a tune issue runs ok. But I am not satisfied with the engine, I thought it would run like hell. I have it dynoed and it has less torque and Horsepower than the stock ZZ4, I am kinda pissed. A stock ZZ4 puts out 405 lbs of torque and 355 horsepower, I think the problem is the heads. Victor jr. heads, are they too big for a stock ZZ4? compression check is about 135lbs all the way around, used right head gaskets, dont know what went wrong.. worse yet I cant find on the Internet any stock ZZ4 with Victor jr. heads.. my engine builder really don't have much to say other than its runs good. but it don't. less torque and less horsepower. What to do? any suggestions appreciated.. the combination just don't work.
thank you very Much. Bud911

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Old 02-18-2005, 01:17 AM
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Did you Map your fuel injection?
and can you tell what the fuel air
Ratio is?
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Old 05-22-2006, 04:27 PM
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Did you get your issues sorted out with your ZZ-4? What did you do to correct the problem? I have a ZZ-4 also and changed the stock cam for a Comp Cam. Let me know, thanks
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Old 05-22-2006, 05:39 PM
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My guess is that the heads are too big for the rest of the motor. The cam that comes in that motor only has 208 @ .050 duration and .474 lift on the intake. That is pretty much stock. A cam in that range is probably only going to make power to around 5000. According to the CHP link below the victor JR's actually have a runner closer to 219cc. A head of that size on a 350 is going to want to make power in a range closer to around 4500 to 8000 RPM. The cam and heads have essentially no part of the powerband that is shared. At low RPM the heads are too large to support mush air velocity and at high RPM the cam gives up.


ZZ4
http://www.jegs.com/webapp/wcs/store...tegoryId=10763

Vr JR
http://www.chevyhiperformance.com/te...98/index6.html

Adam
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Old 05-22-2006, 05:39 PM
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If your cranking compression is only 135 lbs, you've got a problem. What is your camshafts specifications, what are the combustion chamber size on your heads, and what type of pistons do you have? Did you degree the camshaft?
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Old 05-23-2006, 07:56 AM
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If everything else is ok, and it is just the mismatch that is causing the problem, You could sell the victor Jr's and get a vortec top end combination. For all that you need to install the heads it is around $1000 but that includes the upgraded vortec heads and an intake manifold. If you are at 10:1 with the 58cc heads, you would be around 9.5:1 with the 64cc vortecs. Another option would be to sell the heads and get a set of AFR 180cc heads, they are around $1400 though, but you could use your current intake. Either way, the motor will be matched much better and make more hp.

Adam
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Old 05-23-2006, 08:22 AM
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You need to get your cranking compression up. You'd want to see around 180 PSI at least. If you get the compression up the engine will perform as you expect. It's that simple.
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Old 05-23-2006, 08:33 AM
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This thread is over a year old, I highly doubt we'll ever find out what eventually became of his combination.
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Old 05-23-2006, 10:03 AM
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Bahaha, didn't catch that.
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