Picking my car up on sat, which has had the LT4 HOT cam put in. Mechanic suggested I may need to rejet the carb. Is this something I have over-looked? It was running great with the standard ZZ4 cam....

Any opinions appreciated.

Felix

 

You might. On the other hand, it may be just fine.

Only way to know is to run it.

 

Let us know how much power you gained with that cam and L98 heads.

That cam, with quick burn heads, is worth 45 hp over a ZZ4 cam and quick burn heads (430 vs. 385).

That cam with Vortec heads is good for 400 hp. Due to it being a smaller cam, I think the ZZ4 would still make the 385 hp with the Vortec (any one with documented info???)

The quick burn heads were worth 30 hp over the L98 Aluminum heads that came on the ZZ4 crate motor even with the smaller ZZ4 cam and teh loss of 1.2 point of compression. I would imagine you would be lucky to gain 20 hp on top end over the ZZ4 (if any) and lose some bottom end with your current heads unless they have been reworked extensively.

Try running the car on a dyno if possible to test the A/F ratio. That will tell you if you need to rejet. Best wishes on your swap!!!!!!

BTW, try swapping to some lower gears like 3.42 and adding a stall converter. I love my new converter, I can't wait to take the car to the track to see what she'll do!!!

 

Well picked up the car on Saturday. No re-jetting needed, just richened her up a couple of notches. She sounds meaner now- nice lope but not vacuum killing lopey. The car feels more responsive down low and then when you get to 4000rpm + it absolutely flies. Before I would back off or change up at about 5000rpm, but this cam is really on song and needs to keep on up to 5700-5900... It just pulls like a train!

The biggest surprise is that even low down there is more power... there was no take it from somewhere and put it top, which I had thought might happen. Absoultely pleased with the result- a great cam and recommended!

Felix

 

Depending on the carb you have you might need to swap jets. But a simpler way of getting all the performance out of the engine for sure is to buy a Demon carb from Scoggin Dickeys. They have Demon carbs set up for the ZZ4 crate motors and the Fast Burn crate motors. You should check them out. They are pricey though, at around $400. But they're pre-setup for the motor so there is no guessing. The carb ment for the FastBurn crate motor is the one for you. It has the Hot cam in it. Hope this helps!