heads/cam/intake help
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Joined: Nov 2003
Posts: 70
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From: kennesaw, ga
Car: 79 z-28
Engine: Built 406 w/ Nitrous Works 250 shot
Transmission: TCI Th-350
Axle/Gears: 8.5" 10bolt 3.73 and Auburn Pro
heads/cam/intake help
I have a 311( 305 bored .40 over with a 4 speed saginaw) with heads off of a 90 truck, the cam is either .460 int/exh or its .500 int/exh. with 116* lobe seperation. I'm not sure how well those work together, but It's got a victor jr. intake on it and an edelbrock 650 carb. the compression is about 10.5 now, but i got no power under 3300 rpms. I know this intake is made for higher RPMs but it was on the car when i bought it. Id like to keep the cam i have in it. Should i just go for an air gap intake? or should i look for a new set of heads? Thanks for any advice.
- Justin
- Justin
Supreme Member
Joined: Jul 1999
Posts: 18,457
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From: Loveland, OH, US
Car: 4
Engine: 6
Transmission: 5
That's an incredible mismatch of parts.
First, if the heads are really off of a 90 truck, they're swirl-port. So they will pretty much guarantee no power above about 3500 RPM.
Second, that intake is HUGE. It pretty much guarantees no power below about 3500 RPM.
So, the motor probably doesn't make power either above or below 3500 RPM, which pretty much renders it unfit.
At this point it hardly matters what the cam is; even if it's a good match to the one thing or the other, it's still a mismatch. Without some kind of specs, it's impossible to guess whether keeping it is a good idea or a mistake. The general rule is, get a cam that matches the rest of the motor, not build a motor around a cam (the cam being one of the cheapest parts); so I'd lean toward it being a mistake, if you don't know exactly what cam it is.
Yes you should get a different intake and look for a different set of heads.
A set of 416 castings (86-back LG4, 305 TPI, & L69 castings, out of any number of cars from Caprices to Camaros and even boats) are about the best you will be able to get for a 305 among the stock castings. A Performer RPM is as much intake as you'd want to run, either the Air Gap or not, according to whether you drive it on the street in cold weather.
The carb is about the right size, even if not as good as some others at pure performance. You can probably safely re-use that.
First, if the heads are really off of a 90 truck, they're swirl-port. So they will pretty much guarantee no power above about 3500 RPM.
Second, that intake is HUGE. It pretty much guarantees no power below about 3500 RPM.
So, the motor probably doesn't make power either above or below 3500 RPM, which pretty much renders it unfit.
At this point it hardly matters what the cam is; even if it's a good match to the one thing or the other, it's still a mismatch. Without some kind of specs, it's impossible to guess whether keeping it is a good idea or a mistake. The general rule is, get a cam that matches the rest of the motor, not build a motor around a cam (the cam being one of the cheapest parts); so I'd lean toward it being a mistake, if you don't know exactly what cam it is.
Yes you should get a different intake and look for a different set of heads.
A set of 416 castings (86-back LG4, 305 TPI, & L69 castings, out of any number of cars from Caprices to Camaros and even boats) are about the best you will be able to get for a 305 among the stock castings. A Performer RPM is as much intake as you'd want to run, either the Air Gap or not, according to whether you drive it on the street in cold weather.
The carb is about the right size, even if not as good as some others at pure performance. You can probably safely re-use that.