while i still plan on doing a lot more wringing on my combination as it is, i'm also planning the next stage of the project.

for that stage, i've just bought a set of ported aluminum zz4 heads. here are the flow numbers:

.300" intake: 175 exhaust: 128
.400" intake: 206 exhaust: 154
.450" intake: 212 exhaust: 167
.500" intake: 215 exhaust: 172
.600" intake: 215 exhaust: 177

armed with those numbers, i went looking for a camshaft to match.

my first call was to comp cams. i was completely blown away with how rude and unhelpful the guy was. as soon as i told him i had a 305 tbi, he interrupted me, telling me you couldn't make any cam changes to a tbi, that it "wouldn't run right" if you did. the conversation went downhill from there.

my next call was to engle cams, and the difference was night and day. mark engle (son of founder jack engle), was knowledgable about tbi and very helpful. he suggested two grinds:

1.

intake lift: .479 (1.5 rockers) or .510 (1.6 rockers)
intake duration: .212 @ .50

exhaust lift: .492 (1.5 rockers)
exhaust duration: .218 @ .50

112 lsa


2.

intake lift: .492 (1.5 rockers) or .525 (1.6 rockers)
intake duration: .218 @ .50

exhaust lift: .492 (1.5 rockers)
exhaust duration: .224 @ .50

112 lsa

he said he'd recommend grinding either of those cams 2 degrees advanced and suggested i run 1.6 rocker arms on intake, 1.5 on exhaust.

he said he'd had a number of customers use the first cam successfully on 350 tbi trucks with the stock chip, but thought it would take some chip tuning on a 305.

he said the second cam would make more power, but would be much harder to tune.

thoughts?

 

he nailed it.

the other person you might want to talk to is Harld Brookshire with Lunati, he used to own/run UltraDyne cams, that is where i got mine, he is very good at what he does, his extension is 135. you might call him.

Edit....

i will add, that 218/218 is going to be quite a bit more tuning work, i hear that on a 305 about 218* exaust is the most you want to go on a dual pattern, beyond that you might as well go with a signle pattern like he recomended.

 

Well they are about the same and should be easy to dial in with some dyno time and wide band readings. Since they are so similar the second one would give you a few more ponies with a similar tune to the first one. Both have good LSA's to tune around. You are going to have a fuel system and TBI unit that can handle all of this? Many people bash TBI because they don't understand it. Don't those heads have 2.02 valves? You may have some valve shrouding if they are and those flow numbers will go way down as a result.

 

Nope looks like they do not have the 2.02 valves. This should be a really cool set-up when you are done. Where did you get the ZZ4 heads. They aren't for sale apart from the crate motor are they?

 

i thought the ZZ4 used, l98 heads ????

and the fastburn uses, well fastburns

 

thanks for the tip on harold, i'll call him manyana.

i had to think about that 218/218 for a minute, because he didn't recommend a single pattern camshaft. went back and looked and realized i'd gotten the specs wrong. i corrected it in the original post. here's the spec on cam #2 again:

intake lift: .492 (1.5 rockers) or .525 (1.6 rockers)
intake duration: .218 @ .50

exhaust lift: .492 (1.5 rockers)
exhaust duration: .224 @ .50

 

walbro 255 fuel pump, bigger injectors (probably either 55s or 65s), vafpr. if i find i need it' i'll go to a bored out (2") tbi, but i don't think i will.

and no, they're 1.94/1.5s

 

the second one seems large to me, but with tuning, and the right parts should make some big power, but on a 305 a cam that size is going to make power to 7k or so.

the other thing is those heads are alum. with 58cc chambers, witha large cam like that you are likely going to want more compresion than that.