I'm being totally 100% honest. Not trying to be mean or in any way offensive.

If I were you, I'd be pretty happy with where you are. There is no single change you're going to make to your setup that will "unlock" a bunch of horsepower. A few here and there, yes. But not massive gains.

I'd be hesitant to cam the engine more or even to run 1.6 or 1.7 rockers, roller or not, without checking your piston-to-valve clearance.

The heads are an improvement over stock, but 165 cc runners aren't big. You can see them really flatten out at 0.500 lift, and even those flow numbers aren't massive. The port is probably a great match to everything else, but it WILL be a limiting factor to your VE as the RPMs build.

For the fact that you do have a 165 cc runner, I don't see a carb making any real difference in your life be it 600, 650, 750 or whatever. It isn't the limiting factor. Your intake flow rate is.

Looks to me like this is a very solid "regular" setup that will give you years of happy, reliable service.

To get into serious horsepower gains, you need to match your cam, lifters, rockers, heads, rods, pistons, and crank to all work in harmony. I'm spending $6k doing that right now.

Or, if you're feeling a little racy, consider a low pressure supercharger. Underdriving a Weiand or ProCharger to 3 PSI or something would be relatively safe and get you the 80 or 100 hp you're looking for. Just a thought.

Happy trails! Like I said a few posts ago, 270 RWHP isn't exactly something to sneeze at. It isn't "Holy Crap Fast", but it probably makes for a pretty fun car.

 

yep


heck... i have what... like $3000 in valve train alone!!! + heads and lots of head work... a good build will cost from 6-10K$

behive springs
reto roller cam .56 lift
roller lifters
RR rockers
light pushrods
porting polishing port-matching
heads
intake
carb
2.75" exhaust

this i know flows!

 

I agree with Keith here. I made a costly mistake of trying small mods here and there on the 350 I had but after spending nearly 2K on aftermarket parts to gain THAT little UMMP and still not to my satisfaction, spent additional 7K for a totally new 406 roller. Now I'm very satisfied but wasted 2K in course of getting there.

 

but to me the dyno chart shows the HP is still climbing. Usually you run it until the HP starts falling. The torque curve alway falls off at 4 to 5000 rpm.
My be I read the first post wrong but I thought the set up was edelbrock heads (good for 6500rpm) , edelbrock cam (good for 6500rpm and edelbrock intake ( good for 6500rpm) so why was the dyno run shut down at 5300rpm unless you want a good look at the torque curve and many guys do want to see that 2000 to 5000 rpm torque curve.

 

his TQ is/was falling to fast after 4500, thus that was the end of his hp. no need to go further.

Also look closely at the hp curve, its starting to fall off at 4500 also...and at 5k the hp has also gone flat. a 600cfm carb should have no problem on a 350 at 4500rpm.

that could be as simple as springs... but it is defiantly a flow issue, and he does not not flow well above 4500....

still bet its in the heads... i dont care if you put a 1000cfm on that engine, its not going to make that much, if any, difference.

 

Hi,

Buried in my other post was a short comment ("Is this a stock HEI?"). The stock HEI is pretty limited to about 5-5500 rpm before the spark goes away. To make it useful around that rpm level, it should be upgraded with a better module and coil. That simple (and cheap) change will help it a bunch.

Good luck.
walt

 

Cam is the brain of the engine, so you need to decide whether you got a dumb one or a smart one.

 

well, if it is the brain... then the heads are the lungs... and if they are not able to breath... hp will drop off at upper rpm regardless of the cam. the biggest cam in the world will not flow any better than a small little cam if the heads restrict the flow.


think of it this way... you have 3 straws, a 1"id straw attached to a 1/2" id straw attached to another 1" id straw... so you got 1" at both ends, (one end being the carb, intake, cam.... the middle straw the heads, and the last straw the exhaust) and 1/2" in the middle...the whole thing is only going to flow the 1/2" heads/straw.

 

You can compensate for poor flowing heads with one Big Stick. We do it all the time in Super Stock, stock head volume and monster sticks. Powerband is narrow and you gear accordingly.

If people will just stop and think, duration is time. All it is...the duration we hold the valve open. It only makes sense you need less valve duration if the heads flow more air. Someone who says "good set of flow heads you need a big camshaft, doesn't understand.

 

to a point you are correct,,,, but you are only as strong as your weakest link,,,,no matter how big the cam opens the valve, if you got a 1/2" straw you are limited to a 1/2 flow... unless of course you are blown... than that can change things.

and a dyo chart can and does show when a engine drops off as the op has shown,,, his drops at 4-4.5K yet his cam is rated to 6K. his TQ goes flat at 3-3.5K, and after 4 looks as if it starts to drop... he is having flow problems.

that engine is done at 4500 RPM

 

Not true. I don't know when you studied fluid dynamics, but when I studied it there was a concept called "equivalent length". In your straw analogy, the equivalent length of the straw (or its total resistance to flow) increases as you replace 1" straw with 1/2" straw. But the equivalent length of the 1", 1/2", 1" combination is still shorter than if the entire straw was 1/2" dia. and therefore the combined straw will flow more than the same actual length of 1/2" straw.
I also disagree with your theory about cam timing vs head port sizes. Increasing cam duration keeps the valve open more time during each cycle. It has to generate more total flow. This assumes the lift is the same, only duration would be changed.

 

yes, i do remember this somewhat in physics class... but not well enough to argue the point.... regardless of wether the the 1/2" straw will flow better with the two 1" pisces joined, it is still a big restrictive point and it will restrict head flow thus kill upper end hp...




not me

 

You can fudge duration for lift as duration is the ability to make power at a given rpm range. At a given point the powerband is so narrow the car is a pig.

 

I've been reading a lot the last day or so on this subject and here is what I think. The rear gear swap from 3.08 to 3.55 hurt the HP readings on the chassis dyno a little. Changing to the 200-4R has been shown to add 6 rwhp on a dyno. A wash as far as numbers go but much more fun to drive.

Going from a Quad to a Holley 600 I may have hurt my HP numbers. However, I was able to easily tune the Holley and it has very crisp throttle response. Adding a free flowing exhaust system with larger pipes and straight though mufflers probably helped top end HP. Again, a wash...

This will be my new base line for the car but I will not return until I have a 383 with better flowing heads and a roller cam set up.

 

If you were out here I'd gladly help you dial in a QJet.