yellow rose
Overnight Sensation
No they are not. They are losers. Depending on the chamber, I'd use a 48* seat...or if you are off the wall, you can use a 50* seat.
360 - Rebuild - Information & Opinions Needed
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No they are not. They are losers. Depending on the chamber, I'd use a 48* seat...or if you are off the wall, you can use a 50* seat.
MopaR&D
Nerd Member
What about 'radius' cut valve jobs? The machine shop I took my cousin's 440 heads to to get freshened up spec'd a 3-angle radius VJ IIRC... The engine is not yet running but will be soon. It's actually a similar build to what the OP wants, mostly freshened stock parts, mid-range cam, RPM intake, headers etc. going in a '71 Satellite.
To the OP would you mind posting a pic of your engine bay? I have a pair of the Hedman Tight Tubes shorty headers on my '70 Duster and the way they are laid out I think they would work perfectly in a truck application (and are about 1/2 the price of TTI's which I doubt will give you any more power with that mild of an engine).
yellow rose
Overnight Sensation
I never use any radius on an intake. Looks good on the flow bench, sucks for power.
The good thing about trucks is cheap hooker headers will fit with no issues, no need to waste money on expensive headers.
Lots of room, getting ready to order a set for my w150 360 swap.
Built a mag 360 with KB107's, edelbrock mag heads and a comp 262 roller cam, should make a great torque, towing motor.
Lots of room, getting ready to order a set for my w150 360 swap.
Built a mag 360 with KB107's, edelbrock mag heads and a comp 262 roller cam, should make a great torque, towing motor.
DARTH V8R
It's a TRAP!
50*? Yikes.. you running .700" lift solid rollers? I'm taking up to .500"ish lift. 30* seems to outflow big time any other angle up to .350", where the
majority of cylinder filling takes place. 70 throat and your set IMO.
yellow rose
Overnight Sensation
I'd be much more concerned with cross flow than low lift numbers.
I quit worrying about low lift numbers in the late 1980's. A 30* seat is an absolute waste of time and a power killer.
I quit worrying about low lift numbers in the late 1980's. A 30* seat is an absolute waste of time and a power killer.
DARTH V8R
It's a TRAP!
Well I guess your right if your talking aftermarket heads. The OP is using stock P-car heads. Just a 30* cut with no porting will yield significant
gains in the below .400" area.
Sorry, I didn't get my message across very well.
No converter change? Then a cam of [email protected] (tapper rise measurement) should be used.
The replacement 340 cam is a Mopar purple cam with increased duration. You can find in there catolog. It has close to the advertised duration specs but the specs at .050 tapet rise are larger making it a bigger and more aggressive cam. I would use it with at least a 2500 stall and 3.55 years.
The difference between advertised and duration @ .050 can vary a lot so I suggest reading a few cam manufactures web sites that explain this because it would be a very long and lengthy write up for me to do.
No offense but I'm not into "schooling" at this site but just to hang and shoot the breeze.
No problem rumblefish360, I appreciate all the information you've provided this far. I've been browsing sites trying to get more educated on cams and cam specs, it's a learning curve to take it all in for sure. Thanks again for the help!
moper
Well-Known Member
Internal balancing adds smoothness, lifespan, power, ability to hold more power, and economy, in addition to making it easier to find a decent balancer and convertor down the road. I find it amusing that people will spend another $3-400 to go with a hydraulic roller to avoid a cam being wiped, but won't spend another $300 to get an improvement you will feel every time the car is started. Yes - internal costs a little more. Yes - it is worth every cent. We're talking about 5% of the engine build budget (based on a mild build I might build).
30° seats are a waste IMO unless you're working on a tractor engine. The factory Mopar heads are no barnstormers as cast, but they are not so bad that the seat becomes a necessary part to mess with trying to make the port work better at low or mid lifts. Simple things like a backcut on the intake valve and much higher accuracy in regard to concentricity on the valves and seats will go a long way to adding real flow all accross the lift range without compromising anything specific. Get the guides right and use top quality equipment with a machininst that knows how to use it and you're way ahead. My shop uses Serdi equipment for the seats & guides, and valve resurfacing. They cut 5 angles. It's basically a three angle using a 46° seat angle (best compromise in his experience for a street engine) and chamber and throat cuts to help the air move accross the seat. Paying a little more for the valve job frees up power and leaves you without worrying about rocker geometry and shims. Now no flow bench can truly simulate a running engine and there's all kinds of ways to pump up flow numbers that don't make for power on a running engine. But I've watched "before (running shape OEM valve job)" and "after" testing on a my customer's 596 heads on his SF600 bench that had a average increase of 8%. That's just by replacing valves with performance stainless, correcting the cuts on those valves, and doing a modern valve job on the heads themselves.
30° seats are a waste IMO unless you're working on a tractor engine. The factory Mopar heads are no barnstormers as cast, but they are not so bad that the seat becomes a necessary part to mess with trying to make the port work better at low or mid lifts. Simple things like a backcut on the intake valve and much higher accuracy in regard to concentricity on the valves and seats will go a long way to adding real flow all accross the lift range without compromising anything specific. Get the guides right and use top quality equipment with a machininst that knows how to use it and you're way ahead. My shop uses Serdi equipment for the seats & guides, and valve resurfacing. They cut 5 angles. It's basically a three angle using a 46° seat angle (best compromise in his experience for a street engine) and chamber and throat cuts to help the air move accross the seat. Paying a little more for the valve job frees up power and leaves you without worrying about rocker geometry and shims. Now no flow bench can truly simulate a running engine and there's all kinds of ways to pump up flow numbers that don't make for power on a running engine. But I've watched "before (running shape OEM valve job)" and "after" testing on a my customer's 596 heads on his SF600 bench that had a average increase of 8%. That's just by replacing valves with performance stainless, correcting the cuts on those valves, and doing a modern valve job on the heads themselves.
DARTH V8R
It's a TRAP!
So have you used the 50° seat on a LA p-car head? Or just what you read in the LS forums?
Local machine shop here wanted a grand to go external to internal balance.
Don't see how 30° are for tractors. ASK the pure stock drag guys about it.
Local machine shop here wanted a grand to go external to internal balance.
Don't see how 30° are for tractors. ASK the pure stock drag guys about it.
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yellow rose
Overnight Sensation
I'm using a 50* seat on my street car, and I didn't do it without testing that particular VJ significantly. I also spent a large amount of time on the phone with my cam grinder before we settled on the lobes. Even on a head with a net lift of .600 (that is what I'm NETTING) I want to delay (or even reduce) flow below .250 lift.
While this my be counter intuitive to most, I have thoroughly flogged it out. Wish I had gone to the dyno, but I'm already way past giving a **** about the dyno for now. I'll see what it does at the track, and if it falls short of what I think it should run I'll pull the pig out and put it on the pump.
30* seats are an absolute waste of time.
DARTH V8R
It's a TRAP!
Full competition VJ's with angles and seat widths chosen to maximize high-lift flow on a race car reduce low- and midrange performance in realistic street-cam lift ranges. Also you want a fairly thick margin on a STREET engine. 30°/45°/60°. As per the OP's original post.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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IIRC,
the factory 360 2bbl cam was about 252*, and maybe a tic over 200 @050
the factory 340 cam mighta been 218/220ish @050, as I recall.The FSM lists it at 268/276/114,lift .444? Not enough lift IMO for it's size, but Chrysler had to work with the heads,I guess.
the factory 360 2bbl cam was about 252*, and maybe a tic over 200 @050
the factory 340 cam mighta been 218/220ish @050, as I recall.The FSM lists it at 268/276/114,lift .444? Not enough lift IMO for it's size, but Chrysler had to work with the heads,I guess.
yellow rose
Overnight Sensation
moper
Well-Known Member
I don't belong to any LS forums so I assuming that wasn't to me...
A 30° seat will help low lift flow. But, at the expense of lift past .200. Jeeps, AMCs, and tractors use a 30° seat because they all use very small camshafts (lift wise) and the engines were never expected to make horsepower. Just low rpm torque. If the port design is good enough to support it, and one has the ability to use a larger camshaft, low lift flow is not what you want. Aside from the flow impact above low lift, it also makes reversion a much bigger issue because it flows equally well in either direction. So cylinder filling is compromised at low rpm too. Good porters do not want big low lift flow.
Just an FYI - my mentor still raced NHRA Stock Eliminator. He's in SS now but he raced for years in Stock Eliminator and had more than a couple ntional records. Enough that his SS car was given to him by Ford. He had about 15 years developing his valve job and a 30° seat had no part of it even though the camshafts were lift-limited to under .400 at the valve.
RAMM
Well-Known Member
This absolutely correct. I have done it and I have dyno'd and track tested. It is all about reversion. See the thing is the intake valve won't just flow the same backwards it will flow MORE and A LOT MORE backwards up to about .300". I did this with a set of '596's 11/32" 2.02/1.6 and I saw 96 cfm @ .100"! I thought oh boy am I gonna make some power now---WRONG. Engine was ridiculously cammy and @ 408 cubes made a whopping 461 hp @ 5100 and the worst thing was the shape of the power curve. Nothing down low and a huge wollop @ 4000 rpm. 408 was only 5 tenths quicker and 5 mph faster than my 367.
Leave the 30* seats to the Pontiac and diesel lovers. J.Rob
moper
Well-Known Member
...and AMC lovers...lol.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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And old flathead lawnmowers
I see this has become quite the discussion on valve job angles, which is a good read but as it sits (at this point) I won't be getting any of that done. Most I'll do is clean the heads up a touch myself to smooth them out, nothing major at all.
Now, I've seen some posts mention balancing. I've read it's a good idea for less wear and smoother engine, but is it totally necessary in this application? ie. a street motor in a truck, that I don't intend on doing high RPM pulls all the time. Just a basic cruiser that if I feel like I wanna get into it a bit and stomp the gas for a little fun, I can without worries.
Also, if balancing is a big issue, would it be smarter to go with the Speedpro pistons (https://www.summitracing.com/int/parts/slp-h116cp/overview/make/dodge) which are a closer weight to a stock piston, and make up for the small loss in compression by decking the block a little more?
Thanks again for all the info, it's a great read and discussion!
Now, I've seen some posts mention balancing. I've read it's a good idea for less wear and smoother engine, but is it totally necessary in this application? ie. a street motor in a truck, that I don't intend on doing high RPM pulls all the time. Just a basic cruiser that if I feel like I wanna get into it a bit and stomp the gas for a little fun, I can without worries.
Also, if balancing is a big issue, would it be smarter to go with the Speedpro pistons (https://www.summitracing.com/int/parts/slp-h116cp/overview/make/dodge) which are a closer weight to a stock piston, and make up for the small loss in compression by decking the block a little more?
Thanks again for all the info, it's a great read and discussion!
moper
Well-Known Member
Some will undoubtedly say it doesn't, and they did it and they had no problems. I'd say if they did and had no problems ignorance is bliss and they aren't attentive enough to notice higher quality in terms of a running engine. If we have to justify a need, I'd say you're probably in that latter group. That's not meant as a cut - there are many things I accept and ignore, and many more I simply am ignorant about and so I'm happy...lol.
IMO, If the pistons are being changed to anything that is not a stock replacement for that year, then yes - it should be balanced. It doesn't matter if it's going into an old ladies grocery getter or a fighter jet. It's not about your feel, but the engine's "feel". Balancing helps to equalize stress any running engine "feels". By doing so it "frees up" power that would otherwise not make it to the crank hub, lengthens the lifespan of all the internal parts, and happens to feel smoother as you drive it.
IMO, If the pistons are being changed to anything that is not a stock replacement for that year, then yes - it should be balanced. It doesn't matter if it's going into an old ladies grocery getter or a fighter jet. It's not about your feel, but the engine's "feel". Balancing helps to equalize stress any running engine "feels". By doing so it "frees up" power that would otherwise not make it to the crank hub, lengthens the lifespan of all the internal parts, and happens to feel smoother as you drive it.
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