Crossover Tube and Valve Spring Pressure Questions

-

shittyslant6

Well-Known Member
Joined
Jan 25, 2021
Messages
1,712
Reaction score
2,135
Location
California
Right now I am putting together a pretty hot street 318 as the one in the car now has started huffing a considerable amount of oil out the exhaust and the breathers.

The combination is going to be:

1969 318
Cast Crank 10-10 (ARP Main Bolts)
340 rods (shot peened, corners rounded, ARP bolts)
Mahle Full Groove Bearings (Main, Rod, And Cam)
D.S.S. FX-Series Forged Pistons 3.950 bore -3cc flat top
Guitarjones oiling modifications
Isky 292/292 @50 244 .505/.505 108LSA Hydraulic Flat Tappet
Speedmaster 170cc 65cc Chamber Aluminum Heads
Torker 340 Intake (might try and find a Airgap)
770 Street Avenger

My Questions are:

Can I run the hydraulic (current cam in old motor now) with the crossover tube and blocked off drivers side oil gallery? Or will it not get enough oil over to the drivers side to oil properly?

What is a safe range for seat pressure on a Hydraulic Flat Tappet? Currently I have 328lbs of open seat pressure and it seems I start to lose valve control at 6100-6200. Ideally I would like to try and get to 7000+.

Thank you
 
Last edited:
I can't answer your questions,

but that combo, if my numbers are right, is gonna come in around 9.7 Scr which is not nearly enough for that cam, even down at sealevel.
Installed at 104*, the Wallace Calculator predicts just 145 psi, with a Dynamic compression ratio of just 7.3.. Under those conditions, if I am right, that 325 cuber, will be a dog until she gets to winding up, beginning around 3500rpm. So then, yur gonna need a pretty high stall convertor for the street, and probably gears around 4.30s, which is gonna make her pretty much a city-only car.
I'm assuming, from your language that the 292 cam is already in the current engine, which means you already know all this.
That cam peaks around 5600, so IDK why you want to spin it to 7000, except for bragging rights. At 6000 she's already going down the backside of the power-curve, and I see no reason to spin her any faster.

I'm not dissing your engine,
rather, I'm trying to warn you to keep the pressure up^^.
Your 318, with alloy heads, and that 292 cam, with a modest convertor and street gears, at sealevel, to not be soft down low (like if yur running a 4-speed), wants Static Compression Ratio of about 11.0, just to take off like a stock 1969- 318; and she really wants 11.5 to be considered hot.

Just so you know, I ran the Mopar version of that cam, in my 367, at 11.3Scr/180psi/ Dcr of 8.75, at my ~900ft elevation. It was not a dog, but it did not like 3.55s, which is all I wanted to run. It did like the 4.30s, but, as my DD, over 95% of the miles I put on her were gonna be hi-way, so it had to go..
Just so you know, I only ran it for one summer; that was all I could take.
Just so you know, in 1999, when I first put my Barracuda on the road, with this cam, I was only 46 years old.

If I had a 318, I'd put a modest solid lifter cam into it, with an Lsa around 106>108 to help get the pressure up, cuz I hate a soft bottom-end. And I'd probably run a manual trans with an overdrive; like a 5-speed.
 
I can't answer your questions,

but that combo, if my numbers are right, is gonna come in around 9.7 Scr which is not nearly enough for that cam, even down at sealevel.
Installed at 104*, the Wallace Calculator predicts just 145 psi, with a Dynamic compression ratio of just 7.3.. Under those conditions, if I am right, that 325 cuber, will be a dog until she gets to winding up, beginning around 3500rpm. So then, yur gonna need a pretty high stall convertor for the street, and probably gears around 4.30s, which is gonna make her pretty much a city-only car.
I'm assuming, from your language that the 292 cam is already in the current engine, which means you already know all this.
That cam peaks around 5600, so IDK why you want to spin it to 7000, except for bragging rights. At 6000 she's already going down the backside of the power-curve, and I see no reason to spin her any faster.

I'm not dissing your engine,
rather, I'm trying to warn you to keep the pressure up^^.
Your 318, with alloy heads, and that 292 cam, with a modest convertor and street gears, at sealevel, to not be soft down low (like if yur running a 4-speed), wants Static Compression Ratio of about 11.0, just to take off like a stock 1969- 318; and she really wants 11.5 to be considered hot.

Just so you know, I ran the Mopar version of that cam, in my 367, at 11.3Scr/180psi/ Dcr of 8.75, at my ~900ft elevation. It was not a dog, but it did not like 3.55s, which is all I wanted to run. It did like the 4.30s, but, as my DD, over 95% of the miles I put on her were gonna be hi-way, so it had to go..
Just so you know, I only ran it for one summer; that was all I could take.
Just so you know, in 1999, when I first put my Barracuda on the road, with this cam, I was only 46 years old.

If I had a 318, I'd put a modest solid lifter cam into it, with an Lsa around 106>108 to help get the pressure up, cuz I hate a soft bottom-end. And I'd probably run a manual trans with an overdrive; like a 5-speed.
What would make this cam peak at 5600? I am pretty green when It comes to camshaft tuning and specs.
I was going off of the ISKY website when I ordered it because I was under the impression that a longer duration and tighter lobe separation favored higher RPM. Isky says the range for this cam is 2800-7000.

And on the pistons, I was planning on using Mahle powerpack 4.040 bore -5cc domes during a lapse of brain function. (thinking that 3.91 50 over = 4.040)

Which is why I found those other pistons in the original post now.
I am aiming for 10.5:1 and am still looking for a better piston while not breaking my wallet.

(Edit: I have done more research and I have landed on the Icon .60 over -4.90 dome pistons. They should put me at 10.84:1 at zero deck.)
 
Last edited:
Agree that cam will be a dog in a 318, so I hope you like dogs......
A much more streetable cam would be the Isky 270 Mega
 
if you really want to turn the R's then i'd say you should be looking in the direction of a solid lifter or roller setup. that's not to say hydros won't or can't work, but it's not ideal.

is there any particular reason why you want to have that much ceiling in the motor?
 
I don’t think that I would block the oil to the drivers side lifter galley and install the crossover on a hydraulic lifter cam.
 
If you wanna stay hydraulic, put some good anti pump up lifters in it and run .002" lash. Howards Cams 91712. Those will change the ball game for you.
 
What would make this cam peak at 5600? I am pretty green when It comes to camshaft tuning and specs.
I was going off of the ISKY website when I ordered it because I was under the impression that a longer duration and tighter lobe separation favored higher RPM. Isky says the range for this cam is 2800-7000.

And on the pistons, I was planning on using Mahle powerpack 4.040 bore -5cc domes during a lapse of brain function. (thinking that 3.91 50 over = 4.040)

Which is why I found those other pistons in the original post now.
I am aiming for 10.5:1 and am still looking for a better piston while not breaking my wallet.

(Edit: I have done more research and I have landed on the Icon .60 over -4.90 dome pistons. They should put me at 10.84:1 at zero deck.)
Because that's what his slide rules and calculators say. People routinely spun STOCK 340s to 7K back in the day. Get a clue. He's wrong.
 
if you really want to turn the R's then i'd say you should be looking in the direction of a solid lifter or roller setup. that's not to say hydros won't or can't work, but it's not ideal.

is there any particular reason why you want to have that much ceiling in the motor?
Well the trans went out on the way home from a buddies house last Sunday and at the same time the current engine started huffing a considerable amount of oil out of the exhaust and breathers. then my intake bolts pulled the threads out of the heads. all In one day.

so Im building the engine I have in order to get the car up and running again which is why it's a 318 and not a stroker 360 or 340 or something like that. and to get the power I want out of it and to have a little fun too, it'll need to spin a little higher. (I also really love a screaming small block)
 
Last edited:
If you wanna stay hydraulic, put some good anti pump up lifters in it and run .002" lash. Howards Cams 91712. Those will change the ball game for you.
This.

You have plenty of spring imo. My buds 340 crossed the finish line a hair over 7k with a similar setup. 273 rockers and ran a Torker to boot. :)

As far as the oil mods, as long as have 6qt+ oil capacity, i don't think it's needed.
 
Well the trans went out on the way home from a buddies house last Sunday and at the same time the current engine started huffing a considerable amount of oil out of the exhaust and breathers. then my intake bolts pulled the threads out of the heads. all In one day.

so Im building the engine I have in order to get the car up and running again which is why it's a 318 and not a stroker 360 or 340 or something like that. and to get the power I want out of it and to have a little fun too, it'll need to spin a little higher. (I also really love a screaming small block)
what a series of unfortunate events!

understandable that you're looking for power up top. the heads would support that, and if you've got the compression i don't see it as a problem.

i think there's better cam choices, and intake. but if you're working within those parameters then it is what it is.
 
what a series of unfortunate events!

understandable that you're looking for power up top. the heads would support that, and if you've got the compression i don't see it as a problem.

i think there's better cam choices, and intake. but if you're working within those parameters then it is what it is.
yeah; from what's been suggested here and with the lifters Rusty suggested I think I'll stick with my cam and opt out of the crossover tube.

Side note: I got my crank installed after adjusting main clearances. and it takes less than one pound torque to rotate if over. :D
 
Last edited:
Here's the thing. There's ALWAYS better cam choices. Know what I mean? Somebody somewhere will always say that and to some extent, it's true, I guess. But here's my argument on that. If you already HAVE one or have one ordered, there is no better cam choice. Unless it's so badly mismatched that it will be a dead dog no matter what you do and yours isn't. If you install it more advanced, run a good loose ignition curve, you can tune it to run well. Isky grinds some fine cams. They have a LOT of "area under the curve" as they say. Plus, that grind is a good, old school grind with lazy and slow ramps that will actually be GOOD on the street and be easy on the valve train without smacking the valves open and then slamming them shut. There's a lot of good about that. What did we have before the latest and greatest fastest rate of lift cams? Cams just like that Isky and they set lots of records on the strip and won lots of street races DECADES before anyone knew what a fast rate of lift cam was. So don't sweat it. Run it.
 
Last edited:
Here's the thing. There's ALWAYS better cam choices. Know what I mean? Somebody somewhere will always say that and to some extend, it's true, I guess. But here's my argument on that. If you already HAVE one or have one ordered, there is no better cam choice. Unless it's so badly mismatched that it will be a dead dog no matter what you do and yours isn't. If you install it more advanced, run a good loose ignition curve, you can tune it to run well. Isky grinds some fine cams. They have a LOT of "area under the curve" as they say. Plus, that grind is a good, old school grind with lazy and slow ramps that will actually be GOOD on the street and be easy on the valve train without smacking the valves open and then slamming them shut. There's a lot of good about that. What did we have before the latest and greatest fastest rate of lift cams? Cams just like that Isky and they set lots of records on the strip and won lots of street races DECADES before anyone knew what a fast rate of lift cam was. So don't sweat it. Run it.
Yeah spending 1400 on a roller setup wasn't really In the cards for this engine. (if everyone agreed that it was a horrible cam choice then I would've bit the bullet) Even with my 9.1:1 current compression ratio and 2.76 rear gear it seems like the car still gets up and goes pretty well.
It'll be interesting to see how much those lifters help with the breaking up issue past 6100 as well. My buddy Gary was telling me to put those in there but he couldn't remember the name and I couldn't find them based on his description of them. As an added bonus I get to use my adjustable rockers I got from the local speed shop 3 years ago:thankyou:
 
nobody has mentioned the 'S' word yet, lol. a 4" stroker crank gives you 390 cu in or above (depending on the over bore). and yes it'll still rev hard despite what some may have you believe. :thumbsup:
neil.
 
nobody has mentioned the 'S' word yet, lol. a 4" stroker crank gives you 390 cu in or above (depending on the over bore). and yes it'll still rev hard despite what some may have you believe. :thumbsup:
neil.
Other engine and transmission let go at the same time. not ready to pay for a new trans and engine yet. I already have the 318 and crank with bearings. as well as rods. I have to build what I have to get it back going before summers over because I want to cruise with my buddies. if time and budget permitted I would
 
-
Back
Top