dutchdart,

raisíng compression will give about the same torque incrase in percent over the full rpm range. If you raise cr and get 5% more at 2000rpm, you will see 5% more at 3000, 4000 etc... in reality it may be 4.9% or 5.2% as a rule-of-thumb it´s the same at any rpm. Playing with compression will not affect the RPM level of peak torque and peak hp.

Camshaft 1-0-1:
When using a "hotter cam", you will get more horsepower. But, as nothing is for free, you will see that hp at a higher rpm level. AND your low end torque will be LESS! That´s why hot cams require higher stall-speed converters with automatic transmission.
Imagine a diagram showing torque vs. rpm´s:
Your "powerband", the range where the engine puts out useable torque, will be wide, starting and ending at a low rpm´s and be at a low torque level with a stock cam.
Using an aggressive cam, powerband will be narrow, starting and ending at higher rpm´s and be at a higher torque level.

What I meant was: the 252 cam makes less peak hp than the 264, but that peak hp is at a lower rpm level. Then raise compression with the 252 and you will have about the same hp as the 264+stock compression , but at a lower rpm level.
Another concern mentioned by Dusteridiot is that the 264 cam may NEED more compression to make up for the cylinder pressure loss at idle or low rpms. You don´t want your daily driver to idle at 1200rpm, do you?

There´s many things to consider when building a good engine... one could easily fill books with camshaft considerations alone. But don´t worry; keep on asking questions, it´s all been done before. We´re getting closer to make you a satisfied slant street racer:-)

Transmission: the problem when using the overdrive tranny is that the gears are split wider. That means, your rpm will drop from 5000 to 3000 on a 1-2 shift. A non-OD 4speed will drop from 5000 to 3600 when shifting 1-2. (I´m not sure if these numbers are 100% correct but they give you an idea of what´s the deal). The same holds true for 2-3 and 3-4 upshifts. Here aplies what I said about the powerband width: Having the narrow powerband of a hot cam and a large rpm drop with the OD tranny, you will not be satisfied with your acceleration. It just doesn´t match. You´ll have to rev your poor slant tot the moon to get good "go" in the next gear. Your non OD 833 will match up fine with the 264 cam, from what I believe to know.

I took .100 off my head pushrod length is just fine.

Would 9.2 to 1 be enough compression for the 264s?Thats what I came out with for my 170.
HyperValiant

_________________
1960 Hyper-Pac Valiant(rolling test-bed)
1963 Valiant V2OO(Son's summer project,- he just turned 15 )
1972 Valiant 4dr(Daughter Kelly's repair in progress)
1974 Valiant (v8) daughter Kelly's work in progress

Would 9.2 to 1 be enough compression for the 264s?Thats what I came out with for my 170.
HyperValiant

_________________
1960 Hyper-Pac Valiant(rolling test-bed)
1963 Valiant V2OO(Son's summer project,- he just turned 15 )
1972 Valiant 4dr(Daughter Kelly's repair in progress)
1974 Valiant (v8) daughter Kelly's work in progress

That should be about perfect for that cam and might even be OK on 87 octane, but will be fine on mid/premium.

Lou

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Home of Slant6-powered fun machines since 1988

THat cam should be good like Lou said, and you may not notice much if you retard the timing a little to use 87 (I do, but don't gain any mileage when running 87 over 92, just save a couple bucks per tank and lose a bit of 'crispness' on the accelerator...).

-D.Idiot

This is an interesting thread...the build I hope to have time to finish goes like this:

225 ,60 over, all the Docs block mods
...late drool head with chev sb 172 intake and 150 ex from 3/4ton (uses 3/8 guide) including chev springs, retainers etc , mild port, 9.2 compression.

Comp 264 cam (hey! it was free)

2 1/4 exhaust with stock manifold

4.3 Astrovan TBI injection and ignition control for Slant Lean Burn distributor , aluminum Super 6 manifold with Holley throttle body(GM injectors

Controls: Chip, fuel pressure, valve timing >>>>max cylinder pressure 3000rpm

3000lb car 24" tires 3.23 gears with 5 spd

Targets : 24mpg , 15.5 ET, on 87 octane

All the parts are here or available....all I need is a package of 100 early Valiant hours.....

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Yeah....Im the one who destroyed this rare, vintage automobile.....

I did a little research on propane conversions a while back. One of the interesting points was how to do your valve grind to reduce the exhaust valve seat recession. Basically, since propane is very pure there is no ash to prevent the exhasut valve from welding itself to the seat. Also since the fuel can handle 12-1 compression they often run very hot.

So, get the contact area between the valve and the seat as wide as possible. That is, grind it so that there is a wider than stock contact area. Of course real hardened exhaust valve seat INSERTS must be used.

Dr. Seal, who just retired from teaching at WWU's Vehicle Research Institute, designed CNG (compressed natural gas) conversions for some NYC busses. They ran 454 chev's with 9.5 static compression ratio with lotsa boost(25 psi). These engines made big power at a relatively low rpm. To combat valve seat wear each engine was fitted with a 50cc Holley accel pump (no carb, just the pump.) On startup the engine got one shot of leaded fuel. This provided the ash needed to coat the valve and seat to prevent the welding themselves together for an entire day of operation.

Just my $.02
Grind the exhaust seat and valve wide, use hardened seats and find someway of getting some lead or a substitute that will form ash on startup.
Otherwise the exhaust seats will be short lived. Mark

Hey there dutchdart

I cutted 2mm out the head and 1 mm out the block and installed a steel gasket. didn't used custom lenght pushrods, just loosened the lash setting screws. They kinda work near the tip but safely enough to be working good. I have to run on 98 or 100 octane gas or the damn thing will ping, but the high compression ratio really "waked up" my beast. I'm running high 16's at 400m (1/4 mile) with a crappy 1 bbl carb. I figure out that with that big cam of yours and your dual webers, your dart will fly.

By the way, we're the country that has more propane propelled vehicles in the world... (not that I like that crap for my little baby, still can afford the gas, and if not, I'd rather put the beast to sleep over 4 big woodblocks) so there's a lot of people down here that has huge experience on that. Most of the guys that uses propane are using a total timing of 36~39 and I've heard of some people using over 40° (ain't actually saw that, but a very close friend has his car 39 deg advanced and it really pulls on propane...) if you have electronic ignition, they sell an advance variator electronic unit that can help you to reduce timing for fuel or increasing it for propane. Using a low rpm full mech advance recurved dist you should get more juice out of propane too. (Speaking easily: replace that heavy spring for a softer one, with loop)

good luck on your new setup

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.