cam and compression recommendations

In my opinion, on any street engine intended to run on pump gas, 10:1 is a good number to shoot for.

Others will tell you that you can squeeze out more compression and still run on 93 octane BUT you are running the risk that it may not always be available.

Companies have eliminated high octane fuels before, and there is nothing to guaranty that they won't do that again tomorrow.

Just recently after Hurrican Sandy caused local shortages of gasolene, many stations had no premium gas at all, just regular 89 octane.

Something to consider.

As far as a camshaft recommendation for a production camshaft, consult with the manufacturer's tech line. That's what they are there for.

For a custom spec cam, Dan Jones was "designing" them for people just for the asking.

I would inquire with him directly on that one and see if the offer is still there?

You can find his contact information on this form in the members section.

FWIW, I agree with Doug's post: 9-1/2 to 10:1 max. Aluminum closed-chamber heads will often allow a half-point higher than iron heads due to better heat-transfer which minimizes pinging. A performance cam will stretch this a bit further at the cost of reduced mileage.

Example: our iron block/alloy head 351-C uses a mild SVO hydraulic cam & 10-1/2:1 CR, and unless I get frisky with the accelerator at low rpms, the 87 octane tractor fuel they sell as "gas" these days does NOT ping. On long trips with a tuner-Holley, we get 20 mpg at 90+ mph. I built this motor in 1991 and it has not had a sedate life....

With a Pantera it isn't that easy to hear the engine ping because of the location.

The real danger with it is if pinging becomes so extensive that it acts as misfiring.

The issue with detonation is as much with the combustion chamber shape as it is the actual static compression ratio.

The closed Cleveland shape does not lend itself well to low octane fuels, i.e., it tends to detonate easily.

Interestingly enough though, the closed chambers on the 289hp iron heads with a 10.5:1 static ratio do. They easily run with "regular" gas with no decernable detonation.

I think the solution to detonation with the closed chamber Cleveland heads is in the camshaft timing.

I think the modern aftermarket "performance" cams are leaving the exhaust open longer to blow some of the compression out of the exhaust.

That is a number that you need to leave up to the cam grinder. You could in effect lower the pressure in the cylinder the equivalent of a point or more by changing the timing events.

That's all too complicated for me. I leave that up to the witch doctor making up a voodoo camshaft design.

The complication to all of this now, is there are aftermarket heads available with their own combustion chamber designs. This effects flame travel and propagation and other factors which all effect sensitivity to detonation.

I noticed one thing with my A3 heads. First they do respond very noticeably to "indexing" of the spark plugs. Secondly, the colors on the porcelains clearly indicate a dividing line in the combustion chamber itself point to the location of the exhaust valves, black-brown, and the intake side, clear- tan.

I have never seen this on any other engine. To me, this is stranger then the South Seas Anomalies.

I do remember that when I ran the 12:1 TRW pop-up pistons, there was a "fire slot" in the dome.

It was said to be worth 8hp stock. I do remember people like Don Nicholson being on record as stating the shape of the piston dome, to him, was the key.

There were pictures of the domes on his pistons as he massaged them in articles in magazines like Hot Rod, back when he was running the 351C in Pro Stock.

I would also say that he was probably running 14 or 15:1 compression ratio with 115 octane gas to get his 800 hp out of basically a massaged stock specification 351 in Pro Stock.

Those other combinations that you saw like the aluminum block and heads were for match racing where there were few limitations.

The Pro Stock engine was the D2AE-CAN 4 bolt block with the D1AE iron Boss heads.

My 408 is running at 10-1. I can barley get by with 93 octane, and it likes the non ethanol best. FWIW

My 351c is bored out .030" so is a little bigger than 351 and i'm using 302c closed chamber heads that have been milled .010", standard flat top pistons, felpro head gaskets and i run it on 87 octane standard unleaded and i have no detonation/pinging issues at all.

I use the standard Bosch 302 points distributor with a electronic conversion installed (hall effect). The distributor is installed with 0 degrees initial advance, 25 degrees centrifugal advance at 3000rpm and 26 degrees vacuum advance with the vacuum connected to manifold vacuum NOT venturi vacuum.

I am running a hydraulic roller on a 20 over 351c
10.5 compression with 302b aluminum heads, 91 octane no problem with detonation, I am also running a Electromotive crank fire ignition.
Their are a large selection of these type of cams, being a roller the loopy stall quality of a big cam isn't there and drive ability is!
You easily can go with lift in the 590+ intake to 600+ range exhaust and 250+ duration with a 108 to 112 lob separation and not sound radical, but you will have incredible performance, you could develop a superiority complex. Their is never enough H.P.

quote:

.. Intake is RPM airgap Also looking for distributor and carb recommendations.

Forget the carbs....go for injection, a throttle body setup should go well on the RPM airgap. You will need at least 1000cfm throttle body.

The distributor should be set between 16 and 20 degrees of advance (initial), total timing 34 to 36 that's with the vacume disconnected, vacume advance is to allow your car to run at highway speeds with fuel economy due to high advance numbers like 42 to 46 degrees of advance, this is only at high vacume or just above idle i.e. highway cruising.Most built engines those with high performance cams don't use a vacume advance, as vacume is 18 to 20 inches in a stock cam, a street racer will only have 13 to 10, drag cars 4 to 6. a good carb for your application would be a 3310 vacume secondary carb, commonly called a 4410 ( double pumper) the 3310 does not share the secondary accelerator pump, but utilizes the venture vacume to open the secondary butterfly s, this carb is very trouble free and inexpensive ( you could buy 4 of these for the price of fuel injection)This is the carb that was on the SS 396 and other notable muscle cars of the 60's. Any of the electronic distributors will work fine, and they give you the advantage of full adjustment (timing)I like the ones with dial pots and rev limiters.The main asset of the 302 heads are flow and they need a good set of headers and a large air filter, sounds funny but these two simple thing can rob you of all the potential in your heads, a small air filter will not adequately provide 750 cubic feet per minute of air flow. You can learn alote from the mistakes of other owners who have tried just about every engine and cam cab set-up

quote:

Originally posted by Aus Ford:

quote:

.. Intake is RPM airgap Also looking for distributor and carb recommendations.

Forget the carbs....go for injection, a throttle body setup should go well on the RPM airgap. You will need at least 1000cfm throttle body.

quote:

vacume advance, as vacume is 18 to 20 inches in a stock cam, a street racer will only have 13 to 10, drag cars 4 to 6. a good carb for your application would be a 3310 vacume secondary carb, commonly called a 4410 ( double pumper) the 3310 does not share the secondary accelerator pump, but utilizes the venture vacume to open the secondary butterfly s, this carb is very trouble free and inexpensive ( you could buy 4 of these for the price of fuel injection)This is the carb that was on the SS 396 and other notable muscle cars of the 60's.

All things are relative:

you could buy 400 sets of points for the price of one fancy electronic distributor, points were used in every notable muscle car of the 1960's just like carburettors, mostly because that is all there was to use. But i wouldn't suggest it.

I played about, tuned, modified, tinkered with, rebuilt and even built from scratch carburettors for 30 years and i thought they were great, then electronics improved and became cheaper and EFI became widely available. Now i wouldn't give a tinker's cuss for a carb, just like i'd never have a set of points now. Some of them a darn expensive too. (you can't get 4 for the price of EFI)

I've converted a few 351's to EFI and there is NO comparison, even a cranky engine with a wild cam that will barely idle and a single plane manifold with huge ports will run as smooth as a sewing machine.

I was just suggesting an option that i believe is superior and would like to share with other enthusiasts, ultimately it's up to the owner to have what they are comfortable with.