Pump Gas Cam Selection

[Riderjeff]

Howdy all.
New poster here, looking for specific recommendations for a street cam.  I'm resurrecting a '65 T-Bird that's been hiding in my garage for too long.
It's currently got a truck motor under the hood; don't know exactly what it is but it's a 2-barrel carb and a large snout crank from 1971.  Probably a 360/361 but it's just a donor block.

This will be a cruiser, not a racer, unlikely to ever go to the strip except for fun.  It will need to be an economy rebuild, either a 390 or 410. I've got a Streetmaster for the intake, and some C4AE-G heads on the shelf that will probably be rebuilt with stock valves and springs appropriate for the cam. I plan on a set of FPA headers, but that's about it for performance parts.  T-Birds need vacuum, and this will have the stock brakes & vacuum accessories.

The thing is, I'm looking at appx. 9.8 or maybe 9.5/1 compression with dished pistons.  I want to avoid the expense of forged and/or custom pistons.  I'll spend my money on good machining, so I'll have a stock bottom end put together right. 

The question is how much cam will I need to avoid detonation on pump gas? If the block is decked to allow good squish, what do you think would be the best compromise cam for good street manners and no octane problems?  Locally all we get is 91 ethanol blend.

I'd appreciate specific recommendations, rather than numbers, if that's not asking too much.

Thanks in advance.

[plovett]

What rear gear and what converter is it going to have? 

paulie

[Riderjeff]

I'd have to double check the build plate, I think it's a 3.0 rear and I plan on keeping the stock converter and Cruise-o-Matic MX trans.

[plovett]

Compcams 268H, based on what you have said.

But Wait for more advice.

paulie

[Riderjeff]

I like the Comp 268H, but was/am worried about too much cylinder pressure. Was thinking a little more duration would be a bit friendlier, but still need all the accessories to work.  Maybe the 270H?

[plovett]

Building a 410 would make the 270H more viable.   The extra 20 cubes would soak up some of that cam.   

[plovett]

A little more gear would help, too.  Is a 3.25 or 3.50 too much? 

[plovett]

When I put the 268H in the dynamic compression calculator in a 390, with 9.8:1 compression and installed on a 106 degree intake center line, I get a dynamic compression of 8.08:1. 

That is not crazy high.  The heavy car, high gears and stock converter hurt you there.  91 octane will help.

9.5:1 would be better.  0.3 points of compression will net you an almost unmeasurable power difference.  But detonation will be noticeable at some point, if it occurs. 

paulie

[Drew Pojedinec]

There has never been a camshaft, carburetor, or torque converter that I would buy off the shelf.
In any of those cases I would contact an expert, pour all the details out to them, and have them make a custom piece for my application.

[Riderjeff]

Thanks, but as I said in the original post this is an ECONOMY rebuild.  Pretty much everything will be off the shelf!   

[fastback 427]

You can get a custom camshaft from one of the three builders here for roughly the same price as a shelf cam...
I did.

[Sand hauler]

Ditto on what fastback said. And it will be worth it in the long run that I know. Lessons learned the hard way

[blykins]

A custom flat tappet will run you about $65 more than a shelf cam, but it’s definitely worth it.  There are lots of cams that are universal.  The 268H, 270H, etc., are great cams but they share the same specs for every single engine family.  Different engine brands and even different engine families require different specs. 

One beauty of a custom flat tappet is that we can grind them with more lobe taper to help with cam break in. 

You are wise to keep an eye on the duration with the shorter cams.  It can bite you with a tall gear and heavy car.

[Riderjeff]

Ditto on what fastback said. And it will be worth it in the long run that I know. Lessons learned the hard way

Can you guide me to who these builders are?  I'm such a newb..

[plovett]

It's the 3 Bee's!

I am against advertising on the main forum, but I don't think this is that.  They are all gentlemen and won't take advantage.  I think this is just providing information. Jay can decide. 

Anyhoo,

The 3 Bees are:

Brent Lykins

Barry Rabotnik

Blair Patrick

Just google their sites and contact them.  It is funny that the three most prominent FE guys are "Bees", but that is what happened. 

paulie

[Sand hauler]

The 3 bee's , LMAO I like that. Like Paulie said those are the guys

[Drew Pojedinec]

Thanks, but as I said in the original post this is an ECONOMY rebuild.  Pretty much everything will be off the shelf!   

If $65 is gonna break you, FE engines may not be your thing

[427LX]

How about  the 390 GT/ CJ cam? 

[My427stang]

Here's the rub on this question...you said cast piston, tight quench.  That will cost you almost as much as going with a good set of Speedpro L2291s in a 390 based engine because there really is no good cheap piston that will get you to a tight quench without a .041 gasket and a heavy block cut.  There just isn't anything out there that has a decent pin height

If it were mine, I'd go 390 with L2291s with a cut to a 10.155 deck.  Save the 3.98 crank money. That combo will get the pistons .001 proud and run the cheaper blue Felpro 8554 gasket.  That should be also be about the same cost +/- 50 bucks from making the cast pistons work.

Then custom cam or off the shelf, either way, I like custom usually, but when you are in that HP range, I'd be more concerned with the lifter choice.  I like the Camsavers as they give a little more oil to the lobe.  I will say I am not a 268H cam fan, I think it's too short for an engine like this and the combo can use some exhaust lobe.  I'd be in the 272 intake range for advertised with about 8-10 degrees more on the exhaust, conservative ,.050 numbers, 110 LSA on 106.   Spend any extra money on a distributor recurve and a shift kit, it'll be fun

[Riderjeff]

Thanks for all the thoughtful replies, obviously I'm still sorting it out and will probably make the final choices with my builder.

If $65 is gonna break you, FE engines may not be your thing

I had no idea a custom grind was so close in price to off-the-shelf parts.  I figured 2x or 3x more!  Yeah, $65 is pocket change on an FE project...

If it were mine, I'd go 390 with L2291s with a cut to a 10.155 deck.  Save the 3.98 crank money. That combo will get the pistons .001 proud and run the cheaper blue Felpro 8554 gasket.  That should be also be about the same cost +/- 50 bucks from making the cast pistons work.

So, stay with me as I'm new to all this: The L2291 pistons are flat top, no?  So according to on-line static compression calculators with the 8554 gasket that would yield about 10.2/1 or so compression.  Do you think that with the iron heads, 91 pump gas, and an appropriate cam I could anticipate a pretty trouble-free cruiser?  Or would this put me into the "maybe-it-will-work sometimes, but knock other times" area? 

Thanks again for taking the time to help out on this, I want to get it right the first time. (Don't we all?  )

[blykins]

Thanks for all the thoughtful replies, obviously I'm still sorting it out and will probably make the final choices with my builder.

If $65 is gonna break you, FE engines may not be your thing

I had no idea a custom grind was so close in price to off-the-shelf parts.  I figured 2x or 3x more!  Yeah, $65 is pocket change on an FE project...

If it were mine, I'd go 390 with L2291s with a cut to a 10.155 deck.  Save the 3.98 crank money. That combo will get the pistons .001 proud and run the cheaper blue Felpro 8554 gasket.  That should be also be about the same cost +/- 50 bucks from making the cast pistons work.

So, stay with me as I'm new to all this: The L2291 pistons are flat top, no?  So according to on-line static compression calculators with the 8554 gasket that would yield about 10.2/1 or so compression.  Do you think that with the iron heads, 91 pump gas, and an appropriate cam I could anticipate a pretty trouble-free cruiser?  Or would this put me into the "maybe-it-will-work sometimes, but knock other times" area? 

Thanks again for taking the time to help out on this, I want to get it right the first time. (Don't we all?  )

An L2291 is a 10cc piston.  You'd be at around 9.6-9.8 with a 74-72cc head.  You can make it all work together easily, but the cam will be an MVP.

[My427stang]

Thanks for all the thoughtful replies, obviously I'm still sorting it out and will probably make the final choices with my builder.

If $65 is gonna break you, FE engines may not be your thing

I had no idea a custom grind was so close in price to off-the-shelf parts.  I figured 2x or 3x more!  Yeah, $65 is pocket change on an FE project...

If it were mine, I'd go 390 with L2291s with a cut to a 10.155 deck.  Save the 3.98 crank money. That combo will get the pistons .001 proud and run the cheaper blue Felpro 8554 gasket.  That should be also be about the same cost +/- 50 bucks from making the cast pistons work.

So, stay with me as I'm new to all this: The L2291 pistons are flat top, no?  So according to on-line static compression calculators with the 8554 gasket that would yield about 10.2/1 or so compression.  Do you think that with the iron heads, 91 pump gas, and an appropriate cam I could anticipate a pretty trouble-free cruiser?  Or would this put me into the "maybe-it-will-work sometimes, but knock other times" area? 

Thanks again for taking the time to help out on this, I want to get it right the first time. (Don't we all?  )

Brent hit it on the mark, but with a .053 8554 gasket and zero deck, it's 9.5:1 with 72 cc, use a cam with 270-272 advertised on 106 ICL and it'll be happy on pump gas unless you have mixture or timing set wrong.  Nice mellow combo, the rest of the cam specs will change the personality, but in the end, easy combo to run on the street

[plovett]

Advertised cam figures can lead you astray so you can't make blanket statements there.  For instance, Crane, Isky, and Compcams all use different lifts for their advertised figures.  They are still worth looking at, but you should be aware.

0.006" for hydraulic cams and 0.020" for solid cams might be as close as we have to a standard, but not every manufacturer uses those numbers.

paulie

Heck, even Compcams uses different lift figures for the advertised duration of their solid cams.   I think their hydraulics are at least all the same?

[My427stang]

Advertised cam figures can lead you astray so you can't make blanket statements there.  For instance, Crane, Isky, and Compcams all use different lifts for their advertised figures.  They are still worth looking at, but you should be aware.

0.006" for hydraulic cams and 0.020" for solid cams might be as close as we have to a standard, but not every manufacturer uses those numbers.

paulie

Heck, even Compcams uses different lift figures for the advertised duration of their solid cams.   I think their hydraulics are at least all the same?

Good catch, I am talking .006, but a hydraulic at a greater lift would only be more tolerant, just give up some torque and vacuum.  As far as solids, "generally" lash is pretty close to measured numbers, so it's usually within spitting distance to a .006 number.  Again though, the error is usually in the good way (.020 measured with .027 lash is actually tighter and more tolerant)

[plovett]

I am not sure, but just going from memory Crane uses 0.004" and I think (?) Isky uses 0.020" even on their hydraulics?  0.006" is certainly more common.

paulie

[falcongeorge]

I am not sure, but just going from memory Crane uses 0.004" and I think (?) Isky uses 0.020" even on their hydraulics?  0.006" is certainly more common.

paulie

I think Isky uses .007 on hydraulics. not absolutely 100% on that, but that's what I heard.

EDIT: just took a look at my isky master lobe list, it doesn't specify the check height for advertised duration.

[falcongeorge]

Ultradyne was .004, just took a look. Kinda looks like Comp is the odd one out @.006, way to ramp up those hyd intensity numbers on the sly. I have an old Crane master lobe list here somewhere, but I haven't found it yet. Howards is .006 on their master lobe list.

[My427stang]

If it's an odd old cam you have on the shelf, measure it at whatever you want to use for a number, otherwise just know what you are buying when you pick it from the catalong

In the end, all likely within the error of a tool that shouldn't be used exclusively for picking a cam (DCR)...especially when someone doesn't degree it or pour all the pieces. 

[amdscooter]

Freshened up the 390 in my 67 lane seven or so years back almost identical to what you are describing. It was a budget tight build as well.  Heavy car with stock C6 and open 3.00 rear. Thread is here:

http://fepower.net/simplemachinesforum/index.php?topic=735.0

Photobucket wants $$$ now.. I'll need to update the photos. Anyway..

Bottom end .030 with nothing else to write home about but oil mods you can do yourself.  Rebuilt stock cast heads.

Went with the Comp 268H cam kit.. came with correct springs etc. Double roller Ford racing chain & FPA tri-y headers with Dynomax mufflers. Original Streetmaster intake. Added the MSD ignition later. 600cfm holley vacuum secondary carb.

It's a cruiser as well. Fun zone starts over 2800rpm if you are getting on it but peters out fast over 5300rpm or so. Lots of vacuum (over 13 easy) and easy to manage. Nice low rumble.

Here is a video I took just after getting the exhaust done:

https://www.youtube.com/watch?v=olhXxOS43lw

Runs great on 91 California blend pump gas.

this is what she looks like now parked behind the all original Trail 50 I tried to swap my buddy for.. 



My2c.

[Riderjeff]

Very nice! Exactly what I'm trying to accomplish as well. Glad it's all working out for you, it looks great.

Nice Honda 50, I recently peddled my all-original CL-90 to a collector out of the Midwest.

[e philpott]

Trail 70 isn't ? I have three QA50