Cam install

[Bobs68]

I'm getting a 274/274 112 Clay Smith cam and lifters, sorry Jamyrs.

I have a 68 200 with MRaleys old log head, (it's been hogged out, milled and big SI valves with 302 springs, and Weber 5200 mounted on a Clifford adaptor. I'm also running a duraspark 2, with a msd6 module, and clifford headers with Summitts Mustang exhaust with turbo mufflers. My car runs great but not so good in gas mileage. The carb was heavily modified by MRaley's builder. I'm installing a fuel regulator because I've been told that may help my mileage.

So my question is about the cam. Too much, too little or just right. Other than a new double roller timing chain and the gaskets do I need anything else to accomplish this install. I have a friend who says he can help me degree it in, (4 advanced right?).

I have an adjustable rocker arm but have never installed it. Does the adjustable require different pushrods?

I'm really excited about this mod I think its just what I need to go with the other mod's that I've done.

Bob

 

[Bobs68]

By the way I would like some where between 150 and 200 horse power. Will this do it or do I need to change/make further mods.

Thanks again.

 

[wsa111]

You need flat top pistons to get to 10.5-1 compression with that camshaft for decent performance.

You also need to get your distributor curved to 10 degrees centrifigul X 2 = 20 + 18 degrees initial advance for a total in the area of 36-38 total.

Your centrifigul advance needs to be in by 2500-2800 rpms.

Get a vacuum advance with less travel & set the adjustable part from 3-5-12 tested with a handheld vacuum pump. i will post the vacuum advance can #'s later. Bill

 

[FalconSedanDelivery]

Automatic or Stick ?

 

[Bobs68]

Hey Falcon, I have a V8 T-5 and an 8" rear. Right now it's a 3.00 open, but I'm searching for a trac-loc. I'm also running 15" BF Goodrich tires.

wsa111, Will I need to install the flat tops right away? The distro mod you talk about may be over my head, I was going to try the mod in the sticky section, but that probably won't do what you want.

MRaley said they milled .060 off the head, I was going to have an addition .010 milled when I pull it for the cam install. I was also going to have an adapter installed directly to the head. Not sure if I want to continue running the 5200 or switch over to a Holly 350. I believe the Holley would be easier to tune. I also need new valve seals, the car sit for a couple years and I get a little puff of gray smoke on start-up.

I was hoping just the additional milling would get my compression up enough to run the cam, what do you think? If I need to do much more than milling and the distro mod this may not be the cam for me.

Thanks everyone for the advice.

 

[jamyers]

I'm getting a 274/274 112 Clay Smith cam and lifters, sorry Jamyrs.
...

No worries at all, Bob - that's prolly more cam than I really need, hope you have a blast with it!

 

[FalconSedanDelivery]

That cam should be fine , sounds like a good combo , the Dist curve is a must do ( for any combo ) PM me if your interested I re-curve Distributors for a living ( well part of what I do ) .

 

[Gene Fiore]

By the way I would like some where between 150 and 200 horse power. Will this do it or do I need to change/make further mods.

Thanks again.

I'm going to assume you mean horsepower at the rear wheels. Not quite sure but has the head already been modified for direct mount 2bbl? You mention using a Clifford adaptor? Doing the direct mount is worth about 20 - 25 hp with the right carb so if you don't have direct mount setup you will never reach your horsepower goals IMHO. I am pushing about 150 hp at the wheels with my current setup.

 

[Bobs68]

You have a sweet ride Gene. No I'm still going through the Clifford adapter, but I will have the head worked to direct mount while it is off for the cam install.

I'm leaning toward an Autolite 2100. What venturi size would be optimum for this set-up?

Thanks,
Bob

 

[Gene Fiore]

I think I would shoot for something in the 300cfm range...I believe the Autolite with 1.08 venturis is about 287cfm or thereabouts.

 

[170-3tree]

I think that you might be best off going with a smaller venturi. Something like 1.01/1.02.
If you look ay mikes page he has a day at pony carbs where a smaller venturi actually produced considerably more power than the 1.08.

Edit: then again, on a milled log the intake velocities might be higher than with the aluminum head tested, and might allow better gains with the larger carb. But that is just quick theory.

 

[Gene Fiore]

Yeah, I was there that day at Pony carbs. If you look closely at those dyno runs, the 1.08 was about 6 hp lower than the 1.02 but the air fuel ratio was leaner with the 1.08 which most likely accounts for the drop in hp. I think a re-jetted 1.08 would have produced more power than the 1.02...I'm just saying...

 

[170-3tree]

Ahh the powers of being there. Haha

 

[xctasy]

Pump up the compression, use 93 octane, and decide now if you want to go the next step

a) of a direct mount 2-bbl and
b) if you want a 5200 carb with 29/31 mm venturis,
c) or a 38 DGES Weber 2-bbl with 29 mm venturis
d) or a stock 7448 350 cfm 2-bbl Holley
e) or a 4412 500cfm 2-bbl Holley

Going back to 2100 carbs with venturis in the 1.02 to 1.08" range will not work as well as a properly tuned carb with 1.02/1.06" as the 5200 does, or 1.14/1.22" as the reworked 5200 with ground out venturis. Unless its a later Pierce supplied Weber 38, all 38 DGES carbs have 1.14" venturis. A stock 350 has dual 1.1875", and a 500 has 1.375". As long as the carb is jetted to suit, the extra venturi sizes will yield extra flow without a fuel economy or power penalty.

A 500 cfm 2-bbl carb can flow almost 350 hp if a dedicated cam is designed for it. Any 350 cfm 2-bbl carb can go to about 245 hp if there is a specific cam designed to build cylinder pressure. The Weber 38 DGES flows almost 350 cfm, while a 5200 Holley Weber can be taken out to almost 350 cfm as well if you enlarge the venturis.

Stock, a 5200 won't get you past 280 cfm at 3"Hg, as its factory rating for the 26/27 mm venturi version is less than 230 cfm at 1.83"Hg. The max horsepower is 186 flywheel net hp with a specialised cam.

The 274 cam is a standard list cam which will get a reowrked log head up to around the 170 hp flywheel net mark if the carb is a well tuned 5200, 185 hp flywheel net with a hogged out 29/31 version of the 5200, or a 38 DGES or a 350cfm Holley. The compression ratio must be 10.5 or so, the best exhast system is the Hooker tuned length system with dual out 2.125 exhasts, the cold cranking compression must be no more than 175 psi to ensure there is no detonation.


As it stands now, the poor fuel economy is a just symptom of the jet redrilling, and the way in which a 5200 base plate integrates with the stock 1-bbl porting. You have to preserve and move forward on the mraley's set up. From others that have used later model B, L and T-code log heads, it is certainly possible to flow 218 hp with a fully worked head which has an enlarged 1-bbl intake hole. You can go right up to 2", and 131 hp (97.4 kw) at the rear wheels was the figure 73greenmachine got from his 4-speed manual 250 Cortina with 72DA-6049 head.

See figures in page 6 of 73greenmachine's cardomain website.

The head you have is a D7 250 L-code Maverick log with a Stovebolt base adaptor attached to the standard 2-bbl Clifford adaptor. This allows a Holley Weber 5200 to sit in stock position, low enough to fit in the tight 65 Mustang engine bay.

The head easily flow enough for 120 rear wheel hp with an auto, maybee 133 hp with a manual.

Thats about 160 flyweel horsepower net, about the same as the 4-speed manual 82 Mustang GT 5.0 2-bbl.

Due to problems with finding the original jet sizes, the primary and secondary air and main jets were all redrilled with various jet drills to get air fuel ratios right for best power.

 

[Bobs68]

Thanks for all the info xctasy! I would be happy with 160 to 200 flywheel horsepower. I'm going with the 274 cam and will direct mount MRaley's 5200 to the head. I'll search the forum for info on how to hog out the venturis. I'm putting in a holley fuel pressure regulator.

After the 274 install and direct mount carb, I'll see what I have, then decide whether to up the compression or add a turbo. I have lot's of homework to do on either of those before I can make a decision though.

I appreciate guys like you, David, Will and FSD for all your knowledge and willingness to share it with us amateur grease monkeys!

 

[jamyers]

See figures in page 6 of 73greenmachine's cardomain website.

Link to site = http://www.cardomain.com/ride/616166/1973-ford-cortina

 

[Bobs68]

Thanks for the link jamyers.