I have purchased a 352 short block with about 10K on it for my 1966 F250 Camper Special. I know..some'll say should've went 390...but that's not my style. Pardon my contrary nature...

Since I've got the thing opened up I've decided to do some "improvements" to squeak out some more life from the engine.

I've ordered from Jegs a Comp Cams Part #33-248-4.
Exhaust Valve lift 0.562 Intake Valve lift 0.565
Exhaust Duration: 274 Intake Duration: 286

I have a 4bbl intake over which I'll put a Edelbrock or Holley 650.
Can I go to a larger volume CFM carburetor?

The engine will have headers out 2.5 inch pipes going on at re-install.

The heads that came with the engine have adjustable rockers. I have no desire to tangle with those. 3~ cylinders show excess carbon build up which I suspect is due to out of spec valve adjustments...
Can I use the non-adjustable valve train with this cam?

Also, Comp Cams website says I'll have to do 'machining on the cylinder heads.
What do they mean by that?

I've decided to go with dual point distributor (don't try to sell me on electronics ), again contrary retro-grade stubborness.

Can I get some feed back on these questions? I'm no mechanic....just a parts swapper.

Aside from installing new push rods and a high volume oil pump..can anyone make some suggestions as to what else I should do as I put the thing back together....??

TH1567
Go FE or go home.

 

What compression?

Forget the dual points, I know you want to fool with points, but there is no reason to run dual points on this engine. You are not going north of 5500 rpms.

A 650 should be a good size for this.

Regarding the head machining and adjustable valve train--stand by on that. Might have to do with the greater lift. What did they say about springs? Some springs will coil bind with the greater lift, so some caution is due there. And caution is due with respect to the overall geometry, so perhaps the adjustable valve train is a good thing, but I've seen several posts about that so you should get more responses with more complete info.

Good luck with it.

 

Ok, no dual points...my foot ain't that heavy..I'll just go with a good aftermarket distributor...the stock one on my truck is shot and the short block hasn't one.

Compression...that is unknown...but I can't imagine it's much higher than stock.

I'll stand by on the machining.

TH1567
Sleeper's are fun.

 

A 600 would be even better. Since this engine even at 6000 rpm would only need 611 CFM with 100% volumic efficiency, 80% will be the best you can expect. Over carburation is the worst thing hot rodders do on street motors.

 

Mmm...interesting....I was thinking the increased ability to breathe via the camshaft coupled with the headers would allow for a larger CFM....

If that's the case then....I can go with a 600 and tinker with the jetting. What say you guys?

TH1567
Go Ford or go home.

 

Carb size is determined by CID and RPM, not the camshaft.

The formula is as follows;

CID times Max RPM divided by 3456 equals CFM with 100% efficiency. Since 80% is realistic take the CFM and Multiply by .80. Even without the .80 figure 6000 rpm with a 352 is only 611 CFM.

Don't belive me? Go to Holley's site and see what they have to say.

Holley Performance Products Frequently Asked Questions

 

Bear is absolutely correct.

Yes, cam and more breathing overall MIGHT allow you to run a bigger carb, but at 352 cubes with volumetric efficiency not being 100% EVER, you're way below what a 600CFM carb will do anyway.

Keep with the 600CFM (or 650), the smaller venturies on the primaries will help low-end torque, and MPGs.

For the valve-train, you could use the stock non-adjustables, just have to make sure the machine shop gets the valve stem heights somewhere near stock, or be prepared to buy under/over-sized pushrods to adjust them.

The lift and duration is pretty high on that cam. On my 390 build I used double valve springs, with .554/.554" lift and 292/292 duration. I think if you don't get better springs, you'll have valve float at a very low RPM.

See what Comp Cams suggests to use with that cam, be aware you might be getting into more head machining, new guides, and positive-lock valve stem seals. = more $'s.

It might be a little TOO much cam if you aren't going to bump the compression at all. (that's an understatement)

 

Hey Bear,

In no way was I doubting your veracity. I'm no where near as knowledgeable as you are this matter, thus my very broad, open ended post. Your advice is sound and I'll follow it.

Why would I wasted money on something which I can never fully utilize? That would be like buying a hammer without claws, a car with near flat tires, a lawnmower with an out of balance blade...this could go on ad infinitum.

So, I'll either go with the 600 or the 650 CFM but no higher and I'll make sure the compression is compatible....

The machinist says I got to get the Comp Cams recommended springs, so I will even though the ones on my heads are new, they aren't right...
Durned springs are $200....but that's cheaper than a chipped piston!

Got that on the push rods...I've got the adjustable valve train and comps says the stock length pushrods are ok with this cam...but I'll put a call in to get that confirmed....

Thank you and I look forward to more....it's very difficult to parse throught the hundreds of threads to come up with a solution for a specific build....

TH1567
Burn out or don't go out.

 

[quote=th1567;7267305]Ok, no dual points...my foot ain't that heavy..I'll just go with a good aftermarket distributor...the stock one on my truck is shot and the short block hasn't one.

An excellent reason to complete the modernization of this engine on which you are spending a lot of time, energy and money to make sure will run right:

Performance Distributors - High Performance and Racing Ignition Systems

Besides, they are a FTE sponsor....

 

ok! got it...

TH1567
Go retro or go home..

 

You didn't offend me at all. But I have found that rather than just say "I know more about this subject", it is better to post the info so they can see for themselves. I have been know to be a bit high handed once in a while and am working on it.

 

Cool,

I've got a call into to the machinist to check what the compression is on that engine...we think it's 9.0:1 but he'll confirm....but the engine though it's fairly new (you can still see the cross hatch on the cylinder walls) does show signs of an improper break in or some leak down from the valve seals....

He thinks if we can boost compression and go with the Comp recommended springs the engine will perform just fine mechanically. He too is concerned about over carbing the engine but thinks it wise not to going between 600 and 650.

This may be a dumb question at this point but can a carb CFM be tailored to a given set up without exorbitant expense...?

TH1567
Learn it by doing it.

 

Not on any of the popular carbs you'd be buying.

Webers have replaceable venturis which change their inside diameter (and change the speed of the air going past the jets), but you won't be using them

 

Your best bet is a vacuum secondary carb or an air valve carb. The secondary opening is adjustable and can control when, how fast and how far they open.

 

Got it...that is the pathway I'll take. Got a line on a 650 here in my area..lots of edelbrock 600s out there but I'm going with the Holley this time 'round. We've got a great Fuel Systems shop which I guess I'll have them dial everything in...or I'll have my brother tinker with it, he's good at fussing with stuff like that...I'm sort of good at coordinating all the various elements and driving the h.e.l.l. out them.

Comp says the cam I'm going with will produce results from 1750~ to 6100~ RPM. so long as I'm using headers and so on. Comp also says that I should see 320 to 340HP out of this set up, that sounds too liberal to me but if I crack 300~ (I'm not going to measure it) actual I'll be stoked. Bone stock the 352 in a truck was rated at 180HP...

Will update this post as things come together....maybe so pics too if'n I ken..

TH1567
Drive right or drive home.