I have a 347 stroker I'm building. Got an E-cam in it and am finishing up my selection of the top-end. Looking at Trick Flow Twisted Wedge heads, an Edelbrock Performer intake (not RPM version) and a Holley carb.

I understand I need between a 600 and 650 cfm carb for that size displacement. Questions are:

Which is the best carb for my dollar?
Rate Holley vs. Edelbrock carb for me.
Vacuum vs. mechanical secondaries?
Double pumper or not?

Truck is running a manual tranny on an Early Bronco (not too heavy a truck). Main use is street, with recreational off-roading tossed in for good measure. I want something easy to tune but reliable. Thanks!

 

one word go edelbrock on the carb i have had a dozen holleys on my truck and unless your really carb freindly the holley seems to be a pain in th butt .the edelbrock bolt on and forget its even there i have had the same edelbrock carb for three years now and not a problem yet

 

I just finished shopping for the carb for my 347 and consulting 3 different engine builders. With those heads on a stroker, I personally wouldn't go any smaller than 700 cfm. I found a 725 Road Demon Jr. (Barry Grant) with electric choke, vacuum secondaries, and Ford kickdown linkage for $319. Although that's what works for me, you definitely need to match your carb to your cam, head, intake and header combo. That Demon was the best bang for the buck for mine. True, Edelbrocks are pretty much ready to run out of the box, but so is the Demon, which has been wet-flowed and set up at a baseline that allows me to tune it for my needs (with Holley parts). It comes with a manual that outlines tuning tips. Personal preference, I guess......

 

i have heard alot a good about the barry grant as well never ran one though i just no for sure the holleys are trouble if your not carb freindly

 

Trick Flow TW heads and a Performer intake is a horrible combination, it limits your power range to in between about 2500-5500. With that head and cam setup, you want to be running at least a performer Rpm intake with a 700 cfm Vac Sec. carb and you would be good from about 2500-6500+. In my opinion, you should bag the TW heads and get some edelbrock performer heads (1.90/1.50) with a performer intake and a 268 cam (or like roller cam) that would bring your power into the idle-5500+ range, better for a bronco as its hard to even get that thing to 6000.

 

That may be so, RnD, but my Early Bronco only turns up to 4000 RPM max, that that's really winding it up. I want and need all LOW RPM torque and power. The RPM intake is made for higher revs I don't need. But I appreciate the comments.

 

That was what I was trying to get at, sorry if I confused you. The twisted wedge heads are for high Rpm use and a performer intake would be for low Rpm power. The combination would be a poor choice. You would be alot better off, torque-wise- to use the Performer heads as well,with like a 268-ish cam and a 600 cfm carb. If you stuck with the TW heads, you need a bigger intake and carb or you would get crappy torque numbers as well as horsepower. In fact if you wont even go above 4000 rpm, stock E7 heads or even some vintage closed chamber heads would do the job just fine.

 

get the e7 heads there cheap enough to get at a junk yard they are what im using with the performer intake on my new truck im building and i put a crane cam with a 484 /512 lift and 216/228duration i dont know how it is yet im rebuilding the truck frame up long way to go by the way i had the e7 ported and polishded for good measure

 

I have two sets of E7TE heads in my garage already. Since I'm a new guy to engine building, what are the critical characteristics of a set of heads that torque is derived from, and how do those characteristics differ from the TF TW heads to he E7TE heads? I know I'm not trying to go overboard on everything to make it the BEST engine, so I'm willing to live with maybe the non-OPTIMAL components. I'm looking for improvements in each component, so the E cam over the stock is better, Performer intake is better than stock, etc. Thanks for all the input!

 

I would go with demon or holley, easy to tune, and can be customized for whatever you need.
The last edelcrap I had was on a chebby and I had to retune it every other day, when I talked to a local carb shop here, they said that hapens to them after about 5 years of service due to the cheap aluminum they use as it gets worn by the parts moving, throttle plate and plunger.

 

agreed i had lots of trouble with the edelbrock carbs to

 

Your spending the dough to do a 347 I say go for it and get some aluminum heads. You can run a point higher compression without detonation.. Save the 600-700 your going to spend to get those e7's done and get something like the edlebrock heads. They go for around 1200 with springs good to .575 lift. They are also pretty close to being port matched to their manifolds. So that gets you 2 things you need. I run a 470 cfmholley truck avenger. Easy to tune for the novice to holley like me. For you a 670 would do fine.
IMHO.

 

Look at it like this: Your engine is an air pump that operates off of a pressure differential, the difference between High (combustion) and low pressures (exhaust/intake strokes). Lets say you have two tubes, one is 2" in diameter and the other is 1" in diameter, At one end of each tube there is a positive pressure of 100psi and the other end is at 14.7psi (air pressure at sea level) for a pressure differential of 83.3 psi and the flow rate of air is at a theoretical 100 cfm of air (im sure the calculations with these parameters dont work out right, but bare with me, im just making an illustration), The air is going to move faster through the smaller tube because there is less volume to keep moving as opposed to the bigger tube which has alot more volume to keep moving so at the lesser flow rate (100cfm) the bigger tube velocity is less. But when you bump up the flow rate (increase the RPM) to lets say 300 cfm, the small tube reaches
terminal velocity (velocity stays the same, maxed out) where it cannot flow any more air because of the size of the tube. But the big tube CAN flow all of that air and do so at an as fast if not faster velocity because there is more air flowing (More CFM). Basiclly it comes to this: The faster (port velocity) you can get a certain amount of air(displacement), at a given flow rate (RPM) from the area of high pressure to the area of low pressure, the more power you will get.<br><br>

The Reason that the E7 heads would be better for a low RPM application is because of the port and valve sizes. the E7 heads generate more torque because they have a lot of port velocity (easier to get the air flowing through a smaller tube)at a lower RPM than the TW heads which have huge ports and valves (big tube) and it is hard to get a little amount of air flowing fast through a big tube. The TW heads have better port velocity higher up in the range because there is more air flowing to fill the port, putting it simply. All your parts have to be matched to get any real benefit from them.

 

Your right on the the size of the valves. 2.02 would probably be too much for his use. That's why I like the edlebrock heads. They are availble with 1.94-1.60 valves. excellent size for a stroked truck motor. Plus they will out flow the e7 and about 50 pound weight saving.

 

Great information and recommendations from you all. Very much appreciate the illustration...I'm a mechanical guy, so that makes good sense. Just never tinkered with engines much.