Anyone ever drove and could compare a 351C with 2V heads running a 4V intake/4 barrel carb to a 351C with 2V heads to the newer 2V intake/4 barrel carb? The reason I ask is there seems to be a mismatch on the 2, 3, 6, and 7 cylinders between the intake and the ports on the 2V heads with the 4V intake. Does anyone know how this effects performance? Would the newer intake that matches up all the runners and ports run better?

Summit has a 2V intake (4V carb) that I am considering. Anyone ever drove a 351C with this type of intake...

Weiand 7516 - Weiand X-CELerator Intake Manifolds - Overview - SummitRacing.com?

How does it compare to a 4V intake on 2V heads? Anyone?

 

have a Cleveland wit 2bbl heads and Edlebrock dual plane manifold with 600 cfm Edlebrock carb.
it works well in a '70 cougar
when I built it I looked at the stock 4 bbl intake and gaskets and decided the fit did not look good, waaaay too bid for the 2 bbl heads and some mis-match, so went with the Edlebrock that matched very well

 

Ya, with the port mismatch on cylinders 2, 3, 6, and 7, and all the larger runners, it has to be robbing low-end/mid-range power, or it stands to reason. Maybe not. Thanks for the reply.

 

I have a weiand x-cellerator on my 2V Cleveland and it runs great. It seems that this is the perfect match. I noticed a great increase in throttle response and midrange power.

 

Ya, I'm considering getting one as well. Glad to hear it works good with the 2V heads! Thanks for the reply.

 

I installed an Offenhauser intake with 4V carb square bore made for the 2V heads, and it does run better than the 4V intake did. It has a more linear acceleration and overall smoother power curve. The 4V intake will run on the 2V heads, but this Offy seems to run better, at least on my stock setup. :yahoo:

I installed the 4V Edlebrock intake on another 351C that has a set of rebuilt 4V closed chamber heads! What a power house! Whoever said that the 4V heads don't work on the street? I am very happy with those CC heads, and I'm running pump gas with no pre-ignition problems, MSD 6AL, SS valves, new springs/dampners, 650 Holley carb, and believe it or not, it still has the 2V cam (soon to be upgraded), but i just wanted to see how much of a difference the 4V CC heads would make by themselves. Huge difference! It seems to like higher rpm or there is more of a punch from throttle movement above 2000 rpm. It still has ***** below 2000 rpm, but there is more brute force above 2000 rpm. I still like the 4V CC heads better than the 2V heads. Cam upgrade is next. I can't wait!

 

On your intake being a big port going to a small port. Yes their is big mismatch but my question is with the gskts sealin. Are you using cobrajet gskts or standard 2v gskts. i know going from 2v intake to cobrajet heads they don't seal perfect at the top of the port with the 2v gskts. Gonna be some vacume leaks for sure. building a cobrajet headed 400 ford and using a airgap intake from a 351 cleveland with spacer plates. But with the port mismatch I've done some epoxy work on intakes to help get my port matching better. Now I've sent my heads and intake off to a flow bench to get flowed and ports fine tuned for even flow between each cylinder and get the airgap intake to flow to heads evenly. Just dropped off last week. Once I get my flow numbers I will document them on in my 400 4v thread. The air gap is a good intake and if you do some work to them they are even better. I wouldn't reccomend you 4v intake for your application instead look into a weiand intake or something of that type or the edelbrock air gap. good luck and curious to how things work out.

 

Originally, the 2V 351C had a 4V Edlebrock intake bolted on, and it seemed to run good. I tore down the engine, bought all the parts and rebuilt it. When I got to the point of bolting the intake back on, I realized that the 2V intake gaskets would definately not seal properly. I got a set of 4V intake gaskets and high temp gasket sealer, and I had no trouble with leaks.

Now, I have an Offenhauser intake made for the 2V heads with a square bore 4V carb mount. It seems to run smoother with this intake, but both of them ran good, even with the port mismatch.

 

I did a 429 cobrajet intake on a set of Dove heads/non cjheads smaller ports many yrs ago. the ports on a cj are huge compared to the standard port and had problems down low on rpms and once rolling in the 2500rpm and up seem to be OK and was a mudder for many yrs. eventually went to a weiand stealth intake and better matching port set up and just help broaden my rpm range low and high rpms. On your set up going from big port to smaller port creates lots of volume in intake. The shelf from intake to cyl head creates some port disturbance and your possibly losing something especially down in low rpm range. volume in intake port is good especially when its moving/velocity. If slow it tends to puddle up or gasoline goes from a liquid state to a vapor and if slows down to much causes puddling in intake and meaning went to a liquid state. try to keep in a vapor when hitting combustion chamber. another thing to help is the carb with the different boosters within the carbs downleg or annular or straights and several other variations of these things inside carb. The annulars really help get fuel to a vapor especially in a weak signal of air being drawn through carb. their is more to this but not enough time. I like my 4wds and used to mud race for many yrs but I like to build good 4wd mountain trucks her in wyo. Sorry for rambling but this is where I'm at in building my 400 and sent my heads to get flowed and evened out on flows. Catch you later.

 

Thanks for all the information. Sounds like you're going to have fun with that 400!

 

yeah ranger I'm currently working the very problem you speak of and correcting similar to your question. I say going from small port intake to big port head not so bad. Things can be worked and modified. but the Reverse big port to small kinda sucks. It works but the trick is the turndown to intake valve area is decent but with a 4v intake port being so big kinda defeats itself. these are things that keep me up at night!!! my situation is the opposite of yours. check out my albums and you can see where I did some epoxy work to intakes for cobrajet head and kinda get the picture. hit wyoming4x4 and check out some of my photo's