Intake swap on 4V 351C

[spdbk1]

Besides the weight advantage is the Edelbrock intake worth the swap also a set of headers on a 71 351C 4v motor w a 4spd

 

[Sheriff41]

Yes, to both.

 

[jpaz]

Depends on what intake you’re talking about. The Air Gap is really good but the Performer is just an aluminum version of the stock cast iron intake. Some weight lose with the aluminum ones too. Headers are good choice, recommend getting some that are ceramic coated.
I did both, but I went with the Blue Thunder intake and a set of Hooker Competition ceramic coated headers. They fit perfectly and aren’t too low. Don’t get the Super Comps, those are the ones that are too low.

 

[MAD IRISHMAN]

The Edelbrock Performer is NOT just an aluminum version of the cast iron intake. It has been proven ad nauseum to be an improvement over stock.
If someone had bothered to LOOK it is obvious the two are not the same! Performer was designed to enhance lower RPM power & torque.

 

[kcmash]

Agreed on the Edelbrock being different. The 351 4V is known for not having enough intake velocity at low RPM. So the Edelbrock reduced the intake ports size to increase low RPM performance.

On the exhaust side, the 351-4V manifolds have larger ports than most headers, so I see no need to switch to headers.

Having said this, I do not race my car. I have no idea if the Eldelbrock Performer II LB that I put on is more powerful than the stock intake or not. All I know is mine drives fairly nice and has a fun feel with the 4 speed. Of course I don’t think I have even taken it to 4K on the RPMs since rebuild.

Kcmash

 

[Hemikiller]

Yes to the headers. Hooker Competition #6915 for 4V heads, which will work with the 71-73 clutch linkage.




As far as the intake, it's a toss up IMO on Performer vs Stock. You'll save a about 30lbs, but the Performer is not that big a bump in performance for the money. For the extra $75, I'd go with the RPM Airgap intake.

Dan Jones did a bunch of back to back intake testing on a mild 351C-4V engine. Link is below, the data speaks for itself.

https://www.corral.net/threads/budget-351c-rebuild-and-dyno-test.2092114/

 

[Ryunker]

Agreed on the Edelbrock being different. The 351 4V is known for not having enough intake velocity at low RPM. So the Edelbrock reduced the intake ports size to increase low RPM performance.

On the exhaust side, the 351-4V manifolds have larger ports than most headers, so I see no need to switch to headers.

Having said this, I do not race my car. I have no idea if the Eldelbrock Performer II LB that I put on is more powerful than the stock intake or not. All I know is mine drives fairly nice and has a fun feel with the 4 speed. Of course I don’t think I have even taken it to 4K on the RPMs since rebuild.

Kcmash

Exhaust manifolds do have larger ports than 4V headers, I removed the headers for that reason. I do not race either, currently still running stock intake manifold on my 351 M code.

 

[Spike Morelli]

A thought on headers. This may not apply directly, but I remember this and thought I'd share. Years back, I recall seeing a dyno test on, I believe, a 289, where they were comparing exhaust system components. Obviously, the standard 289 2v / 4v factory manifolds were restrictive, and produced the lowest HP numbers. Then they replaced the stock manifolds with a set of Hi-Po cast iron manifolds, and the numbers were about the same, I was suprised a bit. Next, they bolted on late model "shorty" headers. The numbers were still shy of being worth all the hastle with the "shortys", but for space limitations I see why some people chose them. Finally, the dyno guys installed long tube, full lenght headers on the dyno mule. The horsepower now jumped to where you would actually feel it seat of the pants.
Certainly a Cleveland is a different breathing animal from a Windsor Ford, but, although your Cleveland may have the 4v big port heads, the exhaust side is weak in comparison. The heads were cast as a sort of comprimize on the exhaust, due to the front spring tower being right there next to the engine, and Ford had to cast the exhaust port angled down to clear. All race head castings re-shape the port, or raise the roof to rectify this shortcoming. So.....Yes, even if you have the "good" 4v heads on your Mustang, headers will improve the characteristics of the exhaust breathing. If you have a trailer queen, or a dough-nut shop warrior, or only use it to go to parking lot car shows, you may never use the benefits of headers. If you drive a lot, hit the freeway often, and of course, if you race your car, the benefits should be there for you to feel. If you aren't racing, try to get the smaller sized primary tube offered, to keep scavenge velocity up in low and midrange useage. If you do make changes to your Mustang, I'd always keep the original parts whenever possible. They don't make the manifolds for these ( or do they? ) anymore, and as the years go by, you may sell it, and the next owner may be very thankfull that you didn't get rid of parts they may want on the car.
If you don't want to modify your Mustang, and like'em original and factory correct, I can dig that too!

 

[jpaz]

The Edelbrock Performer is NOT just an aluminum version of the cast iron intake. It has been proven ad nauseum to be an improvement over stock.
If someone had bothered to LOOK it is obvious the two are not the same! Performer was designed to enhance lower RPM power & torque.

Well I had both, and I Did research this so don’t tell me I didn’t! The only two advantages are some weight loss and pretty much any aftermarket carb will bolt on. If you think there’s a big performance gain with the performer, you need to do some research. The Air Gap is a great intake as well as the Blue Thunder intake. They both add at least a 25 hp gain, but not the Performer sure doesn’t.

 

[Spike Morelli]

I think the Intake manifold decision could yeild more answers when all the parameters are graphed. This would take a lot of dyno time, and more that one engine, set of heads, carb, or camshaft being used. Hemikiller's entry has a link that's how I see it. I was just at a Christmas party with a bunch of boat racers, and inevitably, the subject of "Dynoed" horsepower figures came up. One guy said his Big Block Chevy Day Cruiser put out a zillion HP at 7500....my question was how often will you take it and hold it at 7500? How much torque/horsepower are you throwing away by going for peak numbers? My Mach is a good example, it shifts at 4000, my designated redline is 5000, if i chose a cam that made it's peak power at 7000, I probably chose the wrong cam and power figures within my working range would suffer. Likewise, I think it would be interesting to be able to dyno our ( every one is different ) engines in the RPM range we will actually drive in, and have a few manifolds to try out. I'd be looking mostly at the Torque readings. Horsepower is relevant, but Torque moves you.

 

[Big Red Mach 1]

Another Blue Thunder fan here along with jpaz. I like mine quite a bit. I also have Hooker long tubes. Mine do hang down quite a bit.

 

[c9zx]

The stock D0AE-L intake is not that bad especially with a .5-1 inch open spacer. The air gap and the Blue thunder are better. The 71 4V intake can be made to work reasonably well. Chuck

 

[Paul M]

Besides the weight advantage is the Edelbrock intake worth the swap also a set of headers on a 71 351C 4v motor w a 4spd

Yes, you'll save @ 30lbs of weight, improve heat distribution. The stock intake is @ 45lbs and the aluminum ones are @ 17lbs. In my case I went with the offy 360 since it sat low enough to use w/ my stock ram air & most importantly it was perfect for the RPM range of my cam.

 

[351c1971]

In addition to the aluminum intake, I have an aluminum bellhousing on the Toploader and a Weiand aluminum water pump.

Does anyone have an estimate for the weight savings for the bellhousing and water pump?

 

[Paul M]

The water pump saves 10lbs. Intake just under 30, close enough to 30. Battery relocated to the rear gets @ 45lbs of weight transferred from in front of the wheel (bad ballast) to the rear where it's needed specifically if it's mounted a little farther in from the stock trunk mount battery location which puts it too far back. I also dropped the heavy 73 urethane battleship bumper for a 71 saving almost 100lbs out Infront of the wheels in the worst place for ballast. aluminum wheels over steel helps.

 

[351c1971]

Hi Paul M
Thanks for the estimate. I'm guessing the aluminum bellhousing saves another 30 pounds. That's 70 pounds for all 3.

 

[fmjcraig]

And don’t forget a healthy diet and exercise, another 50 pounds off…lol

 

[351c1971]

Drivers can always always help by shedding a few pounds
I was also thinking about the weight penalty for options. My guess is that AC, Power Windows and the Fold Down Back Seat add a total of about 150 pounds.

 

[Bobby]

Cmon guys, let's not snipe at each other. We're supposed to help. I went with the Performer because it had the lower profile from the taller RPM air gap intake. The lower profile was necessary for my hood to close and mate with the RAM Air system. My build also used Trickflow aluminum 2V with Sanderson shorty headers and an aluminum Flowkooler water pump. The performance differences in the stock manifold and the Performer are not striking but they are a definite improvement especially in throttle response. I would have to say that there is a 60 to 70 pound weight difference.