Flow rate 2v intake vs 4v intake

289 - 351 cid Small Block Performance
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62Cometman
Posts: 80
Joined: Tue Oct 03, 2017 4:47 pm

Flow rate 2v intake vs 4v intake

Post by 62Cometman »

I have been slowly but surely been accumulating parts for the 260 im building to swap into the my comet. Ive been mulling around the idea of keeping the 2v intake it came with but running a larger cfm carb or possibly even one of the 2 barrel efi units from FiTech. My question is will a 4v intake inherently flow more cfms than a 2v unit? the runners arent any larger i dont believe so this would purely be how much can be run through the opening for the carb itself which would have to be at least up to 500 cfm since thats the largest cfm 2 barrel holly made. I can just as easily get a 4v intake and carb or FiTech unit i was just thinking if theres not performance gain is there anypoint in spending the extra cash on a new intake.
62 Comet 170, dagneham trans, 2.8 7.25 rear 260 T5 8 inch swap planned for the future.

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Rocket989
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Joined: Sat Jan 11, 2014 2:53 pm
Location: Kansas City Metro

Re: Flow rate 2v intake vs 4v intake

Post by Rocket989 »

Stock 2V to stock 4V I would not go through the effort & expense. I’ve had/built a few 260’s and offer the following:

-Intake...I like small single plane intakes on stock head, mild SBF’s. The Weiand X-Celerator, original Edelbrock Torker (twisted carb pad) work great. I used an even smaller runner single-plane Edelbrock StreetMaster on the 260 that used to be in the Comet...worked great!! Dual-plane, I’d use the new Weiand Street Warrior or a plain old Edelbrock Performer.

-Carb...500-cfm or less... I last used a zinc Holley Street Avenger 570 (actually a 465-cfm carb). The Summit 500-cfm carb, Edelbrock 500-cfm, and Holley 1848 (465-cfm w/hot air choke) or an original 1.08 Autolite will all do fine!

Not asked about but relevant:

-The later (pre-68 though) 289 heads with larger 1.78 intake/1.46 exhaust valves (vs. 1.67/1.39) flow a wee better but require rail rockers. Your 260 heads use a close-tolerance slot in the head. Neither is ideal but I’d prefer the latter. The big deal is keeping compression up. If you’re rebuilding there’s like (1) piston available. Zero deck the block & read up on the best/thinnest head gasket to use.

-Cam...it’s very difficult to find a better cam for a mild 260 or even 289 than the original Comp Cams 268H (http://www.compcams.com/Company/CC/cam- ... d=792&sb=0). You can keep your stock, press-in studs and whatever type rocker arm. Great offline power and adds 500+ rpm to the top-end.

-Exhaust..headers will help no matter if they’re 1-1/2 shorties or 1-5/8 long tubes. Our cars are tough on selection...if you decide to use ‘em, ask away... :)

-The distributor mechanical advance curve is a great thing to get right. Not that hard to tweak & worth doing!! :x

Get the little 260 kickin’ some a**!!! :mrgreen:
'cause Johno says you gotta have a sig pic! :)
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62Cometman
Posts: 80
Joined: Tue Oct 03, 2017 4:47 pm

Re: Flow rate 2v intake vs 4v intake

Post by 62Cometman »

Thanks for the reply rocket, i had looked at the C6OE 289 heads but i havent been able to confirm that larger valves will still clear the smaller 3.8 clyinder bore but if it will then id much rather spend the money on them and perhaps just sell the 260 heads to someone that wants a stock replacement. As for the camshaft i was looking at the edlebrock 2122, slightly more duration and slightly more lift. Which i actually have already, it came with the engine however some of the lifters were stuck pretty hard in the lifter bores so i ended up breaking a few getting them out so i would at minimum have to get a new set of lifters which i have heard from some doesnt always work to try and reuse a used cam even with new lifters. I am planning on running the 465cfm holley carb on the edelbrock rpm intake. Im hoping to put about mid 200s to the wheels which im pretty sure is possible with this engine.
62 Comet 170, dagneham trans, 2.8 7.25 rear 260 T5 8 inch swap planned for the future.

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62Cometman
Posts: 80
Joined: Tue Oct 03, 2017 4:47 pm

Re: Flow rate 2v intake vs 4v intake

Post by 62Cometman »

Ive also been considering port and polishing the heads which would likely bring them to the same performance levels as a 289 head but i could do the same to the 289 head and possibly make even more power yet.
62 Comet 170, dagneham trans, 2.8 7.25 rear 260 T5 8 inch swap planned for the future.

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Rocket989
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Joined: Sat Jan 11, 2014 2:53 pm
Location: Kansas City Metro

Re: Flow rate 2v intake vs 4v intake

Post by Rocket989 »

New lifters on old cam (assuming the cam is ok) is fine...not the opposite though. Yeah, 1.78” intake valve will clear.

The RPM intake ports will likely be larger than the ports on the heads (I know they are on the earlier heads...I’ve got a couple sets of C6’s but they’re buried). If the C6 heads have the smog bumps in the exhaust ports, grinding those down & blending the intake runners to match the RPM will help. A decent valve job & springs...good to go! :D Just keep in mind that’s a pretty big intake for a mild 260!

Like I said do what you can to keep compression up!! A lot of Fords #’s were....optimistic. Shoot for as close to 9:1 static as you can!

250’ish at the wheels with a stock head, mild 260 is a long reach IMO but it’ll be fun nonetheless!! :lol: :lol:
'cause Johno says you gotta have a sig pic! :)
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HalleysRevenge
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Re: Flow rate 2v intake vs 4v intake

Post by HalleysRevenge »

I ran World Products Windsor Jr heads on my 260 without issues, those are a 1.9 intake valve

62Cometman
Posts: 80
Joined: Tue Oct 03, 2017 4:47 pm

Re: Flow rate 2v intake vs 4v intake

Post by 62Cometman »

Well i appreciate the response, by chance do you know what your making out of your 260? i got a set of early 289 heads with 1.8 valves that are going on the 260 but it going into a different project mostly due to the cost it would take to rebuild it is more than what i can get a fresh crate engine through work, but im holding onto it and will likely work on it as time allows / money allows, but i want to turn it into a screamer of a little engine :twisted:
62 Comet 170, dagneham trans, 2.8 7.25 rear 260 T5 8 inch swap planned for the future.

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SLCK64
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Re: Flow rate 2v intake vs 4v intake

Post by SLCK64 »

62Cometman wrote:Well i appreciate the response, by chance do you know what your making out of your 260? i got a set of early 289 heads with 1.8 valves that are going on the 260 but it going into a different project mostly due to the cost it would take to rebuild it is more than what i can get a fresh crate engine through work, but im holding onto it and will likely work on it as time allows / money allows, but i want to turn it into a screamer of a little engine :twisted:

It felt peppier but that could be just because it was finally sealing the one down cylinder? No idea on the power, pretty much a head/roller rocker swap with stock 120k mi block and stock 2bbl. But some time(this is all back in 2002-04) after the compression went down on a few other holes so a Jasper 300hp 302 went in. Was lucky enough to get an actual 68 block. Wish I didnt have to hock the good heads from the 260 cause those would have been nicer than the E7 heads that came on the crate engine. the 302 was/is pretty nice with the 4speed, even with the stock 3.0:1 gearing, close to 9:1 compression and a Blue Racer(Wolverine?) RV style cam, 480/500 lift. They recommend at least a 3.70 gear so 3.80 is the plan. Car has been sitting for a long time, need to get back on it.

If you google around you may be able to find the parts specs for the AC Cobra 260. Shelby got 260hp/269tq out of it. 10:1 comp, worked heads, hotter cam(solid lifter?)/timing, etc etc
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bmmaurer
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Location: Mount Dora, Florida

Re: Flow rate 2v intake vs 4v intake

Post by bmmaurer »

I recommend doing what Shelby did to the 260 for the '65 Sunbeam Tiger. Basically Performance Cam, 4BBl intake (F4B or Performer) and a 465 CFM Holley (1848-1). Did it to my 260 and the results were very good. If Shelby designed it, how could one disagree?

Here's the info...

https://www.sunbeamclub.com/forum/tiger ... arb.20977/

https://www.holley.com/products/fuel_sy ... s/0-1848-1

https://www.ebay.com/i/133118523017?chn ... gLnmPD_BwE

https://www.jegs.com/i/Edelbrock/350/21 ... lsrc=aw.ds

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