Trick flow 240 or 270 for 421 big block

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Thejames6972

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Hey all! Im new to this site and thanks for having me!
Ive got a 421 short block consisting of: a 72 cold weather 400 block .040 over, half filled, studded mains, bushed lifter bores. 3.5" stroke offset ground 383 crank, 2.2 bbc rod journals. 6.535" manley i beams with .990 wrist pin. And 1.695 ch ross forged -14 cc dome pistons. Ive got an old rr-660 isky solid roller in it right now.
.660 lift int + exh
.324 adv. Duration int+exh
108 lsa.
My question is i cant decide on a set of heads for this thing. Id like to either go with the trick flow 240s or the 270s
This combo will be going in a 3200lb 72 duster, ss springs on a narrowed and back braced 83/4 with 4:30 gears.
904 tranny with a j+w big block bell, 1:74 first gear and a 4500 stall ptc 9.5" converter.
Any help and suggestions is greatly appreciated!
 
Do you already have an intake manifold? Or what type of manifold do you plan to run?
 
IQ52 said:
Do you already have an intake manifold? Or what type of manifold do you plan to run?
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My intake choice will be based on what heads i buy. I do have a polished tunnel ram for a b block...std port but right now im looking for what will work best on the combo and dont mind spending a few bucks on a nice mw port intake or different std port.
 
Either will work. The 270 heads are the larger Max Wedge port size so you'll most likely have to run an Indy 400-2 type intake since there aren't any other choices for low deck MW intakes. The 240 heads give you a lot more intake choices but you have to use the factory bathtub gasket which is a bit of a pain, or switch over to a semi-custom setup using a solid valley plate which is also a bit of a pain. The 270 heads are cleaner to install since you just bed them in a bead of RTV on top of the valley plate. Both heads use the same rocker arms and have the same exhaust ports. The 270 will make a little more power than the 240 heads but it probably isn't a huge difference. Maybe 30 to 50 hp more depending on the shortblock. Here is a set of 270 heads going on my 470 shortblock. We tested the 240 heads one day and then swapped over to the 270 heads the next day.

DSC_0448 (Large).JPG
 
AndyF said:
Either will work. The 270 heads are the larger Max Wedge port size so you'll most likely have to run an Indy 400-2 type intake since there aren't any other choices for low deck MW intakes. The 240 heads give you a lot more intake choices but you have to use the factory bathtub gasket which is a bit of a pain, or switch over to a semi-custom setup using a solid valley plate which is also a bit of a pain. The 270 heads are cleaner to install since you just bed them in a bead of RTV on top of the valley plate. Both heads use the same rocker arms and have the same exhaust ports. The 270 will make a little more power than the 240 heads but it probably isn't a huge difference. Maybe 30 to 50 hp more depending on the shortblock. Here is a set of 270 heads going on my 470 shortblock. We tested the 240 heads one day and then swapped over to the 270 heads the next day.

View attachment 1715038095
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Thanks Andy! I have been following your 470 build and that thing makes some healthy numbers! The reason im a little leary to use the 270s is i want to be able to produce some decent torque numbers too. And given the rather small cubes of the engine if i went with the mw port wouldnt that put my peak power real high?
 
Thejames6972 said:
Thanks Andy! I have been following your 470 build and that thing makes some healthy numbers! The reason im a little leary to use the 270s is i want to be able to produce some decent torque numbers too. And given the rather small cubes of the engine if i went with the mw port wouldnt that put my peak power real high?
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I dont mind spinning it but dont want to loose out on any low end to mid range grunt its got in it. The cam will eventually be switched to something a tad bigger also.
 
On my 470 the 270 heads made more torque at 4000 rpm than the 240 heads. The difference was almost 50 ft-lbs. I know that sounds wrong but that is what happened.

Bigger heads usually kill off the lower end torque but if the smaller heads are too small for the engine then bigger heads work better. So that might be what is going on with my 470. The 240 head is fairly small and the port velocity is high. Perhaps it is too high and the larger port size of the 270 calms the airflow down enough that it actually works better from 4000 on up. Just a theory but we made a lot of back to back dyno pulls and the data was pretty clear. On my engine the 270 heads made more torque almost everywhere from 4000 to 7000 rpm. There was a weird little dip at 5200 rpm where the 270 torque curve dropped down but then it came back up. Not sure what that was, some sort of resonance or something.

This was with the Wilson standard port intake. The Indy intake didn't work all that well so take it for what it is.
 
How fast are you going to spin it ? That combo will easily go 8500rpm
That is the exact combo I was planing on for my 64 barracuda but I decided
to stay with a 340 only because I have more parts for it. If you are going to spin it go with the 270 MW heads.
 
Thanks for all the info! I think the 270s are in my near future then, i was just worried about port velocity but they seem to be a very well thought out head. Ive heard a couple guys try to bash them saying that they have valve shrouding issues and couldnt be ported any further because of the pushrod pinch using stock configuration rockers. But they were probably just knocking them before they tried them! Lol
 
brian6pac said:
How fast are you going to spin it ? That combo will easily go 8500rpm
That is the exact combo I was planing on for my 64 barracuda but I decided
to stay with a 340 only because I have more parts for it. If you are going to spin it go with the 270 MW heads.
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Ive searched high and low to try to find another combo using a 3.5" stroke crank to no prevail. So i dont know what this thing will really do when i get it all together! It probably would spin even faster if i left the childs and albert aluminum rods in it that i originally had planned on. But then ran across the set of manley i beams and switched them out. Sure would be fun tho to spin 8500 and keep on pullin!
 
brian6pac said:
At a boy, wind it up!
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So as far as strengthening the bottom and top end to be able to handle the said "8500" rpm, what all more can i do? The block is already half filled and studded mains. Maybe a girdle? I saw that BCR makes a pretty beefy one along with their main caps that tie into the webbing. As far as the top end...do rev kits work?
 
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