340 f.a.s.t 1971 version

[ValerianMagnum]

hi Guys wanting to built my new 1971 340 with w2 econo heads / 1.5 crane ( mopar )roller rockers / 292 -501 camshaft , w2 street dominator intake and and ...thermoquad and exhaust manifolds , i want it to look period correct but pushing more than 400 hp , my question is , i want to modify the exhaust manifolds to match the oval port of the w2s ..and does a t-quad is really worth the effort , i wanted to cut the choke tower to flush it like an holley ...doesnt know if its a good idea !

 

[rumblefish360]

First up on the intake, being a square bore pad, you will need an adapter to run the TQ. Cutting the primary chokes air horn nets a few cfm. IMO, for a F.A.S.T. effort, it is t worth it. While the unknowingly will miss the W2 head, the intake is a dead hive away that it is not a factory part.

On the exhaust, *I don’t think* it will work.

If you MUST run the TQ, the adapter will be in the 3/4 inch thick area not including gaskets. Hood clearance will be an issue.

Your better off with a squarebore carb on top.

 

[Locomotion]

Unless I'm missing something, you might want to go through the FAST Class rules again before getting too far into it. So far it appears that you:

1) Can't modify the carb externally.
2) No spacers allowed. (adapter)
3) OEM heads & intake, unless it's on the approved list.

FAST Factory Appearing Stock Tire Drag Racing

There are NHRA Stock class 340's running mid-high 10's. But a lot of it is cam, slicks and other little "tricks".

 

[ValerianMagnum]

No fast class style....street car

 

[rumblefish360]

Then, IMO, just keep the outside looking stock and have at it on the engine. Use headers!

Also, IMO, take that 292/.501 camshafts and sell it. Get on with more lift as to where the W2 breaths nicely.

 

['63GT]

I agree with rumblefish360, but if you're dead-set on the exh manifolds, look up Extrude hone.
Extrude Hone AFM - Abrasive Flow Machining

But I think you will find it way cheaper to deal with the headers.

 

[Locomotion]

No fast class style....street car

Oh, ok.

I guess your W-2 heads have the "econo" exhaust bolt pattern?

There is a W-2 dual plane intake available, if you want to spend the money for a more OEM look. The aluminum version looks to be square bore. (They also have a short deck version.) Seems like there may have been a cast iron version, maybe spread bore, at one time for circle track. Memory is a bit fuzzy.

Yes, .501" cam will choke the W-2 heads. Unless your trying to stay with a milder idle.

 

[ValerianMagnum]

Its the cam that i have....hellrats is a member here that ia running manifolds with w2 heads , i want a combo around 400-450 hp that looks totally stock .... Yes the manifold will be ported , reworked and extrude hone too....i want a tricky seat up and eventually maybe stroke it to a 416 with time

 

[ValerianMagnum]

Yes im leaving a lot on the table...but they still can flow good , a 5.7 hemi as a crazy airflow but is still chocked up by manifolds and a efi system....still makes 345-390 hp , why a crazy high flow 340 cant make that and work well on the street.

 

[rumblefish360]

Ahhhh,I see.

Will you dyno the engine?

 

[mbaird]

Just use a W2 dual plane and paint it. Way easier to port and you might be able to open up the plenum for the TQ..I dont know for sure. I will look at the one I have...
And go roller cam to maximize the W2 heads... especially if they are ported.

 

[moper]

When tested similarly the 5.7 makes over 400. You're building a mismatch anyway. If it were me I'd run a lightly ported std LA head with a larger camshaft to run with the manifolds. 400 hp is easy enough that way, using the 71 T quad intake and carb. Don't remove the choke horn on the Tquad. You can remove the choke plate itself, but leave the horn itself. It's there to stabilize the air before it goes past the boosters.

 

[ValerianMagnum]

My friend will assemble the engine and we will dyno it after.

 

['63GT]

When tested similarly the 5.7 makes over 400. You're building a mismatch anyway. If it were me I'd run a lightly ported std LA head with a larger camshaft to run with the manifolds. 400 hp is easy enough that way, using the 71 T quad intake and carb. Don't remove the choke horn on the Tquad. You can remove the choke plate itself, but leave the horn itself. It's there to stabilize the air before it goes past the boosters.

YES, that OE thermoquad intake is tough to beat. Even tougher when gasket matched.
As Locomotion stated, there are lots of SBs running high 10's with that intake.

 

[408 swinger]

Totally agree with Moper. Even if you have the econo's already, you can reach your goals with a std LA head, for sure with a Magnum based head. Could off set costs by selling the econo's, or, keep them for something REALLY bad ***!

 

[ValerianMagnum]

I sold my 528 hemi for this w2 headed 340..i just dont want to run headers if possible , and i want a street engine. So why would i spend another 2k for ported la heads ? My w2 are ported & polished , i just want a sleeper looking and strong engine. I can always change the cam...but did you guys understood that it will be a street and highway car only ?