#'s Matching 340 build

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RAMM said:
6500rpm is way higher than I have seen with manifolds but.... different builds. How high would you expect that build at 418 cubes to peak? Asking for a friend. J.Rob
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About 1000rpm lower, manifolds... 1200 lower,maybe.wish I had a crystal ball.
If there was a quick way to make the ports 10 cc bigger, it would gain 500 rpm usable hp.
 
Stock x head 408 builds are on here.
Search.Iirr 375-425hp/440-460lbs done by mid 5500rpm was the trend, some ported , but no numbers or volumes to verify to what extent.

Streetable , strong vacuum, with limited rpm and restricted exhaust is shirt lived fun without a 4-5 speed auto.

Ever drive a 1975 455 trans am ?
That is a GREAT example of how short lived the fun is.
Either do the work to the heads. or stay in 3.31-3.58 stroke imo cause it's one thing to battle the heads.. But then to battle the exhaust.
If it were not limit by $$$$, but it is.
 
PRH said:
Well, the reports from a few of my customers who have gone from stock stroke BB’s to strokers is...... they love them.

I refreshed a 383 for a guy who was unhappy with his fast rate hyd cammed combo running into the wall at 5500( valvetrain control issues).

I swapped it over to a SFT.
This was a nicely built motor, with custom quench dome pistons, fully ported big valve 346’s flowing about 280.
RPM intake, and I installed a new HP750 on the motor for the dyno session......1-7/8” headers, pump gas.

Motor made what I felt was really good power, and it revved very well, and peaked at a pretty high rpm.
Over 470hp from 5600 to over 7k.

Went in a pristine 70 Challenger, 3.55’s, auto, 10” converter.
Borrowed some 3.91’s and drag radials, went 114mph, I don’t recall if it dipped into the 11’s or not...... but I’m thinking it did.... barely.

It did everything you’d expect it would.
But...... unless you had it up into the power band pretty far...... it didn’t “feel” that hot.
He ran it for two seasons, then decided to put a 4.25” rotating assy in it, so its now a 489”.

He said it totally transformed the cars personality.
Power everywhere...... not just at high rpm.
Absolutely loves it.
It probably has over 125ft/lbs more that it did as a 383.

I don’t understand the Diesel analogy of the stroker.
The rotating assy for the typical 4” stroke SBM has a much lighter bobweight than a stock 340 does.
The motors are very responsive and snappy.
I don’t find them to be tractor-like at all.

I wonder how many Hellcat owners wish they had less tq.
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They are snappy, stock heads or not..but if kept in the example of using stock heads... if you're used to a 340, you'll over rev it or feel you're shifting too soon.

It's too easy to get sidetracked in this thread basically the money is not there to do a 4-inch Stroker and get the heads up to par for it to really benefit from the 4-inch stroke 'not to say it wouldn't be a torque monster/tire fryer/ quick without adequate heads..
it's just that it will be a shorter RPM band 'not quite like, but distantly, and sarcastically' like a diesel.... I believe is what Jesse meant by it.
 
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Rob
I edited that "close earlier with a roller" post to show I was just responding to Mopar Official's comment above
regular MOPAR Hyd will work , solid slightly better
does he want to drive it like a sports car - 340 higher compression, premium fuel have to wind it up some before shifting
does he want to drive it around town I'd lean toward the stroker for less shifting and boggs,
but either will work for the around town, build with slightly lower compression, run on mid grade - torque cam
68 70 manifolds are pricy and do not help all that much-been there done that
There are some jeep manifolds that work and magnum truck
 
I'm sure your customer will be very happy with the motor when you are done. Good quality machine work will wake that motor up. My friends in the pits know I'm making a pass by the distinct sound of my 340 revving to the stripe.
 
RAMM said:
218 @ .050 with .525" lift? Thats a fast cam dude. J.Rob
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The goal was to have a stock 383 Magnum Idle so seat timing was slightly shorter than stock due to the fast lobe It was a fast lobe wwe used dual Isky springs and broke in on the outer
on a 112 with a not too much longer exhaust but not so fast, less lift (stock B Body HP Exhausts with a cross pipe)
we used our quench dome piston design I have the mock up piston, showed it to Krooser when was out here to pick up my dulie. I could post a pic if anyone wants to see it. This was a 9.1-9.5:1 build (I forget) You could just let the clutch out and drive away from a light, or hit the throttle and fry the tires
We built some 396/ 402 chevies out to 454 with similar parameters, one for a camaro and one for a chevelle (around a 70 I think) both autos
 
i have 6 passes on car last year. 10.40 @ 129 mph.
it's a stock stroke , stock bottom end 1974 360'' with W2 heads that RAMM ported for me. extreme budget build. i even have LA headers and not W2 headers.
there is a few 4'' stroker engines that i keep up with at the track.
don't need a 4'' stroker to go somewhat fast.
i like the way the RAMM thinks, smart guy that knows what he's doing.
 
If we want to build a cost effective 340
and are going to use open chamber heads
snd the power is going to be in the heads no mater what else
one question is- is rob doing his own rods?
If so MP bolts and be done- but pistons?
If buying rods
you could use the 408 1.460 ish CH dish pistons and 6.5 inch (ish) rods and mill the open out of the chambers
or push the piston up into the chamber or some combination looks like 10:1 with a shelf JE piston ending up with a nice tight chamber
what other combos work?
 
Wyrmrider said:
If we want to build a cost effective 340
and are going to use open chamber heads
snd the power is going to be in the heads no mater what else
one question is- is rob doing his own rods?
If so MP bolts and be done- but pistons?
If buying rods
you could use the 408 1.460 ish CH dish pistons and 6.5 inch (ish) rods and mill the open out of the chambers
or push the piston up into the chamber or some combination looks like 10:1 with a shelf JE piston ending up with a nice tight chamber
what other combos work?
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I'm leaning towards a set of JE flat tops @ 4.08" bore. Stock rods and stock steel crank will be retained. Camshaft is under consideration. J.Rob
 
RAMM said:
I'm leaning towards a set of JE flat tops @ 4.08" bore. Stock rods and stock steel crank will be retained. Camshaft is under consideration. J.Rob
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When I hear budget build... JE pistons are definitely not included.

How much are you gonna charge for working and reman on the heads?
Guesstimate on the price for his completed je piston bottom end..?

Is the total going to exceed 4,000?
 
PRH said:
If the customer is wanting a stock stroke 340....... then that’s what he’ll get.
If the conversation drifted towards the area of, “is there anything we can do to get more power out of it, and still keep it very streetable”....... at that point I would have mentioned a 4” crank would be my preferred choice for that kind of result.

As far as the “huge” added expense of the 4” crank...... according to what you’re saying...... it looks like it’s a bit more than twice the price of grinding the stock one.

Your experience with stokers and mine differ.
I don’t find the added cubes to have much of an effect on the peak rpm.
Sure, they lower the peak a little, but certainly not to the degree you’re inferring.

Last year I had a 360 on the dyno that was very similar to the 340 you’re going through.
9.7cr, pump gas, bowl blended J heads(230cfm), Old school dual plane, afb carb, .500 lift ex manifold friendly cam(.842 design).
Dynoed with headers, peak hp occurred at 6200, and it was only down 5hp @6600.

Your position is that by putting a 4” crank in that motor, it would drop the peak by 1300rpm(peak at <5000).

My position is it wouldn’t.
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Depends what Jesse charges to grind a crank. As for 4" stroke kits... I'd opt for a Ohio kit, not forged @1350.00.
I'm curious what the actual budget is, how much alotted for porting, basic block work or complete blueprinting... about 600-800 bucks 'studded' depending on the shop.
I get my cranks ground for 90.00.
In a nutshell...Prices are regional.
 
PRH said:
I wonder how far the difference in price between a set of JE flat tops for a stock stroke 340....... vs a set of Icon inverted domes for a 4” crank would go towards paying for that new crank.
Especially when you factor in the cost of magging and grinding the stock crank.:usflag:
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Like I said balanced h beam kit for 1350.00
But that's not what he wants.
I wish we weren't all so far away, but it's good we arent next door at the same time..lmao..
D. What's last measured int port volume of a ported production head you have done for a 4" sb and what did it redline at and what was the lsa/lift of the cam..and other will wanna know the power or et
 
PRH said:
Around here grinding a stock type crank is about double what you’re paying....... not including magnaflux, which I’d absolutely do on a crank that had bearings that looked like what came out if that motor.

Retail from Summit on a Scat cast 4” crank is $375, shipped free.

So, in my area, the added expense to run the 4” crank is less than $200 compared to a mag and grind.

What Jesse is going to use for pistons are way lighter than factory, so the crank will need balancing anyway.
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Balance will be cheaper based on removing weight and not adding mallory.
If the guy grinding is good, the machine is serviced, and he gets them done quick...he can make plenty of money doing them at 90 ea. That's magd.
I used to have beans do them, 120.00 with acl bearings... Jesse was the grinder but he went on to rep for clevite/maul and makes way more money than he did grinding. The place was sold/obsorbed by the nextdoor shop and the prices went up..and we all took our **** to Rick's in santee or mesa in escondido who have been in biz there since 1946. there .machine tech,mjm, total per'ford'nce, JBA, a ton of places... but they either over charge and dont call or advice to what they do...or they are just young guys with heads/egos bigger than their brand new machines. People set records with old stuff most still cant touch today... and certainly most of the weekend warriors cant hold candle to.
 
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PRH said:
Just look at the link I posted a bit earlier.

What I see there is a 416 running the stock intake and ex manifolds, a 650 carb, and a tiny cam........ in a car that’s seen hundreds of passes down the 1/4 mile.
They have sorted out the timing, jetting, launch technique...... and shift rpm....... and the best ET’s come with the shift point between 6000-6300.

It’s certainly not “all done” at 5k.

My friends stocker is 412”, has .420 lift, and heads that are smaller than the legal limit of 160cc, and only flow about 220cfm.
On a good day it’ll run 6800rpm through the lights(over 128mph).

Like I said, I’m just playing devils advocate.
I don’t expect to change anyone’s mind.
I just know what Ive seen from testing motors on the dyno since 1990, and none of it has indicated that a build like this “has to” peak at under 5K.
I mean....... unless some minuscule cam is used, or the valvetrain can’t keep up.
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That motor probably runs something similar to a cheater cam.

No one said it would peak below 5k.

Dude has an expectation of street manners we arent completely aware of yet.
G stock runs .444 lift too, runs 10.80's and has 320 degrees duration.
 
I was sure interested in this post about a 340 until it got derailed by, well.........................................
 
Im not debating that. I could this or I could that, not my thread, not my build...not my customer. I'm not trying to sell someone elses customer on my line of thought or approach. Already a page or so worth of this. Support of each other is weak in the community of builders. I'll steer toward ideal anytime but let's see what he comes up with. And oh..well how about those 270cfm heads just got bigger on 345 inches and cam can be tall..narrow...but wont have to be big to make this happen.
 
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cpearce said:
I was sure interested in this post about a 340 until it got derailed by, well.........................................
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You know what?
You’re absolutely right.
What I was talking about really added nothing useful to the proposed build.

I know I don’t appreciate it when one of my threads gets derailed in a similar fashion...... so I removed my part of the thread derailment.
Others can as well if they are so inclined.

Carry on.
 
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In one of the mags a couple years ago, they did a stock rebuild of a 340, then tested it with the stock 4bbl, and a 6bbl...... both with manifolds and headers.
The hp peak appears to have occurred at the same point for all(5500).
 
OK
stockrods will work fine Krooser's running them in his circle track build and I never had much trouble with them, something else always broke first
I'd side grind and mag and pitch any where the caps been cut on an angle. then mil spec shot peen *not shot blast or wheelebrator) do the big ends and tobin arp to correct or max legal length the new bushings. In this case get the lengths the same
I'd flat mill the heads to get rid of the open chamber and run a dish to dial in the compression on a nice compact chamber under the plug
the the final quench with the gasket
depending on your equipment you can mock up all four corners then square up the decks and set the deck clearance since we do not have much choice with pistons
what 1.840 ish? you can always just do the bushing in one rod then adjust them for length after the mock up (that's why I have the 9th piston and rod from the 383 stealth stroker build)
cheers
 
I'm going to follow this , have 2 1970 340's sitting in the garage that I might rebuild just for fun .
Be interesting to see what you come up with
 
Very similar build on my 340 that I was talking to you about. Going to follow this thread for sure.
 
The end is near for this build. I should have it on the dyno this upcoming week. Some pics of the progress. J.Rob

GB340Filthyheatshield.jpg


GB340Cleanheatshield.jpg


GB340Thrust.jpg


GB340VJPP.jpg
 
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