Pivoting from 340 to 360

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rt-man

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So, the '72 340 I bought for my '73 Satellite was torn down and found to have significant scoring in the bores due to it sitting around for years. Condensation took that puppy down.

So, my mechanic buddy has an LA 360 block and crank that's been sitting in an oiled bag since 2010. Bored .030 over; I imagine its a cast crank. Line bored, from what he recalls. He's going to examine the cylinders this weekend.

I'd like your opinions on this BUDGET build. Some parts are coming off the 340. Going in a heavy car ('73 SSP), cruiser, 904 with shift kit, 2,000 rpm stall converter, 3.55SG. 318/360 Performer intake, '69 HP exh manifolds, Summit 600cfm vacuum sec carb.

- Hughes cam, 220/224 duration at .050
- Domed hypereutectic pistons, looking for 10.0 CR or better. New rings.
- new oil pan, new main bearings. 360 harmonic balancer and flexplate for the 904
- reuse the accessories, timing chain, etc.

I may be forgetting something, but I don't think so. Keep in mind, its a budget build and I'm not going racing...but would like to smile when I put my foot into it.

Thanks.
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Sounds like a decent plan, but be careful on the compression, pump gas is terrible, with iron heads 9 to 1 is as far as I would go in a heavy car....
 
You did say domed pistons though, which, is a recipe for a disaster. Carry on
 
I would consider a 2500 RPM stall converter. 65'
 
mhh, i understand you're talking budget, but i would highly suggest spending the $35 it takes to put a decent new timing chain on there
(specially if you intend to install the cam properly)
 
Thanks for the input. I'll run the idea of flat top pistons by the MMM (Master Mopar Mechanic). But I already have the stall converter in-place.
 
mhh, i understand you're talking budget, but i would highly suggest spending the $35 it takes to put a decent new timing chain on there
(specially if you intend to install the cam properly)
I would whole heartedly agree! Put a new timing set in it and make sure that the flex plate is for and external balance engine.
 
If you mean domed pistons by the KB popups for the open chamber heads get the ones with the reverse deflector/ dish to keep the CR in the 9:1 range for a heavy car/ medium gears- your converter will be fine do not order the cam till you nail the compression and report
truck /motorhome even a bit less
design it for good quench .030-.040 piston to chamber-
you may need to do a trial assembly and measure
cc your heads- they vary widely and published data is bogus
your converter will be fine do not order the cam till you nail the compression and report
Hughes or Lunati Voodoo or there are a couple of Howards designed for Small block mopar lifter
get your springs for the cam lift- you may be too much for stock HP springs (the red ones with the dampner)
use viton stem seals- center two exhausts run hot
you do not need roller rockers - fixing the geometry is expensive
 
If you mean domed pistons by the KB popups for the open chamber heads get the ones with the reverse deflector/ dish to keep the CR in the 9:1 range for a heavy car/ medium gears- your converter will be fine do not order the cam till you nail the compression and report
truck /motorhome even a bit less
design it for good quench .030-.040 piston to chamber-
you may need to do a trial assembly and measure
cc your heads- they vary widely and published data is bogus
your converter will be fine do not order the cam till you nail the compression and report
Hughes or Lunati Voodoo or there are a couple of Howards designed for Small block mopar lifter
get your springs for the cam lift- you may be too much for stock HP springs (the red ones with the dampner)
use viton stem seals- center two exhausts run hot
you do not need roller rockers - fixing the geometry is expensive


Thanks for the input. Cam and lifters are bought but not installed. The 340 had/has a mystery Mopar purple stripe cam. The 340 was a fresh build done years ago and put away, unfortunately not sealed up very well and rust has crept into the bores and the crank. The engine was just fired for the first time this Summer, so the wear on the timing chain is nil, but your points are taken. I'm not budgeting the small stuff. This is about the pistons. Good input on the springs.
 
I'd just run a flat top piston and let the compression fall where it may. Prob will be a measured 9.5:1 or so. Don't waste time trying to build for quench or using the deflector/quench pad pistons with a cast iron head and no blueprinting. Keep the camshaft in the area you listed. I'd use a Comp but that's me. Get springs to match the camshaft - and be aware a lot of the purported .904 lifter designs need true dual springs so the spring seats and guides will need attention on the heads. (one of the big reasons I'd steer clear of them - you don't need it and you won't feel any difference) I agree - stock stamped rockers are fine assuming the camshaft can work with them (doesn't run lifters that needs adjustable valve train).
 
Don't waste the money on 69 exh manifolds. They don't do much over the stock 340-360 exhaust.

If you have them already, go with it.
 
Don't waste the money on 69 exh manifolds. They don't do much over the stock 340-360 exhaust.

If you have them already, go with it.

Already have the exhaust manifolds (see in the pic; they are on the 340 now) and the cam and lifters. Good thoughts on the springs. Thanks.
 
What about sleeving the 340??? Cylinder scoring doesn't affect performance once it's sleeved??

treblig
 
What about sleeving the 340??? Cylinder scoring doesn't affect performance once it's sleeved??

treblig

Kicked that idea around. The 340 crank has some rust scoring on the ears. The 360 apparently doesn't need any machining. I don't know what it costs in South Texas, but the reliable machinists in my neck of the woods don't work cheaply. I'm probably gonna break even going with the 360 and the new parts vs. machining the 340.
 
IMO, your leaving some on the table with that 600 vacuum carb. You have a decent gear an a ok converter.
 
which purple shaft?
whoever is advocating not building tight quench is way off base
I helped design the KB quench pistons with chief engineer John Erb at Silvolite and lots of dyno time to back up the combinations that work (much better)
problem with the FT pistons is you have to compromise on compression or advance to keep from detonating on the side away from the spark plug
you want the chamber under the plug- it's hard to light off way across the cylinder (worse on a big block and way worse with a dome)
you lower the compression or retard the spark then you have to give it more throttle which means more heat- so you retard it some more- vicious circle also less mileage
you can make FT work in a race motor with race gas and high rpm
they do not work near as well as a well blueprinted quench on the Street or street/strip and especially not Marine or towing/ motorhome
obviously closed chamber heads are easier- we used to take the trouble to weld up the open chamber iron heads
one thing at a time- keep the 600 for now
 
which purple shaft?
whoever is advocating not building tight quench is way off base
I helped design the KB quench pistons with chief engineer John Erb at Silvolite and lots of dyno time to back up the combinations that work (much better)
problem with the FT pistons is you have to compromise on compression or advance to keep from detonating on the side away from the spark plug
you want the chamber under the plug- it's hard to light off way across the cylinder (worse on a big block and way worse with a dome)
you lower the compression or retard the spark then you have to give it more throttle which means more heat- so you retard it some more- vicious circle also less mileage
you can make FT work in a race motor with race gas and high rpm
they do not work near as well as a well blueprinted quench on the Street or street/strip and especially not Marine or towing/ motorhome
obviously closed chamber heads are easier- we used to take the trouble to weld up the open chamber iron heads
one thing at a time- keep the 600 for now

Thanks, Wyrmrider and others. Yes, the 600cfm carb is already bought so will stay put. This will be a street car that will be pushed periodically for fun. Between the carb and intake, I'm sure it will run out of breath over 4500rpm, but I'm good with that. Its a heavy car, to boot, so I want a flat torque curve and to maximize the combination of the drivetrain I HAVE (2000rpm torque converter, 3.55 gearing).
 
I'd just run a flat top piston and let the compression fall where it may. Prob will be a measured 9.5:1 or so. Don't waste time trying to build for quench or using the deflector/quench pad pistons with a cast iron head and no blueprinting. Keep the camshaft in the area you listed. I'd use a Comp but that's me. Get springs to match the camshaft - and be aware a lot of the purported .904 lifter designs need true dual springs so the spring seats and guides will need attention on the heads. (one of the big reasons I'd steer clear of them - you don't need it and you won't feel any difference) I agree - stock stamped rockers are fine assuming the camshaft can work with them (doesn't run lifters that needs adjustable valve train).
Agree 100% for budget build. Just using the flat top KB107's or H116's will get you up to the low/mid 9's for SCR if you use a .028" thick Mr Gasket 1121G head gasket; that is a FAR cry better than the stock SCR. Pushing 10:1 SCR with no quench and open chamber heads and no detailed set-up in a heavy car is problematic.

KB's are not stock piston+pin weight, so I'd go for sure with the H116's for budget; they are stock piston + pin weight and so no crank re-balance is needed.

The KB373 quench heads are interesting but take some head milling to get to a quench gap and some fanagling around to balance the head milling and chamber size for the right SCR, so are not what I'd consider 'budget' and 'ready for assembly'..... and they are not stock piston+pin weight.

BTW, when you install the cam, time it properly, and find the ICA (intake valve closing angle, measured in crankshaft degrees, at .004" lifter lift on closing). If you get it into the 62-65 degree range, you dynamic compression ratio will be pretty good for a budget build. If it is waaay off from that installed dod-to-dot, then I'd do a complete cam timing profile (durations at .004" and .050" lifter lifts, plus intake and exhaust lobe centerlines). Hughes don't give you 'advertised duration' numbers on their cams. So you are kinda in the dark as to DCR.

Can you give us a cam PN? That, and it's timing, are gonna determine a LOT of how your engine will run and behave.
 
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and be aware a lot of the purported .904 lifter designs need true dual springs so the spring seats and guides will need attention on the heads
Just curious: Is this for some 'purported' .904 cam lobes (like what ones?)? Or a general statement for .904 lobes? Not seeing where a 'longer-duration-at-.200"-lift' lobe requires more spring... IMHO it is less of an issue with the springs 'over the-peak'.
 
usually you can finagle the 373's with gaskets or
what you do is assemble all four corners for test and measurement of deck clerance before you deck the block and/or mill the heads
then cut to quench height
well worth it
also check out the KB 232 if you have smaller chambers
on the cam question
Best low compression cam is the Mike Jones Motorhome cam almost 20 degrees shorter than the DC 260 cam on the seat yet 50% bigger at .275
otherwise Lunati Voodoo line is first place to look
and once you understand what you are looking for Howard has a couple of Shelf 904 grinds and both Howard and Bullet have many many custom profiles
you can get 105 pound on the seat run forever profiles or heads up race profiles that eat springs
what you are looking for is matching the dynamic compression requirement with the intake close point and working from there
nm9 is correct a longer duration at 200 may or may not take more spring
I do guarantee that a .842 grind will take more spring than a .904 grind at the same durations - the .904 grind mechanical advantage allows it to loaf
one advantage is running a .904 lifter on a chevy profile is that in a chevy you have to hand select your .842 lifters to get ones with no chamfer - a real PITA
now you go max effort on .904 you have to do it too- but you are still way ahead of the bow tie The NASCAR .875 guys had fun with this too- pushing the limit
I'm thinking that Hughes has switched from ENGLE to Howard
 
If you are talking the KB 190/191s then you might be able to run 10/1 and if you can run full timing, that would make a great combo with all the parts you listed.
That 220/224 must be pretty similar to the 224/230/110 Hughes I used to run., which was a dynomite little torque monster in my combo. I revved that little guy to 7000 all the time; but I had OOTB Eddies on her with the AG intake and TTIs. The point is I loved that cam,I didn't mind the layover after 6000, cuz with 3.55s that didn't happen until 53 mph with the combo I was running, and 7000 was 62mph. And when I downshifted into first at 32 mph, the Rs jumped to 3600, and she was gone.
That's a really good street combo....... just not at 170psi and iron heads.

But if you don't run a tight Q, you are looking at 170ish psi, and that won't fly on pumpgas. Even with Tight-Q it'll be iffy.And you will forever after be forced to buy Premium gas.So; measure,measure, measure, and calculate.
With no quench,I'm gonna throw in with the guys recommending 9.5 or even 9.0
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But really that cam,IMO, is a wee bit small.It may cost you extra machining to get the Dcr down.
Figure it out; the penalty for being forced to run premium gas quickly outstrips any fuel economy gains, in the cost per mile calculation.(* see below)
So you might as well move up a cam size which will close your intake about 3* later. The 360 is a cheap throw together at about 9 to 9.5 with those pistons. When you throw that into the mix you get about 150/155psi and badaboom you are running 87 to 89 fuel. The 3.55s are still ok, but the 2000TC is gonna be a little soft at zero mph. And this next bigger cam will still be happy cruising with 3.55s
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But that 600 , for me, would be a doorstop PDQ,No matter which cam goes in. I tell you what, get yourself two straws from the kitchen, stick 'em in between your lips and start running.How far did you get? Mark the spot. Go back for two more straws and repeat,lol. Ok, I'm just funning ya; don't do that, you might have a heart-attack!
The point is I have a 600vs, a 750vs and a 750DP, and an 850TQ.Not to mention the AFBs and AVSs on the rebuild-shelf. My 367 likes the 750 best for all uses except fuel mileage runs. For that I modded that petite 600.
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But I like that 220/224, and having run the similar 224/230/110 some years ago, in a 367 cuber at something like 190psi, I can tell you that with 3.55s, it was a blast. I would still be running it 14 years later, if it hadn't begun dropping lobes in 2004 .
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In regards to cost per mile
I bought aluminum heads so I could run close to 200 psi on 87E10, with full timing. Guess how much money I saved in 100,000 miles of running those numbers. IDK either cuz the comparison is not fair. I know that with the smaller 224/230/110 cam I was getting mid 20s all the time, with 3.55s and a regular 4-speed; and low 30mpg with the prepped carb, on the hiway with a double overdrive combo.
So lets say 25mpgs for just 60,000 miles is 2400 USg.
With closed-chamber iron heads I woudda run 160psi max and 89 gas I think. And with the loss of pressure, I might have expected 15?mpg. So; 60,000@15 is 4000USg. So Lets say I saved 1600USg. What's that come to in dollars? More than $6000?,plus the difference in fuel costs;Hyup enough for a complete engine rebuild, and more.And that's being conservative.
I loved that cam; shouldda never got greedy with the following 230/237/110cam; it has a completely different personality.
 
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usually you can finagle the 373's with gaskets or
what you do is assemble all four corners for test and measurement of deck clerance before you deck the block and/or mill the heads
then cut to quench height
well worth it
also check out the KB 232 if you have smaller chambers
on the cam question
Best low compression cam is the Mike Jones Motorhome cam almost 20 degrees shorter than the DC 260 cam on the seat yet 50% bigger at .275
otherwise Lunati Voodoo line is first place to look
and once you understand what you are looking for Howard has a couple of Shelf 904 grinds and both Howard and Bullet have many many custom profiles
you can get 105 pound on the seat run forever profiles or heads up race profiles that eat springs
what you are looking for is matching the dynamic compression requirement with the intake close point and working from there
nm9 is correct a longer duration at 200 may or may not take more spring
I do guarantee that a .842 grind will take more spring than a .904 grind at the same durations - the .904 grind mechanical advantage allows it to loaf
one advantage is running a .904 lifter on a chevy profile is that in a chevy you have to hand select your .842 lifters to get ones with no chamfer - a real PITA
now you go max effort on .904 you have to do it too- but you are still way ahead of the bow tie The NASCAR .875 guys had fun with this too- pushing the limit
I'm thinking that Hughes has switched from ENGLE to Howard



Where is this "motorhome" grind that jones has? I can't find it in his lobes.

Like I've said, I've never been able to get Jones to grind a .904 lobe on anything. Ever. I just did an online cam request and I didn't even rate an .875 lobe. He just pulled an .875 lobe. And I promise you the cam I wanted needed a .904 lobe much worse that what the OP wants.

I mean, are you related to the guy?
 
Thanks for the input. I'll run the idea of flat top pistons by the MMM (Master Mopar Mechanic). But I already have the stall converter in-place.
You have a Master Mopar Mechanic at your disposal and you are going to throw all these other cats into the bag? Going to be a bunch of scratching and clawing. And the poor MMM is going to have to sort through all these other conflicting ideas with you? Just let the MMM do his job or he's no MMM. Why even have the MMM if he cannot figure out this stuff?
 
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