#'s Matching 340 build

-
R

RAMM

Well-Known Member
Joined
Nov 22, 2010
Messages
2,655
Reaction score
3,494
Location
Ontario, Canada
This morning I went to the shop to meet a new client and receive his 340 engine. After a deep discussion the engine is currently wounded (making a knocking noise). I've been fortunate enough to be tasked with finding the cause of the sound and performing a full rebuild along the way.

This is a numbers matching type build and MUST retain all external parts/castings and appearance. Internally I have a pretty free reign in the quest for reliability/driveability and more HP 'cuz I can't not try and find more. HP=FUN or smiles/per gallon.

It must run on 91 octane--not 94 and not break the bank.

Tomorrow it gets the exploded view treatment and a plan will be formulated from there. The client has no issued with the whole process being documented and shared here- and I agreed.

The vehicle is a 1972 A body 4spd car with 3.23 gearing.

Looking forward to tomorrow even though it is a 22-23 hr day for me every 4th Monday of the month. Stay safe Stay healthy and Stay in if you can. At least that's all I hear anymore. J.Rob

Glenns340.jpg
 
doug 371 said:
see the wrong water pump for starters...do they care about that?
Click to expand...


I saw that. I have a 73 Dart Sport that’s a factory 340 car. When my cousin bought it, someone had changed all that stuff out, including the radiator to make it pre 1970. I never figured out why you’d go backwards. Evidently, it was more popular that it should have been.
 
4spdragtop said:
Subscribed
Click to expand...

I screwed up and mixed up all the information--His 72' that he has owned since his 'teens is the Duster that is fine and running great.
This engine is for a '69 Dart that was previously built by an aircraft mechanic and has something like 800kms on it. Headed to the shop now. J.Rob
 
Garrett Ellison, post: 1972913254, member: 52437"]Posted by another member today, you could build it with 9.2:1 and still make good power. There may even be a budget .060 over 360 piston that would make it doable.
[FOR SALE] - Mopar Performance 3.65” Stroke Small Block Crankshaft- New
Click to expand...
Hey Garrett, you do realize that pistons for this are a custom order since MP no longer carries parts for there discontinued line. 3.65 - 3.58 = a lot of stroke difference for a stock or even a replacement/performance piston. I guess you could have something made up if a regular slug did t fit. (Honestly, I would love to try just for fun. I love to tinker) While I think it is an excellent route to go, one I’m sure RAMM is up to performing, it would be the rest of the external parts package I would question and call questionable in it’s effectiveness with a 40 cubic inch increase. Below is a quote from the opening post;

This is a numbers matching type build and MUST retain all external parts/castings and appearance. Internally I have a pretty free reign in the quest for reliability/driveability and more HP 'cuz I can't not try and find more. HP=FUN or smiles/per gallon.
Click to expand...

This leaves just one question which I’m not 100% on, is the owner of this engine/car build making use of headers? Because at that point, I’d look into porting the heads really well. If I had to use the exhaust manifolds, that would change a thing or two.

Sr71mopar made a comment, “Kind I’d like a FAST build.”

If I decided to do a FAST engine, it would be for competition and nothing else, (believe me, I think about doing this for fun but on a lower non competition level) but because of the power limitations of a stock head and exhaust manifolds. This becomes less appealing. At least for something I’d like to drive and enjoy rather than street/track race.
 
Ouch! Yes, agreed that exhaust manifolds are a huge obstacle to overcome, even with chemical porting and extrusion honing. And the cam would have to be a custom affair to overcome those manifolds. Pistons may be a little more doable than at first glance. While they are not my favorite due to the oil ring drainback slots and boat anchor weight, if one could come up with a set of low compression TRW 360 forgings... The .300 inch thick crown can afford to give plenty of material to make it fit, and also add some dish for valve relief. But, sometimes just because you can do it doesn’t necessarily mean that’s the way it should be done. But I wouldn’t be able to resist trying!
 
Toasted the rod bearings. Seen this problem when things arent corrected.
Put the bearing back in and check out that alignment to feed holes. The rest might the size of them up to the galley.
 
Rob is this a stock exhaust build?
we did a lot pf dyno time on 360 motorhome builds in the 70s and also raced in a class with stock apperance
general approch big block or small block is go big BIG and get your power done big and early cus you are not going to get top end hp no matter what you do.
(compared with headers)
At tdc on the overlap you can have 15% of cu inch as residual gas wth little extraction
so you have to use what inerita you do have to clean up the chamber.
depending on your porting you will end with little overlap and a somewhat longer ex
 
Ahhhhhh, that ain’t nothin! Sand them down with 800 grit and reinstall them... GTG!

:rofl:
 
PRH said:
Actually, any of the ones I’ve been involved with have been very docile and have excellent drivability and street manners.

Many of the faster ones live on a diet of high octane race gas, and have cams that aren’t really designed for long term street use, but there are several that see regular street duty, and I’m told they are a joy to drive around...... giving away no clues that they are solid 11-second performers running on their repop bias ply tires.
Click to expand...
If I decided to do a FAST engine, it would be for competition and nothing else, (believe me, I think about doing this for fun but on a lower non competition level) but because of the power limitations of a stock head and exhaust manifolds. This becomes less appealing. At least for something I’d like to drive and enjoy rather than street/track race.
Click to expand...

A quote from me...

Yes we had a quick chat where you really gave away nothing but suggested a clue and your politeness in expressing confidence in my thought processes on parts selection was really a nice compliment to me.
(Thank you)

If I decided to pursue this endeavor, I would have to make at least one concession, possible a second one just because it will not see consistent track time but for surely, mostly street.

Compression for pump gas and cam size. If I pulled off a ET of 12.5 or better, I’d be really happy with that pump gas mill. These F.A.S.T. car owners gotta be laughing there *** off between the power and handing out a pasting to the unsuspecting.
 
on stock exhaust
as backpressure rises it handicaps high rpm hp
so my goal was to max out the flow at the lowest and over the broadest rpm as possible
some use pressure demand
what you don't want is backflow of exhaust into the intake , as well as purging the most residual ex possible
so you have to watch the valve job and backcut along with the exaust close (early) and intake (late)
I usually say to minimise ooverlap but that's simpistic
lucky with the long rod opening the intake early to try and track piston demand is not as tough a it is with popular short rod engines
npt only do you have more degrss- dwell- around tdc but the max piston velocity is several degrees later
othing is for you advance the cam an additional 4 degrees to affect Intake close and dynamic compression is that you FUBAR overlap valve events
(that's IF if the big camgrinder did in the first place- not likely if the specs are exactly the same as for a sbc)
quite different than headers open or mufflers
 
You must log in or register to reply here.
-

Back
Top