Motor build up combo looking for opinions remarks

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scamp72

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I would like to do a 318 build up
to see how it will perform . First thing for me is to
install some 340 heads with factory 2.02 valves.
For better flow. Now i know this will kill the compression.
I plan to go with some keith black pistons flat top with valve reliefs
5cc pistons bore=3.940 compression ht.1.81.
Going .030 over should clear and keep from valve shrouding.
Should put me in the neiborhood of 10 to 1 and 323 cubic inches
For the camshaft I was planning a mopar purple cam
268/272 450/455 lift rpm range 1500-5800 rpm
Intake will be weiand action plus 8007 dual plane
with a holley 650 mechanical sec. Hooker headers and flowmaster
mufflers 2 1/2 exaust. I have all the parts here
and some on the way except the pistons. I thought about
going stroker but i really would like to see how this
would perform. Looking for all opinions . Any guesses on
hp? After the build up i will have it put on a dyno .
Let me know what you guys think.I plan to do a future 360 build up,
and have located one just got to get
the time to pick it up. I am in no hurry for the 360
 
Sounds good but I would consider Magnum heads instead of the 340 heads. Those KB pistons at zero deck hieght will need about a 62cc chamber with a .039" gasket to get your 10:1 compression.
 
Also .030 is only .015 per side so shrouding is still a problem. Shrouding doesn't become a problem when the bore starts at 4.04 and bigger with a 2.02 and it's still shrouded somewhat, but better. I generally like .100 or more to be unshrouded and not a problem.


BJR Racing
 
I think you'll like the smaller valve in the head better.
1.88 - 1.60 valves in a teen head and pocket ported will do fantastic.
Magnum heads would be the other head to use over the 340/360 heads.
 
I probably should have dome more home work on the head choice rumblefish
but i already purchased the heads off another site. I havent recieved them yet but since there paid for i'd like to make them work. bgr racing pointed out about the valve shrouding, glad he did. I believe by having the top of the cylinder walls machined that can be corrected. I got a call in to the machine shop about that. I am glad i found this site . Good people with helpful information here. Thanks

Ps. I need to go .030 to clean up what do you all think about .040 vs .030?
Should i do the minum bore needed? .060?
 
With those heads I would go with the KB399 pistons,its a higher comp. piston.
 
May be just me. But if your plan is for a 360 any cash you put into the 318 short block is a waste of money. #1 rule... Form a plan and stick to it.
 
1968FormulaS340 said:
May be just me. But if your plan is for a 360 any cash you put into the 318 short block is a waste of money. #1 rule... Form a plan and stick to it.
Click to expand...
Well when i do the build up on the 360 i figure it will take me a year or so to get it how i want it. So in the mean time gonna see how the little 318 will run. I want to do a 360 stroker motor . But thats later. Never know may run into a 340 along the way.
 
If it were me, I'd just run the heads you bought. I doubt whether you'll notice. Years ago, I had a 318 '74 Barracuda. I swapped in a '68 340 (X heads) that was a ring and bearing job. Drove it for 2 years, and detonated a ring land off a couple of pistons (bad gas I had to use..lol). I removed all the parts fromt he 340, and dropped them back on the '74 318 short. Comp 268H cam, 2.02 valved heads, thick Felpro gaskets, iron '71 intake and T quad, and the 1 5/8 headers. The only thing I could notice was exhaust note, and it liked to rev higher than the 340 did..lol. I'm sure there was a drop in low speed torque, but an E body and 3.23s didnt feel any different driving the car every day (my only car at the time...). I think there comes a point where what you can do with what you have, can supercede what the most well thought out designs tell you needs to be done to avoid "disappointment". Just my opinion tho. I agree with not putting real $$ into a shortblock you plan to replace, if you dont have the bank account to build it the way you may want to right now.
 
scamp72 said:
Well when i do the build up on the 360 i figure it will take me a year or so to get it how i want it. So in the mean time gonna see how the little 318 will run. I want to do a 360 stroker motor . But thats later. Never know may run into a 340 along the way.
Click to expand...


I still don’t get it. Economically it would be better to do a basic rebuild on the 360 you have access to and run that. If your funds do not allow a stroker for a year a rebuild on the 318 would be nothing more than a set back.

As far as seeing what you can get out of a 318, you can read that on this list for free.
 
scamp72 said:
Ps. I need to go .030 to clean up what do you all think about .040 vs .030?
Should i do the minum bore needed? .060?
Click to expand...
The less you bore, the better of you'll be.
 
At 4secondsflat.com He has a set of rods and pistons to make your teen a 349 for $100. You get the MP cast 3.58/318 crank for under $500 and your off!
I agree with Rumble on the 1.88 valves. Velocity is king!
 
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