ign. timing 340 vs. 416

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35regal

35regal

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if all parts are equal in both engines except stroke and bore witch motor would like more ign. timming???
 
340
strokers don't seem to require as much - maybe 32.
 
I think I would start out about the same. 416 cubic inch should like more timing on lower end and less on top end. I used a timing retard for high gear (36 to 32 degrees) and picked up about 3 to 4 mph. Motor was 366 cubic inches. By the way the notchback is awsome!
 
Dustem said:
I think I would start out about the same. 416 cubic inch should like more timing on lower end and less on top end. I used a timing retard for high gear (36 to 32 degrees) and picked up about 3 to 4 mph. Motor was 366 cubic inches. By the way the notchback is awsome!
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thanks, it need alot of cosmetic work, trying to get mech. finished first, right now the 340 has 34 total timming
 
It's not the stroke in and of itself, but the combination of the chamber, piston, fuel, and stroke that determines the best timing. A typical pump gas closed chamber 408 w/a quench dish will only require a max of about 32° and many like 28-30° total. A flat top piston, open iron chamber head, and pump gas, on that same engine, will want a little more, closer to 34°. A 340, with flat tops, open iron heads, and pump gas, may want as much as 38° total. Every car/package is different.
 
I can tell ya' my 366 likes 36 degrees of timing..my 416 was less i think i had it set at 32 degrees...
 
I am running the KB745 step dish forged pistons at zero deck, closed chamber Edelbrock heads with .039" head gasket on a 4" crank SB stroker. Running 93 octane pump gas. Most people I talked to think 32 total is best but Ryan at Shady Dell thinks I should run 35. I have mine at 35 total now but plan to go to chassis dyno soon and try less total timing and see what happens. I definitely don't think I should be running more.

In the book How to Build Big Inch Mopar Small Blocks most of the engine combinations they have listed in the back run 35 total, one runs 34 total, and another runs 36 total.

I used to run 38 total timing on my stock '69 340 with original pistons and open chamber X heads and that worked well.
 
well one of the reasons i posted this was, i had to put a bigger shooter noozle on the secondary side of my 750 hp carb. after i added the 1 inch open spacer, it was a 28 nozzle in the seconday side - changed it to a 35or 37nozzle , with34 deg .timming,that got rid of the hesitation at wot, i just added 3 inch ex. vs. my 2/12 , now i have that momentary hesitation again, im thinking itsa little of both , needs a little more timming, and a little bigger primary size squirter.
 
If its a 340 with open chamber heads I would run 38 degrees total timing. I ran mine around like that for 20 years or so and it worked well for me. It sounds more like a lean condition then not having enough timing to me.
 
yep 340, x heads, it has the kb pistons ,the ones that stick .20 out of the hole, motor shop said to run .20 shim ,then a . 39 head gasket.
 
340sFastback said:
I am running the KB745 step dish forged pistons at zero deck, closed chamber Edelbrock heads with .039" head gasket on a 4" crank SB stroker. Running 93 octane pump gas. Most people I talked to think 32 total is best but Ryan at Shady Dell thinks I should run 35. I have mine at 35 total now but plan to go to chassis dyno soon and try less total timing and see what happens. I definitely don't think I should be running more.
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I have a 360-408 running the KB346 with Eddys running 9.6 compression. Mine likes 30 degrees the best. I have run 28, 30, 32, 34 at the strip on a single day (15 runs in one T&T session!), and the 30 yielded the lowest times.

01.jpg
 
35regal said:
yep 340, x heads, it has the kb pistons ,the ones that stick .20 out of the hole, motor shop said to run .20 shim ,then a . 39 head gasket.
Click to expand...

Why the shim? The x heads are machined for piston clearance?
 
What camshaft and intake? Are the heads stock? What is the carb setup like? Do you mean a hesitation from idle to full trottle, or part throttle to full? What is the whole ignition curve like? What ignition?
 
I set mine at 32 total today and took the car out. Feels as strong or stronger then it was at 35 so I'll leave it at 32 for now.
 
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