302 firing order - should I avoid 1542

Hello,

I'm currently doing my best to spec a 331 stroker from a 1971 302 block, whilst researching this subject i have read (more than once) that the standard 15426378 loads up the front main with the first 2 strokes being above No1 main and should be avoided. Even though the 351 & later 302 13726548 firing order loads the rear, the block handles it better.

How true/proven is this that it causes premature wear on the front mains??

I am not looking for mental HP. 430-450 would be nice, so am hoping its not an issue for a normally aspirated engine or should i avoid 1542 order cams

Cheers
 

Mike Pass

Supporter
If you are concerned about main bearing loads then go internal balance and then you won't have an out of balance of 28oz inches thrashing round on the front of the engine. Also if you go for the 351 firing order then the usual crossover exhaust manifold will be wrong - see Steve Barker's thread on the subject as he redesigned the exhaust for even pulses.
Cheers
Mike
 
If you are concerned about main bearing loads then go internal balance and then you won't have an out of balance of 28oz inches thrashing round on the front of the engine. Also if you go for the 351 firing order then the usual crossover exhaust manifold will be wrong - see Steve Barker's thread on the subject as he redesigned the exhaust for even pulses.
Cheers
Mike
Mike, thanks, i am going internal zero balance anyway. i will have a look at the thread
 

Mike Pass

Supporter
Link to topic
heers
Mike
 
Follow the link in Mikes post #4 above, it shows/explains the pipe sequence where it does not matter which cam /firing order you use..... Further re the int/external balance thing, if you go internal thats fine but think about all that weight on one side of # 1 main vs ext balance sharing that weight to each side of that main... better to spend $$ on lighter pistons & rods. Does your block have blind head bolt holes in block, the later ones went thru to water jacket-bean counters got to the casting patterns, dont like big hp.
 
Jac Mac i don't understand your explanation. I thought internal zero balance means the rotating assy is balanced to within a few grammes to remove unwanted vibrations in the rotating mass. The mass is supported by 5 mains so why would adding an out of balance pully to counter the out of balance assy be beneficial, also this pulley is only supported at one end??

Regarding the stud holes i will need to take a look
 
Jac Mac i don't understand your explanation. I thought internal zero balance means the rotating assy is balanced to within a few grammes to remove unwanted vibrations in the rotating mass. [Zero Balance is when all balancing is catered for within the crankshaft itself regardless of whether its added or subtracted weight. - now I added a bit where I suggested having all the weight internally can be an issue if its added rather than shared on each side of #1 main, at high RPM that will tend to bend the crank in the web between Main & rod journals. ]The mass is supported by 5 mains so why would adding an out of balance pully to counter the out of balance assy be beneficial, also this pulley is only supported at one end?? [ In the Ford engine there is simply not enough room to use a heavier wider larger counterweight @ #1 due to proximity of oil pump & oil Pump drive plus the short 5.09" conrod brings the piston down closer to the counterweight.......... Now all that could have been dealt to by using a longer rod ( 5.315 Boss 302 for example ) but we did not know that back then, in fact there was an old wives tale that suggested the top ring had to be ~ approx ~.400" or so down from deck, thats been fairly well kicked to the curb these days with many combos running less than 0.200". Hope that helps.

Regarding the stud holes i will need to take a look
 
Ahh i see what your saying now. However my original question still remains unanswered, although you mention the issue briefly in quote #3 of mike's link. That topic seems to be based more around not liking the original sound. Does the early firing order cause concern to the mains, enough to choose the later firing order on a road car. It would appear not if i go by the amount of posts on the subject in this forum
 
Ahh i see what your saying now. However my original question still remains unanswered, although you mention the issue briefly in quote #3 of mike's link. That topic seems to be based more around not liking the original sound. Does the early firing order cause concern to the mains, enough to choose the later firing order on a road car. It would appear not if i go by the amount of posts on the subject in this forum
Ford when they introduced the 351w & 351c said that they changed the firing order to revise the loads on the crankshaft ( Remember 351w was introduced in 69, 351c a bit later- dont forget Boss 302 still used 15426378 and revved higher & for longer than the others. , but the 302 SB kept the early fireing order for some years until the roller cam came along )
From my own experience [ 50 plus years with damn near every motorsport code I can think of I cant say I have ever seen a situation where I felt the firing order was an issue ] Your concerns for a road car in my mind should be non existent. I'd avoid the 3.4'' stroker options due to rod ratio, you can build your headers so that the collectors have 1/4/6/7 & 5/2/3/8 *early* or 1/7/6/4 & 3/2/5/8 *late*, both options have a rotaional order in the collector, just some have a reverse rotation, but the engine wont know that.
 
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