So I'm building my first engine, a 13 B 4 port for my SA, anyway the tension bolts from the engine I tore down appears to be mismatched.

The difference is in the length of the threads. Some of them have threads that are approx. 28 mm and some are only 16 mm.

I'm thinking that with torque specs and all, is this a problem?
Replacements would be a couple hundred so what do you say?

 

there should be one different with a m on the head.

 

in the bottom left of every engine ( from behind ) ,, outside the bell housing pattern

BUT its not unheard of that when dowelled
some builders will retap the front plate deeper,, and use more of these longer M headed bolts where all the dowels are


if there is no M,, and the bolts are different lengths,, then someone has used 12a bolts,, and they should be about 20mm shorter than the others

 

I know about the one bolt that is longer, that is not what I am concerned about, I have the one long bolt just as I should have, the issue is with the remaining bolts. Some of them are different in that they have longer threads, the actual length of the bolts are the same, its just that some of them have been threaded a greater distance and I am concerned that it may make a difference with the torque specs.

 

well the bolts do change a bit over the years,, some get longer threads, some get ribbed centres, others get rubber bonded centres

myself,, i still TQ the SD engine ones all the same
,,, 25 pounds force per foot in your lingo
or 34 newton meters for the rest of the world



but meh-- how would i know ??

 

You still have not answered my question.

Is it ok to use tension bolts that do not match (in this case some have longer threads)
in the same engine?

 

mixing bolts shouldn't make any difference so long as the overall bolt length is right so they clamp all the sections together and don't bottom out in the front housing.

 

and a replacement set wouldn't cost you a couple hundred bucks, more like $5. most of us have dozens and dozens of sets of tensions bolts lying around. i have a box that literally weighs about 80lbs with nothing but tension bolts in it, with scattered sets here and there as well.

 

they came out of a once running engine,, what makes you think they don't go back in???


dunno what to do with all of mine,, am contemplating making a spud gun to shoot them

 

Well, I was thinking mixmatched bolts could part of the reason the once running engine was no longer running.

Actually I just want to make sure that I don's put something in that is not A# 1, Would like the new engine to last really long time.