Still in the process of sorting out my 13bt swap, and seem to have run into some possible timing issues: it seems that my timing is somehow off, even though the marks are lined up properly

I get horrible detonation when I go into boost, the engine is a S-5 with the front end plate swapped to the S-6 version (bigger front thrust bearings, better oiling also) and an S3 front cover. C

Currently I am useing the S3 front pulley and it just hit me the timing marks MIGHT be different between the two, anybody know if they are different? this might explain why I am getting the detonation when I boost....


kenn

 

I don't know if they are different, but I would have used the S5 e-shaft pulley boss, so the S5 pulleys would bolt up. That would assure you that the timing can be set correctly. The S4/5 pulleys only mount one way, instead of 4 like the earlier ones. The only thing that may throw the timing off then might be that the timing pins aren't located exactly the same.

 

There is a 5° difference but I don't recall off the top of my head whether it's BTDC or ATDC. I think j9fd3s knows.

As for the front cover, the 20B pin is in the same position as any S3 or older front cover, except it's higher to allow for the larger pulley on those engines. It's safe to assume the pin on S4 and S5 engines is also in the same position, relative to the stock pulley for those models.

 

TII timing marks are at 5*ATDC leading. I believe some older pulleys were marked at 0*.

 

Ah, ATDC. They started marking 13B pulleys at 5° ATDC with the GSL-SE.

 

That would explain a lot.... 5 degrees can make a hell of a difference with detonation problems, I don't have the front pulley for the 13bt as prior to rebuild it had been bent so I used the 12at pulley when I rebuilt it. timing will probably be off in la la land as a result ....

I will try retarding all of the maps by 5 or 10 degrees this time to see what happens

kenn

 

Bump for more info.

kenn