The factory throttle bodys ARE the trouble most of the time.......the existing IAC hole that the factory put inbetween the throttle blade section was basicly sized for the factory engine(IE: very small).....opening it up usually corrects the "comming to a stop" RPM drop issue after Common Engine Mods have been done........as it corrected mine and MANY others........Joe

 

I also have a stock CNC Ported 52mm throttle body.....It's been a whille so I'll take a look later and tell you what my final (ideal for my combo) IAC hole size ended up being "after" the drilling......also worth mentioning, is that if your (also like me) running a throttle body airfoil... that tends to partialy block the airflow to the factory drilled IAC hole which even by itself makes the hole need to be enlarged to get enough airflow.......Joe.....................I ended up with a 1/4 inch drill bit size hole.....that was enough to correct the issue on mine.....some of my friends needed to go even larger to correct the issue, but they were running much bigger cams than mine.......good luck with it.....Joe

 

Update:
I tightened the roller rockers up to 1/4 turn past zero lash and a good deal of the knock is reduced. They are also more quiet.

I still have some knock and it is audible, will have burn off Thai old gas to work on the tune. I have a full bottle of Torko so that will definitely tell the tale.

Also the engine trying to quit when coming to a stop is totally gone. It must have been loose rockers, they ere at 1/8 PZL. My engine guru is telling me to tighten the rockers up even more, he likes 1/2 to 1 full turn PZL. This seams to be contrary to what you guys recommend.

Right now 1st and second gear are useless with 40 degree roads, third and fourth are definitely stronger. I cant wait till the things warm up.

I am going to get a datamaster readout sometime soon to post, maybe someone can identify any problems.

 

I know alot of guys that like a full turn on the lifter too.....I run about 3/4 or so....the car slows down with loose rockes...I have tested it several times

 

Well I designed the cam and I'm telling you go 1/4 or looser. The looser the better. Especially if you set them hot.

Bret

 

Mike,

Means the cam is too big if you put more preload in and it runs faster.

Bret

 

I had the best results with the stock cam at 1/4 TPZL so I do agree with Brett.

I think I have now determined that the KR I am getting is all in the tune and mixtures. If I can hear it occur then it should no be headers, motor mounts, rockers etc. I am going to burn this tank of gas out and get a fresh tank and go from there.

What would I do at that point to revise the tune. What do I need to provide Ion to try to reduce this KR if iy is still present? I do have a Datamaster so I will try to log it on the next tank.

 

Thanks for correcting my mistake Joe, I guess since I didn't have a problem with my ported stock TB, I thought he shouldn't either. Now I see, I'm just not running a big enough cam.