saul 87vette

it all started with the damn trick flow heads
i got the g2s and they had to be helicoiled right away because i had rocker studs pulling out. well i did that but now my car runs poorly and bogs at low rpm and sometimes when it is warmed up and the engine gets heated up the car will start to make some valvetrain noise which boggles my mind. the idle is bad and the engine is really shaky at idle and low rpm, what could it be. any suggestions?

RB83L69

That doesn't sound like very much fun.

Pop the valve covers and check the obvious. If all the valve train appears to be intact, do a compression test next, but you probably won't have to go that far. You might have some seriously wasted pushrods which will definitely make a motor run terrible.

What sort of cam is in it? Is there any possibility of coil bind or anything else that would cause the same symptoms of too high load on the parts? Retainers hitting the guides, things like that? What retainers are on it, and what are all the parts spec'd to in relation to the cam?

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"So many Mustangs, so little time..."
ICON Motorsports

Red Devil

Saul, tell me you checked each pushrod for correct length!! I had in total three different size pushrods when I popped mine on. It is of extreme importance with these heads.

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"Question with boldness even the existence of a God; because, if there be one, he must more approve of the homage of reason, than that of blind-folded fear."

-Thomas Jefferson

Vader

Saul,

You know that on many aftermarket and even some factory performance heads, the rocker studs are tapped right through the upper wall of the intake port runners. A thread insert installed there (especially a Heli-Coil) might have created small vacuum leaks at each cylinder. Perhaps some thread-locking sealer on the inserts would help if you find that is the case. Check intake vacuum.

And don't feel bad about installing thread inserts. It used to be the standard rtreatment for anything aluminum on performance engines - heads, blocks, transmissions, etc. Even brand new blocks would get inserts for added strength, so it's not just a Band-Aid for your problems.

Also, most of the later SBC valve trains make some noise, especially those without spring oil shields and those with better cam profiles. It's not the typical "ticking" noise created by excessive lash, but more of a "whish-whish" sound as the rockers swing over the valve tips and stud guide *****.

I'd take a look at the complete valve train geometry if you're pulling studs. As Devil says, the push rod length check is a great start. Make sure the springs are intact and properly located on the seats.

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Later,
Vader
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saul 87vette

well, the reason that the studs pulled out was that the heads had something wrong with them, they werent tapped right i could tell when i was putting the studs in. i shouyld have helicoiled them right there but strupid me. i used locktight when i put in the helicoil but thats all. the engine had no noise before installing the helicoil, only a pulled out stud so ill have to just pull off the valvecovers. the thing which i cant explain is why it bogs down all of the time at low rpm, and only starts making those noises after it has ran for a long time or sometimes not even then.

Vader

Saul,

I almost hate to even bring it up, but when you get the rocker cover off and the head stripped on the top side, check to see that all the rocker studs are aligned. If there was a manufacturing defect that caused you to lose one stud, the rest might not be tapped very straight either. A rocker stud installed at the wrong angle changes the valve train geometry. Both the push rod length and valve stem position under the rocker could be affected, as well as having some binding of the rockers.

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Later,
Vader
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"I'm gonna talk about some freaky sheet now..."
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JoelOl75

Its not a vacuum leak past the intake rocker arm stud holes or it would be smokin' somethin' bad. Sounds like valvetrain interferance.