The engine is a fresh .030 over 350 with stock Forged crank and rods.It has Forged pop up pistons(don't know the brand),200cc Iron Eagle heads that have bean mildly ported.
"The heads have not bean off the block since it was assembled".Flat Solid cam Spec's:

279 284 252 258 527 527 108

Lash .016 .018

The heads were cc'd and shaved by the same engine shop that assembled the engine.

"These heads were on a previous engine that always acted normal and didn't break any rocker studs 501 lift.Comp Cams 292 Magnum cam-501 lift".

When cold the engine will start normally and run ok.
The guy dials a 12.50 for two rounds and that is prety close to what it runs.
Then suddenly it will drop idle speed and the ET will be way off.
There are no traces of water in the oil,or whipped,frothy oil.

In an effort to find the problem some parts have bean swapped, carb,intake manifold,coil,distributor,and locked out the distributor advance.It runs nothing but race gas.

To date nothing has worked.The engine shop even sent the whole car to a Performance shop of their choice two days after the end of last season.It was returned 4 days before the first test and tune this year.It ran the same and this is after the Performance shop made a couple of changes like jetting, timing, a new cam,
AND A STUD GIRDLE :rolleyes:

I was told that last year it broke three 3/8inch rocker studs.

The first pass it ran a
12.50 at 104 with a 1.66 60ft.
The next pass it ran a 12.54.
On the return road it started the same old low idle thing when he stopped to get his time slip.

The next pass was a 12.63

What's the problem here???

I kinda think either the heads were shaved excessively and now the manifold does't seal correctly,or the heads are cracked causing sealing problems and erratic idle.
That still doesn't explain the broken rocker studs.

What's your guess?

I was just brought on board with this guys set up as the owner is the Boss of one of my friends.I haven't checked the pushrod length yet but that is going to be my first move after hearing more detail about what was done.

Is the advance free, both cold and hot? :confused:

Timing advance?
It's locked out.

Describe the fuel system, front to back.

I couldn't imagine why cracked heads would cause broken rocker studs.

What type of rockers are on the car? Have you checked for coil bind or rocker bind?

Has it ever bent a pushrod? I can't imagine it breaking a rocker stud and not bending a pushrod while it's at it. Another possibility is the oil galley in the pushrod could be stopped up causing that rocker to run dry and sieze up, breaking the stud with it.

Just some wild ass guesses here.

Start with TJC's request to describe the fuel system, front to back. Original tank? Fuel cell? What kind of fittings? What size are the lines? What fuel filter? The whole shabang.

Is he running a fuel pressure gauge?

Tell him to hook up a vacuum gauge and see what it does. I'm guessing he's gonna get a jumpy vacuum signal when the "low idle" situation occurs.

Have him check valve lash before and after each run, and note any differences.

I'm wondering if the 3/8" studs broke on the top or at the deck. If at the deck, they may have been overtorqued when they were installed.

What Chad said, you need to find out about that soonest. If they were breaking off at the head that's probably not a valve train issue at all. Does the thing have guideplates? I've seen some heads that had the pushrod guide holes machined off center. Caused all kinds of trouble. If it does have guideplates have a look at the pushrod holes in the head, they should be large and round.

Tom

Make sure the fuel line is not too close to the exhaust or something else that gets warm.

I'll have to check on what you have requested tonight if I can.

Like I said I was just brought into the loop so I don't know everything about this combo yet.

I will check the parts and reply hopefully tonight.

Anything mechanical will probably have to be checked on the weekend as he closes shop at 5PM and that is where the car is kept.

More to come.

Hei modules will do this when warm, for sure.

But you're going to say it doesnt have HEI, since they spent $750 on parts and time only to find its an $8 part.

Hmmm, this seems like a different thread than last night??? Someone did a lot of editing. ;)

Yup smile.gif

I'm learning more and more about the combo as time goes by.I am adding every little bit of info that I can think of that might help with diagnosis

Originally posted by 427L88:
Hei modules will do this when warm, for sure.

But you're going to say it doesnt have HEI, since they spent $750 on parts and time only to find its an $8 part. Correct.I know it is not an HEI.
I believe it is a Mallory distributor of some sort.
I really have to take a good look at the car.
He closed shop early today to go to a funeral so I didn't get a good look at anything but the front door of his shop graemlins/clonk.gif :(

HE'ssss Baack graemlins/waving.gif

Well I had a chance to check it out a little more.

It has a stock fuel tank with the stock 5/16 outlet tube.The end of the outlet tube has 3/8 braided hose connected to it,this leads to a Holley Blue pump with 8-AN fittings.The other end of the pump has an 8-AN fitting that connects to 3/8 braided line that runs on the outside of the frame rails.It is no where near the headers.Under the passengers side door there is a low profile Earls filter that also is 3/8 in and out.The 3/8 braded line connects to it and is ran to the Holley regulator that came with the pump,8-AN fittings also.The Regulator has a fuel pressure gauge connected to it,it is set to 7psi.The other side of the regulator has a 8-AN fitting that connects to 3/8 rubber tubing that connects to a standard Holley splitter line that feeds each bowl,.110 needle and seat assemblys.

The carb is a 750DP 4779 with dual idle circuits.
Intake manifold is a Weiand Team G 7532.

Headers are 1 5/8 Hooker Super Comps
3 inch pipes connected to (? series)Flowmaster mufflers.

:( Distributor is a Mallory Unilite small cap (smaller than early GM points style cap)W/O vacuum advance.

TH-350 with TCI Drum/Trans go Stage 2 shift kit
Hughes 4200 (approx) stall converter
8.5inch 10 Bolt/Eaton Possi/4.11's
28x9 M/T Slicks

I looked at the 3 broken rocker studs that they had saved.

The break point was above the area where you torque them down.It happened on more than one single cylinder.
They found bent pushrods when they found the broken studs,on the same cylinder.

When I got there they were saying that the idle problem was happening right before I arrived.
This is without the car even making a run.

I started the car and it was idling at just under 2000 in park(No power steering or breaks).

It wouldn't come down untill I dropped it into gear,at wich point the idle came down to 900rpm.

When I put it back into park the idle stayed at 900rpm.I let it idle there for a bit before I gave it some gas.After I gave it a little gas the idle speed climbed to just above 2000rpm and stayed there,untill I put it in gear again,then it dropped to 900 again.

I had my friend sit in the car and do just what I did while I looked at the fuel pressure gauge.
No change in pressure.
I also checked the throttle cable for tension,there was none.

I hooked up a vacuum gauge.

In gear at 900rpm it has about 2-3inches of vacuum that bounces a little.
When the idle rises to around 2000 the vacuum is around 13inches but it seems to fluctuate a bit.

I thought to my self???

Vacuum leak :confused:

The problem is that someone didnt check all the clearances.

In a situation (many times) where the valve train is bending, breaking or deflecting i would venture to think that its becuase its running into a solid stop.

That "stop" could be retainer to seal clearance, valve spring binding, or a piston top.

Check the retainer to seal clearance and the valve spring stack up clearance (with the cam at the height of its lift).

That is not the end, there is more.
I can only type so fast smile.gif

I was told that this was the second intake manifold that was on the car.

The first one was a "NEW" Performer RPM Air Gap.
They said that it didn't fit well and that the ports had oil in them when they removed it.
They told the builder and he said that the intake was warped.

They purchased a Weiand Team G 7532 that has bean on it to this day.So I don't know if it has oil in the runners either.I can't really see it on the plugs.I am fairly good at reading the plugs for fuel mixture but I don't know what to look for as far as the oil.As far as I could tell the porcaline didn't have any oil on it.
And I looked at each plug.

After I asked a few more questions and BS'd a bit they said that the heads were shaved .020 by the builder and that the block had bean decked.
They don't know by how much though.

Could the inconsistent idle, ET, and low performance be because the intake wasn't matched to the heads?

I didn't check the springs for coil bind,retainer clearance and such because the owner was saying that he didn't want to do anything except for get a new 385 Fast burn crate motor.Then sue the builder for his money.
He even called his wife to inform her, :mad: she wasn't happy.
His wife works for lawyers,"GOOD ONES", he said.


Ok input now :D

What valve springs are in it? What diameter? What installed height?

I was told that it is a custom grind from Crower and the springs came with it as they were recomended by Crower for it.

I didn't have the chance to look under the valve cover as he wanted to go home to settle his wife down from telling her the good news about another 5 grand on a motor :D

did he put it together, or did the builder?

The engine was machined and assembled at the same place.

Possibly having more than one person work on it before it was deliverd to the buyer.

The owner of the shop that did the work claims that they have put together the same exact combination several times and they never had any problems, till now.

If the engine was decked, the intake has to be as well. Otherwise it will leak along the bottom of the manifold with the lifter valley causing a huge vacuum leak, and run like absolute crap.
Pull the manifold again, and check for oil seapage as before.
Blocks are usually decked by 0.020" to clean them up, so your machinist 'should' know how much to cut the faces of the manifold, and the manifold ends.

Well .020 off the heads and the blocks been decked .020 to .025 that would add up to .040 to .045 and I don't beleive the intake is sealing huge vacuum leak,a new manifold is not going to seal it would have to be cut down!They make thicker gaskets, but I would take the intake to the builder he should know better!

I think the intake is not leaking also.
The breaking of studs has got to be a clearance issue.

I need to get a good look at it.I was going to meet them at the shop today but the owner decided to go racing graemlins/clonk.gif

Hope he doesn't break anything :(

I think he should take the engine to a machine shop to look at the surfaces and mill/shave the intake to match,just not the original builder.This may prove to be tough though,because every decent machine shop is swamped with people who want their stuff done right now because the first points race is just around the corner.