RPM Airgap

[1970-dart]

i have researched some and see that many people have issues with fitment even with stock applications as far as deck height and head surfaces. some night remember when i bought this 1985 360 i did not know much about it because it came already built.

It came with a new gasket set so i decided to go head and tear it down to put in the new gaskets just because i had them. at that time i questioned the fact that i had two different looking push rods but seemed to be all the same lenght or at least super close.

it had a holly dominator on it so i decided then to put it back on just to be safe but now i have decided to put on the air gap and the recommended gaskets and the holes dont lineup. I started investigate the old intake for signs of being milled and found that they ob longed all the holes on that. so here are some pics of the intake holes and the push rods which still seem to be very close in length. It was hard to hold the push rod/tape measure and get perfect picture at the same time but i think its pretty accurate.


I have not had time to search the stock length of what push rods should be in there...

Thanks for looking Don

 

[Blind Squirrel]

I'm not a fan of mixing parts. But there is nothing technically wrong with using the pushrods as long as the geometry is correct. Wouldn't do it in a performance package setup. As far as the ob-longed holes in the intake. Makes it work for both old and new bolt patterns.

 

[1970-dart]

I'm not a fan of mixing parts. But there is nothing technically wrong with using the pushrods as long as the geometry is correct. Wouldn't do it in a performance package setup. As far as the ob-longed holes in the intake. Makes it work for both old and new bolt patterns.

Thank you for the reply.

is there more than one stock length push rod for a 85 360 ?. That's the problem with stuff that you did not put together and know nothing about. But I assume the geometry is good be used it runs good it's not noisy and I run the car pretty good at times. I suppose the holes could be on longed because block deck and or heads were modified or maybe the heads are newer and older intake would not line up.

I'm not sure that I want to or should hog the holes out on my new intake and if I have the intake modified it pretty much makes it good for only the setup it's currently on.

 

[Blind Squirrel]

I would assume nothing, this is not factory stock. There are several reason why a different than stock length could or would be used, and even different lengths within the same block. Once you start milling things, changing rocker ratio's, bad valve servicing, really crappy shade tree - make it work - bad mechanic mentality. You can run in to all kinds of things. I know you kept track of which rod came out of which hole, a long with which lifter if your putting this all back together with the same parts? If you were running a different ratio on the intake than the exhaust then I suppose you could run different lengths for each set of rockers to correct geometry over the tip. How many of each type is in this motor?

 

[1970-dart]

They are split right down the middle as far as the quantity and they are all in the same spots each time i take it apart. I have been running this for two years now so there are no running issued.

Just putting on a new intake on it and reviewing what I have I have to either machine it or do like the other intake and oblong the holes.

 

[Lelo Dart]

If you have to hog out the bolt holes then you might have the ports not lining up. Isn't there a extra thick intake gasket to make up for head/deck milling?

 

[rumblefish360]

Hogging out the bolt holes is a normal thing to do when fitment is tight. Chances are that the intake is made/cast slightly different from the Holley is possible as well as a possible engine block decking, head milling, intake milling, and gasket thickness all come into play.

Pushrod length on a Hyd. rocker can pretty much still use a stock length on a stock engine with a stock unmilled deck to a very well milled deck. And again, gasket thickness changes help/hurt this.
There is some area here that is forgiving. But as said above, as long as the rocker geomentry is t bad, your good to go.

 

[Blind Squirrel]

They are split right down the middle as far as the quantity and they are all in the same spots each time i take it apart.

All in the same spots when you take it apart? Now that's funny right there. I get a picture of pushrods magically jumping around from hole to hole. Can you tell us anything about the rocker arms?

 

[fishy68]

As long as the pushrods are the same length it's no problem. Just different styles of pushrods. And btw pushrod length makes no difference whatsoever on valve train geometry on a engine (such as a small block mopar) with a shaft rocker system. The shaft mounting height and valve stem height are all that can affect geometry. As far as the intake it appears that the Holley was setting too high thus the reason they hogged out the holes. Definetly not the right way to do it. Check to see if there are dowel or roll pins in the block on the front and rear China rails about half way between the heads. If so pull them out and see if the intake sets down farther. If so that may solve the issue. Also, if your using the cork gaskets on the china rails eliminate them and that can possibly let the intake set down farther and allow proper alignment. I always eliminate the cork gaskets anyway and use RTV and they generally seal up much better. If Neither of those methods work most likely the block and/or heads have been milled a bunch and if your already using thin (.040~.045") intake gaskets the only way to properly fix it is either pull the heads and have the intake surfaces milled down or have the intake itself milled down. My method for determining how much to mill is to set the intake on with no gaskets and use feeler gauges at all 4 corners between the heads and intake to determine how high the intake needs to sit so the holes are a little above center of the bolt holes in the heads. You want them a little above center cause when you tighten it down it'll pull the intake down

 

[1970-dart]

All in the same spots when you take it apart? Now that's funny right there. I get a picture of pushrods magically jumping around from hole to hole. Can you tell us anything about the rocker arms?

All in same spots just means when I take them out i lay them out so they go back in the same place the same way they came out.

Just the stock type non adjustable rocker system.

 

[1970-dart]

As long as the pushrods are the same length it's no problem. Just different styles of pushrods. And btw pushrod length makes no difference whatsoever on valve train geometry on a engine (such as a small block mopar) with a shaft rocker system. The shaft mounting height and valve stem height are all that can affect geometry. As far as the intake it appears that the Holley was setting too high thus the reason they hogged out the holes. Definetly not the right way to do it. Check to see if there are dowel or roll pins in the block on the front and rear China rails about half way between the heads. If so pull them out and see if the intake sets down farther. If so that may solve the issue. Also, if your using the cork gaskets on the china rails eliminate them and that can possibly let the intake set down farther and allow proper alignment. I always eliminate the cork gaskets anyway and use RTV and they generally seal up much better. If Neither of those methods work most likely the block and/or heads have been milled a bunch and if your already using thin (.040~.045") intake gaskets the only way to properly fix it is either pull the heads and have the intake surfaces milled down or have the intake itself milled down. My method for determining how much to mill is to set the intake on with no gaskets and use feeler gauges at all 4 corners between the heads and intake to determine how high the intake needs to sit so the holes are a little above center of the bolt holes in the heads. You want them a little above center cause when you tighten it down it'll pull the intake down

Thank you

I never use the end gaskets and use a bead of silicone. There are no pins of any sort and I'm using the gaskets edelbrock recommended but they are kinda thick.

With the intake on there and one side lined up with bolts in it the other side is off a lot. By half or better of the bolt hole so I suppose that's why Both sides of the holly were hogged out so much.

 

[Blind Squirrel]

As long as the pushrods are the same length it's no problem

That's the thing. In the pictures he provided it "appears" there is around a 1/16th of an inch difference. Pushrods of an incorrect length can cause either a lack of preload on the lifter (noisy valve train) or the opposite and bottom out the lifter in its bore. It appears you may have a make it run get it down the road rebuild. Not a huge deal if that is what you expected.

Just for S&G can you post a pictures of the top several of the valve tips. I'd like to see the wear pattern.

 

[1970-dart]

As

That's the thing. In the pictures he provided it "appears" there is around a 1/16th of an inch difference. Pushrods of an incorrect length can cause either a lack of preload on the lifter (noisy valve train) or the opposite and bottom out the lifter in its bore. It appears you may have a make it run get it down the road rebuild. Not a huge deal if that is what you expected.

Just for S&G can you post a pictures of the top several of the valve tips. I'd like to see the wear pattern.

It was hard to hold them and get school picture by myself because the tape measure has the wobbly end. But I have been running this engine for two years and I can assure you the engine makes no noise and runs fine at all speeds and rpms.

 

[fishy68]

That's the thing. In the pictures he provided it "appears" there is around a 1/16th of an inch difference. Pushrods of an incorrect length can cause either a lack of preload on the lifter (noisy valve train) or the opposite and bottom out the lifter in its bore. It appears you may have a make it run get it down the road rebuild. Not a huge deal if that is what you expected.

Just for S&G can you post a pictures of the top several of the valve tips. I'd like to see the wear pattern.

Your correct that length, even a little can matter. But you also have to consider the measurements were taken using a tape measure. Not a very accurate way to measure them. I can understand the OP did it that way because he probably doesn't have a caliper long enough to measure them with. Since he said it has ran good with this configuration for 2 yrs. it seems to me it's not a big issue. It's quite possible the proper length would be somewhere in between the 2 and there's enough tolerance there to allow them both to work

 

[1970-dart]

Your correct that length, even a little can matter. But you also have to consider the measurements were taken using a tape measure. Not a very accurate way to measure them. I can understand the OP did it that way because he probably doesn't have a caliper long enough to measure them with. Since he said it has ran good with this configuration for 2 yrs. it seems to me it's not a big issue. It's quite possible the proper length would be somewhere in between the 2 and there's enough tolerance there to allow them both to work

Exactly And it was ran by the people before me also. Thanks for the help everybody and I'm just gonna have to figure how much to mill the new I take because I'm not tearing it apart any farther right now and also not hogging out the holes in the new intake.

 

[nm9stheham]

The best I can tell from the pix, the p-rods lengths are the same, looking at both the tip and somewhat up from the tip.

 

[T-N-T]

Thank you

I never use the end gaskets and use a bead of silicone. There are no pins of any sort and I'm using the gaskets edelbrock recommended but they are kinda thick.

With the intake on there and one side lined up with bolts in it the other side is off a lot. By half or better of the bolt hole so I suppose that's why Both sides of the holly were hogged out so much.

Edelbrock gaskets are .060 thick. You can buy .045 and .031 thick intake gaskets that will allow the intake to fit properly if milling has been done to the heads and or block.

http://www.summitracing.com/search/part-type/intake-manifold-gaskets/make/dodge/engine-size/5-6l-340

 

[TrailBeast]

Did anyone consider that a valve job was done where some of the valves were sunk in a bit more than others and the builder made up for the lifter preload with different length pushrods?

 

[1970-dart]

Edelbrock gaskets are .060 thick. You can buy .045 and .031 thick intake gaskets that will allow the intake to fit properly if milling has been done to the heads and or block.

http://www.summitracing.com/search/part-type/intake-manifold-gaskets/make/dodge/engine-size/5-6l-340

the old intake had reg felpro gaskets and that intake has oblong holes and they are hogged out pretty good on both sides. I hate to ruin the $22.00 edelbrock gaskets i put on there to see but im positive that with no gasket at all the intake holes would not lineup. but i suppose im gonna have to try it and see.

 

[1970-dart]

Did anyone consider that a valve job was done where some of the valves were sunk in a bit more than others and the builder made up for the lifter preload with different length pushrods?

possible but if they went to that extreme i think they would have done the intake right and not hogged out the bolt holes??

 

[TrailBeast]

possible but if they went to that extreme i think they would have done the intake right and not hogged out the bolt holes??

It wouldn't really be an extreme if he had them laying around and needed to solve the problem.
I can't think of why else someone would use different lengths other than that, but like other have already said "it really doesn't matter if the engine is ok with it".

 

[1970-dart]

It wouldn't really be an extreme if he had them laying around and needed to solve the problem.
I can't think of why else someone would use different lengths other than that, but like other have already said "it really doesn't matter if the engine is ok with it".

Right.

And also like been pointed out that way of measuring/taking the picture leaves a lot to be desired in the accuracy department. They are very very very close if not exact in length.

 

[TrailBeast]

Right.

And also like been pointed out that way of measuring/taking the picture leaves a lot to be desired in the accuracy department. They are very very very close if not exact in length.

One looked 3/8 and another 5/16 to me.

 

[1970-dart]

I also took off the gaskets this morning and even with no gasket the holes are no where close to lining up. So it's either kill the intake leaving it useless on other engines later on or hog out the holes to make it work now and later.


Ughh I love this enigine it runs so good and has so much power and everything was new and as they said when I bought it. Just the guy I got it from was not the builder either ohh well I just hate the unknowns of somebody else's work.

I still got a great price on a great motor and someday I'll put better heads on it and change out the cam and I'll know what I have.

 

[1970-dart]

One looked 3/8 and another 5/16 to me.

Again the picture was taken with me holding the tape measure and the camera while also trying to hold tight/still the floppy end of the tape measure. I'll try to get better pics of it soon