400 mopar pushrod problem [Archive] - DodgeTalk : Dodge Car Forums, Dodge Truck Forums and Ram Forums

: 400 mopar pushrod problem


bob
03-14-2010, 07:17 PM
i am not able to get a mopar pushrod length figured out... need help.. i have pics but i cannot get them on this site... ductile rockers on a set of 452 heads... factory was stamped... the pushrod length.. then i was also told that a factory head gasket is .018 and i am running a .039??? is there a stock 400 that ran ducktile rockers.??? what lenght..

bob
03-14-2010, 07:44 PM
8 3/16 long pushrods dont seem right.. when you go to turn them down half turn the valves open right away.. so i think they are the wrong lenght.. .020 off heads and .010 off deck... milled... but head gasket is .039.. i was told in 74 the gasket was .018??? how long should stock 400 pushrods be for a 74 with adjustable rockers.. they are crane ductile adjustable rockers...???

durangosilver
03-14-2010, 08:37 PM
Can't help with the length. I know that hughes and mancini advertise a tool to check for what length is needed. Also do you know what head gasket is installed? The factory gaskets were a shim gasket that was the .018" but a lot of the gaskets included in kits these days measure around .040" because of being a composite gasket. You also need to make sure you have enough engagement of the adjusting screw for the rocker. One other item I can think of that may present and issue is the milling of the heads and block. I believe the intake may need to be milled to provide a good seal to the heads as the position of the heads will be different. I just don't remember at what point that this needs to be done. Hope this helps some.

bob
03-14-2010, 08:49 PM
motor already runs.. for the last 2 years like a dream.. but i am going from stamped non adjustable rockers to adjustable.. i was told it would gain 30 hp.. or was that b.s. ... there is a .039 gasket in it now... so i was thinking that i could use whatever would be the stock length.. because the head gasket is taking up a lot of the milling...

durangosilver
03-14-2010, 09:00 PM
There is some HP to be gained don't know on the amount. It comes primarily from being able to remove the preload on the lifters. Where the length becomes critical on the pushrods is how the tip of the rocker rides on the valve stem. Too much one way or the other and it may come off the the stem thru its range of movement. I would think the head gasket would make up for the milling. I know that mancini racing lists different pushrods for adjustable and non adjustable rockers which is due to the different lengths. They just don't list the length.

bob
03-14-2010, 11:07 PM
I cannot understand.... Didn't any factory motor 400 come with adjustable rockers???

charlie1935
03-15-2010, 07:02 AM
I cannot understand.... Didn't any factory motor 400 come with adjustable rockers???

Nope.
:gr_patrio

bob
03-15-2010, 11:07 AM
anyone ever done a 400 like this??? what leng is close... I need a starting point!

bob
03-15-2010, 11:10 AM
how much power can u gain from non to adjustable rockers

charlie1935
03-15-2010, 11:34 AM
how much power can u gain from non to adjustable rockers

If they are adjusted just where the lifter quits clicking it might be just a little.
It would have to be put dynamometer to notice.

bob
03-15-2010, 09:57 PM
i have uploaded some pics in my profile to show you what it looks like.. the silver pushrod is one i ordered and the black one is a measuring tool.. both set a zero lash....

durangosilver
03-16-2010, 08:22 AM
Cool looking ride Bob. Ok the black one is adjustable in the length if I am not mistaken. This is from cranes sight "How do I determine correct pushrod length?

The cam, lifters, head gaskets and heads are all in place that you plan to use. Starting on the base circle of the cam you need to adjust your "Adjustable Checking Pushrod" out, including your lash settings (at the valve), or preload on the lifter (generally .030" - .060"). Make sure the rocker tip never rides off the tip of the valve, favoring the center of the valve through its travel. For longevity on your guides and seals you are looking for the shortest sweep across the valve tip. For increased performance, you want the pushrod side of the rocker tilted back with the roller tip of the rocker off center towards the intake side of the engine. Also you will want at least .040" clearance between the edge of the retainer and the under side of the rocker.

Pushrod Length

This has to be one of the most asked questions ever. If you are putting together a new motor or just changing a set of cam and lifters, guess what? If you changed everything else in the motor don't you think you might want to see if the pushrods you have will work with your combination? Heads/cam/rocker/lifters, etc! Any one of these pieces can and will change your rocker arm geometry which leaves you with pushrod length as your only adjustment. So after you have every other piece (except your pushrods) get a set of Adjustable Checking Pushrods. Or, make them! This is the only way you can acurately find the length that will work and make the best power for your combination!". Also check this link out http://cranecams.com/pdf/18e.pdf . This helps with the alignment of the lube holes in the shafts for the rockers. I personally would call Cranes tech line at this point to make sure of a few things. I believe from my foggy memory that the adjusters need to have no more than three threads exposed above the adjusting nut but you may want to make sure of that. One last thing I think that you need to make sure of is how the length is measured. That is do you need to include the cup that goes over the adjuster in the overall length. Hope some of this helps.

bob
03-16-2010, 11:15 AM
crane went out of business!!! so calling them is sorta hard.. Anyways you set it at half turn and it runs like shit like all the valves are not closeing...???? then i backed it off to zero and ran it and it still misses and farts sounds like valves are hanging up.. put stock rockers and pusrods back in .. runs perfect?????? thats y i posted pics .. and it looks good to me.. So lost... I've done ford with adjustable , chevy's .. this dodge is killing me... To me after what i have gone threw i would rater use the adjustable with solid lifters only.... trying to use them with hyd lifters seeems like hastle...

B-300
04-01-2010, 01:41 AM
I believe adjustable rockers were used only with solid lifters on mopars. Solid lifters are shorter and use a different length pushrod on LA (smallblock) engines. This is likely the same on B/RB engines.

charlie1935
04-01-2010, 07:36 AM
crane went out of business!!!use ...

They still have a website.