Mopar Muscle Association UK

Could use some advice base on real experience here, chaps.
I'd like to make more of the excellent heads that I've got and the temptation is to go for more cam.
The next step up for me is a cam with .5+ lift

E.g
http://www.hughesengines.com/Index/prod ... rtid=30395

I'd like to know what opinions are on what needs addressing

For instance, I have a very nice set of 273 adjustable iron rockers, but will high lift put them at angles they were not intended for and lead to poor alignment and shaft wear etc..?

And then there is pushrods, poston clearance

There are a number of issues here and potentially you only know once you mock the parts up and check clearances. Roger found this with my Hemi and he had to get custom Smith Brothers pushrods to avoid them hitting the underside of the rocker arms.

I do not know your pistons and if they have any cut outs so once you have degreed the cam in you then have to check Valve to Piston clearance.

You MAY have to advance / retard the cam to get enough clearance or you may even find it is too much lift.

Not having roller rockers is a bit of a disadvantage but you may be Ok. Rocker ratio also comes into play here - I assume 1.5:1 ratio?

Others may be able to advise better than myself.

one experience

but experience none the less

i kinda made it up as i went along but suffered no ill consequences as far as i can tell

I have a cam with 0.595 inlet 0.605 exhaust lift specified with a 1.7:1 rocker

I'm using 1.72:1

in a semi hemi head
the inlet is 2.02 inch head on the valve up from a 1.96 inch.
valves angled towards each other at 21*

I was aware of the fact that the valves could collide with each other on overlap so that was checked first.
they hit with both at past full lift only
in fact unlikely for any cam, to have a profile that does that

if you have wedge heads with parallel valves no problem

I wound the motor over to TDC and measured how far I had to push a valve down before it hit the piston.

yes they would hit.

I then wound the motor over to the centreline on inlet and exhaust i.e max lift on the lobe i.e cam and crank in the right place

and check I could push the valve in more than the lift.
and I could in both cases

because I didn't have the head gasket on and the head was just held down by 2 studs I could take it off if I lost a valve.

I can't remember exact figures but they missed the piston by reasonable distance and I also had the head gasket thickness to add


if your head is on and you are removing valve springs I'd suggest a cable tie or rubber band round the valve at the collet groove to stop it falling in.

I learnt a lesson while changing stem seals a while back that doesn't need to be re learnt by anyone else. Even the strongest magnet isn't piking up a valve and getting it back into its guide.


I then went through a process of building it up properly
checked the cam matched the card the simple way. max lift = what it says on the card=what it says on the balancer (after checking balancer TDC was TDC to make sure i could depend on its degree marks.)

with the top end assembled i checked for coil bind retainer stem seal clearance and rocker/retainer clash
i used crane offset (the retainer is dished slightly up to allow more installed height) multifit retainers and collets.
These have a Chrysler sized hole and the collet outer diameter is Chrysler sized. you can however get collets for any valve stem diameter, which i needed because my valves were chevy/edelbrock mopar big block valves they have a thinner stem.

i used 7 degree collets and retainers because my retainers were steel an my spring pressure was just kinda normal

all looked good and the spring height at closed and max lift appeared to be what it should be.

last but not least I coated my valve tips in black marker and wound the engine over

this showed a ware pattern on the valve tip that favoured the rocker pivot side of the valve

= pushrods too short on a floating ball-stud rocker

I took an old pushrod
I cut it in half
I wedged a rod down it
purchased a bag of 20 washers
I assembled my pushrod with a washer in the middle
checked pattern
added another washer
checked pattern

measured both washers thicknesses

I estimated I needed 1.5 washers to get it in the middle worked that out

i measured a few washers took an average 1.5 was pretty bang on what I'd worked out above

then added 1.5 washer average thickness to the standard pushrod length from the Chrysler manual

and ordered

worked out ok

so I got some pushrods from smiths brothers via Turnip.

so out of the build

that bit went well


Dave

As has been said, you'll find out what needs addressing when you mock it up.

As a rule of thumb, if you have valve reliefs, that cam will probably clear. The rocker arms will be fine. If the guides have not been shortened and turned down for teflon seals, they will need to be done to clear the springs. You might need different retainers to get the correct installed height to avoid coil bind. You might have to use rocker shaft spacers and custom length pushrods to get the rocker arm geometry right. That's about it, but well worth the effort for the big increase in power you're likely to see.

Thanks all, does seem like a lot to consider given the engine is complete and has no need to come apart.
The heads have the clearance and springs for .625 lift and 370lb beehive springs so no issues there that I can see.
Pistons are picketed for valve relief too.
Pushrods I'm guessing would have to be made to fit.
If I stayed hydraulic then a Lunati Voodoo cam (.....03) might be a more practical option.
If I stay hydraulic I also already have pushrods on the shelf.

Lunati cam - designed for Mopar
https://www.lunatipower.com/Product.asp ... 45&gid=287

Nothing wakes a motor up like a big roller Cam, but the set up is ££££'s

I had a Lunati in the Barracuda and it was fine.

you don't have to take it to bits to achieve your aims

crower do a nice wide range of guide sizes for seals

the only mob who had anything suitable for my odd sized guides

and of course being odd sized.... cheap on ebay

avoided having to buy a tool and dismantling the head to carve off a chunk of guide diameter

Dave

Pete wrote:Nothing wakes a motor up like a big roller Cam, but the set up is ££££'s

I had a Lunati in the Barracuda and it was fine.

and you might need a

fuel pump
Oil pump drive
dizzy dive

that can put up with a toughened steel cam shaft

the ones in there will be made to work with a normal flat tappet cam shaft which is different material that has been used for ever, hence perfectly matched to those things that rub against it.
None of them were designed to run metal on metal on toughened steel

and their replacements for a roller cam would devour a normal flat tappet cam.

you are alright if your dizzy drive is nylon

Dave

We are getting way off topic talking roller cams, totally unessasary for this application unless you really want to get rid of a grand....

A solid cam with enough lift the let the heads work would be best and not overly expensive.

I'm with Blue, not least as there are specific problems relating to 340 blocks when going roller.
I know Blue is a fan of solid cams and that Hughes cam is one of the fe listed that will run with my set up.
Still got metal lift and that's the concern. As well as the good bit

I was only teasing, but there best thing about them is the lack of worry about breaking the cam in.

Yes Pete, absolutely. I did research but as Blue notes it comes to outlandish dollers