Fitting new LA X/Indy heads to my 340

Pete · Post by **Pete** » Fri Feb 20, 15 9:45 am

http://www.hughesengines.com/TechArticl ... ifters.php

http://www.hughesengines.com/Index/prod ... rtid=24238

Dave-R · Post by **Dave-R** » Fri Feb 20, 15 10:01 am

Loved the Hughes solid I had in my old 440. I would never go back to a Hydraulic.

With big flowing heads like that you need more rpm when driving to keep port velocity high. So you do need to think about suitable cam and rear gears. Parts by themselves never work right unless part of a matching package.

But you know that don't you.

Mick · Post by **Mick** » Fri Feb 20, 15 11:42 am

Dave wrote:Loved the Hughes solid I had in my old 440. I would never go back to a Hydraulic.

With big flowing heads like that you need more rpm when driving to keep port velocity high. So you do need to think about suitable cam and rear gears. Parts by themselves never work right unless part of a matching package.

But you know that don't you.

What he said Miles. Hughes cams are ground on a mopar lobe. If you're on facebook send dunnuck racing a friend request. He's done a lot of testing with different cams in big and small block and it's all online. He did one on cams all similar size to the mopar .590 and the Hughes came out top, made 17 hp more than the .590 which was second best. Racer brown and bullet are good cams as well.
Mick

Les Szabo · Post by **Les Szabo** » Fri Feb 20, 15 12:55 pm

Well for once I refrained from talking about solid flat tappet cams, but its really THE way to go, especially with that much head flow. Hughes also state that with one of their solid series cams and 1.6 rockers you get close to Roller Cam performance, all to do with that large chrysler .904 lifter.

Les

Dave-R · Post by **Dave-R** » Fri Feb 20, 15 1:26 pm

Yeah I did that Les but if I was doing it again I would probably stick to 1.5:1 ratio rockers.
They made it tougher to get the geometry right, pushrod clearance became a nightmare on Stealth heads at least (maybe not others) and pushrods are under even more strain than normal so very likely to bend unless the strongest possible and even then it would be best to carry spares.

Les Szabo · Post by **Les Szabo** » Fri Feb 20, 15 2:08 pm

Probably cos of the Chinese Stealths.....there are rockers and then there are rockers, I guess if you use someone like Hughes for the complete valvetrain package you will be ok, pushrod length is critical of course for alignment.

I can buy BB Chinese heads/rods/cranks myself as order a lot from over their for my business, but there's enough people selling them anyway and I think they need a good look at them and some prep before installation, don't need the hassle for the margin.

Les

Dave-R · Post by **Dave-R** » Fri Feb 20, 15 2:18 pm

I was using Hughes rockers. It was probably those 440 Source heads. They have a lot of extra material for porting.

The 906 heads cleared fine with the same valve train.

However, even though the geometry and pushrod length were correct, I was never happy about the sharper angle produced at the cup and pushrod adjuster at each end of the lift range. It is much less straight than with 1.5:1 rockers due to the adjuster being moved closer to the rocker pivot to give you that extra ratio.

This means forces between lifter and rocker are moving in and out of the pushrod centreline more. Which mean they are more likely to bend.

MilesnMiles · Post by **MilesnMiles** » Fri Feb 20, 15 2:36 pm

Thanks for all the input chaps, but I don't have the money for it all. A new cam, yes, but not one that requires solid lifters and associated rocker gear. Just ain't got the bucks

Current cam is as described here

http://www.moparchat.com/forums/showthread.php?t=101108

Suspect a rear gear change will be in line to use the revs better.

Les Szabo · Post by **Les Szabo** » Fri Feb 20, 15 2:59 pm

Fair enough, ££'s is where its at, but then if your using stock hyd rockers??, they will not be 1.5 ratio, more like 1.42 if your lucky in which case your talking about .450 lift from that 268 cam, and thats way too mild with those heads. You need some cheap factory 273 rockers if you can get them and then your off with that cam install at low bucks. I guess at least you got a good base for the future when funds allow for the right parts.

MilesnMiles · Post by **MilesnMiles** » Fri Feb 20, 15 3:03 pm

Sure, Les I agree. Just need to find some. I was pretty shocked at the cost of aftermarket adjustable rocker gear especially in the light of a couple of owners having breakage issues too.

I'm still unsure about the future direction of the car, so one step at a time. I discussed the set up with the machine shop and they said that the car would benefit noticeably over the Stock J heads and I have options for later.

Dave-R · Post by **Dave-R** » Fri Feb 20, 15 3:47 pm

MilesnMiles wrote: I discussed the set up with the machine shop and they said that the car would benefit noticeably over the Stock J heads and I have options for later.

Indeed that is true. HP is made with the heads.

You might find it more thirsty at low rpms and you might have to idle a bit richer. But on the loud pedal you should feel the difference.

MilesnMiles · Post by **MilesnMiles** » Fri Feb 20, 15 4:49 pm

Dave, any thoughts on timing. I'm going to have more compression, is it wise to just knock it back a touch whilst tuning? I have it advanced enough to just fall short of dragging down the starter.
Thought a little caution may be appropriate for first start up.

Dave999 · Post by **Dave999** » Fri Feb 20, 15 5:27 pm

try it as it is

your CR is higher but your flow is higher due to bigger valves better valve job and better port

=you have more to burn but squashed into in a smaller place

It will be harder to ignite because you squshed more of it into the gap at the spark plug, that will delay your spark slightly.

MilesnMiles · Post by **MilesnMiles** » Fri Feb 20, 15 6:25 pm

nothing like some theory,cheers.

Les Szabo · Post by **Les Szabo** » Fri Feb 20, 15 7:51 pm

I think your original suggestion was correct Miles, don't know how far you got it up on the intial though. Depends how good your ignition is, and also 1 step colder plugs may benefit?, you could, dependent on what your J heads were in CC be near 1 full point up on CR.