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valve train question
Posted: April 17th, 2012, 6:19 pm
by ftpiercecracker1
I am just about to start tearing down my 1990 4.0l and would like to know what, if any, of the valve train can be salvaged.
Also, i was going to use 707 cast 4.2 rods, but since i will be tearing down my personal engine i will have access to the slightly longer 4.0 rods. My question is which option would be the best
(1)
the stronger but shorter 4.2 rods or
(2)
the slightly longer 4.0 rods, i dont really know how strong they are compared to the 4.2 rods
bear in mind this engine when done WILL BE a turbocharged stroker
I am not trying to make crazy power, so if i can just buy or reuse stock parts i will.
thanks for all your help
Re: valve train question
Posted: April 18th, 2012, 6:03 pm
by Muad'Dib
Might be a good idea to go with the 4.0 rods and use forged pistons since your doing forced induction. Thats the only reason to use the longer rods and forged pistons IMO.. but others may and probably will dissagree.
Re: valve train question
Posted: April 18th, 2012, 8:36 pm
by ftpiercecracker1
ya, thats what i have heard as well. Probably going to go that route, just wanted a second opinion.
But what do you think about running a stock valve train?
I plan to get new lifters, refurb the push rods. (maybe the rockers too?) but i would like to know if there would be any problem keep it all stock?
the only thing i might consider doing is getting some hydralic/roller lifters, although i will be honest, i dont know the first thing about them.
price, application, etc

Re: valve train question
Posted: April 18th, 2012, 10:30 pm
by Muad'Dib
With forced induction my assumption is that your going to want that sucker to breathe... so a stock cam more likely than not wont be up for the task. I dont have any forced induction experience though so others will need to chime in.
Re: valve train question
Posted: April 19th, 2012, 5:54 am
by SilverXJ
ftpiercecracker1 wrote:But what do you think about running a stock valve train?
I plan to get new lifters, refurb the push rods. (maybe the rockers too?) but i would like to know if there would be any problem keep it all stock?
The stock cam won't be too bad for a blower, but I am sure there are better options out there. Just not off the shelf. Contact a few of the smaller cam companies (not comp or crane) and see about getting a custom ground cam.
the only thing i might consider doing is getting some hydralic/roller lifters, although i will be honest, i dont know the first thing about them.
price, application, etc

You can't just throw a hydraulic roller lifter on a flat tappet cam. The cam needs to be designed around the roller lifter. There is only one cam like that but its cast and you don't expect a whole lot of life out of it.
Re: valve train question
Posted: April 19th, 2012, 1:21 pm
by ftpiercecracker1
A custom ground cam is definately out of the question, i will be spending way to much as it is.
by the way, it will be
turbocharged not blown
so my cam selection will determine what lifters i will run.
?
does that mean that everything else will have to be modified as well? pushrods, rockers, springs, is there nothing i can salvage?
thanks for the input.
Journey (yes, thats my name)
Re: valve train question
Posted: April 19th, 2012, 5:05 pm
by SilverXJ
Have you looked into a custom grind? It may not be as expensive as you think. When I got mine from Isky it was around $90, pretty much the same as an off the shelf cam. You can also tell them you are using your stock springs and they could do a grind that won't over work them. You have 3 options for lifters. 1) hydraulic flat, which is what most people run, 2) solid flat, which isn't recommended for the street, have to have the lash checked frequently and are noisy, 3) 505 Performance's roller cam with roller lifters, but as I said the cam life will be limited as it is ground on a cast cam core not a proper billet core. You can use your stock rockers with out question if they are in good condition. I can't tell you about the pushrods though as deck height, head gasket, lifters and cam shaft can all effect their proper length. As far as supercharger vs turbo for your piston choices the turbo will be harsher on the pistons as the boost doesn't come on as gentle as a supercharger would. NOS is also worse than a turbo. Not to question your finances, but if you are already over budget on the engine build I don't see how you could create a long lasting turbo system.
Interesting name, any interesting story to go with it?
Re: valve train question
Posted: April 19th, 2012, 8:16 pm
by ftpiercecracker1
wow, i am shocked. 90 bucks really? I honestly thought it would have been much more.
hydraulic flat it is.
depending on the cost, i may just get a fresh set of stock rockers, just in case.
I will probably have my shop install some new springs as well (stock)
push rods will have to wait till the very end,
As much as i dont want to, i will probably break down and buy the

ingly expensive Keith Black pistons, .030 over
save myself some headache later down the road. Dont plan on ever running NO2.
as per my budget, its pretty funny actually. At first i said 1500 and no more, THATS IT! and then i said weleeelll hell if i am going to do this i might as well do it right, *bump* bump* 2000, and THEN i caught turbo fever and it grew again to 3000, as of now i have a "budget" of $3500 and i am really Reeally hoping i will stick to my guns and NOT go over that.
Ah and my name, I wonder what the character limit to an individual post is?
well, the most outstanding things that come to my mind.
1) I contracted both Kawaski's and Rocky Mountain Spotted Fever within a few weeks of each other when i was 3.
2) When i was 14 me and my dad spent 2 weeks in a cabin 25 miles deep in an idaho wilderness area
3) me and my brother have a built 78 j10/gladiator
not a whole lot to be honest,

Re: valve train question
Posted: April 19th, 2012, 8:48 pm
by Muad'Dib
Dont feel bad.. i build a stroker with cast pistons and spend over 5000.
Then again, i sprung for the works and just about all new parts.
Re: valve train question
Posted: April 20th, 2012, 5:39 am
by SilverXJ
ftpiercecracker1 wrote:wow, i am shocked. 90 bucks really? I honestly thought it would have been much more.
That was Isky's price a while ago. You could also check with other small companies and see what their price is.
depending on the cost, i may just get a fresh set of stock rockers, just in case.
I would just inspect yours. Thy don't fail nor have any internal moving parts. Look for groves, pitting etc. Especially in the fulcrum where there are those oil grooves. They tend to wear the arm quite a bit.
I will probably have my shop install some new springs as well (stock)
that is a good idea and they are relatively cheap.
as per my budget, its pretty funny actually. At first i said 1500 and no more, THATS IT! and then i said weleeelll hell if i am going to do this i might as well do it right, *bump* bump* 2000, and THEN i caught turbo fever and it grew again to 3000, as of now i have a "budget" of $3500 and i am really Reeally hoping i will stick to my guns and NOT go over that.
That is usually how it goes
Re: valve train question
Posted: April 20th, 2012, 12:47 pm
by Cheromaniac
ftpiercecracker1 wrote:I am just about to start tearing down my 1990 4.0l and would like to know what, if any, of the valve train can be salvaged.
Also, i was going to use 707 cast 4.2 rods, but since i will be tearing down my personal engine i will have access to the slightly longer 4.0 rods. My question is which option would be the best
(1)
the stronger but shorter 4.2 rods or
(2)
the slightly longer 4.0 rods, i dont really know how strong they are compared to the 4.2 rods
bear in mind this engine when done WILL BE a turbocharged stroker
I am not trying to make crazy power, so if i can just buy or reuse stock parts i will.
Since you'll be taking the turbo route, I suggest you use the longer 4.0 rods with IC944 forged pistons and new ARP 112-6001 rod bolts. The stock cam should be good so I'd reuse it and refresh the rest of the valvetrain with stock replacement parts.
Re: valve train question
Posted: April 20th, 2012, 4:55 pm
by ftpiercecracker1
refresh the 4.0 rods
new: (stock) cam, Maaaybe a custom grind if needed
new: hydralic mechanical lifters
new: stock springs
new: KB pistons
used: old rockers
pushrods, need to wait until later
sounds good to me

Re: valve train question
Posted: April 20th, 2012, 5:41 pm
by SilverXJ
If you do reuse your stock cam I would have it checked over thoroughly. Also, the push rods you may not have the option of waiting until later if preload is incorrect.
Re: valve train question
Posted: April 20th, 2012, 5:51 pm
by Muad'Dib
I think what he meant by waiting for later on the pushrods is to "wait until he can measure and then purchase new or re-use stockers".

Re: valve train question
Posted: April 20th, 2012, 6:45 pm
by SilverXJ
Duh.. makes sense.
