Non Interfering Heads

89SCK@t

Registered User
I only know of one motor that has non interfering heads, the toyota 4AGE. are our motors like that? you know, like it the timing chain/belt breaks there is enough clearance between the valves, fully extended, and pistons, TDC, that they would not collide. I personally dont think they are. Is it as simple as putting a spacer between the heads and block, with all the correct cooling passages and correct sizes for the pistons, that we could too have a non interfering head? oh, we would also need longer pushrods too. has anyone thought about this problem? maybe it isnt a problem, maybe just a problem in my head....hmmm
 
The likelyhood of a timing CHAIN breaking isn't as much of an issue as a timing belt so the concern isn't as great. Plus I believe it would be nearly impossible to fabricate and SEAL in the combustion area a spacer as you mentioned. Additionally, if this was done you would destroy the quench area between the head and the piston. Something that aids in the atomization of the fuel air mixture.

To answer your original question yes the engine is an interference engine. The piston would hit a valve at TDC and full lift. How much I dont know off the top of my head.

Chris
 
If you put a spacer between the block and the head the compression ratio would be ridiculously low.

-Rod
 
All I know is mine would definately interfere, If my timing was off just a little my valves would hit so I really hope my chain doesn't break. Like previously said though, chains pretty much don't break.
 
only two events willlead to your valves contacting your pistons..
*1 stretched chain jumps out of time, This is easily prevented through regular maintenance and upkeep

*2 A catastrophic bottom end event, such as a broken rod,piston or crank. This is pretty much unforseeable, and if it happens, your valves will be the least of your worries.


While yes, a non interference motor seems like a good idea, it isnt realistic. The extended space would improve atomization much like a tunnel ram because the runner length would be artificially increased, but compression would be shot to hell. Also other things like getting your exhaust to fit will be a major PITA, and if youve worked on one of our cars, you know that there is precious little space under the hood as it is, to add height to the heads would take up even more. Lastly, placing a spacer under the head would alter the valve train geometry and necessitate longer pushrods,etc.
All in all, i would leave the non interference to the Toyotas...they need it more than we do;)
 
hmm...

Im getting a lot of responses, very quick too. They only reason I ask is because it is a good idea...to me at least. Why didnt our cars come with non interfering heads? Too much money for the cheap a$$es at FORD to do? Or just too much money period for the amount of the cars produced?

Compression - How much would it lower the compression? Right now its like 8.4 or 8.5 to 1 right? Would it really lower the compression that much? I dont know compression ratios that well, please, teach me.
 
It may be possible to changes pistons and machine them to
keep stock compession raito,to make a free turning Sc.Havent
realy givin it any thought.

I would not even think of shiming the heads.

You may be able to dish the pistons,for more clearance of the valves.
this will lower compression,but inable you to run more boost to bring
it back up.

You would want to keep an eye on the cranking pressures not the compression raito.
 
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It would either take a lot of work on the pistons to keep the compression up to a usable level or it would drop compression down a huge amount to, I would guess to around 6.0:1. Just a guess though. Besides there is no real use for non interfering heads with the chain breaking not being a common problem.
 
Re: hmm...

89SCK@t said:
Compression - How much would it lower the compression? Right now its like 8.4 or 8.5 to 1 right? Would it really lower the compression that much? I dont know compression ratios that well, please, teach me. [/B]

increasing the volume of the combustion chambers lowers compression. shimming your heads would make a large increase in combustion volume, reducing your copression to probably 5:1
 
okay....

Theoretically, if I was to do this, and the compression ratio went that low, I would be able to smell fuel alot, but if I was to, in some way, make it so the supercharger was forcing air into the combustion chamber as soon as the car was turned on, I wouldnt have to worry about it. I know the supercharger is constantly creating boost, but is there a way to weld the clutch on the supercharger(dont our chargers have a vacuum operated clutch?), so that as soon as I turn on the car at 750 rpm, and at idle, I am getting 5lbs of boost? This could correct the low compression that would be created by me by installing the spacer. This is all in theory...
 
ratios of 5 or 6:1 are optimal when running a large blower like a GMC 671, theyre actually required to keep from grenading the motor, but with our little M-90, just not necessary.
anyway like aaron said, why bother modding to prevent something that probably wont be an issue for more than 1 in 50000 motors? the end doesnt justify the means. That would be money better spent elsewhere.
 
the exhaust problem would only be half the problem, the intake would never fit. by raising the heads the engine gets wider, the intake becomes to short.
 
escort 1.9l motor are non- interfering
so are 2.0 liter ford motors
theres a bunch more but i cant remember

the worst motor for this is the new chrysler 2.7 dohc v6's they have 4 timing chains and at 30k the camshaft driver (timing chain pulley on crank slids :rolleyes: over hence the chains fall off and all 32 valves grenade into the pistons:eek: my local chrysler dealer has a 4 man team rebuilding 2.7's 50 hours a week and can barly keep up :rolleyes:
 
Same deal with the new taurus sho. The 3.4L the sproket slips on it's slines and the engine explodes. Those engines run 8,000 bucks from jasper....

Tim

I'd say.... if you leave your car alone... and it does break a timing chain and explodes the engine.... it would be cheaper to just buy a new long block from ford.. than to retrofit this engine to save it if something bad happened.

Either way...
Good luck
Tim
 
hey 89SCK@t, the reason Ford didn't design the engine as non-interference is not that they are cheap, it is because this is a
"Non- Issue"..... have you EVER heard of a timing chain breaking? i'm sure it's possible but i've never heard of it in anything resembling a street driven car......now a belt, that's another story........
 
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