The great 5E v 4E timing debate.

goldenvtr

goldenvtr

Member +
hardcoreep said:
Same thing here. When i did the first conversion years ago, i used the 5E marks, but the car wouldn't even idle properly. I had to put it back to the 4E mark. What I've learned is that if you have the stock CR of the 5E then its best to leave it the cam gear on 5E. This is why people who turbocharge their 5E dont have problems. However, if you change to the 4E pistons then that's the mark to use.
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can you explain why this is?

using camshafts as an example- aggressive cams usualy make lmpy idle but higher power - would than not be the case for the 5e timing marks running lumpy yet make a better overall diffrence.

by using 4e over 5e markings or vice versa - what exactly is the diffrence in the intake / acual timming.

hope im making sence i find it hard to word things
 
spuddy

spuddy

Ulster Area Rep.
Aye in what way are the valves operating differently on each marking.

Was talking to Billy on the phone, we're leaning towards my timing being a tooth off on the 4E marks. 130psi seems low for 7.6:1 compression, though i'm only guessing.
 
goldenvtr

goldenvtr

Member +
i just had another though thanks to billy - i jsut realized ive change from teh stock gasket to a 2.0mm one and use the stock timming marks on teh dizzy - now obviasly a bigger HG raises the height of the head so does this affect the timming by a few deg maybe even 1 deg? as ive notused a timming light but only the camshaft and dizzy markers to set it to the (stock) level

im going to do a compression test again probly monday - i tihnk i got about 140psi on each cylnder last time with the 4e markers my comp ratio has to be low 7's i THINK it was 7.2.1

74.5mm pistons -10cc pistons
87mm stroke
2.0mm HG
39CC per cylnder

if that helps you
 
spuddy

spuddy

Ulster Area Rep.
goldenvtr said:
i just had another though thanks to billy - i jsut realized ive change from teh stock gasket to a 2.0mm one and use the stock timming marks on teh dizzy - now obviasly a bigger HG raises the height of the head so does this affect the timming by a few deg maybe even 1 deg? as ive notused a timming light but only the camshaft and dizzy markers to set it to the (stock) level

im going to do a compression test again probly monday - i tihnk i got about 140psi on each cylnder last time with the 4e markers my comp ratio has to be low 7's i THINK it was 7.2.1

74.5mm pistons -10cc pistons
87mm stroke
2.0mm HG
39CC per cylnder

if that helps you
Click to expand...

I set mine with the stock markers on the cam and dizzy but she was +20 degrees advanced, they are aftermarket cams though so maybe the marker was wrong.

Interesting your compression results, mines identical but only a 1.8mm HG but its 130psi across all 4.
 
billybob

billybob

Untrusted Seller
im getting a brain meltdown need some drink might give me a few ideas on this problem :beer::beer:
 
billybob

billybob

Untrusted Seller
mybe a question is there anybody on the site running forged 5e setups on the 5e cam marks that can give some solid info ,that it can work better than 4e cam timing .and if so will it alter the compression readings mybe:confused:
 
spuddy

spuddy

Ulster Area Rep.
I've sent Harry a PM, I think his 5E is on the 5E marks but not 100%, his is super fast.

I should really put it to 5E markers and take it back to the rolling road for a direct comparisson, just don't have the cash atm though.

I'll be in a better position tomorrow when take it apart and see if anything is amiss.

I read that an aftermarket cam can reduce compression due to the inlet staying open beyond BDC.
 
billybob

billybob

Untrusted Seller
spuddy said:
I've sent Harry a PM, I think his 5E is on the 5E marks but not 100%, his is super fast.

I should really put it to 5E markers and take it back to the rolling road for a direct comparisson, just don't have the cash atm though.

I'll be in a better position tomorrow when take it apart and see if anything is amiss.

I read that an aftermarket cam can reduce compression due to the inlet staying open beyond BDC.
Click to expand...

yes mybe it cam not to up on the cam thing ,
these fellas are getting some great runs
http://www.toyotagtturbo.com/forums/showthread.php?t=48370
 
spuddy

spuddy

Ulster Area Rep.
Maybe the cams are not suitable for the 5E? Is anyone on the 5E running longer duration cams?
 
spuddy

spuddy

Ulster Area Rep.
billybob said:
no think theres a few running them cams in the 5e builds
Click to expand...

I'm just hopeing when I get the cam covers off that its blatently obvious its off a tooth, I did check when building it, though the 0 mark on the lower pully cam cover may have looked slightly off, but didn't seem enough to be a tooth off.
 
billybob

billybob

Untrusted Seller
its has to be put on right as a tooth can effect the performance i should be able to drop up tomorrow to have a look
 
spuddy

spuddy

Ulster Area Rep.
Bring the gun up with ya lad.

Are u coming in the GT? I think I can update ur EMU for ya. Guess we could plug the EMU into mine and update it if your not bringing the GT.
 
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