5K Questions! Won't idle, threads merged.

[ae824ate]

my speedway car wont idle below 1000rpm

And what do you have in your speedway car?

[Figjam14]

And what do you have in your speedway car?

3k

[ae824ate]

3k

What other engine mods? I ran a 292* duration .474" lift cam in my 4k and it idled happily at 800ish rpm with a good tune, lightened flywheel, extractors etc. About as wild a cam as you can get.

http://www.youtube.com/watch?v=yeTWZnLYa2g

[GJM85]

if the engine isn't making any "ʞ©$ɟ me" kind of noises then i'd say there's no issue with the valve train.

 

if you get excessive blow back through the carb or back firing it could be your lifter preload, cam timing or ignition timing. You really need to put the car under load (like driving it) to see what it does.

 

if it runs smooth, no back firing or coughing but won't iddle then it's likely to be the carband/or a major vacuum leak.

 

an overly rich or lean idle jet will not prevent a car from idling. Unless its very extreme. Too ricch black smoke, Too lean goes pop!

 

I hope really hope you are confident with your cam timing.

[5ksev]

i havnt gotten around to learning how to adjust my timing yet.. ill probably studdy up on it tomorrow and see if thats the cause.. it idle's fine at 1000.. but it just sounds a little high.. so i want to try and get it at around 800rpm

[philbey]

coln do 5Ks run with a tappet gap??.

Nope

 

Ok, so side-cam hydraulics are self-adjusting. If they are pumping up and holding the valves open a little then it won't idle. I don't know how you would check that.

 

Lifter preload. Did you check it or not? For those readin, there is no slop in the valve train, when dry, the lifters should be compressed 40-60 thou. More preload than this and you might end up cracking the valves open, any less and you'll get rattle.

 

Nobody has said the obvious yet: dude, you have a cammed car, do you really expect it to idle at 800 revs? Forget it. I have a stock flywheel, a big cam and 12:1 comp, my dyno tuner could not get it to idle any less than1200.

 

Not only that but you haven't timed the car yet, set your timing at about 10 degrees and then report back.

 

The best way to get a lower rev idle is to recurve your dizzy: you need more advance at idle to compensate for the camp lope. But a stock dizzy won't let you rumore than about 10, any more and you'll ping at higher revs.

[altezzaclub]

So philbey,do you check the preload the same way I used to?? Slowly force the lifter down with a big screwdriver and measure the tappet gap at the valve?? Then it rattles like shit when you start it as it pumps them back up again... I'm afraid I learnt all this on a 1949 Typhoon when I was restoring it as a teenager, so it may be a bit dated. (Its just been finished by my youngest brother, 45years later!)

[5ksev]

it drive's completely fine.. backfire's a little when compression braking.. but when coming to a stop sign, or an intersection ( idle ) it will stall..

 

I'm just gonna get a tune anyway, and hope thats it

[philbey]

Dude, you MUST get it timed and tuned or all your money is wasted. I don't think you have an actual problem, big cams don't like to idle that low.

 

Altezzaclub, I simply backed off the the rocker post bolts til the rockers were loose and then very slowly did them up until the freefloat was taken up (not the spring float in the lifter but the slop so it's just touching)

 

Use a razor blade on the top plane of the head to mark a line across the pushrod then tighten up rocker post bolts completely and remark the pushrod, measure the distance between.

[altezzaclub]

Altezzaclub, I simply backed off the the rocker post bolts til the rockers were loose and then very slowly did them up until the freefloat was taken up (not the spring float in the lifter but the slop so it's just touching)

 

Use a razor blade on the top plane of the head to mark a line across the pushrod then tighten up rocker post bolts completely and remark the pushrod, measure the distance between.

 

LOL! That is cute! Enginuity at its best.

[5ksev]

Dude, you MUST get it timed and tuned or all your money is wasted. I don't think you have an actual problem, big cams don't like to idle that low.

 

Altezzaclub, I simply backed off the the rocker post bolts til the rockers were loose and then very slowly did them up until the freefloat was taken up (not the spring float in the lifter but the slop so it's just touching)

 

Use a razor blade on the top plane of the head to mark a line across the pushrod then tighten up rocker post bolts completely and remark the pushrod, measure the distance between.

i plan to get it tuned in the next couple weeks.. ( when shops open back up ) so yeah

[Mason.]

Panelvan love <3

Edited December 29, 2011 by Mason.

[cianw94]

I had a 270 degree cam with 9mm lift in my 4k as well as a few other mods such as a 5kg flywheel, ported head, 4-2-1 manifold uprated valve springs etc. I never had it able to idle below about 1200 RPM. The timing was set at 13 degrees BTDC at idle and all. She may idle a bit lower but cut after about 30 secs. I reckoned with a good carb I would have got it lower and smoother.

[5ksev]

hey all, I'm just going to be posting all my questions into this thread

 

 

so at the moment, iv got a 5k ke70, with a 32/36 weber and was working fine till iv done the following:

 

25/65 270dur .423 lift cam

decked the head to 10:1

double valve springs

new stem seals

new oil filter

20/50 oil

new "double" spark plugs

 

 

now iv gotten it all back together, but yet it wont idle smooth under 1100-1200 rpm, and wont run at all under 1000rpm.. if i get it to idle and take it for a drive.. as soon as i come to a stop it will stall unless i hold it at around 1500 then back off..

 

would it most likely be the carby needing a tune?

 

also, I'm rather confident that i have all the timing right.

[Jono.C]

Nothing to do with idle solenoid?