I just installed a slp runner and a highly ported intake (RCR's old set up) I installed a set of 1.6 RR's running stock ignition, and have the vette allum 58CC heads I get an occasional back fire, nothing major but enough to hear it, I cant remeber if its timing related or not enough fuel involved.
any ideas?
Im almost ready to drive this thing! just need a few pointers on getting it set up correctly, its been a while but I had a carter carb and it said either add more or take fuel out, but I cant remember which to solve a back fire problem.
thanks
Jack

 

Are you sure you don't have any vacuum leaks? Even if it doesn't surge I'd check for leaks first. Mine ended up being around the cold start injector, not sure if this applies to you though. Later

 

Make sure you have your valve lash set properly.

Backfire through the intake means a valve is either open when it shouldnt be ( lash too tight )

Or that ignition is firing before the valve is closed... thats Gonna be WAY to advanced.

 

if its the valve lash it should happen constantaly this dosent happen all the time. I went through the adjustment twice so Im pretty sure thats not it.

 

How did you set them ?

I like to Set them Loose and fine tune them with the engine Running.

Tighten till it stops ticking, then 1/4-1/2 turn more.

 

set them like all other hydraulics, tighten till you cant turn the push rod freely in your fingertips then add a 1/2-3/4 turn my book says 1 but with the slightly larger ratio's the hydraulics can make up that much difference

 

You talkinb about with the Motor Off I take it.

Is that with the lifters in question at TDC ?

 

yes motor off, sitting one at TDC get half the lifters, turn it over one time get all the rest dont remember the order off hand thats where the book comes in handy. unless you know someone with fast enough fingers to do it while runnin! haha

 

18436572?

well, sounds like your in the Ballpark. Probrably not your problem.

Id still pop the VC's off and do it Running

Check your Inital Timing. Getting it set right on these COMPu controlled cars can be tricky if you don't know what your doing. I know I was baffled for a long time befor someone showed me the light.

You need to unplug te EST bypass.

 

when setting the lifters, you put it on tdc for #1 and do the #1 cylinder both valves and then half the others except #8 and then turn the crank 1 turn and will be on #6 TDc to get the rest and including all of #8. makes it a lot easier, thats how the GM engine builders build the motors that are in the cars they dont adjust everything while its running makes one helluva mess.
Where is the EST bypass to disconnect?
thanks

 

The EST is located on the passenger side back by the firewall.If I remember correctly I believe it is a tan wire with a black pug about 2" long.But this is on 91 Camaro.Hopethis helps you out

 

You don't have it running yet?

Sounds like timing too advanced. The EST should be over and to the rear of the passenger wheel well. It'll be a single weatherpack connector. Also double check for vacuum leaks. Keep me up to date...

Bob

 

Yeah bob Im so close to having it running its driving me crazy! I think its a vac leak I tried to make my own gaskets for everything but I can hear a slight whistle and when I sprayed a little carb cleaner around the flanges it went away, so I ordered the right gaskets yesterday. So if everything works well I will have it done this weekend, I guess Ill have to look for the ESC plug I dont think mine is where yours is anymore since this is not in a camaro anymore.
thanks
Jack

 

I was wondering when you say it keeps popping through the intake.Does it only do it when you get on the accelerator,under load,etc..I 'm wondering cause I'm having the same problem my self.Mine does it when ever I get on the accelerator.It don't matter if I'm going 5mph or 55mph if I try to rev it to quick it will pop through the intake.

 

this was just occasionally and when I let off the accelerator. yours may be more timing if its when you are accelerating and all the time, or as people have said valve lash but if you havent chenged anything and it just started happening, it could be something as simple as the dist coming loose and getting way off or as drastic as a timing chain stretching to the point of slippage but then there would most likley be some real bad mechanical probs due to valves and pistons getting to know each other reall well

 

I had a similar problrm once and I found the popping was caused by the manifold water temp. sensor. There was an intermittent contact and the engine was not going into closed loop which was in turn sending the wrong timing signal to the dist. Only way to know for sure is with a scanner. I used an AutoXray and it worked fine. Good luck.

 

Well I guess I should have mentioned that it's a new motor.I had it professionally built.All new timing chain and gears.I believe the valve lash is ok.but you may have something there with the timing Monte-SS I check it again.I too have an Auto X-RAY.It says I'm going in to closed loop.So I don't think that's it but thanks for the ideas.I have a list of my mods in sig.I'm in the process of burning my own chips

 

looks like a pretty nice set up I just hope that the 5 spd holds up, I think I remember reading or hearing something about the 5 spds not holding together too well behing a 350 which was why they never came out from the factory that way untill the 6 spds came out.
Since its a new motor if you have any probs with it you should be able to take it back to whoever built it and they should have to check the basics once its running since your having problems, but that also depends on the builder. I had a rebuilt 350 where one of the rocker nuts came loose, that was the only prob I had with it till I tore it down a few years later to find a broken ring, there went my 383 block!

 

"I just hope that the 5 spd holds up, I think I remember reading or hearing something about the 5 spds not holding together too well behing a 350 which was why they never came out from the factory that way untill the 6 spds came out. "


yep T-5s are pretty weak, that is why they only came with 305.

now if the thing survives hard launches, the only other weak spot is 5th gear, it is very weak. it ataches to the case in a very thin place, there is a site somewhere that sell a new piece for it, kinda like changing a tail shaft. not too hard.

but it makes 5th strong enough to take a bigger v8, other wise 5th wont go out, you will just crack your trans housing from all the torque.

or just remeber to only race in 1-4 use 5th for easy saving gas driving.

4th is very strong and itis your drive gear anyways.


course a T-56/T-6 same thing would be great, but they cost like 1000 used and thats a deal most time they go 2000+

 

got the new gaskets in last night after I went to work, so I went and took the plenum off to get it ready before I went to work, pulled one runner off and DOH! I somehow managed to make 2 holes for the bolt on the bottom center of the top part of the runners, the gasket was still stuck to the runner and on one side there was a nice little gap about 1/16" and about /12-1" long! damn! oh well now that the gaskets are here as soon as I get out of class then its all going back together and I should be set!!! wooooooooohoooooooooooooooooooooooo!!!