Hey guys i just tried to fire up my new 383 stroker built by racerides.com, and it is backfiring through the intake after statring. I double checked the distributor isnt 180 degrees out, and the plug wires are fine.

It has a 570 lift solid roller cam. I didnt adjust the valves, but im wondering if racerides maybe didnt either. They told me they did. I'm hoping a intake valve is just too tight and not closing. It sounds like a bent valve :-(

Any ideas? would the distributor one tooth out cause this? I'll check the valves next time i get a chance.

Shane

p.s. carb is brand new holley 800 doulbe pump and distributor is accel HEI. Heads are Dart Iron Eagle 215 cc.

 

i just wanted to add it sounds like its only on one cylinder

 

Recheck your plug wire routing is correct. Though that is thru the exhaust right?

Make sure your choke is set correctly too.

 

Question A- was rotor pointing at wire #1 when installed?
B-whats base timing??
C-cam timing??
D-Why didn't you cold adjust?? bump the motor until the valve is closed and tighten until pushrod barely spins. Give another 1/2 turn approx. repeat through all 16. this could be a big problem. Your intake is opening and letting a charge in and then firing while the intake valve is still open. You'll know if the valve is bent because the retainer/ valve will sit lower than normal. ie-even with the rocker loose it still won't come up all the way. Or you could do a comp test. This will definitely confirm your worst nightmare. It did for me .

 

i will bet you my camaro that your distributor is off a tooth

 

If it's a solid cam, then he has to check the lash, don't try to adjust the valves that way, you could run into more problems then you think. Get a feeler gauge and check the lash.

It doesn't matter where the rotor's pointing, as long as you wire it where number one hits.

Also, if it's a Holley and you already backfired, check the power valve if you don't have a blow out protection, get one. If the power valve is blown from the backfire, it will continue to give you problems until you change it. Let me know what you find out.

 

Thats exactly what I just said.

didn't even notice he had a solid or that it was a roller.

 

lol @ these replies.

1.) i said in my post the wire routing is correct
2.) you dont set solid roller cams like that, you use a feeler guage. i have not set the valves becuase they were supposed to come set. i will check them asap, as i think this is my problem.
3.) holley double pumpers dont have power valves. those are used on vacuum secondaries.

As to the distributor being off, i guess that could be possible. The reason i doubt it though is because the motor runs "good" until it gets around to a certain cylinder, then it backfires through the intake, then keeps going fine until it gets back around. If the disitributor was off a tooth, i wouldnt expect it to run like that.

When i set it to TDC, the rotor was pointing at the #1 cylinder, and the rotor was lined up with the #1 plug wire

Thanks for your help guys!

Shane

 

I KNOW!! my mistake. Didn't even see the fact it was a solid roller. I always give instruc. on hydrolic flat tappets because its what the majority runs. Next time I'll try reading.

 

Are you sure???? I seem to remember my 650 holley mech secondary having a power valve.....

otherwise what would enrich the mixture when you moderately accelerate....

 

Double pumpers most definitely do use power valves. Here's the list of which ones use what PVs. You'll notice that all 4100 models use PVs.

http://www.holley.com/HiOctn/ProdLine/CarbList.pdf

Lash is critical on a solid cam. The "ballpark" methods that work perfectly fine on a hydraulic, are hopelessly inaccurate on a solid.

I do them one at a time. I start by finding a valve that's near fully open, doesn't really matter which one. Let's say I pop the VCs off and see that #1 intake is full open; at that instant, since the cylinder 4 cyls away in the firing order is exactly 180° "out of phase" with it, the #6 intake is exactly on its base circle. So with #1 intake exactly fully open I adjust the #6 intake. Then I turn the engine exactly 90° with a crank socket, now #8 intake is exactly full open, so #5 intake is on its base circle, so I adjust #5 intake. I go all the way around the motor that way. If the motor is cold I set the lash about 10% tight with iron heads, or about 10% loose with aluminum heads (different thermal expansion rates).

I usually use a dial indicator to find full open on a valve, for precision. I prefer a narrow feeler gauge. If I do it like this, I can build a solid-cam motor on the stand, glue the VCs down, drop it in, and have perfect idle and zero noise for 10k miles.