Issues with new motor

[sukkoi19]

Just put a new motor in a 90 LX. CHP 306 with GT40X heads, "F" cam, Cobra intake, blah blah blah.

Anyway the damn thing wont run right. Ive backed the timing off to 0, but still I get detonation at the slightest throttle input. Cranked fuel pressure to no avail, gone over the distributor install like 20 times. I just can figure out how to get this motor running right. Its got all new pushrods and lifters, 1.6 rockers, everythings lines up on the valve train so I dont think thats it.

It surges like crazy as well. Ive tried advancing the timing as well, but for some odd reason the starter can barely crank the motor at anything above 14 deg.

My only thought is that CHP gave us the wrong piston as these one have super domes on them, and I think the heads are 58cc. Although I had more than a 100,000 valve to piston clearance so I really dont think thats the issue.

Any help would be greatly appreciated, and by the way the 02s are new and the computers on the factory tune.

 

[venom88]

Try to move all of the plug wires around one plug on the cap.

 

[65ShelbyClone]

Try to move all of the plug wires around one plug on the cap.

I think if that was the problem, it wouldnt run at all. He wouldnt be able to set the timing anywhere near where it need to be.

Put the engine on TDC, pull the cap off to see where the rotor is pointing and rotate the distributor so the rotor is under the #1 terminal. Then put the #3 wire on the one next to that and then the # 7 and so on in order of rotation of the distributor. Whole firing order is 1 3 7 2 6 5 4 8.

The other possibility is that CHP did in fact give you domed pistons. Just because you have 0.100" of P-V clearance doesnt mean it didnt happen. High performance slugs are usually cut for big valves and lift.

 

[jrichker]

Have you considered the fact that the blanacer may have spun and is not lined up with TDC? See http://forums.stangnet.com/showthread.php?t=479142&highlight=stop for an excellent description by Michael Yount on finding TDC, even if your balancer is off.

If the balancer is good, try 2 gallons of Toluene or Xylexe added to 5-8 gallons of pump gas. The result will be 100 octane +gas that should eliminate any pinging that is a result of a high compression ratio. Toluene or Xylexe is available at Home Depot, Lowes or any good paint store for $6-S10 a gallon. Do a search on jrichker and Toluene or Xylexe and you will find an entire tech note on what it is and how well it works.

 

[bln92cpe]

MY CHP 306 runs great, and its not even tuned yet.

 

[sukkoi19]

TDC is not the issue, Ive set the timing from TDC like ten times now. Rotor is pointing at numero uno, so thats not the issue. I think Im just going to toss in the race fuel and see if that helps. You guys should see these domes, they rise more than a 1/2 inch off the deck.

Thanks for the replies.

 

[chevyeater]

May be too much compression for pump gas. use the race gas and see what happens. could also be vacumn leak causing lean condition evident by the surging.

 

[Uber5.0]

I know that it's been ages since this thread was last posted, but I'm a friend of sukkoi's and just joined this month. FYI, it ended up that the race fuel helped. He runs a mix of 93/110 oct at a 5:4 ratio or so to stop detonation. Even with timing set a 0 degress, it detonates at acceleration with 93 straight. Wish I would have gotten some pics of those pistons before he put them in.