Jump to content

Pop-Backfire when cold


snomobeelr

Recommended Posts

Ive been driving and she's been fine since May. until Last weekend. Starts fine, idles fine. Revs fine in Park.  When I drive and she is not fully up to tempature she is popping out the exhaust. Its not constant just every 30 sec to a minute  until she warms up then, she is fine???   Inital Timing is 18 , full advanced 36-38 . New plugs. Its like she is loaded up until she warms up .  No changes were made. Ill have to recheck the timing I guess and start there. Don't thinks its bad gas or would happen all the time ? Right ? Manual Fuel pump was running at 7 lbs. 

 

 

DUI  HEI Distributor
Carburator:    850 cfm
Engine Cubic Inches:    468
Compression Ratio:      10.1
Intake Manifold Brand:  Edlbrock AIR GAP RPM
American Racing Headers  1 7/8"
3 inch Exhaust
....................................................................
Cylinder Head Type:     Brodix race rite oval port
Intake Valve Diameter:    2.250 in.
Exhaust Valve Diameter: 1.880 in
...................................................................
Type of Camshaft:       Hyrdaulic Roller Lifters
Camshaft - Intake Duration @.050:       232
Camshaft - Exhaust Duration @.050:      244
Camshaft - Intake Lift at Valve:        595
Camshaft - Exhaust Lift at Valve:       581
Lobe Separation:        107
Link to comment
Share on other sites

  • I did a compression test and also checked for valve guide wear on the out of variance cylinders.  My engine was reacting similar and that was the problem. When she warmed up, and things expanded, she ran much better….Seems that the nut bag who did my engine took a few shortcuts on my heads and didn't replace my valve guides. He didn't set the valve geometry correctly either. This is especially important if you're using a roller cam and roller rockers. The engine was slowly beating itself to death. Luckily I caught it early and was able to redo the heads and set it up properly. 

Hope yours isn't as serious. 

Ed C.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...