390 Backfires
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
The leaking exhaust valve is next to the exhaust crossover. I have the Performer RPM intake manifold, so I blocked off the crossovers. You are also right about the ports; although, they seemed to seal well.
Are these heads worth the work that you mentioned? I don't see any visible cracks in the combustion chambers. Thanks Orich.
Are these heads worth the work that you mentioned? I don't see any visible cracks in the combustion chambers. Thanks Orich.
Ha those the block off gaskets that burn out in a short time as, I found out on my engine.
Orich
Junior User
Joined: Oct 2011
Posts: 57
Likes: 0
I had this exact issue on my 390. I tested the crap out of everything and it turned out
to be the vacuum advance was "pulling" advance too much. Everyone here can attest
that each FE has it's own sweet spot for timing. My 390 is built somewhat "hot"
so I disconnected vacuum advance and it runs awesome without it. So...I just run
it with no advance.
to be the vacuum advance was "pulling" advance too much. Everyone here can attest
that each FE has it's own sweet spot for timing. My 390 is built somewhat "hot"
so I disconnected vacuum advance and it runs awesome without it. So...I just run
it with no advance.
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Laughing Gas
Joined: Jul 2010
Posts: 1,128
Likes: 124
From: Chico, Ca.
I appreciate the input. The heads are definitely leakers. I ordered a set of completely rebuilt D2 heads with larger valves on ebay. Is it okay to reuse the old head bolts? They look to be in great shape.
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
A stock rebuilt you can get by re-using the bolts but yeah don't know what the engine has been through. 40+ yrs a lot can happen to an engine's bolts by some people not using the correct tools like a Torque wrench but just doing it by it's feel.
Saw many guys over the yrs putting an engine back together with using a torque wrench then snap a bolt here & their. And would end up having a leak where they broke the bolt at. The ol backyard shade tree mechanics that can do every thing but doing it right!
Orich
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
The manual say to tighten the heads in 3 steps until your at 90lbs.
I can't remember off the top of my head what each step lbs but think it was 50 lbs for the first tightening. But It's been a few yrs since putting on heads so check your manual for each poundage pull.
Orich
I can't remember off the top of my head what each step lbs but think it was 50 lbs for the first tightening. But It's been a few yrs since putting on heads so check your manual for each poundage pull.
Orich
Hotshot
Joined: Jul 2005
Posts: 13,834
Likes: 26
From: Middle Tn.
The manual say to tighten the heads in 3 steps until your at 90lbs.
I can't remember off the top of my head what each step lbs but think it was 50 lbs for the first tightening. But It's been a few yrs since putting on heads so check your manual for each poundage pull.
Orich
I can't remember off the top of my head what each step lbs but think it was 50 lbs for the first tightening. But It's been a few yrs since putting on heads so check your manual for each poundage pull.
Orich
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Laughing Gas
Joined: Jul 2010
Posts: 1,128
Likes: 124
From: Chico, Ca.
The new heads will arrive next week, so I am cleaning, cleaning, cleaning..... I have been wiping down the block with acetone, but at this rate it will never get clean. Can I be more aggressive? The top of the pistons have some carbon deposits that start to come clean with the acetone. I have read about using brake cleaner, 80 grit sandpaper on a long sander, grease in the bores to collect the dust, etc. What is the best way? Thanks.
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Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
As all long as you don't scratch the top of the pistons. I've use brass wire wheel on a hand drill.
I have used diesel on stuck build up of carbon help loosen it. Sometime you can use a good putty knife work off the built up of it.
Acetone is really good for wiping off the surface before applying gaskets it dry's to fast.
Orich
I have used diesel on stuck build up of carbon help loosen it. Sometime you can use a good putty knife work off the built up of it.
Acetone is really good for wiping off the surface before applying gaskets it dry's to fast.
Orich
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Laughing Gas
Joined: Jul 2010
Posts: 1,128
Likes: 124
From: Chico, Ca.
Got the heads installed and painted black (they came blue). Started taking a closer look at the lifters. None of the lifters are dished, but they are all flat. They should be convex? Can I assume that the cam is similarly worn? Thanks.
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Laughing Gas
Joined: Jul 2010
Posts: 1,128
Likes: 124
From: Chico, Ca.
Ok. New heads are installed, as well as a new cam and lifters. I have a pushrod checker, and a 12" digital caliper. I have the engine at TDC, which should allow me to check 1, 3, 7, 8 intake, and 1, 4, 5, 8 exhaust. #4 & 5 exhaust, and #7 & 8 intake lifters are not all the way down in the bores. Do I just rotate each lifter until it bottoms out, then check for pushrod length, or am I missing something? Timing chain is installed straight up. Thanks.
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