The engine came out of my '90 Mustang convertible. I had those heads on there for just a couple of weeks before the vert decided to take her own life by T-boning a tree. I took the motor out and swapped it, and all the electronics, into the Maverick. The wiring was a B*tch. The chamber and valves in #5 are, BY FAR, cleaner than any other on the engine - like it never fired once after I put the engine in the Maverick. Interesting theory, but #5 is the only NON-pitted valve in the engine. See above.
Oh, OK I thought #5 had the pitting...must have had one too many beers last night. Let us know what the problem was when and if you find out.
So, you think you have been missing on cylinder 5 all this time? If so, be sure to add another 1/8 of your dyno results to your total horsepower
Looks to me like that valve got beat up by a ballpoint pin. * The theory of the leaking valve guides makes sense - I just wouldn't have thought that this would happen in relatively new heads from AFR's factory. Never know though. I had my brand new heads on my 347 gone thru right out of the box. Not that they were bad.....but the engine builder did find some issues he wanted to address. Definitely not a bolt-on and go item.
Scott, I thought the same thing. But, it would be 1/7th more, right? (1 / 7)*350hp = 50 more ponies - 'theoretically' totalling 400 rwhp which wouldn't surprise me. Good info Craig (especially the ball-point pen theory). --------- I dropped the heads off at a Performance Machine shop to resurface the heads, lap the valves, and shim the springs to get more seat pressure. The engine builder is going to call me back to tell me what the max cam lift is that I can use with these springs. Of note / their opinions 1) One guy there at the shop, who appeared to be in-the-know, said that the pitting of the aluminum head itself could be due to insufficient grounding. Hmmm... I'll add a big ground strap to each head (I only had one small one going from the firewall to one head and another going from the 'frame' to the block). 2) Pitting of the valves do appear to be from detonation. 3) CR is 11.4:1 not 11.2:1 (what a few tenths amongst friends). Up the octane to help prevent detonation.
I knew someone would get technical about that...but the simple layman's thinking would be 1/8 (8 cyl engine). I originally put 1/7 then thought few would catch what the 7 was for...
hrmmmm glad I have a 4guage ground strap from the battery to the block.. then the rest of the cars grounded to the engine still waiting to see what the shortblock looks like.
Edelbrock Performer Rpm Heads. 1100 bucks(new from summit) Machine work to correct Edelbrocks "Supposed" bolt on heads 700 dollars (seats didn't seal against a vacuum test but pressure checked fine) Fine shot used for bead blasting coming out of cooling passages and the drain back area was 3 drilled holes with debris with cotton fuzz stuck to them..dingle berries of aluminum hanging from the drilled holes.. guides seemed to be fine .. Never assume your heads are bolt on.. NEVER NEVER NEVER!!!
Just curious,by the look of the top of the pistons,it appears to me you are running pump gas in it [race fuel usually burns alot cleaner] isn't your compression a little high for pump gas? Please correct me if i'm wrong. Also if #5 wasn't firing it must be an injector prob or your oil would be really gas washed if there was no spark to burn it off.Just a thought. Derek.
Yes, we assume the injector is not working on 5. I'm going to have all the injectors bench tested and flowed before going back together. I'll also check the pulse in the wiring harning. And, yes, the compression is too much for pump gas (93 octane). As I understood it, it was border line at 11.2:1. Now that I've learned that the CR is probably 11.4:1, all the more reason to use racing fuel only. NOW they tell me! Live and learn.
www.edyno.com A good site to tell you the static compression, other info rod ratio, etc. Gives you guideline for gas octane. Pretty much comp over 9.5 I would not run pump gas. Too many variables and $$ invested! Highly arguable point here, you got to really know your engine and cam! I think detonation with pic shown. Does your EFI have a knock sensor? I'm old school and have got up to those years yet. Heck, I just found out last week they make radial tires!
what cylinder is that in relation to the blown head gasket? i have seen that before, when there is a blown head gasket, water is introduced and witht he combustion, water will corrode metal under heat and pressure. that is why there are pitting.. if the head gasket was not blown on that cylinder, then i would say that the valves on that cylinder are shot, allowing oil and stuff into the combustion chamber. call up AFR and tell them what happened. maybe they will warranty it if it is determined that the valves guides are to blame. since the heads are so new
Did these valves come in the AFR heads? I wonder what brand they are? My guess is the detonation opened up the pit, but the "hot spot" probably centered around a trash inclusions that was in the drawn stainless rod the valves were made from. These are the same inclusions that valve spring makers try to eliminate as the usually become the point of a broken spring. Higher quality steel = less microscopic crap in it. Just because you cant see it, doesn't mean it's not there. Valves are probably OK for most applications until you push the compression ratio. Cleaver
