89cobra5.0

Ok, so you guys may remember me as the guy who has the 347 with e7 heads. Anyways whats on my car I believe is in my sig, but my car is having issues now. There is pinging sometimes (detonation), and just last night I heard what sounded like a machine gun of pinging as I gave it half throttle onto the freeway (or can also be described as like a metallic machine gun).. My tuner at Fresno Performance said that my e7 heads are causing an 11:1 compression ratio, which is causing issues because of basically bottle necked airflow from my heads. He recommends getting a nice set of Trick flow heads, but realistically I dont know if I could save that much before, say the end of the year, and I have a feeling my car isnt going to last that long, it hurts me to run it like this. It would be around $1000 for the heads if I can find them for that and $500 for labor installing them. My problem is that I only have like $200 saved up right now, and within the next two months I would like to have new heads (school full time, work part-time but the hours blow and its only $8.25/hr, soon to be 8.50 lol.)

Anyways, Ive been reading flow charts, forums, reviews, etc of the gt40 and gt40p heads. I am under the impression the p heads flow a bit better than the regular 40's (flow data), but require different headers in order to work, and thats it. I was looking at some pro comp aluminum cylinder heads, and well, the flow chart shows they are better, but not really by much. (TF outflowed pro comps by like 30 on the intake side. so theyd be about 50 over the 40/40p). sorry Im not too knowledgable about this area, only that more airflow is better. Anyways that was at .500 lift and I have a .498 lift cam.

I know I talk a lot, but my question is this. Should I get the 40's, 40p's which require new headers, or the pro comp aluminum heads($700 complete/shipped)? I know they arent the best out there, but I simply cannot afford $1000+ heads right now and my car is getting worse and worse every day I drive it. It doesnt sound like the car is running on all cylinders as it bucks, the idle is not lopey anymore, and its pinging like hell. could it possibly be a broken spring on one of the heads? Sorry for such a long post, Im just extremely frustrated and need a fix asap. Right now I am leaning towards the Pro Comp heads.. Thanks in advance for any input.

NotchAbove

Wow, where to start here. I'm sure others will say this is what you get for putting stock E7's on a 347. 11:1 compression is pretty high for a street car, but in your sig it says you have a tune. So...something doesn't add up. (You should not be running lean (pinging) with a tune.) Obviously you should have just kept the 302 and put a head/cam/intake on that and you would have done better or the same with HP levels.

You really need a set of TFS or AFR's, and an E cam is another choke on that engine. Sorry to not have anything positive to say, but its decent advice and I'm sure the others will say the same thing as well.

I do not know about the ProComps but they are Chinese knock offs, you get what you pay for.

NotchAbove

Also you are probably pushing those valve springs to their limit, they max out at .500 lift, and your running .498 so you could have valve float being they are 20 year old heads.

67mustang302

You need bigger heads and a cam.

89cobra5.0

There wasnt any way I could keep the 302.. it blew after 265,000 miles.. I broke the crankshaft, so I had to get a new engine (block, internals etc.) so why not start off with the cubic inches to allow for growth? I had whatever could be used off the broken 302, put on to a different new/used and treated 302 block with forged 347 internals. Money was/is a big issue with this build (I just turned 20). Most of the time when its pinging is during like 1/2-3/4 throttle, but my tuner said at wot there is a totally different timing map, so wot is different than partial.. Anyways thats what is confusing me. I took the car to him about a week or two ago and he was playing with it a little (making small adjustments on the tune) to try to get it to idle better. It currently also has starting issues sometimes and surging idle, which seems to happen about every time when I put the clutch in in 1st at a stop. But it has its hits and misses. He said the comp ratio is just under 11:1 and it has a perfect air/fuel ratio on my dyno sheet.. Thats been a couple of months now though and the performance got progressively worse. I'm really starting to think it is something with the springs or the spark.

Woah, come to think of it, my dad and I had the car idling in the driveway and he was checking the wires and before he got one off I saw that two ignition wires were touching on the distributor and actually saw a spark jump from one to another and then touch the intake manifold. Damn, do you think it could be a simple fix like my wires being burnt from that jump so a cylinder isnt getting the right a/f mix? I can wait for some good heads if it would run without this problem, if it just needs new sparkplugs/ignition wires etc.. And I know the e303 sucks, I need to be CA emission legal..

89cobra5.0

I just saw on the brothersperfomance site, they have a set of ford racing aluminum turbo swirl heads that flow 240 @ .550 for $625 and free shipping I think. Thats a lot better than the pro comps.. Im gonna try to shoot for these heads asap..

I just know once a get a set of aluminum heads a lot of problems I shouldn't be having anyways will go away. I know it'll be a totally different car with even those heads... Plus those springs wont mind my little .498 lift cam, and maybe ill look into 1.7 rockers for about .528 lift.

89cobra5.0

Then again Im looking at a comparison of different cylinder head flow charts all in one graph and the TFS are awesome... I think im gonna have a meltdown! =[ ugh

Do you guys think it could be a fix like new springs/ignition wires? If so then I could replace those and would definitely just save for some TFS.

Joel5.0

11.1 CR with E7 heads?...... how was it figured out? Even though you found out that E7 heads on a 347 are a mismatch, I don't think they are the cause for the pinging problem you have to correct.

mjr46

^^^^^^^^^I was thinking the same thing as I read this thread!!!......I have 58cc 185's vs 64 cc?? e7's.....and my CR is 10.5 to 1, the tuner is incorrect if you have the typical flat top 347 pistons.....anyway I'd check the base timing and total advance after that I'd make sure the egr system is functional, a simple koer should run the test, make sure the system/engine isn't running lean and that the cooling system is functioning properly and you are running premium fuel.....anything that'll elevate cumbustion chamber temps that will flacilitate detonation needs to be looked at

PJC Racing

^^^+1, doesn't sound like it was "tuned" very well.