thumper/tmoss combo at track=not happy

blksn955.o

Founding Member
Mar 15, 2002
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st.louis mo 314
well since the Thread about the Dyno=not happy got lost in the great SN crash of 05 here is a new starter.

***back story***

went to the dyno and pulled like 161hp out of a DSS pro bullit shorblock, Thumper ported gt40 heads, Tmoss ported exploder gt40 intake, TFS1 cam. Ran rich @ 11.9 and got the A/F to go were I wanted it to with the tweecer to 13.1 or .2. Only gained 1hp from leaning it out. Mind you I pulled 230ish rwhp with box stock gt40 heads, TFS1 cam, Tmoss ported stock lower and only 7cyl. as I had a 30% drop in #4 or 3.

I shimmed the valvetrain as both the heads and block are milled, and I am not floating the valves anymore, when I shimmed the rockers the lifters were makeing all kinds of noises from being compressed too much. I need to re-do the measureing when I put on the 1.7rr but I need to get the valve stem caps to cleat the cobra rockers and I will prob. need to re-measure at that point.

I found a little gain in power, but did not pick up the gain as to the power I am down on. I started to look at plugs and stuff at this point to investigate further. I found the plugs in 6 & 7 were looking realy odd compared to the others, I thought they may be fouled as the #6 plug boot was burnt threw from the headers. I replaced the plug wires with FMS 9mm ones, and two new plugs for 6 & 7. Drove around and it felt alittle better than before.
******info from lost thread/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

****new info******
Last Fri. at Gatway Int. Raceway (for you WFC fans I live about 20min. away from there) as our local mustang site was running a 5.0 v 4.6 shootout. Made 1st pass at 14.5 @ 98mph, 2nd pass was 15.00 @ 95mph, and finaly a 16.9 @ 60mph I had very, very loud backfires at 4,000rpms. I parked the car and called it an evening.

Drive home and Sat. morn. I pull the plugs on 6 & 7, the plugs look like I just pulled them out of the box, mind you again this is after about 35-40min. round trip and 3 1/4 passes. I mean no signs of wear or fuel at all, the metal looks clean and the white parts look as white as can be. I hook my ind. timing light to the plug wires on 6 & 7 last night and there is spark going threw the wires and getting to the plugs, I then pulled off plug wire 6 and then 7 and then both with no change in idle tone, quality, rpms at all. I am preaty sure I have
a) a bad inj. on 6 & 7
b) some kind of clog in the fuel rail by 6 & 7
c) some kind of elec. line conn. issue or break in the harness

Anyway, taking into account that I went 14.5 @ 98mph with a friggan 6cyl V8 realy has me wanting to get things sorted out to see what this combo will do.

sorry for the long post.
 
I had a problem with my #5 plug going bad after a couple of miles and I though it was the ring but after running some fuel system flesh with a fresh tank of gas the problem finnally went away the clog i guess keep the injector open and failed out the plug but you can take the injectors to get clean and an engine shop
 
Well if you pulled 161 with that engine then there's something definately wrong and I wouldn't drive it much till you get it sorted out. You should probably be making over 260 rwhp with those mods. Check the distributor, do a compression check, make sure the timing is set right. Also I read some guy had a problem with backfiring at high rpms and it was a bad diverter valve.
 
Hey bud, You should be making atleast 270rwhp.
I made 264 rwhp and 308rwtq w/ my bone stock gt-40 irons, cobra intake and cobra cam.
Id say you should be in the 270-280 range and 310-330 range for the tq
Good luck on getting this figured out. BTW, did you check your distributor and make sure you didnt put it back in the wrong way.
 
FWIW, The dyno day was about 1-1.5 months ago and I did alot of wrenchin to get some bugs worked out, such as new plug wires, rocker shims to help the valve float issue I had, pulled the dizzy a few times to make sure the thing was in correct, 2 new plugs. The car runs alot better than it did when I was on the dyno but is not were it should be, and 2cyl. is a very big power robber I am sure.

Just need some free time to mess with the wires, I have a major field paper due the 10th of May, a soc. psyc. paper due the 28th of April, finals the 2nd week of May, some college exit exam, Grad. the 14th of May, and get married the 14th of May. Plus we just bought a starter home last month and have been messing with unpacking/getting used to making a house payment. :fuss: I think I will change my name to Mr. Stress.
 
i wonder if you accidently switched the two injector harness' on those two cylinders, it wouldn't be pulsing fuel at the right time therefore it wouldn't burn it right?

either way it has to be something in the injectors or something, If you want to try a different injector i have some spares or a complete set......


jason
 
I havent had any time to mess with it yet any further, I have a paper due Mon. and should have time mon. or tues. night. I am going to move the inj. and plugs to a diff. two cyl. and also get those light up injector tester deals (along with checking out the connection of the inj. plugs). to see if I am even getting power to the inj.

If I am not getting power I am going to have to trace the wires to the break/short/whatever it ends up being.

If its a bad pair of inj. then I will get them sonic cleaned and flow ballanced.

If its fuel rail blockage issue then I guess I need to get something to clean it out.
 
I have a few "angles" I may "know" someone that has done it for free before as well as from what I remember its like 90-100$ for the cleaning/ball. and new FMS inj. are like $220ish.

That and I have heard of some preaty nasty inj. working great after the work has been done.
 
mytight95 said:
i wonder if you accidently switched the two injector harness' on those two cylinders, it wouldn't be pulsing fuel at the right time therefore it wouldn't burn it right?


jason

That is what it sounds like. The backfires you heard were probably the gas finally igniting in the headers. Either that or your timing is off.