Ok, Let me know what you guys think.

Would you build on this motor. I am thinking of adding a cam and maybe working the heads.

Its a carbed 92 L98.

#1-170
#3-170
#5-165
#7-170

other bank

#2-165
#4-170
#6-165
#8-165

what do you guys think. Was this a good test or was it on the low side. Is the difference in cylinders ok?

thanks.

 

Try waiting for an answer in your other thread.
https://www.thirdgen.org/techbb2/sho...hreadid=192629

 

looks reasonable to me.

how many miles are on this engine?

 

This is the one with 4 # 6 not running?

Those numbers look fine.

What did the plugs look like?

 

Those look like good numbers, and respectable balance across the cylinders.

 

Seems healthy..

better than my 305's (R.I.P ) 65-90 psi range across all 7 running cylinders.

 

lol where can i buy this magical V7 you speak of....now wouldnt that be a cool toy to show off!!!

 

In my cousin's garage, actually, lol

 

I beleive around 60k to 65k. Not positve.

 

Yeah the same.

Well all the plugs had black soot on them. #4 had a little white on the tip. #6 The tip of the plug was all white on the flat surface. and #8 seemed to have a small portion of white around the base. #6 was really noticable.

I pulled the valve cover on that side and cranked the motor over. I inspected the valvetrain and everything looked ok. Is it possible I have a cracked head or maybe head gasket?

What caused the plugs to be like that. The other side just had black soot?

 

Because some guys might be interested in the results and the subject of the other post says nothing about a compression test.

Trust me, I have been around the site for a while. The post subject can fool you sometimes.

 

The two most common reasons for black plugs are excess fuel (rich) and oil burning. If the plugs are covered with dry soot it probably isn't oil burning, so it would seem you need to get the fuel mixture in control.

 

I have the fuel pressure at 6psi and the carb is a holley 750 vs with 72 jets in the front. I am running AC R45TS plugs gaped at
45. Should I regap the plugs at 35? Could this be the problem?

The carb is stock except for the choke flap removed and has the stock metering plate in the rear. Oh yeah, it has a different spring for the secondaries.

It seems to backfire threw the carb when I get on the throttle hard.

 

Equals "very lean secondaries". It's possible, though not as likely, that you have 2 wiped exhaust lobes; obviously if an exhaust valve doesn't open enough to allow complete cyl evacuation, then when the intake valve opens, there will still be presure and maybe even fire in the cyl, which will light off the incoming intake charge, i.e. backfire. Needless to say, following the rule of logic, a situation that requires 2 discrete defects to produce any given symptoms is far less likely than a situation where a single failure can account for it; although, 2 identical failures in a system composed of identical components, caused by the same external influence or whatever, is perhaps reasonable (2 wiped lobes from incorrect valve spring setup, etc.)

If you put a yellow spring or some such in it your secondary diaphragm, take it out, and put in a brown or even a black one, and see if it runs better. Or even, try another carb; borrow one from somebody or something.

If you're blackening plugs and backfiring under load, then your primaries are too rich, and your secondaries are too lean. Try lowering the primary jets 3 numbers at a time until the car begins to surge at cruise, then go back up 2 steps; and put a 8.5 power valve in the primaries, as that should be about right for the cam you have.

6 psi is borderline too much fuel pressure. 4-5 is plenty. With a carb, ½ psi would be enough, as long as the pump can keep the bowls full at that pressure. Raising the fuel pressure does not necesarily make the car run any better, unlike FI.

 

I am going to turn the fuel psi down and clean the plugs and regap them to 35 and try it then.

I dont know which spring is in it. I bought it used, but it was running on the car it cam off of fine.( a 355) I am thinking of getting a adjustable secondary diaphram also.

So a 8.5 power valve is what I should use with the stock cam?

 

You've got a stock cam in it?

I thought it was a XE268 for some reason.

Oh well, with a stock L98 cam, use a 10.5 PV.

 

Yeah, the motor is stock except for , intake, carb, dist and headers. I have more plans for it later on. For now I just want the damn thing to run right so I can get to the track.

 

I though I would address the this problem. It looks like the carb had a 31 squirter in it and 72 jets in the front.

I changed to a 25 squirter and 70 jets. I then unhooked the back butterflys and wire them shut. I know it running on a 2 bbl now, but it seems to work.

Before it would puff black smoke out the ehaust. Now it looks fine, the carb is not backfiring, and the plugs cleaned right up. It still has a slight mis though.

Looks like I will be getting a 4150 conversion kit and a adjustable seconday diaphram.

Oh yeah, the motor seems stronger than the TPI even with just the 2 bbl working.