Hey guy's got a question. I have a small block 422" 318 in my car. Car has always run high 6s until recently when I changed over to a set of Indy heads that Larry Smith ported. I went out with the new heads back in May and it run a 6.59 in the 1/8. with a 1.45 60' time. I still had a set of slightly modified 1 5/8 to 1 3/4 stepped TTI headers on it at the time. I figured bigger is better so I went to TTI big tube headers that were made for the W style heads. Car has gone slower the past two times I have been back out. Car feels like a pig out the gate with a best of 1.49 60' and a best of 6.67 at 102.5 in the 1/8th I was hoping the headers would have picked it up a little but it sure went the other way. Before I put my other headers back on can I get some advice from you guys ? Jetting ? timing and everything were the same. Thanks in advance for any opinions. But on a side note I did cut a 000 light yesterday. Can you say almost red ,, LOL

You might need more converter, you put bigger heads on that raised the torque curve most likely. Then you put bigger headers on doing the same thing. It might need to leave at more RPM.

I changed converters and rear gear at the same time, from 4500 to 4800 and from 4.56 to 4.10. The flash RPM went up almost 800rpm the 60ft dropped .08 to a best of 1.41. 416" W2 motor in a 3550lb A body. That 60ft was on a 6.63pass@101.3

Thanks for the advice on that . It makes sense but a converter is way out of the budget right now.

I bet the converter is on the tight side now. Torque peak is higher now w/ the larger heads and headers.

Thanks to the both of you for the advice. I was really hoping the car would pick up a little more with the bigger headers. Simple temp solution I guess is go back to the smaller tubes.. The car felt much better before the change..

What has the MPH done in all this ?

Actually fell off a little , about 1/2 MPH.

I just went from a big header to a small one on my junk. It took away some top end, but it will print 1/8th mile timecards now.

I really am suprised that my car fell of all the way across the board. MPH and ET went away. My car was doing 1.45 60 on a regular basis and was at 103.5 or so. Twice now the best it has run was 1.49 60 and 103 or 102 mph. They were a pia to put on too.

I dont think its a converter issue then. put the other headers back on

I don't know if this will help but my son says it will. I took the 950 HP carb off built by Jessie @ Biggs long ago and found 78 primary jets and 86 secondary. I replaced them with 80s front and 88s in the rear. Took the car for a street ride not hard and the car felt just as crisp. Any opinions on if bigger jets may help ?

Jetting should be done at the track to get the best results, some times the butt dyno will mislead you. I look at the 1/4 mile MPH for the best WOT jetting and tuning
I try to fatten up the carbs first until the MPH slows down and then jet it leaner until it slows down again and split the differences for the safest tune up

That what I plan to do when I get back to a test session. I figured I would start jetting it up a little right out the gate to see how it likes it. Hopefully it will show me some improvement

Don't be surprised if you can't jet it fat enough to slow the MPH down in the 1/4 mile, been there done that more than once. If you run into this you need more fuel volume, not more fuel pressure
The fuel system will only flow the maximum amount that the smallest restrictor will allow to flow through it
I've seen the fuel tank pick up be that restrictor as well also the needle and seats be that restrictor

What heads were on it before?

Which Indy heads did you use?

New intake manifold as well?

I had a set of open Chamber Eddie heads that had been worked on a lot by my local machinist. They did pretty good for what they were. I have a set of Indy 360-1s on it now ported by Larry Smith and yes the Indy single plane intake also.

Thanks for the advice , I am going to try and take the car back to a test session tomorrow night.

It would have been a fast night at Keystone if we were running tonight. My ears perked up when I heard our dew point was 38 on the 6pm news. I hat sure beats the sweaty balls dew point that we usually suffer through locally. Rain moving in so it will climb rapidly

Mine shaft air right there. I hope to see high 60s dew points tomorrow. Still Summer around here. LOL

Something like a std Victor or M1 intake on the old heads?

Those two top ends are going to have noticeably different power curves, especially down in the lower range........ along with how they affect how quickly the motor will rev when the throttle is opened all the way....... which will absolutely affect how the motor goes up against the converter.
And the bigger headers would just exacerbate that phenomenon.

In order to really exploit the bigger heads(to the point where the bigger headers start improving the ET) you’ll likely need to run a lot more cam and converter.

Heads and headers are two of those things where bigger isn’t always better........at least when it comes to footbrake drag cars.