I just got my truck running after a head swap and header change and made it out to Milan on Sat. Listed below is the combo with before and after times.

Old combo
88 D100
10.5:1. 493
850 demon carb
Indy dual plane
346 heads with 2.14 in. 1.81 ex., mild bowl work and gasket match
1-3/4 headers
Comp xe294 hydraulic cam
Comp 1.5 roller rockers
Performer rpm fuel pump
-8an lines from cell to pump
3/8 lines from pump to carb
Manual valve body 727
Converter flashes to about 3000 rpm
4.10 8-3/4
295/65r15 drag radials

Best time 12.10 and 110mph @ about 3800lbs.
1.68 60ft

New combo is the same but with sidewinder heads with bowl work and gasket match by Marsh Performance, 2” primary headers, 3-1/2” collectors.

Best time 11.98 and 110mph @ about 3650-3700lbs. I will be putting the truck on scales tomorrow.
1.65 60ft

I thought the weight decrease alone would have put me into the 11’s and I thought I should have gained at least a little mph. The only thing I can think of is maybe the fuel filter doesn’t flow enough to keep up.

I also have a porter .600 lift 266 @ .50 solid flat tappet can to install also but I was trying to wait to finish my Dana 60 and get a new converter.

What do you guys think? Was I crazy to expect 11.60’s out of this combo?

If you can increase the jetting, fatten it up, enough to slow the MPH down in the 1/4 mile then you have enough fuel volume for your motor
If not, then you don't
Not enough fuel volume has been a large part of a lot of drag cars and other drag race vehicles not performing as expected with other changes to the vehicle
Mine included

What was the weather previously? Its been pretty brutal here this week. 300 flash stall is pretty tight.
Doug

I never thought about it like that. I am going to change the fuel filter before I take it out again, but I will definitely give that a try. Thank you.

The previous temp was probably about 70. It was about 80 degrees last Saturday.

It seems to me that I am losing about 100hp somewhere.

You can jet it a step at a time like Cab says until it slows then obviously take it back a notch. I think your mph didn't do anything because you didn't change the cam with the heads. Basically you just made the engine more efficient but a decent cam will really wake it up. When you change the cam then the converter your expectations will probably happen. Weight and brick shape are hard to overcome. Cool though!

Pretty much agree w/ everyone else...the weather likely had a lot to do w/ it. I'd bet it'd be at least a tenth quicker in the same weather you ran the 12.10 in previously.
The new cam along w/ a looser converter will def. wake it up.

Put a fuel pressure gauge on it to make sure you have enough fuel to feed that monster.

I wouldn’t be surprised if the lifters are giving up at whatever rpm 110mph is.

I’d schedule a few pulls on a local chassis dyno.

The 60’ is soft if you’re looking to get into that mid-11 zone.

That mechanical pump setup is not going to give you a ton of volume or pressure. That said, I think your cam, converter and gear are holding you back more than anything. 3800lbs with that .520 lift cam and 4.10 gear on a 30 inch tall tire aren't going to make a ton of steam in my opinion.

It will be going on the scales at work tonight. I will update later. Hopefully I can get out to the track in a week or two to verify I am getting enough fuel. If I am, do you guys think putting the new cam in before I get the converter will hurt performance at the track?

Nothing of a technical nature to add, but damn, I love that truck. That's bad ass.

That thing is super cool.

If you decide to go the chassis dyno route, Jake's has a pretty nice one + alot of experience to go with it.

Something else to think on.
Had your old heads been cut or surfaced? You have an aluminum head that if I remember right has a big chamber. Like 84 maybe? If you have added chamber and gone to aluminum which in theory costs you a little compression, you have gone backwards in compression.

The new cam and the 3000 stall won’t play very well together.

In fact, I wouldn’t consider the current 250@.050 hyd cam and the 3000 converter to be a very good match.

I’m sure that’s a lot(most?) of why the 60’ is a bit soft.

I just got the Truck off of the scales. 3340lbs without me and 3600 at race weight. It was actually a little bit lighter than I expected. I also got everything to upgrade the fuel system from the pump to the carb. Hopefully I can do some testing and tuning here shortly. I really need to get the new converter so I can install the cam😁

A lightweight!

I think the weather had to contribute a decent amount, and will agree with the others that the converter is too tight.

I have a similar mild 493 in my Plymouth, the 9.5" converter flashes to ~4400. Even the old off the shelf 10" "3000 stall" flashed to ~4k. I normally run 3.55's and a 28" tire and weigh 3700 lb at the line.

It is pretty light for an all steel 1/2 ton truck. Lol. What is your combo and what does it run? If you don’t mind me asking.

Just a little tidbit...... and you may already be aware of this.......

But the fuel level setting on those demons isn’t like the old holleys(bottom of the hole).
I usually run those with the fuel sitting about 2/3 up the sight glass, set with the engine running.