Jetting changes after changing heads
02-22-2018, 07:02 AM
#1
Jetting changes after changing heads This probably sounds like a stupid question but I did search and can't find what I'm looking for
I have a 5.3 that I built that was dynoed at Westech
It is dialed in and runs perfectly
However it's time for me to buy some better heads and I don't want to spend the money to do a dyno again
I am horrible at jetting. I can never tell what it is the engine wants
My question is what direction will the tuning need to go?
I am going from stock 243's to probably the tsp/PRC stage 2.5 5.3 heads.
They should flow quite a bit more.
My common sense tells me I will need bigger jets. But in the slight research I did, I found the opposite, people saying they had to go smaller on jets with better flowing heads?
Thanks
I have a 5.3 that I built that was dynoed at Westech
It is dialed in and runs perfectly
However it's time for me to buy some better heads and I don't want to spend the money to do a dyno again
I am horrible at jetting. I can never tell what it is the engine wants
My question is what direction will the tuning need to go?
I am going from stock 243's to probably the tsp/PRC stage 2.5 5.3 heads.
They should flow quite a bit more.
My common sense tells me I will need bigger jets. But in the slight research I did, I found the opposite, people saying they had to go smaller on jets with better flowing heads?
Thanks
02-22-2018, 04:25 PM
#2
10 Second Club
Buy and install an AFR meter 
SO much easier than reading plugs
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OR
https://www.summitracing.com/search/...oview=SKU&ar=1
SO much easier than reading plugs
https://www.summitracing.com/search/...oview=SKU&ar=1
OR
https://www.summitracing.com/search/...oview=SKU&ar=1
Last edited by Doug G; 02-22-2018 at 04:35 PM.
02-22-2018, 04:41 PM
#3
+1
You're dropping a good bit of money on heads and I would hope matching cam. Think of a wideband as an investment/tool tax. You can even tune your lawn mower with it.
As for jets I would think it will be almost impossible to predict. Just have to try it and find out.
You're dropping a good bit of money on heads and I would hope matching cam. Think of a wideband as an investment/tool tax. You can even tune your lawn mower with it.
As for jets I would think it will be almost impossible to predict. Just have to try it and find out.
02-23-2018, 05:17 AM
#5
Buy this
I don't have one and from what I have read the reading can get corrupted by outside air. One of the comments said to add a foot or two of silicon hose to get a sample farther upstream
You know if you increase the air flow enough you may need to switch to a larger carb.
I don't have one and from what I have read the reading can get corrupted by outside air. One of the comments said to add a foot or two of silicon hose to get a sample farther upstream
You know if you increase the air flow enough you may need to switch to a larger carb.
02-23-2018, 06:14 AM
#6
Buy this https://www.amazon.com/Innovate-Moto.../dp/B000CO9MF8
I don't have one and from what I have read the reading can get corrupted by outside air. One of the comments said to add a foot or two of silicon hose to get a sample farther upstream
You know if you increase the air flow enough you may need to switch to a larger carb.
I don't have one and from what I have read the reading can get corrupted by outside air. One of the comments said to add a foot or two of silicon hose to get a sample farther upstream
You know if you increase the air flow enough you may need to switch to a larger carb.