Heads

[KitS]

All else the same, change only the heads, what would make more low end (<4K rpm) torque? Stock heads, big valve heads or fully ported big valve heads.

KitS

[modok]

In most cases larger valves or larger ports will make less low end. There are some exceptions.

[KitS]

What kind of exceptions?

[jpaull]

It would help if you posted some more details. What is the CC and Cam?

If you had a large cc engine, with mild cam, and the heads dont flow enough air, using stock heads would restrict the airflow enough that you lose both torque and horsepower.
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[email protected] MPH 1/4 Mile & 8.1 @ 83.7MPH in 1/8 Mile with Mild Type 1 VW Mag Case 2234cc commuter engine in stock weight bug w/only .491 total lift(CB2292 Cam), 42x37 heads, 48idf's, Street tires, Belt on, Mufflers, Pump gas, video of the run here: https://youtu.be/M3SPqMOKAOg

Transmission by MCMScott:
Rhino case, Klinkenberg 4.12, Superdiff, 002 mainshaft with 091 first idler. Weddle 1.48 Third & 1.14 Fourth.

[Dusty1]

[Alexander_Monday]

Re lumpy idle:

This is the way it was explained to me decades ago by Doug Berg when I asked for my first cam recommendation for a VW. He suggested an FK87 for the combination I was building and I said won't that idle at 1300 to 1500 due to the overlap. He laughed and asked if I was a V8 guy and I said yes. This is the gist of what he said to me:

Reversion diluting the intake with exhaust is why a high rpm cam will make an engine idle choppy. Reversion is usually caused by the amount of overlap the cam has and how efficient the scavenging of the exhaust system is. As rpm rises scavenging increases and reversion has less time to dilute the intake. With the runners sharing a plenum more reversion will be pulled by another cylinder because it is on the intake stroke which exasperates the effect. With the dual carbs you are going to run with each cylinder having its own barrel it should idle below 1000.

Lo and behold it idled nicely at 900 rpm, when I know from my V8 racing days a V8 with a common plenum manifold and FK87 specs would have never idled that well.
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Danth’s or Parker’s Law:
“If you have to insist that you've won an internet argument, you've probably lost badly.”

Alexander_Monday->What were the rings gapped at?
bedlamite->Almost enough.

[KitS]

The engine in question is a 2020CC with a W110 cam. Used for off road, so less than 4K most of the time.

KitS

[Brian_e]

Panchito's with the bowls blended will be about the perfect heads for what you are doing.

Anything much bigger will loose torque down low.

If its low end torque you are after, I would run a web 218 instead of the boring w110. 9.0:1 will also work great, and make the power down low better.

Brian
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So more or less the lazier and stupider you want to be, the nicer quality parts you need to buy.
-Modok

Narrowed beams, Drop adjustable spring plates, Bus disk brake and IRS kits.
www.type-emotorsports.com

Type E Engine Parts and Supplies
https://type-emotorsports.com/collections/engine-parts

[jpaull]

[Brian_e]

jpaul is correct. The upper RPM limit is set by the smallest Cross Sectional Area in the whole port. This can be figured out using math.

Big engines with a small CSA will pull hard, but then fall on their face quick and early. You can keep adding throttle, and it just won't pull anymore. That is because the cylinders can't be filled due to the small CSA.

This is why it is most important to design the whole engine as a package. You can figure out the MCSA needed depending on your displacement and upper RPM limit you plan to rev. Then use that number to calculate the correct valve size that will get the engine to its RPM. The rest of the port MUST also be made to work with the CSA. This is where most heads are screwed up. Like the typical "Big Valve" head which is nothing more than a 40mm valve stuffed into a stock diameter port. They flow just like a stock valve head, and often worse.

Once you know the valve size, you can then pick a cam with the duration that will suite your RPM range, and the lift that suits your heads flow potential.

A well thought out engine, with all components carefully matched to a specific RPM range is awesome to drive. Lots of usable power, with a wide powerband. A poorly matched combo will be soft down low, and then cut off early.

Brian
_________________
So more or less the lazier and stupider you want to be, the nicer quality parts you need to buy.
-Modok

Narrowed beams, Drop adjustable spring plates, Bus disk brake and IRS kits.
www.type-emotorsports.com

Type E Engine Parts and Supplies
https://type-emotorsports.com/collections/engine-parts

[Dusty1]

[DesertSasquatchXploration]

I want to see a side by side with good stock 35.5x32 heads compared to these make the CR the same change nothing but a correct tune.

https://www.larrysoffroad.com/product-page/044-big-bore-cylinder-heads-cut-for-85-5-87mm

[KitS]

Are the Car Craft heads any good?

https://carcraftstore.com/cylinderheads-stocktowild.aspx?variation=4029

[Brian_e]

[sled]

you get what you pay for, ESPECIALLY with heads. There's a reason those heads are so cheap.
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drive your split.

[Brian_e]

[DesertSasquatchXploration]

Car craft heads are the same as larrys offroad they are a super budget line AA brand. Sold as IAP or kuhltek car craft just raised the price last month they were under 200 for new stock heads 100% china everything springs valves retainers keepers seats.

Car craft was selling those Big valve heads for 219 making them the cheapest new big valve head available. I looked at them the engine builder suggested them for my little 1776 they are stock ports with big valves installed. no bowl work they are ugly.

But if you need new stock heads cheap on a stock engine Car Craft heads will work he has great prices but good quality heads they are not.

[Brian_e]

[KitS]

OK, how about the "Mini D" head from Brothers? Remember ing here that I am not looking for high RPM, low end torque is more important to me.

[Dusty1]