Hello there,

I wanted to get me new heads for my 74 400 engine. I already have a performer intake and a Thermoquad.
I also want to buy a Lunati Voodoo 10230701LK cam and hedman elite headers.

I wanted to buy edelbrock 5090 heads but read that they are not the best choice.
I want more compression with stock pistons. Everything is choosen for low RPM power.

I would buy a set of the sidewinder or 440 source heads.You can mill them a little to help with compression if need be.

the edelbrock 5090 would have 74 or 75 cc chambers. the sidewinder only has 84cc and the stealth 80 cc.
so for compression I think 74 or 75 cc would be good since I have a really low compression engine.

With a stock piston 400 it really doesn't matter what heads you run, compression is going to be low with no quench.

You'd be better off getting new pistons to fix the low compression rather than new heads at this point.

I know I won't see anything above 9,5:1.
I wanted to change the heads, because I wanted new valve springs etc. for the new cam.
So I thought I could get new heads straight away. So I'm searching some with a bit more compression for my stock pistons.
I don't want to change my pistons at this point because I think I gonna get me a stroker kit some time in the future.
It's a money thing and I want to drive my car this summer.
So it's either a stroker kit or cam, heads, headers etc.

I run the 84 cc Edelbrock heads. I have headers, rpm intake on a low compression motor. Gets my 3500 pound Volare to 12.4 in the 1/4.

If I were buying again I would get the sidewinder heads.

Also, I run a steel head gasket.

why would you choos the sidewinder next time?
and why did you choose the 84 cc instead of the 75 cc?

Any of the heads you are looking at will give you more flow, more power and less weight. I don't think compression differences will have a big effect with the current build.

Perhaps pick based on what would work best down the road when you go with the stroker. Run the compression numbers that way. A 3.75" stroke 451, for example, may work well with shelf flat top pistons and 80-84 cc's. Stroke longer than that will probably need a dish piston to dial in compression for pump gas with any of the choices.

I think you are on the right path. Not only would I purchase the 75 cc head, I would mill it to the desired compression ratio, or to the highest compression ratio with a reasonable cut on the head.

Giving up 10 cc on a low compression motor when you are already buying heads and doing the work just does not make sense.

Most people misunderstand what increasing CR does. There are formulas out there that that people use that generally show you the increase in peak power. These power increase numbers are modest and understate the actual result. Increased CR is one of the simple few things that you can do to increase the power from idle to red line. If you take an engine's power curve, and change nothing but engine's compression ratio, the entire power curve moves up. For the same change in peak horsepower, the CR change will result in more average hp increase.

Wow, what a coincidence. Look at this curve. If you follow how power curves change with typical performance upgrades, you will know that there usually isn't one change that can result in this kind of change in the area under the power curve.

https://board.moparts.org/ubbthreads/ubbt...tml#Post1821935

It will with any kind of a cam. low compression engine + high performance cam = crappy combo.

thanks for the infos guys.
the thing with low compression and a new cam is the reason, why I want to do the head swap together with the cam change.
The only problem is, that I read, that the 5090 e-street heads are no good.

is this a stock 400 with open chambered heads? How soon/serious are you about replacing it with the stroker? As said SCR is where you are hurting. you could mill the heck out of the open chambered heads or get a set of 516 iron closed chambered heads & home port em (tho you are in Germany/not sure what's available there) & as you know it would not be practical to ship some OE lo po iron heads. You could go with the alum heads with the smallest chambers & adv the oe stock (I'm assuming) cam 4 deg & dial in the dist subsystems then transplant the alum heads when the stroker comes together.

it'll take some time (2 years) until I stroke the engine.
I already bought new springs for dialing the distributor.
I wanted to get alu heads with small closed chambers (as you said for the shipping issues).
It's actually cheaper to buy them in the USA (even with shipment).
the whole plan (without stroking) is:
- mild cam (Lunati Voodoo 10230701L) mostly because I have the 2 bbl cam in
my engine but with a 4bbl carb.
- dialing the distributor
- tuning the carb (thermoquad; maybe buy a rebuilt one for high performance)
- new heads (which one?)
- new air cleaner for cold air intake (my car has a aftermarket open air
cleaner)
- a 3.2:1 gear set in the rear axle (maybe a bit later)
- new smaller wheels (I have huge ones now; 20" rims)
- hedman elite headers
- new spark plugs and all the small stuff

My suspension is already rebuilt.
The car should be technically good and fun to drive but a bit looking like a worn out car.

With a 74 400 on stock pistons you won't see anything NEAR 9.5 with a head change. Even with a set of 440 source heads milled down to 75cc you still won't see above 8.5 compression, likely closer to 8.0. Which is still better than your stock 7.5 of compression.

You can get a smogger 440 to perform decent, but your gains will be in:

Distributor tuning
carb tuning
exhaust
cam
torq converter
rear gear.

The cam you are choosing is very mild, a good choice for your compression and gear ratio. Your car will be a good cruiser but not a ground pounding, tire shredding machine. IMO if your stock heads are in ok shape, run them. Now if you were building for 1/4 mile performance, not highway cruising, I would go to a 4.10 gear, 3000rpm stall converter, move up a few steps in cam size, holley street dominator intake(will work with thermoquad), 440 source heads, headers, 3" dual exhaust and you could see some 12 second 1/4 mile times.

I thought stock compression is 8.2 : 1

I have a dual sidepipe exhaust with cherry bombs. The two pipes are not connected. Should they be connected?

It's good to hear that I am on the right way.
I don't want to go on a 1/4 mile but I want to get that 4000 pound ship moving. I'd like to have a really heavy car accelerating pretty fast. High speed is not the priority.
Would a 3.5:1 be a good compromise?
When I get a wilder cam I should use other heads right?

Would getting new heads be a super bad idea? I mean I would like to save money, but I also want to get a bit more power. But the engine runs really nice and I don't want to rip it apart completely

The 75 cc Eddy head mill to 70 cc will put him over 9:1. You could probably get to 9.5:1. Slapping on a 84 cc stealth head will be 8:1.

You can spend an additional $1000 to make another 30 or 40 hp with good heads, or spend $3000 on gears, converter, big exhaust, tire to make a turd feel better......

It doesn't have to be complicated. There are 10,000 different things you can do to make the 400 run better, but what you have chosen will make a substantial difference in your car. The 6090 heads were designed for exactly your purpose and the 10230701 cam will work fine in your engine. If you chose to go to a 3.55:1 gear the whole combination will make the car feel like a rocket ship vs what it is now.

When you learn from these few changes and later want to do the stroker, sell the heads and go to a more performance oriented cylinder head.

This is a quick example of what a 400 will do with less compression, cam and airflow than you are planning.

low compression 400 on the dyno

I'm impressed by those numbers from a 7.5:1 400! Now that's the perfect static CR to add a turbo

Remember the Direct Connection books (my '82 edition) had an 8:1 400 in a Duster and it ran deep into the 11's with 4.30 gears and the right converter, cam and intake combo.

I thank you guys for the informations. It helped me a lot.
Are there special head gasket i should use (thinner or better)?