400 with 383 heads help!!!

[northerncuda2021]

Been having a hard time to get engine running(back fire through carb/ehaust/poor vacuum/wont idle). Bought vehicle not running but said it was just tuning issues!!! Never could get it.  Ended up pulling and tearing down engine. This is what I found.  Looks like a stock 400 from 1975 block .  It has 383 heads # 240516-8.  All I want is a nice running engine, don't really car about power. just turn key and drive  The cam says EP-45 CWC.  Is this a bad combination to have a decent running engine. As far as I could tell everything else looked good. Timing was good checked and double checked!!  Even triple  lol

Wish I had 20k laying around as a 392 hemi swap would be hapenning!!!  Thanks guys any question please ask as Im sure I forgot something!!!

had a elbrock intake/HP holly 650/firecore distributor

Northerncuda2021

[JonH]

You need to identify the camshaft. I suspect that is the issue. Is it hydraulic, or flat tappet? My guess is flat tappet and valve lash not correctly adjusted. If it was me unless I could determine what that cam is, I would replace it with a new one that matches what you expect from your engine, trans, rear combination and expected use. If the heads and short block are in good shape, you will be good to go...

[oldmoparbuff]

Have you done a compression test?
Are you triple sure Distributor is not 180 degrees off?
Vacuum leaks
Are you running points or electronic ignition?

[Rich G.]

Sounds more like a carb or ignition problem. You should have done a compression test and other tests before tearing it apart. There is no valve adjustment on a stock 400 unless they changed the rockers.

[northerncuda2021]

Compression 130 psi -160 psi

[northerncuda2021]

Would run above 2000 rpm. That's it.  Electronic ignition

[northerncuda2021]

Yes hydraulic lifters.  Yes I'm going measure can forsure and go from there   Thank you. I might reach out to you again. I'll see how it goes

[northerncuda2021]

You need to identify the camshaft. I suspect that is the issue. Is it hydraulic, or flat tappet? My guess is flat tappet and valve lash not correctly adjusted. If it was me unless I could determine what that cam is, I would replace it with a new one that matches what you expect from your engine, trans, rear combination and expected use. If the heads and short block are in good shape, you will be good to go...

Yes hydraulic lifters.  Yes I'm going measure can forsure and go from there   Thank you. I might reach out to you again. I'll see how it goes

[northerncuda2021]

Have you done a compression test?
Are you triple sure Distributor is not 180 degrees off?
Vacuum leaks
Are you running points or electronic ignition?

No vacuum leaks I could find.  Vacuum was really really low!! No distributor wasn't 180 off as it would run ok when reved up.  I checked and checked.  It was forsure right.   Electronic ignition with new fire core distributor.

[northerncuda2021]

Sounds more like a carb or ignition problem. You should have done a compression test and other tests before tearing it apart. There is no valve adjustment on a stock 400 unless they changed the rockers.

Yes I did a compression test varies from 130 psi to 160 psi.  I went through carb looked good. Holley HP. New distributor and ignition. I tried and tried and finally gave up and pulled engine.  Still not seeing anything jumping out.  Frustrating as hell

[Chryco Psycho]

I can call you & we can talk this through if you want

[DeathProofCuda]

You need to identify the camshaft. I suspect that is the issue. Is it hydraulic, or flat tappet? My guess is flat tappet and valve lash not correctly adjusted. If it was me unless I could determine what that cam is, I would replace it with a new one that matches what you expect from your engine, trans, rear combination and expected use. If the heads and short block are in good shape, you will be good to go...

Yes hydraulic lifters.  Yes I'm going measure can forsure and go from there   Thank you. I might reach out to you again. I'll see how it goes

Cams are relatively inexpensive.  Given that you've already torn it down, I'd probably just opt for a new cam and lifters set, so that you know what you've got and know that it works for your combo.  Make sure that you use a degree wheel when you install it (don't just line up the dots) so that you know that the valve timing is correct. 

[Chryco Psycho]

The 516 heads on a low compression 400 makes total sense increasing the compression from high 7:1 into the high 8:1 range , cheap fix over trying to buy high compression pistons for a 400 . Check the timing chain , could be a tooth off , the CWC is familar but not brand specific just the core maker .  I would look for a 112 cl cam with lower duration to help build more compression such as the Lunati 701 or 702

[northerncuda2021]

The 516 heads on a low compression 400 makes total sense increasing the compression from high 7:1 into the high 8:1 range , cheap fix over trying to buy high compression pistons for a 400 . Check the timing chain , could be a tooth off , the CWC is familar but not brand specific just the core maker .  I would look for a 112 cl cam with lower duration to help build more compression such as the Lunati 701 or

Thank you so much. Make sense.  Once I get back in shop I'll do some measuring on camshaft to confirm exactly what I got and then I'll reach out to you just to confirm.  Thanks a million!!

[Timmy2Tires]

Always a good idea to bring #1 up to TDC and make sure your timing mark and pointer are in line.