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2G Difference in 4g63 and 420a heads? I have searched.

HexenLord

Probationary Member
2
0
Mar 27, 2006
Middletown, Ohio
I've been wondering about some of the differences between the 4G63 and 420A heads. Mainly the exhaust ports and bolt pattern. Now I know that the exhausts are not interchangable as the bolt pattern is completely different. I was wondering about the port spacing and size.

Are the location of the exhaust ports the same on these heads? Or are the runners the same width apart on 420a and 4g63 exhaust manifolds? I had planned on using a 4g63 exhaust manifold and either cutting/welding the flange from a 420a exhaust manifold or custom fabricating one so that the 4g63 exhaust manifold can be used on my 420a head. Obviously if the ports are spaced further apart or closer together this would be impossible, as the runners on the exhaust manifold/header would not line up. I'm not worried about clearance issues with using a different manifold, mainly if its possible to get it bolted to the head.

If anyone could take some pictures of each of the heads with a tape measure against the exhaust ports or even holding up an exhaust manifold or header from a 4g63 to a 420a head (or other way around) that would be great. Thanks guys!
 
Solution
they are not the same.
if you have a 420a flange and try to match it to say a 2.4 spyder header, it doesn't work that well. but if you have the opposite a 4g64 header flange, you can mate it to a 420a runners if you cut them right.

I can get you measurements of some sort. Ill get them up here in a bit.

so 420a has 50mm between ports and the port size is 46mm x 25mm
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4g63 1g (don't have any 2g to check) has 45mm between ports and the port size is 50mm x 30mm
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here is a 420a gasket on a 4g head, the middle two ports are that bad but the outer ones are.
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streetlegends

Proven Member
309
7
Sep 7, 2005
Lawton, Oklahoma
HexenLord said:
I've been wondering about some of the differences between the 4G63 and 420A heads. Mainly the exhaust ports and bolt pattern. Now I know that the exhausts are not interchangable as the bolt pattern is completely different. I was wondering about the port spacing and size.

Are the location of the exhaust ports the same on these heads? Or are the runners the same width apart on 420a and 4g63 exhaust manifolds? I had planned on using a 4g63 exhaust manifold and either cutting/welding the flange from a 420a exhaust manifold or custom fabricating one so that the 4g63 exhaust manifold can be used on my 420a head. Obviously if the ports are spaced further apart or closer together this would be impossible, as the runners on the exhaust manifold/header would not line up. I'm not worried about clearance issues with using a different manifold, mainly if its possible to get it bolted to the head.

If anyone could take some pictures of each of the heads with a tape measure against the exhaust ports or even holding up an exhaust manifold or header from a 4g63 to a 420a head (or other way around) that would be great. Thanks guys!
My question is why are you fabing things for the 420a when they make everything for this motor. Are you trying to good turbo? You can buy kits for this motor all day everyday. The best thing I can tell you do is go to your locate junkyard and get an 4g63 exhaust manifold and compair them.
 

DSMcrazy3

N/T DSM Wiseman
DSM Wiseman
2,196
60
Dec 29, 2004
Humble, Texas
The ports should be spaced the same distance apart, and generally the same diameter. Unless further modified.

If you're looking to turbo your car there are much easier ways to go about doing it. Look on Ebay for "420a turbo manifold" you should have a nice list come up. I recommend the one Mike Hart sells at "thestreetsource" on Ebay, many people have purchased from him with few problems. The 4g63 manifolds are hard to cut and reweld to. I would advise against it.
 

Mangold

Proven Member
82
1
Mar 17, 2004
The Woodlands, Texas
While I have no idea why you are wanting these comparisons done here is what I know.

They are absolutely and completely different. I probably do not have to tell you this but the 420a is a Chryster motor, aluminum heads. The ONLY thing a 4g63 and 420a share is the dispacement, at 2.0L and that's not even exactly the same. They are a few CCs off if I am not mistaken.

The cams are on oposite sides and the intake manifolds are backwards on the two motors. So yah they are in no way shape form or fashion similar.

And I do believe I still have my old 2g 4g63 head in my friends garage and possibly my old 420a head that was cracked when I was spraying. I will try to get ahold of him and have him take a few shots of the two heads side by side with measuring tapes if possible.

But if you could please explain to me why you are wanting this comparison done I would appreciate that. ** My friend lives in my home town 305 miles away from where I am, so I need to give him a good reason to go digging around for my old parts. :p

Edit: sorry, I am on a roll today. I screwed up two posts today. 420A does indeed have a cast iron block. I am thinking of the B16a, I spent a couple weekends helping a friend put that in and now I have Honda motors on my mind I guess I dunno. Thank you Velocita for the correction.
 

HexenLord

Probationary Member
2
0
Mar 27, 2006
Middletown, Ohio
My 420a is already turbo, but I was looking for a better manifold and have found some made by a local shop for the 4g63. I was thinking if the runners were in the same location and the ports on the head were an equal distance apart (as compared to the 420a head), I could cut off the flange and weld on or fabricate one that would allow me to use the custom manifold.

Btw, mangold, thanks for the information... but I already know the general differences between the two heads. I was just wondering about a few of the measurements. I do not care about the major differences between the two heads. I'm only worried about the spacing and location of the ports to possibly interchange the exhausts.

I am now considering going down to autozone or advanced auto and buying an exhaust manifold gasket for each to see if the holes for the exhaust ports line up, regardless of size differences.

Once again, any help is appreciated.
 

VelocitàPaola

Moderator
5,067
156
Jun 14, 2005
Ft. Lauderdale, Florida
Mangold said:
I probably do not have to tell you this but the 420a is a Chryster motor, aluminum block.

How did this rumor get started? 420As have cast iron blocks; aluminum heads.
 

1500_gsauto

Probationary Member
1
0
Dec 16, 2021
Oklahoma
Hey I am curious as to whether or not the 4g63 and 420a exhaust ports are identical or not. Does anyone have the exhaust port specs for the two heads to prove a header swap is possible or is my plan a bust?

I’m reviving this ancient thread because I can’t find a 4-2-1 style header for the 420a that is less than $150.
 
Last edited:

dustyboner

DSM Wiseman
1,940
1,050
Mar 13, 2016
abq, New_Mexico
they are not the same.
if you have a 420a flange and try to match it to say a 2.4 spyder header, it doesn't work that well. but if you have the opposite a 4g64 header flange, you can mate it to a 420a runners if you cut them right.

I can get you measurements of some sort. Ill get them up here in a bit.

so 420a has 50mm between ports and the port size is 46mm x 25mm
You must be logged in to view this image or video.




4g63 1g (don't have any 2g to check) has 45mm between ports and the port size is 50mm x 30mm
You must be logged in to view this image or video.




here is a 420a gasket on a 4g head, the middle two ports are that bad but the outer ones are.
You must be logged in to view this image or video.
 
Solution

pauleyman

DSM Wiseman
7,269
2,191
Nov 19, 2011
oklahoma city, Oklahoma
Hey I am curious as to whether or not the 4g63 and 420a exhaust ports are identical or not. Does anyone have the exhaust port specs for the two heads to prove a header swap is possible or is my plan a bust?

I’m reviving this 9 16 year old thread because I can’t find a 4-2-1 style header for the 420a that is less than $150.
150$ is expensive?
Good, fast, cheap.
Pick two.
 

BLACK'98DSM

Proven Member
3,303
1,134
Feb 9, 2019
Alabama
I would personally just save your pennies and buy the correct header. But you can make a 4g63 manifold work with some fabrication. This is obviously for a turbo manifold but the principal is the same. You'll need a matching downpipe for the header unless you want more fabrication. With too much fab you'll be surpassing the price of the 420a header.

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