Patrick03

There was a really good description of the various Z28/LT1 intake manifolds that I read a few months ago. For the life of me I can't find it. I think it was buried in one of the engine build threads. Anyone remember which thread I'm talking about? The post described the differences across model years for these intakes.

I'm going to keep my eye out for one and want to make sure I get the best part number for my application. I want to keep my stock '64 365hp looking reasonably original.


Thanks,
Patrick

wmf62

what is wrong with your current, and I presume OEM, intake? you are not going to gain much by changing...

Bill

6T7L71CPE

Posts are by DZAUTO!

https://www.corvetteforum.com/forums...28-intake.html

https://www.corvetteforum.com/forums...ke-to-run.html

Patrick03

Nothing wrong with current manifold. Just looking for incremental improvements.

DZAUTO

I did that.
The early Z28/LT1 manifolds are the tallest factory manifolds that GM ever made for the small block. In my opinion they are one of the best all around manifolds ever made (street or very hi-perf).
There are basically 2 versions, with a slight variation: 67-68, 69-72.
The BIG difference is at the very front, at the water passage.
The 67-68 Camaro Z28 version had the alternator on the left side, thus, the water outlet for the thermostat housing was different and the threaded holes for heater hoses were slightly different.

The 67-8 is on the left, the adapter plate is simply for installing a Q-jet instead of a Holley. The one on the right is actually a 69, but is the same as the 70-72 (with a slight variation, explained later).



The threaded hole, next to the hole for the oil fill tube, is for the air cond adjusting bracket on the Camaros (although, Z28s DID NOT have AC available). The 69-later Corvettes still had the alternator on the left side, but the attaching brackets were completely different from the Camaro brackets.



This compares the rear, the differences are insignificant.


From the side they're nearly identical.



This is the bottom. The 67-8 is now on the right. Notice the big difference on the underside is in the water passage areas.



The 69-72 manifolds are the same--------------- EXCEPT, for 69 (ONLY)------------------ there was still a hole for the oil fill tube, but it was plugged with a freeze plug (easily removed so that an oil fill tube can be installed).
The 70-72 manifolds were still identical to the 69 manifold, except that the hole for the oil tube was completely cast over. Any good machine could easily open this up so that an oil fill tube could be installed.
My most favorite choice is the 69 with an oil fill tube installed.

This is a 68 manifold on a 350 on my son's 68 Chevelle.









This is a 69 Manifold on my 70 Chevelle.

Patrick03

Thanks everyone, that's the info I was looking for. Do both versions of the manifold work with my existing thermostat housing? Or do I need a different housing?

Thanks,
Patrick

6T7L71CPE

Depending on your needs, there is also 14044836, the service replacement intake. Might be cheaper.

https://www.ebay.com/sch/i.html?_fro...44836&_sacat=0

65tripleblack

This is the best one to look for. It is a service replacement beginning from mid seventies, so much less expensive than a production part. It is much improved over the production piece because of the beefy mount flanges which eliminate or greatly reduce sealing problems against the heads. They also allow you to open the runners to accept a 1206 FelPro gasket set. I strongly recommend this version:

MikeM

I would do a cost/benefit ratio analysis. What little you stand to gain vs what it's going to cost you.

Also, beware. From long ago, seems I remember the L-79 intake as used on Chevy II and Chevelle were taller than any of the SB intakes and won't fit under a Corvette hood. But I could be wrong.

Nowhere Man

Mike the same intake was used on a Chevelle and Chevy II as a Vette

DZAUTO

The BOLT PATTERN for all Chevy thermostat housings is the same. Thus, ANY Chevy thermostat housing will bolt up to any SB manifold. The issue will be if the hose connection for whatever thermostat housing you have will be facing the direction you need for your upper hose.

Critter1

That's the 1st thing that ran through my mind when I read the 1st post.

wmf62

he said in post #4 he is looking for 'incremental' improvement, so $$ doesn't count

Bill

Patrick03

Thanks for all the great info guys. This is exactly what I was looking for. And yes, money does count, but it sounds like there is pretty good consensus that going from my 365hp intake to the Z28 intake really doesn't get me much. I'll still look around and if a good priced one shows up, I'll try and grab it.

DucatiDon

Not worth the effort IMHO.

The oil fill tube on the 64 points to the pass side, while these later manifolds points to the driver side, which requires a different thermostat housing (see the cast iron in DZs pic above) to position the radiator hose around the tube. Ive had 63, 64, and now the Z28. The 64 has three holes below the carb, while the Z28 has two slots.

All fit fine under the hood with stock air cleaner and carb.

jdk971

i think the z28 manifold, will make the air filter closer to the hood. may need to use a
thinner air filter. jmho jim

MikeM

In '65-'66? Don't think so but my memory could be off. I've been to five goat ropin's and six county fairs since I heard that. Somebody with a parts book handy can check if they want.

MikeM

I had a Z 28 manifold on a '64 Corvette with the stock drop base air cleaner. Seemed to fit fine. Long ago. What do I know?

TJefferson2020

I have a 1970 LT1 with original intake and air filter and it fits under my 64 hood just fine.

Nowhere Man

then what intake would they used. there was only one SB aluminium intake for each respected year