ram horn manifolds

[77 K20]

I've been looking online for weeks and still haven't found a clear answer if they will fit. I have an appointment on Thursday with a good exhaust shop and guess I will find out for sure then.

A few have said they fit on a 4x4 no problem. One guy said the driver's side motor mount gets in the way and he had to use a torch and cut part of the "clam shell" away to allow clearance for the flange stud.

Can anyone comment/add anything before I possibly waste a lot of time heading to the shop (it is 120 miles away).

Driving will cost a lot in fuel, but will be a good shake down test. A little while ago I found out I had a bad camshaft (lobes were round). Since then have installed:
-new starter
-new alternator
-new transmission pan called a slam guard. 3/16" thick, powder coated. Provides great protection.
-new airfilter housing
-new cam. "BLUEPRINTED 350HP 327 HYD SBC"

Intake Duration at 050 inch Lift: 222
Exhaust Duration at 050 inch Lift: 222
Duration at 050 inch Lift: 222 int./222 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.447 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.447 in.
Valve Lift with Factory Rocker Arm Ratio: 0.447 int./0.447 exh.
Lobe Separation (degrees): 114

So far I love it- but hard to hear how the engine sounds with a leaking passenger side exhaust manifold and the rest of the exhaust is rusted and falling off.

The engine builder suggested the 2.5" ram horn exhaust manifolds and some 2.5" Thrush welded mufflers to save a bit of $$.

 

[bucket]

Do you already have manifolds? I know there were a few different versions, and some had the outlet pointed at an angle to the rear on the driver side. IIRC, my '69 and '70 Impalas have this version, but they are not the larger outlet. I'm not sure if the angled outlet was ever made in the larger diameter. I'm also not sure what versions might be available as aftermarket replacements.

 

[77 K20]

I already have them. From what I gather only the center dump ones come in 2.5"- and that is what I bought. They have brackets built into them that need to be cut off (alternator brackets I guess)

I hope they fit without any issues. I have already soaked the old exhaust manifold bolts for a week and made sure all will back out easily. So at least the shop will not have issues with that.

 

[bucket]

From what I gather only the center dump ones come in 2.5"- and that is what I bought.

The "angled outlet" manifolds I was talking about are center dump ram's horns also.

Please let us know how the install goes

 

[77 K20]

The install took a while- but turned out very nice. The exhaust shop used a chop saw to get rid of the bracket that is built into the manifolds, then used a grinder to clean them up. They were bolted up and the truck was raised. Passenger side fits perfect. Drivers side- had problems. By putting in the studs for the flange one of them was directly resting on the motor mount. So he cut away part of the motor mount and then welded in a new side to it to make sure it was still strong. That gave him the clearance needed for everything.
And since there still wasn't a ton of room around the drivers side motor mount the spark plug wires I bought for a '75 Corvette wouldn't really work (Corvettes had ram horn manifolds and their wires had 90 degree boots on them- and run under the manifold along the block, around the back of the block and then up to the distributer). He had some straight boot wires I think from a big block. Brought them up and over instead.

The Thrush welded mufflers sound great at idle, or just cruising thru town (had the exhaust turned down and dumped before the axle). On the highway- kinda annoying. Not quite sure what to think yet. Around 2100 RPM there seems to be some sort of harmonic that even if you are taking it easy they "wake up" and get a bit louder. Not too bad if I'm accelerating thru that zone, but if I was cruising right at that RPM it would drone.
Didn't have a whole lot of time to study it- as I had other issues that are troubling me right now. It took 1.5 qts of oil for me to go 130 miles yesterday. I hate oil leaks. Exhaust shop said the valve covers gaskets were leaking and they redid them. I then drove 40 miles and not a single leak. Ate dinner- then started driving again to get back home. 70 miles later I pull off to find the leak is back. Doesn't look as bad- I'll look it over in the morning when I get get on my crawler and head underneath with a flashlight. The front drive shaft is SOAKED.

 

[MrMarty51]

Might just could be the oil sending units sprung a hole init.

 

[77 K20]

In the last pic you can see where the motor mount had to be cut away. Under the mount he welded in more metal to make sure no strength was lost.

 

[77 K20]

Also some pics of the exhaust.

You can see how the old exhaust had broken off and was hitting the driveshaft on the way to the exhaust shop.

 

[77 K20]

And also since I had to change the trans filter anyway I put on a Trans-Dapt Slam Guard transmission pan. Basically has a skid plate welded onto it. It has a silver powercoat on it that looks like it will last a very long time.

 

[77 K20]

Might just could be the oil sending units sprung a hole init.

I looked- and it has a mechanical oil pressure gauge- and followed the "pipe" to where it connects on the driver's side. Didn't see a leak. Also pulled off the torque converter inspection cover. No oil in there (there would be for a rear main seal leak, right?). Also checked to make sure there is a bolt in the block near the fuel pump.

My last guess was the crankcase was getting over pressurized somehow at highway speeds so I replaced the breather and the PCV valve. Guess I'll wait and see if it does it again on my next highway trip. It seems to take about an hour for it to happen at 65-70 mph.

 

[Jims86]

Run some tailpipes out, and the noise wont be so bad...the underside of the bed is an echo chamber.

 

[bucket]

Looks good. Where did you buy the manifolds?

 

[77 K20]

Looks good. Where did you buy the manifolds?

I just bought them from Summit Racing with all the other parts I needed. They are the dorman brand ones ($48/each). They had some nicer looking ones for $300- but this is my work/play truck. Not a show truck. Didn't see how they would make any difference at all in my application.

I am very happy with them.

 

[bucket]

I think I'll try them on the K5 I'm building, they would look cool with the Crossfire Injection I'm going to run.

 

[kleedus]

i have that same cam and mufflers in my 71 c10 but i used headers took the rams horns off for the headers.

the mufflers sound awsome with headers and i love that cam i also put it in the 65 4x4 i am building


why not just put headers on it