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DOHC on CHEVY 350? POSSIBLE?

50K views 38 replies 21 participants last post by  cobalt327 
#1 ·
Just for fun, I was wondering what all might be involved in running Dual Overhead Cams or even a Single Overhead Cam with an early model Chevy 350 CID engine. Has this ever been attempted? Is it even possible?
 
#4 ·
If I was a millionaire I may try that for fun. Maybe there is a 4cyl gm motor with the same head bolts, water passages, and bore spacing? I'm interested now... If one of the big three just used the same spec from half a v8 for an inline 4 I think it would be GM. If you want you could check head gaskets at the auto parts store? Head bolts are a biggie.. water passages and oil can be routed for a one off. I would start off with a old 2.5 inline 4 and compare the head gaskets. Got a friend at the auto parts store? or go in when they are slow and keep comparing head gaskets?
 
#15 ·
ENGINE

350 c.i. V-8 ZR1 LT5 lotus designed and bult by mercruy marine.

C.R.
11.0:1

Horsepower
375@5800

Torque
370@4800

Acceleration
Sec.

0-60 mph
4.9

Standing 1/4 mi.
13.4@109 mph


It is amazing how much performance has changed in last 20 years. It only cost $58,995. What would that be in inflated dollars.
 
#17 ·
The bolt on conversion kits for the SBC's are very interesting... Looks like the Moser/Harvey Crane Jr, DOHC heads from the 70's are about the closest thing to what I was imagining when I started this thread! I guess nobody's really experimenting with this sort of thing nowadays...

This company say's they've built over 50 OHC chevy's but no DOHC.


I guess I won't be running DOHC on my 350 anytime soon...
 
#18 ·
torque plate bolt pattern.

I remember the torque plate you use when boring and honing blocks on the Sunnen machine would fit several engines..A lot of times engine designers had to stay with dimensions that would work on the multi million dollar machining lines. Small block fords were built on the machines that did the Y blocks. The ford FE engines 332 -428 were done on the old MEL line . merc edsel lincoln l , etc. 429-460's use the old lincoln machinery. I wonder if any of the ohc 4 Cylinders have the same dimensions as V 8's ? .
 
#19 ·
You can get a SBC block w/undrilled decks from Dart according to Tony Hornak- either the Little M or Iron Eagle. Just request NO head bolt holes.

The water jacket passages would still be there, but w/no head bolt holes adapting a different head would be somewhat easier.

They say the chain on the front of the SOHC Ford was 6 feet long. Driving the cams would likely be as hard as mounting the heads!
 
#21 · (Edited)
Making DOHC for a SBC

I was just browsing through the internet wondering this same question when i ran across this thread, figured i'd post this on here to see if you guys would be interested in it.

I work for my family's aluminum foundry & CNC shop located in Muncie, IN, we do green sand, air set, permanent mold, and die-cast molding for various companies around the US, we've been in business since 1947, but just recently we have decided to get into manufacturing our own products and considering the past 3 generations of my family are car enthusiast we decided to delve into after market automotive, specifically starting with chevy first. we are currently in the process of manufacturing a 671 blower and we produce sbc valve covers, grenade shifter knobs, and breather caps.

What im getting at tho is, asking you guys if it would be possible to manufacture a DOHC that would fit onto a early model SBC, i know more about manufacturing than i do about valvetrains. would there have to be any modification the the block or could someone buy these and be able to bolt them on? I was talking to some guys at a car show this weekend, they said it is possible by just plugging the oil galleys and having the DOHC but from what iv found, no one makes them.

And for the pricing part, it wont be nearly as expensive as you guys might think for us to make them, we recently bought a rapid prototype 3D printer which we can design any part in a CAD program, have the printer print the part out for us in ABS, spend about 2 hours cleaning it up, and we can cast parts right off the model. I can have a cast part in a customers hand starting when the printer turns on, within 24-96hrs depending on the complexity of the part(id give a few extra on cylinder heads:) ). we eventually plan on manufacturing our own complete aluminum small blocks from start to finish but thats a little down the road :).
 
#22 · (Edited)
Dzuari said:
I was just browsing through the internet wondering this same question when i ran across this thread, figured i'd post this on here to see if you guys would be interested in it.

I work for my family's aluminum foundry & CNC shop located in Muncie, IN, we do green sand, air set, permanent mold, and die-cast molding for various companies around the US, we've been in business since 1947, but just recently we have decided to get into manufacturing our own products and considering the past 3 generations of my family are car enthusiast we decided to delve into after market automotive, specifically starting with chevy first. we are currently in the process of manufacturing a 671 blower and we produce sbc valve covers, grenade shifter knobs, and breather caps.

What im getting at tho is, asking you guys if it would be possible to manufacture a DOHC that would fit onto a early model SBC, i know more about manufacturing than i do about valvetrains. would there have to be any modification the the block or could someone buy these and be able to bolt them on? I was talking to some guys at a car show this weekend, they said it is possible by just plugging the oil galleys and having the DOHC but from what iv found, no one makes them.

And for the pricing part, it wont be nearly as expensive as you guys might think for us to make them, we recently bought a rapid prototype 3D printer which we can design any part in a CAD program, have the printer print the part out for us in ABS, spend about 2 hours cleaning it up, and we can cast parts right off the model. I can have a cast part in a customers hand starting when the printer turns on, within 24-96hrs depending on the complexity of the part(id give a few extra on cylinder heads:) ). we eventually plan on manufacturing our own complete aluminum small blocks from start to finish but thats a little down the road :).
Single and DOHC heads have been designed for the SBC through the years- and in every case, they've not been successful.

The problem is, there's just not enough performance gain for the complexity, expense and packaging issues involved, IMO. If you DO decide to go w/the OHC deal, the drive system is a major part of the design, the Ford SOHC from the 60's had a 6 foot long(!) chain to drive it.

You would want to get a cam grinder, as well as a valve supplier/manufacturer on board, as well. That way, you wouldn't be saddled w/the learning curve associated w/the dynamics and metallurgy of cam followers, valve manufacturing, springs, lash caps/bucket shims (or whatever was to be the means to set lash), seals, retainers etc.

If I were sitting on an aluminum foundry w/the ability to do it, I would start by using a much more conventional design, like a 23° layout, w/180cc-200cc runners, and maybe an intake to match.

If you hire a good enough consultant for the initial design, and touted it as "Made in the USA", it might sell. Someone like Larry Widmer or even Jon Kaase- someone who's hopefully not already under contract to someone- which usually means there are "no compete" clauses involved.

Anyway, good luck w/all that. It would be killer to have a new face in the game w/a good product, made here. ;)
 
#23 ·
When the current generation Corvette was released a few years ago, there were a number of articles that discussed why the Vette still had a pushrod motor. The bottom line is that for the same HP output, the overall package dimensions were much smaller for the pushrod motor. Here's a side-by-side comparison of a 5.0 Ford and a Mod motor 4.6 as an example. DOHC and even SOHC motors are much wider, more complex, and more expensive to build than pushrod motors.

 
#24 ·
They say a picture's worth a thousand words! Plus, stock the 5.0L is over 20 ci larger, and can go to 347 cid (+~66 cid) w/o drama.

BUT- there are basically stock 4.6 bottom ends making HUGE HP- boosted HP- that is. But that doesn't make the package any smaller. It is a W I D E powerplant, however you want to slice it.
 
#25 ·
One thing you guys need to look at is race rules..most rulebooks call for production based motors so an aftermarket DOHC may not be a legal race part when an improved head such as the Dart Iron Eagle is for certain classes of racing. Anything is possible. If I had that kind of capablity I would look at making some true 12 port heads for the inline crowd..A true 12 port head on a 300 ford six could make some serious HP and be in the range of doable for the rodders checkbook..

Sam
 
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