The stock Cadillac cylinder heads do a good job of getting the fuel air mixture into the engine and exhaust out at lower RPM's but are a little restrictive higher up the RPM range. Here is a little story about the evolution of my cylinder heads. 

First of all, a little disclaimer. I did very little of this work myself. A race engine building friend did the porting and a local automotive machine shop did the machine work and assembly. I did the research on what parts to use. 

The stock valve sizes are 1.87" intake and 1.50" exhaust and as you all know, the middle two cylinders on each bank share an exhaust port. That port is larger than the end ports. What got me started on this whole thing was I took an old head apart and slid in a couple of 1.94/1.60" Chevy valves. It looked like it would be a no brainer to install the bigger valves so off I went.

My engine builder buddy had never touched a Cadillac head before so I cut one up so we could see where the flow could be improved and where the danger areas were where you would have to be very careful removing material. Here are those discovery photos. I'll explain them in a reply.

Views: 160

Reply to This

Replies to This Discussion

I've been building a mild Holden six motor (think smaller version of a blue flame six) here in Oz for a mates son. Its out of a 1960 model, so old and slow. Another good mate, gave the head a mild tickle on the bottom. We've gone with bigger valves, some flow porting in the runners and a small amount at the mouth of the port. The manifold has been ported to match and is dowel pinned to head. We whacked a bit off the face to kick the compression a tad, then topped it off with some Comp Cams 350 chevy springs and retainers. We've got twin carbs, extractors, mild cam, 40thou over pistons, alloy cam gear and stuff in the build. 

Should make the new driving experience more fun than before 


Pretty cool project. Nothing like a straight 6 for torque and smooth running. What carbs is it running? 

I had a 1985 BMW 535i (3.5 liter inline 6) for many years and put a ton of kilometers on it. I think I ended up at 385,000. Loved that car. 

Its got twin Stromberg's on it.

The poor ol early Holden 6's,known as the "grey motor", because they were grey, had one really big issue, they only have 4 main bearing in them.

Keep the revs around 5,500 to 5,800rpm,all good.

Rev 'em past 6,000, and the crankshafts tend to fall out of the block. This little thing will have 5,500 rev limiter fitted.

Nice. Should be a good little runner. Looking forward to hearing more about this project. 

Kevin, why you hijack somebody else's thread? How about creating your own instead of piggy backing? Did you eat the wax instead of putting it on the car? That would explain a lot!!!    ;-)

Oh Anders, so sorry I missed this until now...... :-) LOL

I've missed being able to tell you to go root ya boot. LOL



  • Add Photos
  • View All


Turn signal switch needed

Started by Roy in 1963/64 Cadillac Specific Discussion. Last reply by John Aguilar 19 hours ago. 5 Replies

Looking for a turn signal switch for my '64 coupe DeVille. The mechanic working on it said it's the cause of the passenger rear blinker and brake light not working. This is a big issue since police…Continue

Current 1963/64 Cadillac Listings on eBay

Started by Jason Edge in For Sale. Last reply by douglas krathwohl yesterday. 1 Reply

To see all 1963/64 Cadillacs Listed on eBay in the USA…Continue

Tags: ebay

Caddy Bling

Started by Joe DiIaconi in 1963/64 Cadillac Specific Discussion. Last reply by Tony and Ginny 429 yesterday. 8 Replies


1964 left hand (drivers side) headlight door lower trim (boomarang) needed

Started by Michael Francioni in Wanted to Buy yesterday. 0 Replies

Must be in good condition for show car or open to a good donor for rechoming but must be pit free. send info to along with pictures. Thanks...…...Continue

Blog Posts

1964 Cadillac Fleetwood sixty special / transmission dipstick needed

Posted by Pablo on September 20, 2020 at 9:57pm 1 Comment

How are you doing folks, I’m looking for a transmission dipstick, any info I will appreciated, thank you very much

1963 Cadillac hood driver side hinge

Posted by Steven on September 16, 2020 at 9:23am 1 Comment


 Does anyone know were I can buy a 1963 Cadillac hood driver side hinge or is there any other hinge that would fit? 



Bad Guage?

Posted by Karl Schwarz on August 26, 2020 at 3:08pm 5 Comments

So I am troubleshooting my fuel gauge issue. I bought a new sender and tested it. It  it goes from 1-ohm (empty) to 35-ohm (full). When I test it (outside the tank), when the float is in the up (full) position it only moves the gauge to about 1/2 full. When at the bottom (empty) position the gauge shows empty. This is the same issue I have when I fill and then use the gas in the tank - the gauge never reads ore than half full. Based on what I've read on this thread it would seem like the…



Posted by Fritz Seitz on August 11, 2020 at 2:35am 0 Comments

I have been working on a

Does anyone have suggestions?


  • Add Videos
  • View All

© 2020   Created by Jason Edge.   Powered by

Badges  |  Report an Issue  |  Terms of Service