Trick Flow DHC 175 heads.
 

Has anyone tried the new Trick Flow aluminum double hump heads?

I’ve been running them on my 61 for about a year now. Car runs well, and I’m very happy with them.

Drothgeb

Did you notice any improvements in performance? What was the reason for new heads? Were these installed on stock motor?
Thanks
Terry

I bought them to increase the compression ratio and generally improve performance with the original engine. Ended up building a fresh 350 for the car instead, so I can’t comment on a performance increase. They should perform similar to other aluminum heads with similar flow (255/207 iirc). The CNC’d chambers look nice, and I was able to run almost 11:1 and 36 degrees of timing without a knocking (DCR was 8.7:1).

Unfortunately, that 350 had an oil leak from a hairline crack by the cam plug. Sooo, I pulled that engine and just finished building a 383 replacement. Just bolted the heads on yesterday, and will be installing the engine today. Originally, I was going to buy the heads without the accessory holes, just for the look. But in the end, I bought the ones with the holes. They make great attachment points for the engine hoist.

https://cimg7.ibsrv.net/gimg/www.cor...4abd928477.jpg

Do you feel that there has been a substantial increase in performance? I recently ordered a pair from Summit, but have had second thoughts about installing them. Finding performance comparisons between original heads and Trick Flows has not been too successful. I had my L79 rebuilt three years ago an I'll have to say that it has been running great. A little extra would be nice though.

That is a nice looking engine, set to go into a very nice car. I did not see this post until I had posted my questions. :thumbs:

Drothgeb,
What CR will you now have with the 383?

Keep in mind the Trick Flow heads only have 60cc combustion chambers. That makes them a great choice for 327 and 350 engines with flat top pistons. But, if your l79 still has dome pistons, I don’t think they are going to work. If you switched to flat tops during the rebuild, then they would work well. Considering flow is about 25% better than the stock double hump heads, I would expect you’d see noticeable increase in power.

With 12cc D dish pistons, I’ll have 10.7:1 static, 8.56:1 dynamic. Cam is 225/225 .560” lift w1.6 rockers.

I have the original style Speed Pro domed pistons. Would there be clearance problems? Too much compression?

Probably both

Original non-2.02 461 heads were 62 cc's, not much bigger than these 60cc chambers. The GM unshrouding machine work on 2.02 heads added 2cc's, increasing to a 64cc chamber. A compression ratio calculator will tell you the difference of 2cc's is about 0.41-0.50 in static CR in a 327 (not much, about the same change as the factory 0.012" variations in deck height between broach cutting tool changes, and less than the CR change when GM decided to double the 0.018 head gaskets in 63).

Running a factory cam with less than 0.500" lift is not likely to have valve clearance problems, but checking the clearance during the assembly should always be performed with a known thickness head gasket (or none, and add in the gasket thickness).

The cam intake valve closing point will likely have more of an effect.

^^^
Id run them in a hot second, it will be night/day difference. Run a more modern cam to take further advantage!
60cfm is huge....

I’m not sure if the Speed Pro’s dome will actually fit inside the Trick Flow’s combustion chamber. Certainly worth a check. If there is any interference, things could be adjusted with a Dremel.

On a 327 set to a .040” quench with the 5cc domes, CR would be in the upper 11s. With the L79 cam DCR is around 9:1, thats pretty high for pump gas with full timing.

Check my thread from last year titled “Roller Cams”. I changed out stock L79 heads and a Comp Cams 268H cam to the Trick Flow heads and a custom roller cam. I picked up 40 rwhp. The block had flat top pistons. I ran the thin ss head gasket. After tuning on a dyno we ended up with 302 rwhp. That’s puts the crank hp in the 370 range there was a nice bump in the torque as well. The engine pulled strong past 6k and was a blast to drive.

Last summer the engine acted like it had a blown head gasket, we removed the heads and found a cracked block. I replaced the engine with a Blueprint 383/430hp last October. I am still sick about loosing the original engine but life goods on. I have really enjoyed this 383. In my opinion the Trick Flow heads are a great mod for a 327, that’s running flat top pistons. I would run the .40 head gasket if I was doing it again.

Also, the 302 rwhp was made with ported 2 1/2 inch manifolds pulling a 7 blade fan and an ac compressor.

That sucks about the cracked block, I know how you feel. Did you move the Trick Flow heads over to the 383?

Well, I am am discouraged, but not terribly. I was hoping to keep everything in a stock configuration other than the look-a-like heads. Push rod length and valve clearance were going to be checked and that was about it. As I noted earlier, the engine has been running extremely well. Guess I'll leave it the way it is.

The shop that did my work wanted the heads so I sold them as a credit on my bill. I don’t think the heads would work all that well on a 383 so I bought the long block and used my manifolds, dizzy etc. I am running my AED 650 on it and it runs extremely well. We had to rejet the carb but it was a pretty easy change over. I have to stay that given the choice between the two engines, the 383 wins hands down. It dynoed at Blueprint at 442hp and 454 torque.

Your calculations are a bit high for a L79 with the 5cc dome (.125" dome) pistons and 60 cc chambers. Speed Pro lists the CR at 11.2 with 58cc chambers, and I get the following with typical stock 0.012 deck height and a FelPro gasket:

https://cimg2.ibsrv.net/gimg/www.cor...a422dc3d0b.jpg


The DCR with the L79 cam is under 8:1 and very reasonable.
https://cimg3.ibsrv.net/gimg/www.cor...b84bf0444b.jpg