Low Budget 350 Chev - Page 5
This section is a little out of order as stated on the last page, but while searching for information on the web I came across a manifold manufacturer I had not heard of before. Their product had me interested as it would most certainly produce more horspower than my old single plane manifold I had for the budgie.
It didn't take much to find out who imported these manifolds and a few phonecalls the next day found a dealer with stock.
The manifold I was rather interested in was one that looked very similar to a Victor Jr which looks similar to Chevy Bowtie manifold. The manifolds were cast using a new process that is completely different than traditional sand casting. They are supposed to be more accurate castings due to the fact the molds are made of steel and virtually eliminate core shift.
The model I settled for came in two options, std cast or full polished. The cost difference here in Australia was minimal so even though there was no need, nor no power gain in using the full polished model, I opted for one thinking maybe if it turned up as a dud, at least it may sell quicker at a swap meet if it was shiny!
On first inspection the manifold looked OK, it was polished as well as I have seen around here but I wouldn't say it was as good as stated on the box "Fully Show Polished". If you wanted a show polished finish, how it came out of the box would definitely be a good starting point that would save a lot of time. Anyhow the shine was not the reason I purchased the manifold..
My existing 307 Chev engine in the Altered only uses a dual plane manifold suitable for a street car. The reason being the 307 (short stroke) does not make a lot of power mid range and a dual plane manifold helps keep power a bit lower. With the new 350 engine I hope to make power in the mid to high rev area, and with the extra cubes it will breathe a lot more than the 307 cubes. I did have a basic single plane manifold that could have been utilised but the air gap type single plane manifolds are known to be good for making horsepower in the mid to upper RPM area. Besides they look more like a race manifold than my old single and dual plane manifolds..
The new manifold ports appear to be a good starting point for port matching as well as there is a lot of material around the ports to allow for port matching. The company states they are intentionally left a bit smaller at the head face to allow for port matching. There were also additional threaded holes at the rear of the head water ports to allow coolant to be plumbed across between the two heads. Seemed like a good idea to me for anyone with a circulating coolant system.
In summary, without the convenience of a flow bench or dyno these manifolds look quite presentable, and for a high performance street machine or a budget race car, they would provide more than acceptable service and value for money.
It looked that good compared to the manifold on the existing 307 Chev, that I thought I might as well waste a pair of gaskets and put it on the Altered for the last race meeting of the season. It may not work too good on the little cube engine, and may even slow it down a bit, but what the heck it sure looks the part!
I dropped the manifold and the carb off to get a new water neck made up (It doubles as the front mount of the air scoop) and it came back polished from the shop as well.
The whole setup, with the carb mounted on a 1" spacer, and the new polished water neck was that flash, that before I knew what I had done, I was standing back admiring it mounted on the engine in the Crisis Altered.. I even forgot to take some pics of it before fitting it to the old engine so I have posted some I took when I remembered,
We race in two weekends time, so I will post the results in the sidebar after that weekend.
Next in the series.. Preparing & rod clearancing the block.
Other pictures of the intake manifold can be found in the Crisis Altered Photo Album as well as a large pic of the engine suitable as a background for your desktop.
The results from simply changing the manifold were surprising. I did not expect it to work too well on the 307 cubes with no compression. Remember it was purchased for the 355 cube engine so velocities would be down a little etc.
Anyhow the car ran a personal best of 10.28 @ 135.23mph almost 2 tenths quicker! Now I am wondering what the 355 will run..