On the dyno Friday (the first of 6 identical units), delivered Saturday, it's already in the car. A 406" SB based on a Dart block, Ross pistons, with 23 degree (235 cc-in house ported) Pro-Toplines, a Blue-Racer solid roller, Blue-Racer 1.6/1.5 Rockers, Eagle 4340 (internal) crank, 5.850 rods and a "nylon" timing gear set. Super-Victor and a 4500 Holley. 10.95 (measured) C.R. Runs fine on 93, customer will be using 100 unleaded for racing however. Made 580 HP @ 6600 and 523 Ft.Lbs. @ 5500. The main reason for posting these results is to show that the mfr's. are not always "right-on". The ring gaps
in this unit are .018" top and .013" second, with low-tension oil rails. There is no vacuum pump, nor are the Ross pistons anything special (e.g., no gas-ports, etc.), right from the box. The "quench" area is huge. P/Deck is .032" and Corteco head gaskets are .038". We have a total of 34 degrees timing for the entire test. No problems at all. Only requirement was 2.000" primaries, it wanted nothing smaller, this was the only other item (header size) we had time to test, in order to make the delivery schedule on time. Thanks, Gary in N.Y.
P.S. There are NO "fancy" parts in these units, everything from the boxes. The next ones up will recieve a bit more "flogging". 2 of the remaining 5 will see 6.000" rods. We see 600+HP (on 93) around the corner. The heads performed flawlessly. "Heads up" Rick in N.Y., These 400's will certainly be a "ride". Real nice combo!

It may work fine but why set it up at .070 quench and use a " nylon" timing gear set? It may work OK but I bet a smaller quench and a steel gear set would make me feel a little better about my engine durability. How come you put it together with those parts set up like that?

It may work fine but why set it up at .070 quench and use a " nylon" timing gear set? It may work OK but I bet a smaller quench and a steel gear set would make me feel a little better about my engine durability. How come you put it together with those parts set up like that?

We're very fortunate to be able to test all these units when we feel it's beneficial to us and our customers. We get to see what actually works or doesn't. Some areas of engine building, like the "quench" number or the ring gaps, etc., that many out there dwell on just don't "ring" entirely true with us. We feel they are not as important as many believe. I see many people here try to figure their "dynamic compression" ratios and actually pick the wrong cams out to be able to use a certain octane fuel. This doesn't work at all. It merely gives you the entirely wrong cam for the combination. As for the "nylon" timing set, I have the S363 crank gear, S362N (Nylon) cam gear and the TC495 chain in one blown 548" BB unit up here for 3 years now. This one has 700+ lbs. open spring pressure. It helps to isolate the engine/chassis harmonics (vibrations) from reaching up to the cam and roller lifters (both hyd. and solid). Plus it'll give you some add'l upstairs HP by retarding the cam (slightly) in the upper RPM range. The BB unit above makes about 1100+ HP, is in street-car that weighs in around 3850#, and runs 9.30's with street tires.
We don't install ANY parts that are not going to be able to "hang-out" for their intended duration, in other words, we know they will be in there until the "freshen-up" and will not be the cause of any repair. Thanks, Gary in N.Y.
P.S. Ross has a piston (#90458) in their catalog for a blown 350 that has a piston to deck clearance of .130". That works out to be a .168" "quench" when you factor in the head gasket. We have many of these units that have been done over 5 years ago and are still running fine. For "all-out" race units we do have a different set of rules however. Most of what we do here is for "high-end" street cars. Not all get the nylon, we leave that up to the customer, and we do freshen some of those up pretty regularly, at least every other season.

If you put the quench at .040 and opened up the second ring to .018 you probably would have seen 590-600.

Never heard of nylon gears... Hmm... where can I find a set on the internet to read more about them??

We're very fortunate to be able to test all these units when we feel it's beneficial to us and our customers. We get to see what actually works or doesn't. Some areas of engine building, like the "quench" number or the ring gaps, etc., that many out there dwell on just don't "ring" entirely true with us. We feel they are not as important as many believe. I see many people here try to figure their "dynamic compression" ratios and actually pick the wrong cams out to be able to use a certain octane fuel. This doesn't work at all. It merely gives you the entirely wrong cam for the combination. As for the "nylon" timing set, I have the S363 crank gear, S362N (Nylon) cam gear and the TC495 chain in one blown 548" BB unit up here for 3 years now. This one has 700+ lbs. open spring pressure. It helps to isolate the engine/chassis harmonics (vibrations) from reaching up to the cam and roller lifters (both hyd. and solid). Plus it'll give you some add'l upstairs HP by retarding the cam (slightly) in the upper RPM range. The BB unit above makes about 1100+ HP, is in street-car that weighs in around 3850#, and runs 9.30's with street tires.
We don't install ANY parts that are not going to be able to "hang-out" for their intended duration, in other words, we know they will be in there until the "freshen-up" and will not be the cause of any repair. Thanks, Gary in N.Y.
P.S. Ross has a piston (#90458) in their catalog for a blown 350 that has a piston to deck clearance of .130". That works out to be a .168" "quench" when you factor in the head gasket. We have many of these units that have been done over 5 years ago and are still running fine. For "all-out" race units we do have a different set of rules however. Most of what we do here is for "high-end" street cars. Not all get the nylon, we leave that up to the customer, and we do freshen some of those up pretty regularly, at least every other season.


I don't understand you worrying about the hormonics vibrations reaching the cam and lifters but could care less about the quench area which benefits much more potential power gains. I have seen numerous times what a .037" quench area does for an engine and the ring gap certainly plays more role than your gjving credit for. Quench does get a little less important on blown engines but it still plays a part.

Thanks, Gary. Interesting post!

Quench is still important on blown engines as well. I am talking pump gas blown engines. Now as far as power output it might not make a huge difference, but as far as trying to keep them alive while running on less that great fuel (in my case 91 octane) you need all the insurance you can get. I know this is part of the reason I am able to run 12lbs of boost on 91 octane (roots blower)/w 8.47:1 compression. Most will say you can't do it.

I am not sure I foolw what this fpost was/is supposed to support or mean? If the nylon gears are the same style or make that came stock on GM vehicles over the years, I wouldn't put those in a lawn mower let alone a performance build. I have seen the fail WAY too many times. I am hoping there is another "better" quality one that is being pushed here. As far as ring gaps, are you saying bigger is better or that it just doesn't make much if any difference? If that is the case there is not need to change from the manufactures specs which is what should be followed anyways.

Are you saying the engine made more power than it would if the quench was tight and the ring gaps were tighter? Does it make more power because of the nylon cam gear? Or are you just saying the engine will stay together for a year with a nylon gear?

As far as the harmonics with a blown engine a lot of it is taken up by the 3" rubber belt. This is why you can get away with running a crank hub in place of a dampner. In some case this is even a smarter or better choice.

I am just unclear as to what this post means or is trying to prove.

I believe this post is an FYI. They received a group of engines and did some pulls. Told us how they were constructed and what parts were used and want would not work.

I can see using a nylon cam sprocket to eliminate 3rd & 4th order harmonics from transferring from the camshaft to the crankshaft and vica versa. Also, makes less noise than a steel set-up. Compare the nylon sprocket to the subframe bushings, when rubber was there, you didn't feel the road noise. Now, replace them with alum bushings and all of a sudden, its noisy inside.

Same principle applies. However, this is not to say I'd run right out and replace my steel set-up with a nylon setup, not just yet anyways.

You can get nylon sprockets from your local dealer.

Everett, only one engine was tested (or the results given). Who's to say that same engine with metal gears wouldn't have produced the exact same performance, see my point? There were no comparissons. I have no doubt nylon gears will "work" they came that way from the factory for years. I am sure they absorb some of the noise as well. The question I have is what is the trade off? If it doesn't make any more power, then why use a weaker component. See where I'm coming from? If it makes 5 HP difference is that worth the trade off? Depends on the use of the engine/vehicle. For my street cars there is no way I would use nylon. Hot oil for extended periods of time makes the nylon brittle (unless they have come up with a better nylon). How many oil pump drive shaft sleeves have you found in the bottom of the oil pan? (I have never pulled apart and engine and found one still in place), they always get brittle and crack into pieces. The same goes for plastic/nylon timing gears. I guess for race only applications it might be ok if you monitor it closely. The problem I have is I don't know the reward, but I know the risk. A timing gear failure can cost you an engine, heads, or both.

I don't doubt the results I just don't see any back to back tests to prove either way, that the ring gaps, quench, and/or timing gear made a difference. Maybe I am mis-understanding the point?

Is it just that with those parameters he was able to make XXX amount of power? Is that the point? If so, OK?

99% of your NHRA Superstock/Stock engine builders use the nylon timing gear sets as dyno test has proven they do make more horsepower/less harmonics, ive even used them on dragrace only engines with zero failures, as a matter of fact they looked just like new after 150 to 200 quarter mile passes. I understand people being afraid of them after seeing them fall apart in every day driven street engines however thats usually after 100,000 miles or more.

I am not questioning the harmonics, but how much more power? What RPM does a Superstock/stock engine turn? In these cases every 1/10th of a HP is important. My point is how does this apply to the typical engine on this site? Most of the street strip engines are not seeing anywhere near the RPM of Super/Stock engines so the benefit will probably be very tiny if any at all.

150-200 1/4 mile passes is only 37.5-40 miles. Why not run them longer? Like I said on a race only engine I can see it, not on a street car.

To your competitive NHRA Superstock/Stock racer 5HP makes a big difference because they way they approach things is 5HP here, 5HP there adds up and that may make the difference in winning or losing a heads-up race in National Event competition, as stated ive run them a complete season 150-200 runs and when freshining the motor up at the end of the season they looked like new and even used them again with zero failure/problems.