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Thats a nice improvement. Fluctuation could be a small leak or a valve too tight or may just be that cam.. Diagnosing with the internet crystal ball is tough, good luck
After beating the vacuum issue to death I narrowed the leak down to #4 cylinder. Checked everything twice but still no solution. Pulled the intake and the gasket was stuck on pretty well except on the lower part of #4 intake. Sooo I'm hoping I found the problem. Haven't put it back together because I decided to pull out the old DANA rear end and install a 9". Of course shackles were shot so I'm having to install everything new except the springs themselves.
That's a big step in the right direction. Next time you have it off, add a radius for the transition from the carb to the ports and give it a port clean up. You can take it farther than that with a gasket match but if the heads have not been given the same treatment then it won't be worth the time.
If you have room, try a 1" or 2" 4-hole or divided spacer. Don't use an open spacer and don't spend a fortune on one of those fancy tapered spacers which are like a 4-hole on the top and open on the bottom, unless you simply want to try it.
Thanks Charlie. I did radius the ports and did a little cleaning up but didn't port match the intake and heads. I did however clean up and match the exhaust ports on the heads. Once I get it running satisfactorily I will install either my Ram Horns or Sanderson exhaust manifolds and add dual exhausts.
The Sanderson headers may be better for power. I'd get those installed and if you want to use the rams horns in the future, you can have a pipe made that will join up with the existing pipe for the headers.
Gasket matching the exhaust is something that will help with a better set of headers but nothing currently available for a truck will allow you to take advantage of it. The inner perimeter of most exhaust gaskets is larger than the id of 1 1/2" tubing so effectively, the port in the header is smaller than the port in the head. You can address that to a small degree with headers but since it is not a big heavy casting, you can't remove too much material to help the transition.
This is why i say the Sanderson headers may be better. Port matching the rams horns may allow them to equal or better the Sandersons.
Have a look at this thread if you have not already, Exhaust test to end all tests? Lots of great exhaust info relating specifically to Y-Blocks.
In that thread, you can see that the Sandersons are worth about 10 average hp and 12 average ftlbs over factory, unmodified rams horns. That's on an engine that is about 300hp, with heads that are mildly ported.
Thanks for the info Charlie.
Another reason I haven't installed Sanderson's or Ram Horns is I haven't figured out what to do about the exhaust system. I'm not a kid anymore and don't want to have the exhaust droning especially while cruising. Don't mind a little noise if I get into it hard but not shaking and rattling my windows I've read that cross pipes are not cool on Y Blocks but that's contradictory to what I know for other engines. If I had to say I'd like a deep rumble. Not sure if that's doable with a Y-Block.
Cross pipes are fine. The reason a lot of Y-block people don't like it is because it's not the way it was done in their youth and a cross pipe does change the sound from the "Y-Block sound"
An H-pipe is tested in the link I provided. I don't know of any reliable testing that has been done with a Y and an x-pipe.
I have Red's stubby headers, very similar to the Sanderson offering, 2 1/2" pipe from the header to the tail pipe, with an X crossover and Hooker Aerochamber mufflers. It is quiet enough that you can talk and retain your hearing on the highway, has a good low rpm rumble, and nice wide open sound.
Some samples below. Keep in mind this is low end, built-into-the-camera sound recording quality, and on a higher performing engine. As a result, I think the 1st two sound a little more muffled and not as crisp and yours will probably be a little quieter overall, if you did everything the same because more power tends to be louder.
That's just the type info I was looking for
Just gotta settle on a muffler now. Too bad someone doesn't have a post of Y Blocks with different mufflers. It wouldn't be exact for your application but it would give a Y Blocker some in site.
i have a ramshorn on the pas side,easy to hook up pipes,on the drivers side i took the pas side manifold,blocked the cross over with a home made plate.this alowed a nice long bending pipe miss the clutch linkage and oil filter,as well as the toyota steering box.the manifold looks like it was made for easy duel exhaust inst. also i moved the engine over to pas side 2in.(inst a 292 into 48 merc with a 4speed od from a grenada. aways from the road,but 1 day .do not know how to do pictures so gave up on that performance, cliff in surrey BC
Cliff,
Pretty easy to post pictures now. Just hit the little icon that looks like a picture and it asks if you want to take a picture or use one you already have on your computer. Much easier than it use to be when you had to put them in a photo app (like photobucket) and then paste the URL in the blank.
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I've read that cross pipes are not cool on Y Blocks but that's contradictory to what I know for other engines
. If I had to say I'd like a deep rumble. Not sure if that's doable with a Y-Block.
