Bad Combo?

[Old77]

What is the benefit? That'll make me have to get access to a welder which I do not have.

My cousin does work like that on the side and he's just up in Independence. He could do that for you pretty quickly for a very reasonable price.

 

[RangRayy]

My cousin does work like that on the side and he's just up in Independence. He could do that for you pretty quickly for a very reasonable price.

Very good to know I will keep that in mind. That'll have to be done before the mufflers so maybe I figure out where they will be and then get a pipe(s) accordingly.

 

[rich weyand]

What is the benefit? That'll make me have to get access to a welder which I do not have.

The exhaust pulses do not alternate sides. The pulses from right and left sides go as LRRLRLLRLRRLRLL, so the left side exhaust is L--L-LL-L--L-LL-L and from the right, same thing. When that double pulse occurs, the H-pipe allows the overpressure to vent to the other side and vice versa. Increases low-end torque.

You can buy the pieces to clamp in to a DIY setup.

http://www.jegs.com/i/JEGS/555/3065...9&cadevice=c&gclid=COealOW72ccCFZGMaQodGh0O5g

 

[Joe383]

Make sure when you connect your vacuum advance hook it up to the passenger side front fuel metering block half way up the metering block. Don't hook it up on the bottom part on the throttle plate. You only want it to advance under a load when the throttle blades are open. Honesty if it was me I would just get a factory roller cam from a vortec motor from the junk yard. I did this for a low out put 5.0 ford once and swapped to the HO 5.0 roller cam and everything cost me $100. The vortec set up should be about the same. There is no cam break in. I would still do valve springs with any cam swap. You also have to use a factory roller cam timing chain with it. If you decide you want a larger cam later you can reuse your lifters. Could also use the ram jet cam if you want a little more power. I think it is around $175. Either way if I had a roller compatible block I would not use a hydraulic flat tappet cam. I would also use the performer EPS intake. I have had a few performer intakes and 2 performer EPS intakes. I like the EPS more. It makes more power. I know you would like to use a Q jet but if it was me and you wanted something that is good on gas I would look at the Street demon 625 carb. Q jets are great tell you get a cam that they don't like. Tuning them for performance is a little bit of a pain. If you do use a Q jet don't rebuild a used one. Get one that's remanufactured. Every Q jet I have ever had has had at least a little bit of slop in the primary throttle shaft.

 

[Old77]

The exhaust pulses do not alternate sides. The pulses from right and left sides go as LRRLRLLRLRRLRLL, so the left side exhaust is L--L-LL-L--L-LL-L and from the right, same thing. When that double pulse occurs, the H-pipe allows the overpressure to vent to the other side and vice versa. Increases low-end torque.

You can buy the pieces to clamp in to a DIY setup.

http://www.jegs.com/i/JEGS/555/3065...9&cadevice=c&gclid=COealOW72ccCFZGMaQodGh0O5g

This is awesome! I'd always heard that the H-pipe was the way to go but had never heard anyone explain it like this!

 

[RangRayy]

Make sure when you connect your vacuum advance hook it up to the passenger side front fuel metering block half way up the metering block. Don't hook it up on the bottom part on the throttle plate. You only want it to advance under a load when the throttle blades are open. Honesty if it was me I would just get a factory roller cam from a vortec motor from the junk yard. I did this for a low out put 5.0 ford once and swapped to the HO 5.0 roller cam and everything cost me $100. The vortec set up should be about the same. There is no cam break in. I would still do valve springs with any cam swap. You also have to use a factory roller cam timing chain with it. If you decide you want a larger cam later you can reuse your lifters. Could also use the ram jet cam if you want a little more power. I think it is around $175. Either way if I had a roller compatible block I would not use a hydraulic flat tappet cam. I would also use the performer EPS intake. I have had a few performer intakes and 2 performer EPS intakes. I like the EPS more. It makes more power. I know you would like to use a Q jet but if it was me and you wanted something that is good on gas I would look at the Street demon 625 carb. Q jets are great tell you get a cam that they don't like. Tuning them for performance is a little bit of a pain. If you do use a Q jet don't rebuild a used one. Get one that's remanufactured. Every Q jet I have ever had has had at least a little bit of slop in the primary throttle shaft.

I get the idea of roller but I am not sure that I want that for this build. Now on my '51 gmc rat build yeah I'll do that, the block I have for it is setup for roller as well.

I had planned on getting the street demon 625 carb. I've started pricing everything while also looking on Craigslist for local deals but nothing is out there for my needs

 

[RangRayy]

This thread has gotten lengthy and filled with great information but I know I'm not the only one out there that's has thought about or wants to do a TBI to Carb swap. I just want to cover all the bases so there's no confusion in this kind of swap. We've covered intake, carb, cam and lifters, ignition and exhaust. All that I can tell is left is fuel supply and management.

I know a fuel pressure regulator helps supply the right pressure for the carb with the in tank tbi fuel pump. I read that on some of these 87-95 blocks they have the blocking plate for a mechanical fuel pump and some do not. Is this true? I looked at my block and I have a plate and assumed that all blocks had the provisions for a mechanical pump due to them being casted all the same just did not have the innards. I could be wrong.

But if I am able to use a mechanical pump why wouldn't I? I could get away with no regulator and ditch the inside electric pump.

Thoughts? Also should I get an Air/Fuel gauge?

 

[MikeB]

I get the idea of roller but I am not sure that I want that for this build.

You may have mentioned this, but does your engine currently have a roller cam? If so, you can buy a GMPP HT383/RamJet 350 roller cam for around $170. (I actually bought a new take-out for $120.) More than likely, your existing roller lifters are fine to re-use.

That cam, or even a stock 96-00 truck roller cam, has a lot more area "under the curve" than a flat tappet cam, even one with more duration. That makes for a wider power band, typically 300-500 RPM or so. And you don't have to worry about cam break-in, or using oils with high ZDDP levels.

 

[RangRayy]

You may have mentioned this, but does your engine currently have a roller cam? If so, you can buy a GMPP HT383/RamJet 350 roller cam for around $170. (I actually bought a new take-out for $120.) More than likely, your existing roller lifters are fine to re-use.

That cam, or even a stock 96-00 truck roller cam, has a lot more area "under the curve" than a flat tappet cam, even one with more duration. That makes for a wider power band, typically 300-500 RPM or so. And you don't have to worry about cam break-in, or using oils with high ZDDP levels.

I don't believe it is a roller stock I haven't checked yet. I'd be willing to bet it isn't but just has the provisions for it. My only issue is if it's not roller going roller adds more expenses. Although there is peace of mind with out having to break in or use special oil. I had forgotten about all that so maybe I retract my statement. I haven't bought any parts yet still waiting to see what this next contract yields which is up on the 15th of this month. All my money is tied up in case we strike.

 

[Joe383]

Going roller is easy. It is a little expensive if you get all new stuff but I would not hesitate to use old roller lifters. I would just go to the junk yard and pull the whole roller assembly out of either a vortec 350 or an LT1 from a early 90s Camaro. Or just take the roller lifters, spider hold down, lifter guides, cam retaining plate out of a motor and then get a new cam. If your going to go with the Street demon I would recommend the Edelbrock EPS intake its a killer intake. The only problem with a factory roller cam is it wont have a fuel pump lobe on it and if you use a factory roller cam or a GM cam like the ram jet cam you have to use a different distributor gear. The GM cams like the ram jet and LT4 also require a bronze tipped fuel pump push rod if you go that rout. I have a Comp cam in my 350 and I can use normal parts with. A good roller cam will yield better performance. I will never use a hydraulic flat tappet in a roller block again. If you could run a normal fuel pump that would be great. You want about 6PSI like preferably. You could get away with a pump with 4-7 but I know at least edelbrocks are designed for 6 PSI. They will work fine out side of this but it is what they recommend. I had one that was being fed with a 4PSI electric pump that the last owner had installed and it was just fine. I know your not planning on a large cam or nothing but if you do go with the street demon carb it dose state its not designed for a cam with over 220* 0.050 and a LSA at least 110. You could go tighter on the LSA if it was a smaller cam I am sure but they are pretty much saying don't use a street strip cam with the carb. Although tight LSA usually yields better peek torque I would look for something in the 112 LSA range to give a wide power band and a smooth idle. Also if your looking for a cheep HEI my neighbor has the summit street strip HEI in his Camaro and it works great. I think it is around $90 new which is a steal. I might get one for my vortec motor if I decide to run HEI.

 

[MadOgre]

The problem is that no roller cam has a torque curve from off idle. All roller cams are from 1500 RPM up.

You will find that a lot of blocks from 87 up have the cast in fuel pump boss and a cover sometimes, but when you remove the cover most likely you will find that the area is cast in. So you would have to have a machine shop bore the pump push rod for a mechanical pump. Also most Roller cams do not have a provision for mechanical fuel pumps.

The vacuum advance connects to full manifold vacuum which is the lowest vacuum port on the carb! I have fought with Rich about this before and Rich is correct that full manifold vacuum is what you use for a non smog setup for vacuum advance.

The H pipe being as far rearward as it has to be on a 4wd truck loses a lot of its effectiveness. It does however add to a better sounding exhaust. The real advantage of a cross pipe is found when installed right behind the collectors usually crossing as an X or H below or directly behind the transmission pan.

The X is supposed to help increase exhaust velocity by sucking kinda like a venture effect over the empty exhaust side. where as the H pipe is more for pressure equalization. Anyways the closer it is to the collectors the more effective it becomes in doing its designed purpose.

This venture effect is why a single exhaust with a Y pipe increases low end torque for small displacement applications. Larger displacement applications find that the single exhaust just becomes restrictive and that out weighs the benefits of the single Y.

 

[MadOgre]

The junk yard cam swap is a good idea for roller engines! The only problem would be finding one in good shape and obviously finding one that is a performance grind. But otherwise a good idea for on the cheap performance.

Though sometimes its invaluable having a cam card to reference when adding other engine components.

 

[MadOgre]

You can not retro fit the newer roller assembly from a roller block into a non roller block. The block is cast differently to accept the factory roller assembly. If you want rollers in a non roller block you have to use a roller conversion kit where the rollers are tied together.

The roller blocks are cast with a flat pad around the lifters and a raised area in the center of the galley where the tension plate bolts to. These blocks do not have provision for a mechanical fuel pump.

 

[RangRayy]

Pictures of what you're talking about on where to hook the vacuum advance?

 

[RangRayy]

The roller blocks are cast with a flat pad around the lifters and a raised area in the center of the galley where the tension plate bolts to. These blocks do not have provision for a mechanical fuel pump.

So best to stay with electric for now. But why is there a plate covering it if it's just a casting?