350 TBI tows 5000/6000lbs

[donforeman]

Very pretty work there! No use doing that to my van head, but very nice anyway. I looked up the eq ch350c heads, very nice and have some upgrades over the factory castings. They have stainless valves in the assembled version and are priced about the same as the GMPP heads. Are they a true 170cc port? Some list it at 176-178 not 170. I am not an expert at this stuff at all but I think for my use, smaller is good. Jegs has some of their brand vortec heads on sale today.

I do appreciate the help.

[Carnut1]

Very pretty work there! No use doing that to my van head, but very nice anyway. I looked up the eq ch350c heads, very nice and have some upgrades over the factory castings. They have stainless valves in the assembled version and are priced about the same as the GMPP heads. Are they a true 170cc port? Some list it at 176-178 not 170. I am not an expert at this stuff at all but I think for my use, smaller is good. Jegs has some of their brand vortec heads on sale today.

I do appreciate the help.

Thanks, I did the quickie porting but not the cc ing or measuring of port lengths etc. Marvin did that for program inputs. If they fit the budget and you don't mind some timing tuning I think they would be a nice head for your project. I am not sure of the port cc before or after cleanup. I removed very little and they responded very well.

[Carnut1]

Even stock I am sure the Eq vortec has a flow advantage over the 193's ported and the Eq has the sweet vortec chamber. I was very impressed with that casting, it was about as heavy as a Chevy bowtie I ported the same day but better flowing. Thanks, Charlie

[donforeman]

OK thank you very much for the information. I will buy heads today instead of messing with the 193 castings. I just watched a video by Brzezinski where he went over the EQ vortec head and did mention the larger intake volume and said that may be an advantage or disadvantage, but had a lot of praise for the longevity of the casting.

[Carnut1]

OK thank you very much for the information. I will buy heads today instead of messing with the 193 castings. I just watched a video by Brzezinski where he went over the EQ vortec head and did mention the larger intake volume and said that may be an advantage or disadvantage, but had a lot of praise for the longevity of the casting.

Cool, I am sure someone on ST has timing curve input so those new heads do just what you want with no downside. I would still do some cleanup on the vortec tbi manny and ported throttle body. Thanks, Charlie

[cardo0]

Pretty cool you are sharing all this with us as many of us have towing needs. I love that RAMJET cam and believe its just what you should use for it's torque and value. And I like that eldelbrock intake also. Myself I don't think you need much more head for what you are trying to do with them and definitely not larger runners. Just a good valve job and thinner shim gaskets is all I would spend on that. Unless you can find some aluminum L98 corvette heads.
Sometimes a secound gen LT1 exhaust manifold will work where a ram horn won't and they flow just as good - all kinds of those sitting in the junkyards.

Good luck.

[donforeman]

Thank you for the advise. I don't want to get anyone too excited. Basicly the ramjet cam is just a tighter lc version of the stock roller and the vortec heads are just that. I think the 96 engine was rated at factory rated at 260hp. Mine I think is 190ish now. It for sure will not set any records but it's an improvement over what is there and the van is in very good shape so it's worth putting a little time and money into.

[Carnut1]

Thank you for the advise. I don't want to get anyone too excited. Basicly the ramjet cam is just a tighter lc version of the stock roller and the vortec heads are just that. I think the 96 engine was rated at factory rated at 260hp. Mine I think is 190ish now. It for sure will not set any records but it's an improvement over what is there and the van is in very good shape so it's worth putting a little time and money into.

I made the mistake of too narrow lc on a tbi engine once. Has this cam been used on tbi engines with no issues before? It is a small cam so the map sensor should have plenty of vacuum. Just thinking of possible issues. Thanks, Charlie

[donforeman]

Yes its been used with tbi a lot, not a no brainer, it takes tuning and some have failed, but more get it to work. With chip changes, mostly dialing in the fuel, raising the idle speed a little and more timing at idle. The short duration helps it.

[dfarr67]

I did not read the whole thread, do a search on fast355/fast305, he really made these tbi's go.

[levisnteeshirt]

i have a 95 k1500 350 5 speed ,,, set the valve lash ,, factory is way tight , i gave em 1/8 turn past zero hot idling , i could feel a difference ,, some had over a full turn of preload ,, the spacer that sits under the factory air cleaner has to go ,,, its function has to be to limit power ,, could do away with the tube going to it and put a breather on that tube from the valve cover ,,, placing the air filter straight on the TBI i also felt a difference , no doubt ,, i gave it about 5 degrees more initial timing ,,, I recently put mid length headers on it with the Y pipe for the headers and gutted the converter ,,, i also put the 1in open spacer on it ,, the spacer seemed to do more than the headers ,,, i put one of the 18 psi springs in the TBI ,, huge difference but i could watch the gas gauge fall so i took it out ,,, i think my engine is a little tired since the headers and cat gutted didnt seem to do much ,, but i had on it before 2 resonators from summit after the cat ,, it sounds good and not loud even after gutting the cat ,,, i have a pair of HO 305 heads I'm gonna try on it ,, might do an in frame rebuild if i pull the heads and the holes all look good

[gmc406]

i have a 95 k1500 350 5 speed ,,, set the valve lash ,, factory is way tight , i gave em 1/8 turn past zero hot idling , i could feel a difference ,, some had over a full turn of preload ,, the spacer that sits under the factory air cleaner has to go ,,, its function has to be to limit power ,, could do away with the tube going to it and put a breather on that tube from the valve cover ,,, placing the air filter straight on the TBI i also felt a difference , no doubt ,, i gave it about 5 degrees more initial timing ,,, I recently put mid length headers on it with the Y pipe for the headers and gutted the converter ,,, i also put the 1in open spacer on it ,, the spacer seemed to do more than the headers ,,, i put one of the 18 psi springs in the TBI ,, huge difference but i could watch the gas gauge fall so i took it out ,,, i think my engine is a little tired since the headers and cat gutted didnt seem to do much ,, but i had on it before 2 resonators from summit after the cat ,, it sounds good and not loud even after gutting the cat ,,, i have a pair of HO 305 heads I'm gonna try on it ,, might do an in frame rebuild if i pull the heads and the holes all look good

You are in desperate need of a custom tune. Then everything would come together. The stock computer can only learn so much until it needs a tune. Especially when you change the springs in the TB. It was running to rich.

P.S, I don’t think there was any need to swap springs in the first place. Before I went to my 406, I had my 350 with Eddy heads, mild Comp cam, headers, etc.... I was still running stock TB, with stock injectors, stock fuel pump and stock fuel press. All I had was a custom tune to pull it all together.

[pdq67]

Well, what's going on here?

How is it turning out for you?

It's funny that GM's old stock little-bitty -929 hy-cam was used in every base low compression V-8 made back then from the lowly 283 to the big 400 carbed engines. Heck, my bought new '67 Camaro's 350SS engine had one in it!! About 10 to 1 CR, 295hp/380T L-48 engine...

Get your CR up to as close to say 9.5 to 1 as you can get it and if you want to, use Felpro's #1094 .015" thick steel shim head-gaskets by installing them with good old messy Indianhead Shellac Gasket Cement. Then torque a couple of times after some heat cycles.

Oh, and while you have her apart install a pair of old-fashioned 64 cc heads on your, I figure, dished pistons to make her breath better.

Keep the TBI if you want to tune it and make sure it isn't choked down from the factory anywhere, otherwise no more than a good old E-Brock 2101 Performer intake and a stock early 350 Q-Jet will do nicely, As always, jmho.

One last point is you might hunt up, (Oklahoma), Travis and chat with him because he is into this stuff big-time! if you do, say hello to Travis from ol' pdq67..

pdq67

[Newold1]

donforeman

I think you have made some pretty good choices getting to this point and there are very few ways to improve the "TOW" unless your changes really add torque in that 2000-3500 rpm ranges as that is probably where the engine is going to be 80-90% of the time when towing. Torque increase is what will really benefit the towing times and I think you changes and additions with a "good" retune will net some decent torque increases it is just where will the torque increases occur in rpms and how much additional torque will be at those rpm ranges.

I have not seen a lot of discussion here on exhaust modifications and I know you want to stay with the stock manifolds for heat and fitment reasons and that's OK, but from the head manifolds back there is also a few nominal changes that can add some power and torque in those lower ranges as long as they don't lower the back pressure to much. Yep that's right keep a little backpressure. Not sure what the existing system is but a decent dual exhaust of about 2" max. size and some nice full size mufflers with good (non drone) flow with an H-pipe before them will help also.

I have built a lot of tow truck vehicles over the years , all chevy based and I can tell you, based on towing terrain and engine size, almost every time we went for a just power increase versus low rpms torque, the towing was not greatly improved and the gas mileage tended to go in the toilet. We learned also that everytime we went for a big small muffler larger pipe,straight thru exhaust system the low and mid rpm acceleration and torque dropped and a lot of these systems created so much drone in the van or pickup w/shells that at most highway speeds they drove you crazy on longer runs.

Another place we gained mileage and efficiency was getting rid of oversize heavy tread type tires. When we used fuel saver tires like those from Goodyear Advantage type with a definite highway tread and air pressures up around 45-50 psi. These tires also were much quieter at highway speeds.

I am assuming you've got a added transmission cooler as towing with a higher frontal area van and box trailer will tend to over heat the fluid pretty quick and eventually toast the transmission. (also when your not expecting it!). I am also a big believer in some of the new synthetic transmissions fluids available.

Just thought I would throw some of theses ideas, thoughts and experience out there for you to consider. I have towed way to many heavy trailers way to many miles over my years! I wish todays diesels were available back then because looking back that's how I would have gone on most!
I as well as others here are waiting to hear back how your changes have helped. Hope you have great results!

[HDBD]

When I used to tow a large trailer, about 10k loaded, nationwide with a half ton hd 92 chevy I had a roller cam (ramjet) 383 tbi low compression and I used a whipple supercharger under driven to just 3lb boost. Worked well once the transmission issues were sorted. I did ultimately lose the thrust bearing in the motor which has never been on my radar on a SBC before so lost interest and bought a dually with big block. Never knew what took the thrust out.