270 Hemi Cam Modification & Timing Set

73RR

Wow! thanks for the tip (link) to the DeSoto roller lifter info.

I don't want to hijack this 270 Cam thread. Do you think this topic (early Hemi roller lifters) is worth a new thread? Did you read the thread on the Red Ram Build?

charlie

 

Get ahold of Hot Heads. They know everything. Otherwise you can get a new cam from Contreras cams. Bill

 

Did you check that part of the Hemi Tech Index?

 

All of the EarlyHemi engines use the same style lifter although there have been several part numbers used depending on the exact application. The generic 'VL-8' for example is a catch-all for just about everything from 51-58.
The late LA lifter, HT2011, is acceptable for most applications although it is not perfect. Also, keep in mind the difference in pushrod tips as it changed from 1/4" to 5/16" in 1967 to better serve the high performance engines then available.
The best lifter option right now is the Comp Cams pieces from the discounter on ebay.

As to rollers. once-upon-a-time, one of the manufacturers used a sliding link bar...would make the fitment issue a non-issue.

 

George, I did a shallow search of the Hemi Tech pages, but when I went to the link 73RR provided there was lots of info.

I'm not qualified to provide info for a new thread but I'm interested in the topic.

charlie

 

Good stuff. Have you set up an engine with the modern aftermarker rollers?

The articles I have read suggest that rollers lifters allow a more aggressive profile but still maintain a good flat torque curve. Is that your understanding?

charlie

 

Probably why a lot of us use the early 361-413 lifters, @ least in the Chr hemis, though they 2 aren't exactly the same. An adjustable bar would be the ticket!

 

Aren't roller cams steel?

 

Nice post! Thanks for the input. I knew the LA lifter were not all the same so I really needed this info. I was thinking about changing to a solid and having my rockers converted to adjustable but now I think I will just go with the LA lifters, have my cam reground and use adjustable push rods. I think for my budget that will be my best option.

 

Yes, flat tappets use cast that is why I think I'm going to stay with the flat tappet and have my cam reground. For me it's just a cost thing and I always try to do the most with what I already have.

With that being said if I have a complete set of magnum rollers, spider. I have a complete low mailage 5.2 that the block was damaged when the jeep was totaled. I bought it for the heads to put magnums on a 340 but then the guy wanted to use Eddy's so I still have the magnum.

If I could have my cam reground and use rollers on it I would go that way but it is my understanding that the rollers will eat up the cam.

 

New Hemi rollers will be billet, no clue what is used in brand 'x' engines.
In the 'old' days, cast rollers were offered by most of the big guys. I have two examples in the shop.
The 'wheel' doesn't really care what it is riding on.

You cannot grind a flat tappet cam into a roller profile...there simply is not enough lobe to start with.

.

 

OK I have been doing some more research on roller cams and have come up with some interesting info.

Billet vs treated cast camshaft

What I have read and been told by a powertrain engineer here at work is this. The billet will last thru almost anything except oil failure. High heat, sustained high rpm's, high spring pressure, high lift, the billet will do it all. But it is OK to run a heat treated cast iron roller cam if you are running a street engine with mild lift, lower spring pressure (less than 150 seat, 300 open) keep the oil pressure good and cooling good and it will last for 100,000 + miles. The engineer here at work told me the prototype engine run billet but the OEM cams are heat treated cast.

 

So even if he magnum roller will work in the Dodge Hemi a full custom cam is required?

 

OK I just got back to this, my wife has been sick and in the hospital for a 5 days and just got back home Sunday so been low key the last week or so. Anyway back to playing in the shop.

The issue with my 1955 270 Poly/Hemi long snout cam is it can't simply be shortened, drilled and tapped to use the LA timing gear. The cam snout is 1.00 and the LA gear is 1.06

I've been looking at the stock gear and my LA gear and I had a few ideas.
First if I just wanted to shorten the cam to eliminate the fuel pump cam and use a short timing cover, that could be done by:
1. Machine (shorten) the cam then drill and tap the center
2. Use the stock retainer (the pressed on part, not sure what its called) and use the stock timing gear.
3. Pull the round pin from the pump cam and shorten it to fit between the gear and retainer only.
4. Make a plate to hold the gear and pin in place against the retainer.

Then I was thinking if I want to run the LA gear I could try to machine the center out to the same size as the stock gear (1.625"). The LA gear will also have to be milled thinner in the center as the LA is 0.725" and the stock is 0.315". I have an old LA gear that I'm going to see if I can make it work. I'll take some pictures as I go.

 

My 241 is running what you are suggesting.

 

Sun

With a modified LA gear or just a short cam with a regular gear?

Thanks

 

Short cam regular gear to clear chevy water pump.

 

Here is a few pics of the modified LA gear. I machined 0.475 off the backside of the gear and opened the center from 1.06" to 1.615". Then had to drill the hole and pressed in the pin. All I have to do now is shorten up the pin on the front side and make a plate to bolt on the front.

One good thing about doing it this way is if someone wanted to leave the long snout and use the stock fuel pump cam you could do it.

 

The only drawback to modding the gears is...if you strip one away from home you're stuck vs modding the cam to where un modded off the shelf LA timing set could be put on by any shop.

 

You do have a point. Not sure how often this happens. I have broken all kinds of stuff but never a roller timing gear. Knock on wood I have skipped a gear on stock ones.

Now I'll have to keep the stock one in a safe place in case I need it in a hury. LOL

 

As wide as an OEM hemi chain is you'd think it would be hard to break, but a buddy had the fuel pump arm break on his stock 354 & it took out his timing chain!

 

That sucks. Did the pistons shake hands with the valves?

 

...or just make a couple more 'specials' while everything is still fresh...
They are small, don't take up much space, fairly cheap to buy.

.

 

No, lucked out on that.

That'd work!

 

These are factory Mopar gears. Even though only one center hub is listed in Leo's book, there are indeed two. The centers interchange in these gears for either short or long nose cams.

Also, any of the LA gears I have played with have the "windows" in a different location than the early hemi, so you must rotate the hub in order to have a place to put the drive pin. At that point, you will need to re-index the timing mark.

 

What years are these gears? I only have limited experiance with the Hemis but I have had 3 1955 270's and 1 1955 Plymouth Poly apart and have only seen the single belt type.

As far as the timing mark window on my LA gear above that was one of my concerns was the hole being in a window of the gear. So befor I even started cutting I set the LA gear on top of the Hemi gear and lined the timing makes up. The placement of the pin on my LA gear is in the same place a the Hemi and in the web not the window so I guess I got lucky.

Thanks for the info.

 

Double roller chains were used in some truck applications.

 

OK I was thinking they were standard and my stuff was oddballs. LOL

Do you know if they used bigger intake valves in the trucks for the 270 as well? I have a set of heads I took apart last night and the intakes are bigger than my two other sets of 270 heads. Maybe they are 315 or 325 heads someone put on a 270.

 

The roller chains are standard......for their application.

Check your cylinder head casting numbers.

 

Monc440 I have a set of 270 truck heads The intakes are the same as pass cars but the exhaust have hollow 7/16 stem valves.