Topic: tvt691 or ov691

[markiemark]

ok well my buddy wants to build a indian and we got to motors we looking at both same price and both run. ones a tvt691 and the others a ov691 which would be better off getting?? 

I was learning towards the ov691 since i think it has the 1/4 valve stems and that seem to be from what i read the best way to go.

[George Herrin]

I don't think the ov691 has the 1/4 stem valves. Not 100% sure but don't think so. Either can be converted to 1/4 inch with a little work on the heads. VKE Motorsports sells liners for the valve guides to convert to 1/4 valves. Use 17hp single carbs instead of stock ones.

[overkillphil]

I have two of of the OV691's here and when I spoke with a Tecumseh rep (before they got bought out and he probably got fired! ), he informed me that the main reason for the model number change was that Tec was now manufacturing these engines for the international market and in fact were making either some or all of these in (I believe) the former Czech Republic, or some eastern European country in that vicinity.

He made it sound like it was more of some internal standardization of model numbers and other features.  Who knows.  I had such a hard time getting ANY INFORMATION AT ALL that I was just grateful to speak to someone who actually knew they made small engines at all!  Good thing we have guys like George and Bert around...
FWIW

[George Herrin]

They only make one v-twin. 42 cubic inches. NOW the only differences are first generation had heads with 5/16 valve stems and stamped steel rockers and cast iron cams. The newer second generation motors have heads with 1/4 valves and a cast type rocker which will not hold up to raceing with good spring pressure and cast cams with a plastic cam gear. Carbs are all essentially the same I have seen a very late model with some tiny carbs smaller than usual. I have seen em rated from 17 to 25 hp but all are 42 cubes. Tins and sheet metal change alot depending on year made.

[rceagle1a]

I just got a white 1650lt mower with a tvt691 tec in it. It has 166 hours on it. What besides rods and a flywheel will this motor need to be competitive.

[George Herrin]

The TVT motors come with heads that have 5/16 stem valves. You should put 1/4 inch stem valves in them. EC sells stainless valves and the inserts to reduce the guides to 1/4 inch. USe EC dual springs and retainers shimmed to 1.25 install height. HEad work is the key to the hp in these motors (The porting and such). ARC rod and flywheel is mandatory, use the vanny twin coil wiring harness or reverse the diodes in the stock harness. CAM Precision Cams what can I say been using them for years. ISKY cams also has a great cam for the Indian. Call Bert he can set you up with that grind. Precision just tell Mike I sent ya. Block striaght bores and good ring seal. Carburetion... This is the most tricky part for those not familiar with twin carbs. FIRST do not use the stock carbs use the 17 or 17.5 carbs. Snyncing them is key. Down load the service manual for the twin and it will tell you how. OR email me And I will send it pdf. As for jetting each is different. Bert doesn't like my carb setups and I don't like his but both run well. Easiest order a set of built carbs from EC. Not cheap but they are the best ones out there in my opinion. They spent many hours getting mine to run like it needed and many laps on the track at the shop testing. Rockers the TVT has the stamped steel I have run them several years now and no problems I do wear them out but never broke one. Bert used to have a guy that made rollers not sure if he still does or not. I have a set of them and cannot tell you how many years I been running them now. Thats the basics and I been running and winning with the Indian for many years.

[berthyd]

The TVT motors come with heads that have 5/16 stem valves. You should put 1/4 inch stem valves in them. EC sells stainless valves and the inserts to reduce the guides to 1/4 inch. USe EC dual springs and retainers shimmed to 1.25 install height. HEad work is the key to the hp in these motors (The porting and such). ARC rod and flywheel is mandatory, use the vanny twin coil wiring harness or reverse the diodes in the stock harness. CAM Precision Cams what can I say been using them for years. ISKY cams also has a great cam for the Indian. Call Bert he can set you up with that grind. Precision just tell Mike I sent ya. Block striaght bores and good ring seal. Carburetion... This is the most tricky part for those not familiar with twin carbs. FIRST do not use the stock carbs use the 17 or 17.5 carbs. Snyncing them is key. Down load the service manual for the twin and it will tell you how. OR email me And I will send it pdf. As for jetting each is different. Bert doesn't like my carb setups and I don't like his but both run well. Easiest order a set of built carbs from EC. Not cheap but they are the best ones out there in my opinion. They spent many hours getting mine to run like it needed and many laps on the track at the shop testing. Rockers the TVT has the stamped steel I have run them several years now and no problems I do wear them out but never broke one. Bert used to have a guy that made rollers not sure if he still does or not. I have a set of them and cannot tell you how many years I been running them now. Thats the basics and I been running and winning with the Indian for many years.

Ah, I don't talk about cam grinds to anyone anymore.

Bert

[berthyd]

OK, Isky cam basics for any 691 V-twin:

Stock or near stock Engine- #3 grind. Good for 5000rpm

Billet rods and flywheel, 1/4" valve stems- #4 grind. Good for 6200rpm, but you will be breaking an occasional rocker or push rod.

Full out w/ roller rocker arms- #1 or #5 grinds. Both will go 7500rpm+. The 1 has more bottom, the 5 more top.

To fully utilize the big grinds, you need to have carbs done right and excellent heads. Also, exhaust must be right.

Bert

[birdman_express]

OK, Isky cam basics for any 691 V-twin:

Stock or near stock Engine- #3 grind. Good for 5000rpm

Billet rods and flywheel, 1/4" valve stems- #4 grind. Good for 6200rpm, but you will be breaking an occasional rocker or push rod.

Full out w/ roller rocker arms- #1 or #5 grinds. Both will go 7500rpm+. The 1 has more bottom, the 5 more top.

To fully utilize the big grinds, you need to have carbs done right and excellent heads. Also, exhaust must be right.

Bert

Somebody check Bert for temperature, I swear he has fallen ill.

Nice info there... 

[George Herrin]

Enjoy it thats the best ormost your gonna get from him.

[berthyd]

Enjoy it thats the best ormost your gonna get from him.

I may soon tell all. I may just give up on the TVT engines and start building single OHV B&S stuff 'cause I like fireworks.

Bert

[Jeff Digou (Pitguy)]

 

[Old Goat]

I may soon tell all. I may just give up on the TVT engines and start building single OHV B&S stuff 'cause I like fireworks.

Bert

Bert, I would be more than happy to test one out for you, when you get it ready!    If I can't break it you'll know you got it right! 

[birdman_express]

Bert, I would be more than happy to test one out for you, when you get it ready!    If I can't break it you'll know you got it right! 

And when he is done testing it, then let Ed drive it, cause he can break it. LOL

[twh3362]

markiemark  have a race ready tvt691 engine ready to bolt on and race bp class .